PROF. OKOTH SHEILA

Fermented food samples (n = 191) including maize gruel (ogi), sorghum gruel (ogi-baba), melon seed (ogiri), locust bean (iru) and African oil bean seed (ugba) from Southwest Nigeria were quantified for 23 mycotoxins, including aflatoxin B1 (AFB1), fumonisin B1 (FB1), and sterigmatocystin (STE) using liquid chromatography-tandem mass spectrometry. The practices, perceived understanding and health risks related to fungal and mycotoxin contamination amongst fermented food sellers was also established. Data obtained revealed that 82% of the samples had mycotoxins occurring singly or in combination. FB1 was present in 83% of ogi-baba samples, whereas 20% of ugba samples contained AFB1 (range: 3 to 36 µg/kg) and STE was present in 29% of the ogi samples. In terms of multi-mycotoxin contamination, FB1 + FB2 + FB3 + STE + AFB1 + alternariol + HT-2 co-occurred within one sample. The awareness study revealed that 98% of respondents were unaware of mycotoxin contamination, and their education level slightly correlated with their level of awareness (p < 0.01, r = 0.308). The extent to which the analyzed mycotoxins contaminated these food commodities, coupled with the poor perception of the population under study on fungi and mycotoxins, justifies the need to enact fungal and mycotoxin mitigation strategies along the food chain.

Fusarium verticillioides and Aspergillus
flavus cause Fusarium ear rot (FER) and Aspergillus
ear rot (AER) of maize, respectively. Both pathogens
are of concern to producers as they reduce grain yield
and affect quality. F. verticillioides and A. flavus also
contaminate maize grain with the mycotoxins fumonisins
and aflatoxins, respectively, which has been
associated with mycotoxicosis in humans and animals.
The occurrence of common resistance mechanisms to
FER and AER has been reported. Hence, ten Kenyan
inbred lines resistant to AER and aflatoxin accumulation
were evaluated for resistance to FER, F.
verticillioides colonisation and fumonisin accumulation;
and compared to nine South African lines
resistant to FER and fumonisin accumulation. Field
trials were conducted at three localities in South Africa
and two localities in Kenya. FER severity was
determined by visual assessment, while F. verticillioides
colonisation and fumonisin content were
quantified by real-time PCR and liquid chromatography
tandem mass spectrometry, respectively. Significant
genotype x environment interactions was
determined at each location (P B 0.05). Kenyan
inbred CML495 was most resistant to FER and F.
verticillioides colonisation, and accumulated the lowest
concentration of fumonisins across localities. It
was, however, not significantly more resistant than
Kenyan lines CML264 and CKL05015, and the South
African line RO549 W, which also exhibited low FER
severity (B5%), fungal target DNA (B0.025 ng lL-1
)
and fumonisin levels (B2.5 mg kg-1
). Inbred lines
resistant to AER and aflatoxin accumulation appear to
be promising sources of resistance to F. verticillioides
and fumonisin contamination.
Keywords Fusarium ear rot Aspergillus ear rot
Resistance Mycotoxins Maize inbred lines
In

This study was undertaken with an aim of exploring the effectiveness of medicinal plant extracts in the control of aflatoxin
production. Antifungal properties, photosensitization, and phytochemical composition of aqueous and organic extracts of fruits
fromSolanumaculeastrum, bark fromSyzygium cordatum, and leaves from Prunus africana, Ocimum lamiifolium, Lippia kituiensis,
and Spinacia oleracea were tested. Spores from four-day-old cultures of previously identified toxigenic fungi, UONV017 and
UONV003, were used. Disc diffusion and broth dilution methods were used to test the antifungal activity. The spores were
suspended in 2ml of each extract separately and treated with visible light (420 nm) for varying periods. Organic extracts displayed
species and concentration dependent antifungal activity. Solanum aculeastrum had the highest zones of inhibition diameters in
both strains: UONV017 (mean = 18.50 ± 0.71 mm) and UONV003 (mean = 11.92 ± 0.94 mm) at 600mg/ml. Aqueous extracts
had no antifungal activity because all diameters were below 8 mm. Solanum aculeastrum had the lowest minimum inhibitory
concentration at 25mg/ml against A. flavusUONV017.All the plant extracts in combinationwith light reduced the viability of fungal
conidia compared with the controls without light, without extracts, and without both extracts and light. Six bioactive compounds
were analyzed in the plant extracts. Medicinal plant extracts in this study can control conidia viability and hence with further
development can control toxigenic fungal spread.

ABSTRACT
Aflatoxin, a carcinogenic toxin, is produced mainly by Aspergillus flavus and Aspergillus parasiticus. Contamination of maize (Zea mays L.) grain by these fungi occurs before harvest, and the easiest strategy to prevent this is to develop/use maize varieties resistant to Aspergillus spp. and aflatoxin accumulation. The objective of this investigation was to identify potential sources of resistance among 23 maize inbred lines (13 obtained from the MAIZE Competitive Grants Initiative, International Maize and Wheat Improvement Centre and 10 from Agricultural Research Council, South Africa). The inbred lines were planted in a randomized complete-block design at two locations each in Kenya and South Africa. Maize ears were inoculated at silking with three toxigenic strains of A. flavus. The inoculated ears in each plot were harvested at 12–18% moisture, dried, and visually assessed for Aspergillus ear rot (AER). Aflatoxin concentration in the kernels was determined using liquid chromatography–tandem mass spectrometry. Significant variation for both AER and aflatoxin concentration existed among the inbred lines at both locations in Kenya and one location in South Africa. Combined analysis revealed a significant (p < 0.001) lines × locations interaction for both AER and aflatoxin concentration. Higher incidences of AER (0–86.0%) and aflatoxin concentration (0.21–6.51 µg/kg) were recorded at Kiboko in Kenya than at the other three locations. A stronger genetic correlation (rG = 0.936, p < 0.0001) between the AER and aflatoxin concentration was recorded in Potchefstroom than at the other three locations. Repeatability of aflatoxin concentration was high at Kiboko (0.87) and Potchefstroom in South Africa (0.74). Three inbred lines, CML247, CML444, and CML495, emerged as potentially useful sources of resistance to AER and aflatoxin accumulation as they showed low levels of aflatoxin contamination in both localities in Kenya and in South Africa.

Most Plasmodium falciparum-detecting rapid diagnostic tests (RDTs) target histidine-rich
protein 2 (PfHRP2). However, P. falciparumisolates with deletion of the pfhrp2 gene and its
homolog gene, pfhrp3, have been detected. We carried out an extensive investigation on
365 P. falciparumdried blood samples collected from seven P. falciparumendemic sites in
Colombia between 2003 and 2012 to genetically characterise and geographically map
pfhrp2- and/or pfhrp3-negative P. falciparumparasites in the country. We found a high proportion
of pfhrp2-negative parasites only in Amazonas (15/39; 38.5%), and these parasites
were also pfhrp3-negative. These parasites were collected between 2008 and 2009 in
Amazonas, while pfhrp3-negative parasites (157/365, 43%) were found in all the sites and
from each of the sample collection years evaluated (2003 to 2012). We also found that all
pfhrp2- and/or pfhrp3-negative parasites were also negative for one or both flanking genes.
Six sub-population clusters were established with 93.3% (14/15) of the pfhrp2-negative
parasites grouped in the same cluster and sharing the same haplotype. This haplotype
corresponded with the genetic lineage BV1, a multidrug resistant strain that caused two outbreaks
reportedin Peru between 2010 and 2013. We found this BV1 lineage in the Colombian
Amazon as early as 2006. Two new clonal lineages were identified in these parasites
from Colombia: the genetic lineages EV1 and F. PfHRP2 sequence analysis revealed high
genetic diversity at the amino acid level, with 17 unique sequences identified among 53
PfHRP2 sequences analysed. The use of PfHRP2-based RDTs is not recommended in
Amazonas because of the high proportionof parasites with pfhrp2 deletion (38.5%), and
implementation of new strategies for malaria diagnosis and control in Amazonas must be
prioritised.Moreover, studies to monitor and genetically characterise pfhrp2-negative P. falciparumparasites in the Americas are warranted, given the extensive human migration
occurring in the region.

More than 80% of available malaria rapid diagnostic tests (RDTs) are based on the detection of histidine-rich protein-2 (PfHRP2) for diagnosis of Plasmodium falciparum malaria. Recent studies have shown the genes that code for this protein and its paralog, histidine-rich protein-3 (PfHRP3), are absent in parasites from the Peruvian Amazon Basin. Lack of PfHRP2 protein through deletion of the pfhrp2 gene leads to false-negative RDT results for P. falciparum. We have evaluated the extent of pfhrp2 and pfhrp3 gene deletions in a convenience sample of 198 isolates from six sites in three states across the Brazilian Amazon Basin (Acre, Rondonia and Para) and 25 isolates from two sites in Bolivia collected at different times between 2010 and 2012. Pfhrp2 and pfhrp3 gene and their flanking genes on chromosomes 7 and 13, respectively, were amplified from 198 blood specimens collected in Brazil. In Brazil, the isolates collected in Acre state, located in the western part of the Brazilian Amazon, had the highest percentage of deletions for pfhrp2 25 (31.2%) of 79, while among those collected in Rondonia, the prevalence of pfhrp2 gene deletion was only 3.3% (2 out of 60 patients). In isolates from Para state, all parasites were pfhrp2-positive. In contrast, we detected high proportions of isolates from all 3 states that were pfhrp3-negative ranging from 18.3% (11 out of 60 samples) to 50.9% (30 out of 59 samples). In Bolivia, only one of 25 samples (4%) tested had deleted pfhrp2 gene, while 68% (17 out of 25 samples) were pfhrp3-negative. Among the isolates tested, P. falciparum pfhrp2 gene deletions were present mainly in those from Acre State in the Brazilian Amazon. These results indicate it is important to reconsider the use of PfHRP2-based RDTs in the western region of the Brazilian Amazon and to implement appropriate surveillance systems to monitor pfhrp2 gene deletions in this and other parts of the Amazon region.

In Suriname, an artesunate monotherapy therapeutic efficacy trial was recently conducted to evaluate partial artemisinin resistance emerging in Plasmodium falciparum. We genotyped the PfK13 propeller domain of P. falciparum in forty samples as well as other mutations proposed to be associated with artemisinin resistant mutants. We did not find any mutations previously associated with artemisinin resistance in Southeast Asia but we found fixed resistance mutations for chloroquine and sulfadoxine-pyrimethamine. Additionally, the Pfcrt C350R mutation, associated with reversal of CQ resistance and piperaquine selective pressure was present in 62% of the samples. Our results from neutral microsatellite data also confirmed a high parasite gene flow in the Guiana Shield. Although recruiting participants for therapeutic efficacy studies in very low malaria endemic areas is challenging due to the low number of malaria cases reported, conducting these studies along with molecular surveillance remains essential to monitor artemisinin resistant alleles and to characterize the population structure P. falciparum in areas targeting malaria elimination.

