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The soil inhibiting entomopathogenic nematodes (EPNs), in the family Steinernematidae and Heterorhabditidae, are useful insect biological control agents. They have been used in the management of economically important crop pests. The EPNs are mutually associated with symbiotic bacteria genus Xenorhabdus and Photoharbdus respectively. The study aimed to isolate, characterize and evaluate the pathogenicity of symbiotic bacteria associated with EPN Steinernema sp. Kalro (Accession MW151701). The EPN Steinernema sp. Karlo was multiplied using the insect baiting technique. Its bacteria symbiont was isolated and characterized based on microscopic, biochemical, and physiological features like Gram staining, urease, motility test, and glucose fermentation test). Molecular identification and phylogenetic analysis were performed on 16S rDNA nucleotide sequence. Pathogenicity of the bacteria isolate was evaluated against Tuta absoluta larvae with mortality data recorded after 24 and 48hours of exposure to the bacterial cell suspension. The bacteria were found to be motile and glucose fermentation positive. Sequence analysis of 16S rDNA region resulted in 1500bp sequence with maximum similarity of between 97 and 98.93%, with Xenorhabdus spp Accessions from Genbank. It closely matched to Xenorhabdus sp. My8NJ with 98.93% similarity (Accession AB507811.1). Mean percent larval mortality of 68±4.9 and 88±8.0 in the lowest cell suspension was observed in 24 and 48h of exposure