A total of 52 samples of finished fish feeds and ingredients were collected from smallholder farmers in
Kenya, Tanzania, Rwanda and Uganda, and analyzed. Culture and molecular techniques were used to
identify fungal isolates from the feedstock, and mycotoxin profiles were determined using liquid chromatography–tandem
mass spectrometry. The most prevalent fungal species recovered in the samples
was Asperigillus flavus (54.5%). Other fungal species recovered from the samples were Aspergillus tamarii
(9.1%), Mucor velutinosus (9%), Phoma sp. (6.1%), Aspergillus niger (6%), Eurotium rubrum (3%) and
Penicillium chrysogenum (3%). Fourteen mycotoxins were identified: aflatoxins B1, B2, G1 and G2, fumonisin
B1 and B3, deoxynivalenol (DON) and acetyldeoxynivalenol (sum of 3-ADONand 15-ADON), ochratoxin
A, roquefortine C, alternariol, T-2 toxin, and nivalenol. DON (92.9%), aflatoxins (64.3%) and
fumonisins (57.1%) were the most prevalent within locally manufactured feeds, while no contamination
was found in imported feed. Samples from Kenya were the most contaminated with aflatoxin (maximum
806.9 lg
kg1
). The high levels of aflatoxin and trichothecene type A and B contamination found in this
study point to potential risks to fish performance and to the health of consumers of the fish and derived
products.

A 24-week feeding experiment was conducted to assess whether males and females of Oreochromis niloticus exhibit differences in
their hematological responses and organosomatic indices to dietary AFB1 contamination. Triplicate groups of O. niloticus (initial
body weight: 24.1 ± 0.6 g) were fed with four diets (Diets 1 to 4) containing 0, 20, 200, and 2,000

Groundnut is one of the staple foods in many parts of the world. Due to its high nutrient content, the nuts are liable to colonization by aflatoxigenic fungi and subsequent aflatoxin accumulation. This study was aimed at determining susceptibility of locally grown groundnut varieties to Aspergillus flavus in Homa Bay County, Western Kenya. A pretested questionnaire was used to survey agronomic practices on groundnut cultivation in 75 randomly selected households in the study site. From each household farm, 100 g soil samples and 500 g of groundnuts were collected at harvest and A. flavus isolated on Modified Rose-Bengal Agar and identified. Aflatoxin was then extracted from each of the groundnut samples and quantified using direct competitive enzyme linked immunosorbent assay (ELISA). Red Valencia was the most cultivated among the 8 varieties identified. Farmers (66%) obtained the planting seeds from the local market and most (92%) did not use fertilizers with majority (94%) having no knowledge of aflatoxins. There was no significant inter-variety difference in aflatoxin accumulation (p=0.744, F=0.581, Df=6, 61). A highly significant association (t = 2.652; P = 0.010) was found between storage state of the groundnuts and aflatoxin levels, with 94% of the samples stored unshelled having aflatoxin levels below 10 ppb. Overall, only 6.7% of kernels sampled from all the divisions did not meet the EC aflatoxin limit of ≤4 ppb while 4% did not meet the KEBS limit of ≤10 ppb. Though the agronomic practices were poor, aflatoxin levels were predominantly low in the region suggesting that the aflatoxin accumulation is likely influenced by agro-ecological zoning as other studies have also been indicated.

Key words: Groundnuts, Aflatoxins, Aspergillus flavus.

Soil fungi are important components of the soil biota and their diversity is a good indicator of soil
health. Soil fungi respond differently to land use practices and to their relative populations. The cooccurrence
and diversity of Trichoderma and Fusarium species against various land use types
(LUTs) was investigated. The genus Trichoderma contains many important species with potential
for biocontrol of soil-borne plant pathogens as well as high saprophytic capacity while the genus
Fusarium has many species that are highly pathogenic to plants and with potential for mycotoxin
production. This research adopted a cross-sectional study design. Soil samples were collected
from 3 land-use types (LUTs) in Kabaa irrigation scheme in Machakos County, Kenya, that is,
intensive land-uses under irrigation and rain-fed agriculture and undisturbed lands. From the top
soil layer, 100 soil samples were collected. The samples were processed and 369 Trichoderma and 1,546 Fusarium isolates recovered. Fusarium had a higher abundance than Trichoderma in
the highly disturbed lands. In the undisturbed lands, Trichoderma had a higher abundance than
Fusarium. There was a clear negative correlation between Trichoderma and Fusarium occurrence
and diversity. The study further revealed that disturbance had a positive effect on Fusarium but a
negative one on Trichoderma.

We evaluated the efficacy of chloroquine and primaquine on uncomplicated Plasmodium vivax malaria
in Cruzeiro do Sul, Brazil, in 2014. Patients ≥ 5 years of age with either fever or history of fever, and laboratoryconfirmed
P. vivax monoinfection received chloroquine (total dose = 25 mg/kg) and primaquine (total dose = 3.5 mg/kg),
and were followed up for 168 days (24 weeks). We used microsatellite genotyping to differentiate recurrent infections
caused by heterologous parasites from those caused by homologous ones. No new P. vivax episode occurred by Day 28
among 119 enrolled patients, leading to Day 28, with adequate clinical and parasitological response (ACPR) of 100%
(95% confidence interval [CI] = 96.7–100%). Twenty-eight P. vivax episodes occurred by Day 168, with uncorrected
ACPR of 69.9% (95% CI = 59.5–79.0%). Fifteen of these episodes were caused by either homologous haplotypes
or haplotypes that could not be determined. Excluding the 13 recurrent episodes caused by heterologous parasites,
Day 168 microsatellite-corrected ACPR was estimated at 81.2% (95% CI = 71.0–89.1%). Chloroquine and primaquine
remain efficacious to tr

Most Plasmodium falciparum-detecting rapid diagnostic tests (RDTs) target histidine-rich
protein 2 (PfHRP2). However, P. falciparumisolates with deletion of the pfhrp2 gene and its
homolog gene, pfhrp3, have been detected. We carried out an extensive investigation on
365 P. falciparumdried blood samples collected from seven P. falciparumendemic sites in
Colombia between 2003 and 2012 to genetically characterise and geographically map
pfhrp2- and/or pfhrp3-negative P. falciparumparasites in the country. We found a high proportion
of pfhrp2-negative parasites only in Amazonas (15/39; 38.5%), and these parasites
were also pfhrp3-negative. These parasites were collected between 2008 and 2009 in
Amazonas, while pfhrp3-negative parasites (157/365, 43%) were found in all the sites and
from each of the sample collection years evaluated (2003 to 2012). We also found that all
pfhrp2- and/or pfhrp3-negative parasites were also negative for one or both flanking genes.
Six sub-population clusters were established with 93.3% (14/15) of the pfhrp2-negative
parasites grouped in the same cluster and sharing the same haplotype. This haplotype
corresponded with the genetic lineage BV1, a multidrug resistant strain that caused two outbreaks
reportedin Peru between 2010 and 2013. We found this BV1 lineage in the Colombian
Amazon as early as 2006. Two new clonal lineages were identified in these parasites
from Colombia: the genetic lineages EV1 and F. PfHRP2 sequence analysis revealed high
genetic diversity at the amino acid level, with 17 unique sequences identified among 53
PfHRP2 sequences analysed. The use of PfHRP2-based RDTs is not recommended in
Amazonas because of the high proportionof parasites with pfhrp2 deletion (38.5%), and
implementation of new strategies for malaria diagnosis and control in Amazonas must be
prioritised.Moreover, studies to monitor and genetically characterise pfhrp2-negative P. falciparumparasites in the Americas are warranted, given the extensive human migration
occurring in the region.

Transmission intensity, movement of human and vector hosts, biogeographical features, and malaria control measures are some of the important factors that determine Plasmodium falciparum parasite genetic variability and population structure. Kenya has different malaria ecologies which might require different disease intervention methods. Refined parasite population genetic studies are critical for informing malaria control and elimination strategies. This study describes the genetic diversity and population structure of P. falciparum parasites from the different malaria ecological zones in Kenya. Twelve multi-locus microsatellite (MS) loci previously described were genotyped in 225 P. falciparum isolates collected between 2012 and 2013 from five sites; three in lowland endemic regions (Kisumu, Kombewa, and Malindi) and two in highland, epidemic regions (Kisii and Kericho). Parasites from the lowland endemic and highland epidemic regions of western Kenya had high genetic diversity compared to coastal lowland endemic region of Kenya [Malindi]. The Kenyan parasites had a mean genetic differentiation index (FST) of 0.072 (p = 0.011). The multi-locus genetic analysis of the 12 MS revealed all the parasites had unique haplotypes. Significant linkage disequilibrium (LD) was observed in all the five parasite populations. Kisumu had the most significant index of association values (0.16; p < 0.0001) whereas Kisii had the least significant index of association values (0.03; p < 0.0001). Our data suggest high genetic diversity in Kenyan parasite population with the exception of parasite from Malindi where malaria has been on the decline. The presence of significant LD suggests that there is occurrence of inbreeding in the parasite population. Parasite populations from Kisii showed the strongest evidence for epidemic population structure whereas the rest of the regions showed panmixia. Defining the genetic diversity of the parasites in different ecological regions of Kenya after introduction of the artemether–lumefantrine is important in refining the spread of drug resistant strains and malaria transmission for more effective control and eventual elimination of malaria in Kenya.

n November 2013, a Plasmodium falciparum malaria outbreak of 11 cases occurred in Cusco, southern Peru, where falciparum malaria had not been reported since 1946. Although initial microscopic diagnosis reported only Plasmodium vivax infection in each of the specimens, subsequent examination by the national reference laboratory confirmed P. falciparum infection in all samples. Molecular typing of four available isolates revealed identity as the B-variant (BV1) strain that was responsible for a malaria outbreak in Tumbes, northern Peru, between 2010 and 2012. The P. falciparum BV1 strain is multidrug resistant, can escape detection by PfHRP2-based rapid diagnostic tests, and has contributed to two malaria outbreaks in Peru. This investigation highlights the importance of accurate species diagnosis given the potential for P. falciparum to be reintroduced to regions where it may have been absent. Similar molecular epidemiological investigations can track the probable source(s) of outbreak parasite strains for malaria surveillance and control purposes.

Plasmodium vivax recurrences help maintain malaria transmission. They are caused by recrudescence, reinfection, or relapse, which are not easily differentiated. A longitudinal observational study took place in Turbo municipality, Colombia. Participants with uncomplicated P. vivax infection received supervised treatment concomitantly with 25 mg/kg chloroquine and 0.25 mg/kg/day primaquine for 14 days. Incidence of recurrence was assessed over 180 days. Samples were genotyped, and origins of recurrences were established. A total of 134 participants were enrolled between February 2012 and July 2013, and 87 were followed for 180 days, during which 29 recurrences were detected. The cumulative incidence of first recurrence was 24.1% (21/87) (95% confidence interval [CI], 14.6 to 33.7%), and 86% (18/21) of these events occurred between days 51 and 110. High genetic diversity of P. vivax strains was found, and 12.5% (16/128) of the infections were polyclonal. Among detected recurrences, 93.1% (27/29) of strains were genotyped as genetically identical to the strain from the previous infection episode, and 65.5% (19/29) of infections were classified as relapses. Our results indicate that there is a high incidence of P. vivax malaria recurrence after treatment in Turbo municipality, Colombia, and that a large majority of these episodes are likely relapses from the previous infection. We attribute this to the primaquine regimen currently used in Colombia, which may be insufficient to eliminate hypnozoites.

We studied the relationship between sclerotia formation and aflatoxin production by Aspergillusflavus
strains isolated from maize kernels from Nandi County. Isolates recovered from maize kernels
were tested for their ability to form sclerotia on different growth media. PCR analysis was
done on the isolates to detect 2 structural genes, aflD and aflQ, involved in aflatoxin biosynthesis
pathway. Positive A. flavus isolates for one or both genes were grown on Yeast Extract Sucrose
Agar medium and aflatoxins quantified using LCMSMS. All the isolates formed large sclerotia and
their formation was influenced by media type but could not be related to amount of aflatoxins
produced both in vivo and in vitro. Though sclerotia are perennating structures and so contribute
to survival index of a fungus, their initiation is regulated by external factors though ability to form
is genetic. This brings ambiguity of their presence or abundance as a measure of toxicity.

Application of Fungi for effective removal of hydrocarbon contamination from soil is being considered as the better option when it comes to biodegradation. Other method like physical and chemical bioremediation leads to production of toxic compounds and these methods are not cost effective. In the present study, soil samples from four different oil contaminated soils were assessed for any recovery of fungi present. Cultural characterization was used as preliminary identification using keys. Initial isolation from the oil contaminated soil was done using potato dextrose agar. Colonies were observed and characterized morphologically. The isolates were grown at varied temperatures and pH. Eight fungal isolates were recovered from polluted soils namely, Trichoderma viride, Trichoderma spirale, Neosartorya pseudofischeri, Neosartorya aureola, Aspergillus flavus, Aspergillus terreus, Penicillium griseofulvum and Trichoderma longibrachiatum. The optimum growth temperature range for the eight fungi was 30 o C and 40 o C. There was no growth at 50 o C for all isolates except some slight growth by Aspergillus flavus. Optimum growth at pH 7 and pH 9 and poor growth at pH 5 was noted. This study will contribute to the database on locally available fungal diversity and their ecology.

Several interrelated and site-specific agronomic factors ranging from agroecological conditions to systems management practices have been shown to variably affect arbuscular mycorrhizal fungi (AMF) diversity in the soil. Also, there have been various attempts in the past to evaluate the potential of AMF field inoculation but a majority focussed on the use of exotic strains, disregarding the potential of the existing naturally occurring strains. In an attempt to address these problems, our study aimed to develop ‘best-bet practice’ based on soil fertility amendment practice (SFAP) that encourages occurrence and diversity of AMF in the soil. Control treatment (no application) was compared with three (3) SFAP used singly or in combination with AMF or two other soil nutrients enhancing organisms (Bacillus and Trichoderma) which included the following: (1) Mavuno (macro- and micronutrients and secondary nutrients) fertilizer, (2) calcium ammonium nitrate (CAN) plus triple super phosphate (TSP) and (3) cattle manure. Maize (Zea mays L.) and common bean (Phaseoli vulgaris L.) were planted at on-station and on-farm plots for two consecutive cropping seasons with the experiment replicated in two benchmark sites of Embu and Taita-Taveta Districts. Embu site recorded a lower soil pH and also very low phosphorus levels compared to Taita site. The number of AMF spores per kg of soil was very low, ranging from 30 to 100, at Embu in the first season and application of SFAP resulted in no significant difference. However, in the second season, use of Trichoderma + CAN plus TSP was shown to significantly stimulate AMF species in the soil, with a 250 % increase in species density compared to use of Bacillus + Manure. At Taita, after the first cropping season, significant change in spore density was only recorded from AMF applied singly with a 66.1 % increase in spore density compared to Control treatment. In comparison, after the second cropping season, use of AMF applied singly, AMF + CAN plus TSP and AMF + Manure increased spore density by 135.4, 109.6 and 100 % respectively compared to Control treatment. Use of AMF applied singly increased species density in the soil by 100 and 81.1 % compared to CAN plus TSP and Trichoderma treatments respectively after first season at Taita site: while after the second cropping season, application of AMF + CAN plus TSP, AMF + Manure and AMF + Mavuno increased AMF species density in the soil by 60.3, 51.5 and 55.9 % respectively compared to Control treatment. These findings provide evidence that it is possible to increase the number of AMF spores in the soil through inoculation with native species and also possibly stimulate dormant species through other SFAP treatments.

Keywords

Arbuscular mycorrhizae fungi Soil fertility amendment practices Native species Spore density Species density AMF inoculation

Abstract
Background: Determining the source of malaria outbreaks in Ecuador and identifying remaining transmission
foci will help in malaria elimination efforts. In this study, the genetic signatures of Plasmodium falciparum isolates,
obtained from an outbreak that occurred in northwest Ecuador from 2012 to 2013, were characterized.
Methods: Molecular investigation of the outbreak was performed using neutral microsatellites, drug resistance markers
and pfhrp2 and pfhrp3 genotyping.
Results: A majority of parasite isolates (31/32) from this outbreak were of a single clonal type that matched a clonal
lineage previously described on the northern coast of Peru and a historical isolate from Ecuador. All but one isolate
carried a chloroquine-resistant pfcrt genotype and sulfadoxine- and pyrimethamine-sensitive pfdhps and pfdhfr genotypes.
Pfmdr1 mutations were identified in codons 184 and 1042. In addition, most samples (97 %) showed presence
of pfhrp2 gene.
Conclusions: This study indicates that parasites from a single clonal lineage largely contributed to this outbreak and
this lineage was found to be genetically related to a lineage previously reported in the Peruvian coast and historical
Ecuadorian parasites.
Keywords: Plasmodium falciparum, Malaria, Ecuador, Outbreak, Microsatellite markers

Aim: This study was undertaken in order to determine the effect of land-use intensification on
occurrence, distribution, and diversity of Trichoderma fungus.
Study Design: Cross-sectional study.
Place and Distribution of Study: Mycology Laboratory, University of Nairobi between March and
September, 2014.
Methodology: Soil samples were collected from both Mwala and Kauti irrigation blocks in Kabaa
irrigation scheme of Machakos County, in Kenya under three land use types (LUTs): intensively
cultivated farmlands under irrigation, rainfed intensively cultivated farmlands and undisturbed lands.
A total of 100 soil samples were obtained from the top 0- 20 cm depth. Trichoderma species were
isolated using the dilution plate technique using Trichoderma-selective media (TSM).
Results: A total of 369 Trichoderma isolates were recovered from the three LUTs. These were
identified and classified into eleven species. The species identified were: T. harzianum, T. koningii, T. viride, T. asperellum, T. atroviride, T. spirale, T. virens, T. tomentosum, T. brevicompactum, T.
crassum and T. hamatum. The most abundant Trichoderma species was T. harzianum with a
frequency of isolation of 38.87%, followed by T. koningii and T. viride at 18.03 and 15.49%,
respectively. Trichoderma hamatum had the least isolation frequency at 0.41%. T. harzianum also
had the widest distribution. The difference in abundance of Trichoderma in the three LUTs was
significant (P=0.05). The undisturbed lands had a higher abundance of Trichoderma compared to
the disturbed areas. Mwala irrigation block A had the least abundance while block D which is more
recent in cultivation had highest mean abundance of Trichoderma. Difference in Trichoderma
species mean richness between LUTs was not significant (P=0.203). Undisturbed lands had the
highest richness. Undisturbed lands also had the highest diversity while irrigated lands were the
least diverse
Conclusion: Enhanced land-use intensification lowers the abundance and diversity of Trichoderma
in the soil.

Land-use intensification has a significant influence on occurrence of soil microorganisms. The effect of this phenomenon on Fusarium species is poorly characterized. One hundred soil samples were obtained from 3 replicated land- use types (LUT) in Mwala and Kauti irrigation regions in Machakos County. These included two intensive land-uses under irrigation and rain-fed agriculture and undisturbed lands. Mwala irrigated lands were divided into four blocks based on history of cultivation. Using soil dilution plate technique, 1,546 isolates of Fusarium were recovered and identified into twelve species namely; F. oxysporum, F. solani, F. nygamai, F. equiseti, F. chlamydosporum, F. beomiforme, F. verticillioides, F. proliferatum, F. acuminatum, F. compactum, F. semitectum, and F. merismoides. Fusarium oxysporum was the most abundant and diverse Fusarium species. Fusarium semitectum, F. compactum and F .merismoides had the least distribution being isolated from only one LUT. Fusarium beomiforme and F. acuminatum were recovered from irrigated farmlands only while F. verticillioides, F. proliferatum and F. acuminatum were restricted to disturbed lands only. The difference in abundance of Fusarium between the three LUTs was significant (P = 0.047) with irrigated lands having the highest abundance. Mwala block A had the highest abundance, richness and diversity of Fusarium. Lands with a higher intensity of disturbance had a higher abundance and richness of Fusarium than the less undisturbed lands. This may have severe implication on crop production as most species of Fusarium isolated are pathogenic. Sustainable ways of controlling these potential crop pathogens should be sought.

The aim of this study was to identify Aspergillus species isolated from maize kernels and soils of
maize fields of Nandi County using macro and micro morphological characteristics. A cross sectional
research design was used in the study and purposive sampling was employed to determine
districts of Nandi County and sub locations where sampling was done. This study was part of a
larger project whose aim was to survey aflatoxin exposure in the maize value chain. Aspergillus
species were isolated from maize and soil samples using quarter strength potato dextrose agar
and modified Rose Bengal agar respectively. Pure cultures of the isolates were sub cultured and
transferred onto differential media; malt extract agar, czapek yeast extract agar and czapek dox
agar for species identification using macro morphological characteristics. Fungal slides were prepared
from pure cultures on potato dextrose agar media after three days to identify micro morphological
characteristics. Based on morphological characteristics, seven sections of Aspergillus
namely: Flavi, Fumigati, Nigri, Circumdati, Clavati, Nidulantes and Candidi were identified. Aspergillus
section Flavi was the most predominant with 57% followed by section Nigri with 27% from
maize and 58% of section Flavi followed by 26% of section Nigri from the soil across the three locations.
Aspergillus sections Nidulantes and Candidi were rare and only recovered from the soil
samples of Kaptumo location. All the Aspergillius flavus that formed sclerotia both from the soils
or maize kernels were of the L strains. In conclusion Aspergillus section Flavi was most frequent
during the isolation process and dominated with Aspergillus flavus from both the maize and soil.
Morphological characteristics remain the primary tool for detection and identification of Aspergillus
species. The significance for high incidence of Aspergillus section Flavi is in regard to their
aflatoxin production profiles that poses a health threat to the community and it is of public health
concern. Morphological characteristics as a primary tool for Aspergillus identification should be
embraced and more personnel with the knowledge are required since modern and faster techniques
are scarce and expensive.

Malaria control is hindered by the evolution and spread of resistance to antimalarials, necessitating multiple changes to drug
policies over time. A comprehensive antimalarial drug resistance surveillance program is vital for detecting the potential emergence
of resistance to antimalarials, including current artemisinin-based combination therapies. An antimalarial drug resistance
surveillance study involving 203 Plasmodium falciparum malaria-positive children was conducted in western Kenya between
2010 and 2013. Specimens from enrolled children were analyzed in vitro for sensitivity to chloroquine (CQ), amodiaquine (AQ),
mefloquine (MQ), lumefantrine, and artemisinin derivatives (artesunate and dihydroartemisinin) and for drug resistance allele
polymorphisms in P. falciparum crt (Pfcrt), Pfmdr-1, and the K13 propeller domain (K13). We observed a significant increase in
the proportion of samples with the Pfcrt wild-type (CVMNK) genotype, from 61.2% in 2010 to 93.0% in 2013 (P<0.0001), and
higher proportions of parasites with elevated sensitivity to CQ in vitro. The majority of isolates harbored the wild-type N allele
in Pfmdr-1 codon 86 (93.5%), with only 7 (3.50%) samples with the N86Y mutant allele (the mutant nucleotide is underlined).
Likewise, most isolates harbored the wild-type Pfmdr-1 D1246 allele (79.8%), with only 12 (6.38%) specimens with the D1246Y
mutant allele and 26 (13.8%) with mixed alleles. All the samples had a single copy of the Pfmdr-1 gene (mean of 0.9070.141
copies). None of the sequenced parasites had mutations in K13. Our results suggest that artemisinin is likely to remain highly
efficacious and that CQ sensitivity appears to be on the rise in western Kenya.

Suspected artemisinin resistance in Plasmodium falciparum can be explored by examining polymorphisms in the Kelch (PfK13) propeller domain. Sequencing of PfK13 and other gene resistance markers was performed on 98 samples from Guyana. Five of these samples carried the C580Y allele in the PfK13 propeller domain, with flanking microsatellite profiles different from those observed in Southeast Asia. These molecular data demonstrate independent emergence of the C580Y K13 mutant allele in Guyana, where resistance alleles to previously used drugs are fixed. Therefore, in Guyana and neighboring countries, continued molecular surveillance and periodic assessment of the therapeutic efficacy of artemisinin-based combination therapy are warranted.

During 2010–2012, an outbreak of 210 cases of malaria occurred in Tumbes, in the northern coast of Peru, where no Plasmodium falciparum malaria case had been reported since 2006. To identify the source of the parasite causing this outbreak, we conducted a molecular epidemiology investigation. Microsatellite typing showed an identical genotype in all 54 available isolates. This genotype was also identical to that of parasites isolated in 2010 in the Loreto region of the Peruvian Amazon and closely related to clonet B, a parasite lineage previously reported in the Amazon during 1998–2000. These findings are consistent with travel history of index case-patients. DNA sequencing revealed mutations in the Pfdhfr, Pfdhps, Pfcrt, and Pfmdr1 loci, which are strongly associated with resistance to chloroquine and sulfadoxine/pyrimethamine, and deletion of the Pfhrp2 gene. These results highlight the need for timely molecular epidemiology investigations to trace the parasite source during malaria reintroduction events.

Keywords: Falciparum malaria, Plasmodium, Peru, microsatellite markers, parasites, malaria, Peru

The impact of microbiological commercial products (PHC Biopak, Rhizatech and ECO-T) on
the occurrence of mycorrhizae and Fusarium in the rhizosphere of tissue culture banana
(Gros Mitchel cv.) was assessed. Tissue cultured banana plantlets were inoculated with PHC
Biopak (Bacillus), Rhizatech (mycorrhiza) and ECO-T (T. harzianum) under greenhouse conditions
using a completely randomized design in a Vertisol, Rhodic Ferralsol and Humic Nitisol sampled
from the major banana growing regions in Kenya. Potted plants were later established under field
conditions in the three agro ecological zones. Roots and soils sampled at end of potting and at
flowering were assessed for AM fungi colonization and Fusarium populations. The effect of product
inoculation on AM fungi colonization varied and only significant (p<0.05) in Rhodic Ferralsol with
Rhizatech increasing intensity of colonization by 31.9% and PHC Biopak increasing the frequency
of colonization by 38.6% compared to the non-inoculated control (12.9%). F. oxysporum, fsp. cubense,
F. proliferatum and F. incarnatum were recovered from the experimental soils. Foc was the most
abundant in the three soils (prior to inoculation) accounting for 60.6% of all Fusarium colony
forming units. After inoculation, at the end of potting stage and at flowering, F. proliferatum was
mostly isolated from the three zones accounting for 35.2% of the total fungal population. Foc was
isolated from Humic Nitisol and Vertisol accounting for 11.5% of the total fungal population. PHC
Biopak, ECO-T and Rhizatech suppressed Foc colony forming units per gram of soil by 47, 68 and
55%, respectively in the Humic Nitisol. ECO-T reduced Fusarium colony forming units per gram
of soil by 6% in Rhodic Ferralsol and PHC Biopak by 50% in Vertisol compared to the
non-inoculated soils. There is potential in use of commercial microbiological products to suppress
Foc and the efficacy of the products depends on soil physico-chemical properties.
Key words: Tissue culture banana, Trichoderma

Background: Recent studies have demonstrated the deletion of the histidine-rich protein 2 (PfHRP2) gene (pfhrp2)
in field isolates of Plasmodium falciparum, which could result in false negative test results when PfHRP2-based rapid
diagnostic tests (RDTs) are used for malaria diagnosis. Although primary diagnosis of malaria in Honduras is
determined based on microscopy, RDTs may be useful in remote areas. In this study, it was investigated whether
there are deletions of the pfhrp2, pfhrp3 and their respective flanking genes in 68 P. falciparum parasite isolates
collected from the city of Puerto Lempira, Honduras. In addition, further investigation considered the possible
correlation between parasite population structure and the distribution of these gene deletions by genotyping
seven neutral microsatellites.
Methods: Sixty-eight samples used in this study, which were obtained from a previous chloroquine efficacy
study, were utilized in the analysis. All samples were genotyped for pfhrp2, pfhrp3 and flanking genes by PCR.
The samples were then genotyped for seven neutral microsatellites in order to determine the parasite
population structure in Puerto Lempira at the time of sample collection.
Results: It was found that all samples were positive for pfhrp2 and its flanking genes on chromosome 8.
However, only 50% of the samples were positive for pfhrp3 and its neighboring genes while the rest were either
pfhrp3-negative only or had deleted a combination of pfhrp3 and its neighbouring genes on chromosome 13.
Population structure analysis predicted that there are at least two distinct parasite population clusters in this
sample population. It was also determined that a greater proportion of parasites with pfhrp3-(and flanking gene)
deletions belonged to one cluster compared to the other.
Conclusion: The findings indicate that the P. falciparum parasite population in the municipality of Puerto Lempira
maintains the pfhrp2 gene and that PfHRP2-based RDTs could be considered for use in this region; however continued
monitoring of parasite population will be useful to detect any parasites with deletions of pfhrp2.
Keywords: Plasmodium falciparum, Histidine-rich protein, Rapid diagnostic tests, Microsatellites, Honduras

The recent emergence of artemisinin resistance in the Greater Mekong Subregion poses a major threat to the global effort to control malaria. Tracking the spread and evolution of artemisinin-resistant parasites is critical in aiding efforts to contain the spread of resistance. A total of 417 patient samples from the year 2007, collected during malaria surveillance studies across ten provinces in Thailand, were genotyped for the candidate Plasmodium falciparum molecular marker of artemisinin resistance K13. Parasite genotypes were examined for K13 propeller mutations associated with artemisinin resistance, signatures of positive selection, and for evidence of whether artemisinin-resistant alleles arose independently across Thailand. A total of seven K13 mutant alleles were found (N458Y, R539T, E556D, P574L, R575K, C580Y, S621F). Notably, the R575K and S621F mutations have previously not been reported in Thailand. The most prevalent artemisinin resistance-associated K13 mutation, C580Y, carried two distinct haplotype profiles that were separated based on geography, along the Thai-Cambodia and Thai-Myanmar borders. It appears these two haplotypes may have independent evolutionary origins. In summary, parasites with K13 propeller mutations associated with artemisinin resistance were widely present along the Thai-Cambodia and Thai-Myanmar borders prior to the implementation of the artemisinin resistance containment project in the region.

Plant-parasitic nematodes cause severe damage to a wide range of economic crops, causing upto 5% yield losses
globally. In Kenya, vegetables are affected, among other pests, by parasitic nematodes, causing upto 80% loss in yield.
Nematode control is very difficult and relies heavily on use of chemical nematicides. Use of these chemical nematicides
leads to biological magnification, and elimination of natural enemies of other pathogens, thus creating a need for
greater application of pesticides, increased production costs, and development of insecticide-resistance. These factors
have led to a growing interest in search for alternate management strategies. The objective of this study was, therefore,
to document nematode-destroying fungi in selected, major vegetable-growing areas in Kenya as a step towards
developing a self-sustaining system for management of plant-parasitic nematodes. Soil samples were collected from
five vegetable-production zones, viz., Kinare, Kabete, Athi-river, Machakos and Kibwezi, and transported to the laboratory
for extraction of nematode-destroying fungi. The soil-sprinkle technique described by Jaffee et al (1996) was used for
isolating the nematode-destroying fungi from soil, while, their identification was done using identification keys
described by Soto Barrientos et al (2001). From this study, a total of 171 fungal isolates were identified as nematodedestroying.
The highest population was recorded in Kabete, at 33.9% of the total, followed by Machakos, Kibwezi,
Athi-river, with the least in Kinare, at 24.6, 22.2, 11.7 and 7.6% of the total population, in that order. Arthrobotrys was
the most frequent genus, with mean occurrence of 7.3, followed by Monacrosporium with 6 and Stylophage with 5.2.
A. dactyloides was significantly (P=0.002) affected by the agro-ecological zone, with the highest occurrence recorded
in Kabete, and the least in Athi-river. Kibwezi recorded highest diversity index, with a mean of 1.017, while, Athi-river
recorded the least, with a mean of 0.333. Kibwezi had the highest species richness, recording a mean of 3.4, while, the
least mean of 1.6 was recorded in Athi-river. Mean species richness of 2.2 was recorded for both Kabete and Machakos,
and 1.8 for Kinare. From the three genera recorded, Arthrobotrys was more effective at trapping nematodes compared
to Monocrosporium and Stylopage. The genus Arthrobotrys had the highest number of trapped nematodes, with a
total population of 57, followed by Monacrosporium, the least being Stylopage, with 45 and 36, respectively, in a period
of 104 hours. From the study, it is evident that agricultural practices affect occurrence and diversity of nematodedestroying
fungi, and, Arthrobotrys can be used as a bio-control agent for managing plant-parasitic nematodes.
Key words: Artabotrys, biological control, plant-parasitic nematodes

Guyana and Suriname have made important progress in reducing the burden of malaria. While both countries use microscopy as the primary tool for clinical diagnosis, malaria rapid diagnostic tests (RDTs) are useful in remote areas of the interior where laboratory support may be limited or unavailable. Recent reports indicate that histidine-rich protein 2 (PfHRP2)-based diagnostic tests specific for detection of P. falciparum may provide false negative results in some parts of South America due to the emergence of P. falciparum parasites that lack the pfhrp2 gene, and thus produce no PfHRP2 antigen. Pfhrp2 and pfhrp3 genes were amplified in parasite isolates collected from Guyana and Suriname to determine if there were circulating isolates with deletions in these genes. Pfhrp3 deletions were monitored because some monoclonal antibodies utilized in PfHRP2-based RDTs cross-react with the PfHRP3 protein. We found that all 97 isolates from Guyana that met the inclusion criteria were both pfhrp2- and pfhrp3-positive. In Suriname (N = 78), 14% of the samples tested were pfhrp2-negative while 4% were pfhrp3-negative. Furthermore, analysis of the genomic region proximal to pfhrp2 and pfhrp3 revealed that genomic deletions extended to the flanking genes. We also investigated the population substructure of the isolates collected to determine if the parasites that had deletions of pfhrp2 and pfhrp3 belonged to any genetic subtypes. Cluster analysis revealed that there was no predominant P. falciparum population substructure among the isolates from either country, an indication of genetic admixture among the parasite populations. Furthermore, the pfhrp2-deleted parasites from Suriname did not appear to share a single, unique genetic background.

The common bean, Phaseolus vulgaris is an important crop for food security and nitrogen fixation through Rhizobium symbiosis. Commercial Rhizobium inoculants are being promoted to fix nitrogen and enhance bean production in the Lake Victoria basin. Rhizobium symbiosis depends on nutrients, especially phosphorus, which is widely applied as diammonium phosphate (DAP) in the Lake Victoria basin. Water hyacinth, Eichornia crassipes (Mart.) Solms-Laubach (Pontederiaceae) is being developed into compost, with perceived benefits of improving crop production and limiting its disastrous spread in Lake Victoria. High nutrient content in water hyacinth compost can stimulate Rhizobium nodulation and nitrogen fixation, consequently improving plant growth and pest resistance. However, it is not yet established whether Rhizobium inoculants and water hyacinth composts are compatible options for plant growth promotion and pest suppression in beans. A field experiment with two trials was conducted to assess the compatibility of commercial Rhizobium inoculant, DAP, cattle farmyard manure (FYM), and four formulations of water hyacinth compost i.e., water hyacinth only (H), with molasses (H+Mol), cattle manure culture (H+CMC) or effective microbes (H+EM). Rhizobium inoculated plants had high number of root nodules when grown with H+CMC and H+EM. Plants were large in size with short development period when grown with the composts, especially H+CMC and H+EM. Those grown with H+EM produced high number of flowers. Rhizobium inoculated plants had high anthracnose incidence than non-inoculated ones when grown with H+CMC. Those grown with H+EM had low anthracnose incidence, but was high in FYM. During flowering, Rhizobium inoculated plants had higher Aphis fabae population than non-inoculated ones when grown in FYM or without fertilizer. Those grown with H+EM had the lowest A. fabae population. Yields in water hyacinth compost were improved, especially for H+CMC in the second trial. DAP treated plants had more flowers and pods having heavy seeds, with low anthracnose and A. fabae infestations; but had low germination rates that reduced the yields. In conclusion, the commercial Rhizobium inoculant is predominantly compatible with water hyacinth compost formulations containing effective microbes and cattle manure culture, which could enhance tolerance of bean plants to aphids and possibly to anthracnose disease. These two water hyacinth compost formulations need further investigation for their potential in enhancing food production and alleviating the water hyacinth problem in the Lake Victoria basin.

Keywords
Aphis fabaeCompostLake VictoriaNitrogenRhizobiumWater hyacinth

The common bean, Phaseolus vulgaris is an important crop for food security and nitrogen fixation through Rhizobium symbiosis. Commercial Rhizobium inoculants are being promoted to fix nitrogen and enhance bean production in the Lake Victoria basin. Rhizobium symbiosis depends on nutrients, especially phosphorus, which is widely applied as diammonium phosphate (DAP) in the Lake Victoria basin. Water hyacinth, Eichornia crassipes (Mart.) Solms-Laubach (Pontederiaceae) is being developed into compost, with perceived benefits of improving crop production and limiting its disastrous spread in Lake Victoria. High nutrient content in water hyacinth compost can stimulate Rhizobium nodulation and nitrogen fixation, consequently improving plant growth and pest resistance. However, it is not yet established whether Rhizobium inoculants and water hyacinth composts are compatible options for plant growth promotion and pest suppression in beans. A field experiment with two trials was conducted to assess the compatibility of commercial Rhizobium inoculant, DAP, cattle farmyard manure (FYM), and four formulations of water hyacinth compost i.e., water hyacinth only (H), with molasses (H+Mol), cattle manure culture (H+CMC) or effective microbes (H+EM). Rhizobium inoculated plants had high number of root nodules when grown with H+CMC and H+EM. Plants were large in size with short development period when grown with the composts, especially H+CMC and H+EM. Those grown with H+EM produced high number of flowers. Rhizobium inoculated plants had high anthracnose incidence than non-inoculated ones when grown with H+CMC. Those grown with H+EM had low anthracnose incidence, but was high in FYM. During flowering, Rhizobium inoculated plants had higher Aphis fabae population than non-inoculated ones when grown in FYM or without fertilizer. Those grown with H+EM had the lowest A. fabae population. Yields in water hyacinth compost were improved, especially for H+CMC in the second trial. DAP treated plants had more flowers and pods having heavy seeds, with low anthracnose and A. fabae infestations; but had low germination rates that reduced the yields. In conclusion, the commercial Rhizobium inoculant is predominantly compatible with water hyacinth compost formulations containing effective microbes and cattle manure culture, which could enhance tolerance of bean plants to aphids and possibly to anthracnose disease. These two water hyacinth compost formulations need further investigation for their potential in enhancing food production and alleviating the water hyacinth problem in the Lake Victoria basin.

Soil biodiversity represents the variety of life belowground whose interaction with plants and small animals forms a web of biological activity. It improves the entry and storage of water, resistance to soil erosion, and plant nutrition, while also controlling soil pests and disease, and facilitating recycling of organic matter in the soil. Soil biodiversity is therefore the driver of healthy soil for sustainable crop production.

However, intensive agricultural activities are reported to lead to loss of soil biodiversity. This has been attributed to environmental degradation, and consequently to climate change. This paper highlights the importance of soil biodiversity and some factors associated with its loss, and presents a case study on selected soil organisms in Kenya. Results from this study indicated that land use changes affect soil biodiversity, and soil biodiversity determines the distribution of the aboveground biodiversity.

Keywords

Biological control Crop productivity Soil biodiversity Soil health Sustainable utilization of soil

Belowground biodiversity is one of the key indicators of the sustainability of a land use. This study sought to document the occurrence and diversity of nematode destroying fungi in an area characterized by small scale agriculture in Embu County, Kenya. The study area was divided into six main land use types namely; coffee, fallow, forest, maize/bean intercrop, napier and tea. Nematode destroying fungi were extracted from five soil samples from each of the land uses. A total of 161 isolates of nematode destroying fungi belonging to nine genera and 19 species were isolated and identified. The genera represented were Arthrobotrys, Dactyllela, Dactylaria, Harposporium, Monacrosporium, Myzocytium, Nematoctonous, Paecilomyces and Stylophage. The occurrence of nematode destroying fungi was significantly (P=0.02519) affected by the land use types in the study area. With the exception of Arthrobotrys superb, Dactyllela haptospora, Dactyllela reticulate, Harposporium anguillulae and Monacrosporium ellipsoporum all the other 19 isolated species were not affected by land use types. The highest total mean occurrence of nematode destroying fungi was recorded in maize/bean, followed by nappier, coffee, forest, fallow and tea , in that order. The respective frequency of detection of the fungal species was 7.6, 7.2, 5.0, 4.0 and 3.6. The Shannon index of diversity was highest and lowest at 1.971and 1.177 in the land under maize/bean intercrop and tea, respectively. The species richness was higher in napier, followed by maize bean, coffee, forest and least in tea. Out of the fungi that were isolated, the highest proportion of 23% was from the maize/bean intercrop, while the least 11% was from land under ea. Arthrobotrys oligospora was the most frequently isolated species with a frequency of 24% while Nematoctonus pachysporus had the least frequency of occurrence of 1%. It can be concluded that land use influences the diversity of nematode destroying fungi and nematodes in the soil. More work is needed to determine the efficacy of these indigenous isolates on plant parasitic nematodes.

This study was conducted to determine the effect of selected soil chemical characteristics on the occurrence of entomopathogenic nematodes (EPNs) under different land uses in Embu and Taita Districts in Kenya.
Study Design: The sampling points were systematically marked in a grid-mesh construction using GPS marking.
Place and Duration of Study: Soil sampling was done between January 2008 and May 2008 in Embu district in the highlands of Central and Taita-Taveta district in the Coastal highlands of Kenya.
Methodology: EPNs were baited from soil using Galleria mellonella larvae and infective juveniles identified using morphological- biometric characteristics. The nematode occurrence was evaluated through relative abundance and recovery frequency expressed as percentage from the soils.
Results: EPNs were detected in 43.3% of the samples with Steinernema spp being the dominant species. The occurrence of EPNs is affected by selected soil chemical properties, land use systems and heavy metals.
Conclusion: Soil fertility management practices and heavy metals influence the occurrence of EPNs and should be considered for their effective use as biological control agents.

Striga hermonthica is a parasitic weed which largely constrains maize and sorghum production in Western Kenya. The weed mostly invades small scale farms and depending on severity, it may cause damage ranging from 10% to complete crop failure thereby aggravating the food insecurity in that region. This study aimed at evaluating fungal isolates as possible biocontrol agents against the weed. Fungi were isolated from diseased Striga hermonthica and their virulence efficacy against the weed tested in a greenhouse. All the fungal isolates tested caused infection and consequently death of the weed. Fusarium incarnatum had the highest infection rate of 92% followed by Gibberella intricans and F. chlamydosporum at 90% each. Fusarium oxysporium caused the highest mortality of 60% with Gibberella intricans, causing the least mortality of 36%. F. oxysporium was the most aggressive and potent fungal isolate against the weed hence a suitable candidate for exploitation as a mycoherbicide against the weed.

Keywords
Striga hermonthica; Fusarium; biocontrol; Mycoherbicide

Arbuscular Mycorrhizal Fungi (AMF) are important
in agriculture and have received attention as they are
considered a part of an active and diverse soil
biological community essential for increasing the
sustainability of agricultural systems. However, most
of agricultural practices have a negative impact on
AMF association and agricultural soils are AMF
impoverished. Interventions to replenish AMF
include re-introduction through inoculation or
manipulation of existing AMF to increase density. A
major problem with inoculation is that there is
possible competition with native (indigenous) AMF
species. Indigenous AMF will be more adapted to the
soil environment than introduced strains but with
conflicting results on the effects of AMF inoculation
on crop yield, more field studies for different
ecological areas are required. The objective of the
study was to compare the effect of inoculating crops
with indigenous AMF applied applied singly or
combined with other Soil Fertility Amendment
Practices (SFAP) on root colonisation and subsequent
performance of maize (Zea mays L.) and common
bean (Phaseolus vulgaris L.). Analysis was also done
on the best soil amendment practice that encourages
crop colonisation by AMF. This was tested under
field experiment and compared with control treatment
(no soil amendment practice) and three other soil
fertility amendment practices used singly or in
combination with AMF; (1) MAVUNO (macro- and
micronutrients and secondary nutrients) fertilizer, and
(2) Calcium Ammonium Nitrate (CAN) and Triple
Super Phosphate (TSP) (3) cattle manure. Maize and
bean performances were determined and compared
between the treatments for a period of two
consecutive seasons with the experiment replicated in
two benchmark sites of Embu district (highlands of
central Kenya) and Taita-Taveta district (coastal
highlands). Soils at Embu have high soil pH than at
Taita which results in low phosphorus levels and
possible micronutrients deficiencies. Even though no
significant differences were observed from root
colonisation by AMF with application of SFAP,
significant differences were observed at the crop
yield. Bean crop was more responsive to AMF
inoculation than maize in terms of yield. Combination
of AMF inoculant with other organic and inorganic
fertilizers resulted in higher crop yield compared to
AMF applied singly. Thus, utilisation of indigenous
AMF species has potential to constitute an
environmentally friendly method of soil fertility
amendment over time to improve maize and bean
production potential of small-scale holders but
consideration should be done on the local soil
nutrients conditions, other soil fertility amendment
practices in use and the targeted crop.
Keywords: Arbuscular Mycorrhizae Fungi; Soil
fertility amendment practices; indigenous species;
inoculation; crop yield; colonisation intensity.

This report was compiled by the Tropical Soil Biology and Fertility Institute of the
International Center for Tropical Agriculture (CIAT-TSBF) at the request of the Food and Agriculture
Organization of the United Nations (FAO) Commission on Genetic Resources for Food and
Agriculture. It is focusing on the state of knowledge and trends in the conservation and use of microorganisms and invertebrates in cropping systems based on roots and tubers -, including cassava,
potatoes, sweet potatoes, yams, cocoyam and aroids. The main emphasis is to understand the status
and trends of micro-organism and invertebrate diversity in root crop-based production systems and to
review the current and potential contribution of such organisms to these systems. Areas for future
research and gaps in knowledge are also identified and highlighted.
The soil is “alive”, harboring organisms whose diversity and abundance is largely unknown.
Specific information is still lacking on the importance of species that are key to specific functions and
their role in maintaining below and above-ground biodiversity. It is this information gap that this
report addresses. Most of what is presented deals with the integration of the root and tuber crops with
soil organisms and their functions.
When soil organisms eat, grow, and move, they contribute to the delivery of ecosystem
services that are essential for human society. Among the key ecosystem services mediated by soil
biota are: the transport, storage, and provision of clean ground water; the storage of carbon and the
prevention of trace gas emissions crucial for climate control; the provision of nutrients; pest and
pathogen regulation; and supporting plant growth and above-ground biodiversity. Most of the
structure and functioning of the above-ground individuals and communities are regulated directly or
indirectly by altering the dynamics of nutrients that are available to plants.
As production of the root and tuber crops expands, it is important to use production
technologies which secure a safe and clean environment that minimizes use of synthetic chemicals.
Research is needed on how best to integrate soil organisms in the production of the crops both as biofertilizers as well as use as bio-control agents (BCAs). Mechanisms of co-existence of soil organisms
in mutualistic, proto-cooperation, commensalism, neutralism, antagonism, predation and parasitic
relationships can be used to explore further how best to integrate these associations with the root and
tuber crops. Biological control methods have provided alternative safer methods to pesticides and
herbicides for pathogen, insect pest and weed control. However developing BCAs is labor intensive
but this may lead to localized niche businesses that provide jobs and create wealth. Benefits might
also accrue to the growers who use BCAs because of the premium price for pesticide-free and organic
produce. This may not yet be happening but the major benefit from BCAs may be in preserving root
and tuber crops from postharvest breakdown because of the perishable nature of root and tuber crops
that can inhibit large scale exports apart from cassava which are first dried before chips are exported.
Emerging technologies in biological sciences allow the study of these soil microorganisms
beyond the microscope. Gene marking, DNA finger printing, PCR amplification, genomics,
proteomics and metabolomics and associated microarray technologies have enhanced opportunities for
throughput in bio-prospecting and understanding mechanisms of soil organism action that can lead to
discovery of novel properties and products especially from microorganisms. More research is needed
to ensure food security and to increase food production levels in developing countries in part by a
better understanding of how to manage soil biological processes. In order for this to be realized, there
will be need for budgets, reference databases, North-South collaborations as well as championing

Land intensification is thought to lead to soil degradation and consequently to loss of soil biodiversity. A study was undertaken to assess the effect of land use on nematode community and nematode destroying fungi in Taita districts, Kenya. Soil samples were collected from land under various uses which were natural forest, plantation forest, tea, coffee, napier grass, fallow, maize/beans intercrop and horticultural crops production. Chemical analysis of the soil properties was done to determine the amount of carbon, nitrogen and potassium in every land use system. The level of carbon declined with land-use intensification with the highest organic carbon level of 7.6% being recorded in soils from the forest while land with high disturbance recorded 1.6% carbon. Similarly, the intensively cultivated soils had lower nitrogen and phosphorous levels compared to the forest. Nematode and nematode destroying fungi were isolated from the soil and identified. Eighty five isolates, distributed in eight genera and fourteen taxa of nematode destroying fungi were identified. The frequency of isolating nematode destroying fungi increased with increased in land use intensity. All the sampled land use types were significantly (P-value = 3.81x10-07) different in occurrence of nematode destroying fungi. The ratios of free-living to plant parasitic nematodes were 5.18 and 0.54 in the natural forest and annual crop production systems, respectively. The frequency of isolation of nematode destroying fungi was positively correlated to abundance of plant parasitic nematodes.

There are many species of indigenous mushrooms in Kenya which form part of the traditional food system but whose nutritional and cultivation studies have not been completely determined and hence under utilized. The indigenous P. citrinopileatus was collected from Kakamega forest in Western Kenya, characterized and grown at the Kenya Industrial Research and Development Institute laboratories. The objective of this study was to evaluate indigenous P. citrinopileatus mushroom with the aim of qualifying and quantifying chemical information that might serve as a guide to exploit its potentials and benefits for human nutrition. The proximate composition (moisture, energy, fibre, crude fat, ash, minerals and protein) and amino acids contents (by high performance liquid chromatography) and vitamins of the indigenous P. citrinopileatus mushroom were determined. Proximate analysis of P. citrinopileatus revealed that it contained 22.10% protein, 1.32% crude lipid and 20.78% fibre. The mushroom was also found to contain variable amounts of minerals. The most predominant mineral found in the mushroom was Potassium with value of 2.28%. Copper, zinc and iron minerals were generally low with values from 0.0002, 0.0015 and 0.01%, respectively. Eight essential amino acids were detected namely Leucine>Valine> Threonine>Lysine>Phenylalanine>Isoleucine>Methionine>Tryptophan in decreasing order of abundance. Glutamic acid though non-essential was present in high proportion (3.07%). Vitamin B3 (Nicotinic acid), vitamin B5 (Pantothenic acid) and vitamin B2 (Riboflavin) were the most abundant vitamins in all samples analyzed. While vitamin B12 (Cyanocobalamin) and vitamin A (retinol) were the least with values of 0.3 and <10 μg/100 g, respectively. In conclusion, Pleurotus citrinopileatus mushroom can be an excellent source of micronutrients and antioxidants components.

Management of HIV and AIDS has been on activities such as awareness creation, condom distribution and provision of anti-retroviral therapies (ARTs). Considering that even when available, ARTs pose real challenges with respect to compliance and resistance and that they sometimes adversely affect HIV and AIDS patients, nutritional compliments and alternatives are increasingly being researched with an aim of optimizing management of this disease. This study is evaluating the role of indigenous food formulations in management of HIV and AIDS in the Lake Victoria Basin. One hundred twenty eight (128) subjects from the (Rural Education and Economic Enhancement Programme (REEP)) were identified and participated in a baseline review at the REEP offices in Butula to determine their nutritional, clinical, haematological and immunological characteristics. Only subjects confirmed to be HIV-seropositive were considered for this report and the on-going randomized controlled nutritional intervention study. Most of the subjects (54.7%) were aged 36-54 years while 39% were in 18-35 years group. Seventy nine (79%) of female and 65% of male had normal weight (BI range of 18-25 kg/m2). Haematologically, 63% of female and 47% of male were anaemic as 56% of male and 71% of female had over 500 CD4+ cells. The mean CD4+ cell count for males and females was 725±396 and 794±466 cell/mm, respectively. Although the study subjects were of comparable nutritional parameters, female subjects had much lowered immunological characteristics than males. We anticipate that the nutritional supplements proposed for the intervention phase of this study will impact favourably on their status. The study will address nutritional deficiencies and disorders among the study subjects by utilizing locally available foods that are rich in micronutrients. After the project, study subjects and the general population will be counselled on growing and consuming micronutrient-rich foods as the surplus will be used for income generation and poverty alleviation.

Surveillance of food and feed quality in Kenya has not reached effective level due to the expensive procedures of mycotoxin analysis and poor structures in quality control. Most foodstuffs and feeds sold in local markets do not go through any quality control measures. The outbreaks of aflatoxicoses every year since the major outbreak that occurred in 2004 (CDC, 2004; Muture and Ogana, 2005, Azziz-Baumgartner et al., 2005) suggests that the population is exposed to aflatoxins in their diet. Chronic exposure could be a more serious problem than the outbreaks of aflatoxicosis that attract attention at the time they occur. This paper analyses the extent to which market food and feed samples expose the residents of urban Nairobi Province to aflatoxins. Using TLC method of aflatoxins analysis, maize for food and feed samples collected randomly as part of routine surveillance between the years 2006-2009 were tested. Only 17% of the total maize sampled and 5% of feed were fit for human and animal consumption respectively. Maize Grain Grade 11 and maize milled products were significantly highly contaminated compared with Maize Grain Grade 1 throughout the period of sampling. There was no significant difference in level of contamination among the feeds tested

Surveillance of food and feed quality in Kenya has not reached effective level due to the expensive procedures of
mycotoxin analysis and poor structures in quality control. Most foodstuffs and feeds sold in local markets do not
go through any quality control measures. The outbreaks of aflatoxicoses every year since the major outbreak
that occurred in 2004 (CDC, 2004; Muture and Ogana, 2005, Azziz-Baumgartner et al., 2005) suggests that the
population is exposed to aflatoxins in their diet. Chronic exposure could be a more serious problem than the
outbreaks of aflatoxicosis that attract attention at the time they occur. This paper analyses the extent to which
market food and feed samples expose the residents of urban Nairobi Province to aflatoxins. Using TLC method
of aflatoxins analysis, maize for food and feed samples collected randomly as part of routine surveillance
between the years 2006-2009 were tested. Only 17% of the total maize sampled and 5% of feed were fit for
human and animal consumption respectively. Maize Grain Grade 11 and maize milled products were
significantly highly contaminated compared with Maize Grain Grade 1 throughout the period of sampling.
There was no significant difference in level of contamination among the feeds tested.

The growth and yield performance of indigenous Pleurotus citrinopileatus on selected locally available substrates were determined as a prelude to its domestication. Seven substrates namely; bean straw (Phaseolus vulgaris), sawdust of African mahogany (Khaya anthotheca), rice straw (Oryza sativa), maize cobs (Zea mays), wheat straw (Triticum aestivum), sugarcane bagasse (Saccharum officinarum) and banana leaves (Musa sp.) were tested for their suitability for production of the indigenous Pleurotus citrinopileatus. Each treatment had 9 plastic bags each containing 1 kg of fresh weight of substrate, each spawned with 50 g of indigenous oyster mushroom, Pleurotus citrinopileatus. The treatments were arranged in a completely randomized design. Data was collected on days to pinning, fruiting body yield (fresh weight) and biological efficiency. Data collected was subjected to analysis of variance using Minitab version 14. Mean separation was done using Tukey test and effects declared significant at 5% level. The substrates were significantly different (p<0.05) in biological efficiency; yield and days to pinning. The best performance was obtained from the bean straw substrate. Maximum yield (397.71 g kg-1 wet substrate) and biological efficiency of 148% were obtained from bean straw at spawn rate of 5%. This study recommends bean straw as a new substrate for cultivation of Pleurotus citrinopileatus at spawn rate of 5% under local conditions which is being reported for the 1st time in Kenya.

Two agro-ecological zones in Kenya were selected to compare the distribution in maize of Aspergillus spp. and their toxigenicity. These were Nandi County, which is the main maize growing region in the country but where no human aflatoxicoses have been reported, and Makueni County where most of the aflatoxicosis cases have occurred. Two hundred and fifty-five households were sampled in Nandi and 258 in Makueni, and Aspergillus was isolated from maize. Aspergillus flavus and A. parasiticus isolates were tested for the presence of aflD and aflQ genes. Positive strains were induced to produce aflatoxins on yeast extract sucrose and quantified using liquid chromatography-tandem mass spectrometry (LCMSMS). Aspergillus flavus was the most common contaminant, and the incidence of occurrence in Nandi and Makueni was not significantly different (82.33% and 73.26%, respectively). Toxigenic strains were more prevalent than non-toxigenic strains. All the toxigenic strains from Makueni were of the S-type while those from Nandi belonged to the L-type. Quantitative differences in aflatoxin production in vitro between isolates and between strains were detected with S strains producing relatively larger amounts of total aflatoxins, B toxins and lower values for G toxins. This was in accord with the frequent aflatoxicosis outbreaks in Makueni. However some L strains produced considerable amounts of B toxins. Given the widespread distribution of toxigenic strains in both regions, the risk of aflatoxin poisoning is high when favorable conditions for toxin production occur.

Fusarium oxysporum sp. cubense threatens the survival of TC Gros mitchel
banana worldwide. Control by fungicides has failed with breeding rather than
control of pathogen preferred. A study funded by BMGF was conducted by
CIAT-Tropical Soil Biology and fertility institute to evaluate commercial
biological and chemical products for use in Africa. A complete randomized
design experiment under greenhouse conditions evaluated the potential of
Rhizatech (mycorrhiza) and EcoT (Trichoderma hazianum) on suppression of
Fusarium spp. on vertisols, eutric nitosols and humic nitisols from banana
growing regions in Kenya. Fusarium spp. were isolated using Peptone
Pentachloronitrobenzene agar. Identification manual for Fusarium by Burgess
using cultural and microscopic characteristics distinguished isolates as
Fusarium oxysporum. The isolates were white and pink in vertisol, white in
eutric nitosol and purple with white tint and white in humic nitisol. Colony
forming units (CFU) were significantly (p < 0.05) different. The CFU before
inoculation was 8.0 × 102 for eutric nitosol, and vertisol and 2.5 × 102 in
humic nitisol. Rhizatech reduced CFU in eutric nitosol and humic nitisol by
87.5% and 36% respectively. EcoT reduced CFU in vertisol and humic nitisol
by 12.5% and 44% respectively. Response to products depends on soil type
and there is potential in use of products to suppress disease.

Trichoderma has been widely studied for their biocontrol ability, but their use as biocontrol agents in agriculture is limited due to the unpredictable efficiency which is affected by biotic and abiotic factors in soil. Isolates of Trichoderma from Embu soils were evaluated for their ability to control Fusarium oxysporum f. sp. phaseoli., in vitro and promote seedling growth in the greenhouse. Bioassays were run using dual cultures and diffusible compound production analysis. The Trichoderma isolates significantly (p < 0.01) reduced the mycelial growth of the pathogen. The principle mechanisms of niche competition, mycoparasitism, and antibiosis were observed in growth of the pathogen mycelium in the presence of Trichoderma spp., through development of inhibition zones. There was coiling of hyphae around the pathogen mycelium coupled by lysising of cell wall Trichoderma spp., where T. reesei and T. koningii were the most effective isolates. Studies were indicative of the synergistic ability of Trichoderma spp., being an effective biocontrol of bean seedlings against Fusarium wilt while also promoting plant growth.

The study aimed at identifying soil fertility practices that promoted nematode destroying fungi in the soil and the treatments comprised of Mavuno fertilizer, Triple super- phosphate and calcium ammonium nitrate (TSP+CAN), cow manure and a control where no amendments were applied. This experiment was replicated in ten farms for three planting seasons. There were significant difference (P= 1.705 x 10-06) in occurrence of the nematode destroying fungi between soil fertility treatments. The highest mean occurrence of nematode destroying fungi was 1.6 which was recorded in soils amended with cow manure and the least was in soils from the control plots. A mean of 0.78 was recorded in soils from both TSP+CAN and Mavuno fertilizers. Plots amended with cow manure gave the highest diversity of nematodes followed by the control, then TSP+CAN and least in Mavuno with shannon indices of 0.34, 0.15, 0.13 and 0.11 respectively. Sixty percent of all the isolated nematode destroying fungi genera were from plots treated with cow manure and only twenty percent were from plots amended with the inorganic fertilizer

Fusarium root rot of maize and beans is a common problem in Taita District, Kenya causing economic losses to the small scale farmers. The pathogen attacks maize and beans at all growth stages causing rot at the seedling stage, yellowing of the leaves, stunted growth, and death if severe. Potentially effective crop rotations to maintain the pathogen at low levels are not currently practical due to the small size of farms while fungicides are out of reach to the small scale farmer due to high prices. This study aimed at assessing alternatives to fungicides in controlling root infection by Fusarium sp. in maize and beans cropping systems. Field trials were done in Taita District where agriculture contributes to 95% of household income with limited use of any soil fertility amelioration by farmers. The following were tested in the trials; three types of inorganic fertilizers, cow manure, and Trichoderma inoculant. Planting was done during the long and short rains. Soil and roots were collected from the rhizosphere during harvesting and assessed for inoculum density while the roots were evaluated for incidence of infection by Fusarium spp. The most common species in both soil and roots were F. oxysporum (Schlecht) Snyd.et Hans. and F. sporotrichoides Sherb. Addition of soil amendments had a positive effect of reduced root infection and in some cases lowering inoculum density in the soil. Of the four integrated soil fertility interventions, Mavuno fertilizer had the highest yield and was the most effective in suppressing root colonisation by Fusarium spp

The occurrence of the edible basidiomycete Pleurotus citrinopileatus is reported for the first time in Kenya. The mushroom was collected from the dead logs and branches of Antiaris toxicaria (Pers.) Lesch., Polyscias fulva(Hiern) Harms, and Ficus thoningii Bl. in Kakamega forest. These trees are indigenous and are new hosts for this species. This mushroom is used as food by local communities in Kenya but it has not been documented nor studied. It is used solely as a product of the wild. People collect it and prepare it traditionally with other foods for consumption.

Natural entomopathogenic nematodes (EPNs) are considered as potential biological control agents against soil-borne insect pests. This study was conducted to determine the impact of land use on the distribution, occurrence and diversity of entomopathogenic nematode community. Isolation of EPNs was done using the baiting technique and application of morphological identification methods revealed presence of the genus Steinernema. Land use intensification negatively affected the occurrence and recovery frequency in soils of Embu and Taita districts. The occurrence of EPNs was high in soils from coffee than maize and beans which had more nematodes than planted forest and napier grass followed by natural forest and tea respectively. PCR-RFLP of the internal transcribed spacer region on the ribosomal(r) DNA of the EPN isolates and digestion of the products by Alu I enzyme showed molecular variations among the isolates. The study has demonstrated that the frequency of occurrence and species variation of EPNs is different in various land uses

Species in the genus Trichoderma are important commercial source of several enzymes, biofungicides and growth promoters. The most common biological control agents of the genus are strains of T. harzianum, T .viride and T. viriens. In this study, sixteen selected isolates of T. harzianum from different land use types in Embu, Kenya were tested for antagonistic action against five soil borne phytopathogenic fungi (Rhizoctonia solani, Pythium sp, Fusarium graminearum, F. oxysporum f. sp phaseoli and F. oxysporum f. sp Lycopersici) using dual culture assay and through production of non-volatile inhibitors. Seven isolates were further characterized using RAPD-PCR procedure to determine genetic variability. All T. harzianum isolates had considerable antagonistic effect on mycelial growth of the pathogens in dual cultures compared to the control. Maximum inhibitions occurred in Pythium sp-055E interactions (73%).The culture filtrates obtained from Czapek‟s liquid medium reduced the dry weight (mg) of the mycelia significantly while those from the potato dextrose broth showed minimum inhibition growth. Pythium sp. was most sensitive compared to other pathogens. Genetic similarities generated using Jaccard‟s coefficient of similarity ranged from 0.231 to 0.857 for isolates 055E, 011E, 010E and 015E. Since all T. harzianum isolates evaluated were effective in controlling colony growth of the soil borne pathogens both in dual cultures and in culture filtrates they could be tried as a broad spectrum biological control agent in the green house and under field conditions.

Species in the genus Trichoderma are important as commercial source of several enzymes and as biofungicides/growth promoters. The most common biological control agents of the genus are strains of T. harzianum, T. viride and T. viriens. In this study, sixteen selected isolates of T. harzianum from different land use types in Embu, Kenya were tested for anatognism against five soil borne phytopathogenic fungi (Rhizoctonia solani, Pythium sp, Fusarium graminearum, F. oxysporum f. sp phaseoli and F. oxysporum f. sp Lycopersici) using dual culture assay and through production of nonvolatile inhibitors. Seven isolates were further characterized using RAPD-PCR procedure to determine genetic variability. All T. harzianum isolates had considerable antagonistic effect on mycelial growth of the pathogens in dual cultures compared to the controls. Maximum inhibitions occurred in Pythium sp- 055E interactions (73%).The culture filtrates obtained from Czapek’s liquid medium reduced the dry weight (mg) of the mycelia significantly while those from the potato dextrose broth showed minimum inhibition growth. Pythium sp was inhibited the most compared to other pathogens. Genetic similarities generated using Jacquard’s coefficient of similarity ranged from 0.231 between isolates 055E and 011E to 0.857 between isolates 010E and 015E. The technique of RAPD was efficient in demonstrating the DNA polymorphism in the isolates of T. harzianum tested showing intraspecific genetic variability. Since all T. harzianum isolates evaluated were effective in controlling colony growth of the soil borne pathogens both in dual cultures and in culture filtrates they could be tried as a broad spectrum biological control agent in the green house and under field conditions.

The diversity of nematode destroying fungi in Taita Taveta, Wundanyi division, Coast Province, Kenya, was investigated between May 2006 and December 2007 aiming at harnessing their potential in the biological control of plant parasitic nematodes in the area. Given that the intensity of land cultivation is continually increasing in the study area, it is prudent to document the status of the nematode destroying fungi before the remaining forest habitats are ultimately disrupted. Soil samples were collected from forest, maize/ bean, napier grass, shrub and vegetable fields, which represented the main land use types in the study area. The soil sprinkle technique method was used to isolate the nematode destroying fungi from the soil. The fungi were identified to species level. Eighty-five isolates, distributed in eight genera and 14 taxa were identified as nematode destroying fungi. The species identified were Arthrobotrys dactyloides, Arthrobotrys oligospora, Arthrobotrys superba, Acrostalagamus obovatus, Dactyllela lobata, Harposporium aungulilae, Harposporium liltiputanum, Harposporium spp, Haptoglosa heterospora, Monacrosporium asterospernum, Monacrosporium cianopagum, Myzocytium, spp, Nematoctonus georgenious and Nematoctonus leptosporus. Vegetable land use had the highest diversity of nematode destroying fungi. The results show that the study area is rich in nematode destroying fungi with A. oligospora being widespread and a possible candidate for biological control of plant parasitic nematodes

A green-house study was conducted to investigate the ability of an isolate of Trichoderma harzianum (P52) and arbuscular mycorrhizal fungi (AMF) in enhancing growth in tomato seedlings, tea and napier grass cuttings. The effect of these bio-inoculants on growth was compared with the influence of Diammonium phosphate (DAP) fertilizer and the interactions of these three factors (P52, AMF and DAP). The plants were grown in plastic pots filled with sterilized soils. A completely randomized design was used and growth measurements taken on height shoot and root dry weights. It was observed that isolate P52 and DAP fertilizer individually enhanced growth in tomatoes, tea and napier while AMF only enhanced growth in tomatoes. Combinations of P52 and DAP; P52, AMF and DAP enhanced growth significantly (P<0.05). Trichoderma harzianum and AMF showed potential for use as biofertilizers to reduce on chemical inputs in the perspective of sustainable agriculture and conservation of natural resources.

Genetic relatedness among twenty six Fusarium species isolated from soils in six different Land Use Types (LUTs) across a land use gradient was evaluated using Random Amplified Polymorphic DNA (RAPD) assay. The six LUTs were horticulture, maize, napier grass, fallow/shrub land, planted forests as well as indigenous forests. Six primers were used in this assay. Amplification products were examined and presence or absence of each size class of bands was scored as 1 and 0, respectively. The resulting matrix was used to compute Jaccard’s similarity coefficients and Unweighted Pair Group Method with Arthmetic mean (UPGMA) cluster analysis using computer package NTSYS-pc. Jaccard’s similarity coefficients ranged from 0.257 to 0.583 among the Fusarium species studied indicating high genetic diversity. The UPGMA cluster analysis grouped the 26 Fusarium species into two main clusters with the first cluster comprising of 17 species with genetic similarity values ranging from 26.2 to 58.3 %. The second cluster comprised of 9 species with genetic similarity values ranging from 29.5 to 56.34 %. Fusarium avenaceum and F. nygamai depicted the highest genetic similarity of 58.3 %.

The effect of Land Use Types (LUTs) on distribution and diversity of Fusarium species in soil were evaluated in Taita Taveta district, Kenya. Soil samples were collected from sixty points across a land use gradient covering six different LUTs, at 0 to 10 and 10 to 20 cm soil depths. Using Fusarium-selective media, a total of 1865 Fusarium isolates were recovered from the soil samples which resulted into 26 Fusarium species with Fusarium oxysporum and Fusarium solani being the dominant species in this area. Difference in Fusarium abundance, diversity and richness across the LUTs was significant (P<0.001) with horticulture being the richest and the most diverse LUT. The top soil layer had significantly higher Fusarium abundance and richness (P<0.05). A Principal Component Analysis (PCA) based on the relative Fusarium species abundance differentiated the LUTs with 79.69 %. There were significant positive correlation between P and pH levels with Fusaria abundance, richness and diversity (P<0.001). Abundance and diversity of Fusarium was also positively correlated with soil Mg and K (P<0.05). However, a significant negative correlation between exchangeable acidity and abundance (r=-0.605), richness (r=-1.317) and diversity (r=-0.16) was observed (P<0.05). Negative correlation was also observed between Nitrogen and richness (r=-2.94) and diversity (r=-0.67) of Fusarium species.

Due to the increased concerns about the effect of agrochemicals on soil health and soil biodiversity, use of biological methods has become most acceptable alternative methods for farmers to control soil pathogens during crop production. A study was therefore undertaken to determine the occurrence of nematode destroying fungi in Taita Taveta with the aim of isolating and characterizing them for biological control of plant parasitic nematodes. Twenty eight fungal isolates, distributed in three genera, were identified as nematode destroying fungi from all the positive soil samples. Out of the isolates that were identified, 71, 25 and 4 % were in the genera Arthrobotrys, Monacrosporium and Nematoctonus respectively. Arthrobotrys oligospora had an occurrence frequency of 42.9% which was the highest followed by A. dactyloides, M.cionopagum, Monacrosporium sp and Nematoctonus sp with frequencies of 28.6, 17.9 and 7.1and 3.6% respectively. The occurrence of nematode destroying fungi was affected by land use and organic inputs (P ≤ 0.05) while it was not affected by crop rotation (P ≥ 0.05). Napier land use was more diverse than the other land uses with a mean shannon diversity index of 0.717 followed by horticulture (index 0.497). Maize /bean, coffee/beans, fallow and shrub land uses had a mean shannon index of 0. The same trend was observed on richness where napier had a mean richness of 2.2, horticulture 1.8, maize bean 1 while shrub, fallow and coffee/ beans all had mean richness of 0.2. A.oligospora was the most frequently isolated fungi (42.9 %) and showed high potential in biocontrol of plant-parasitic nematodes and was recommended for further studies and development as a biological control agent.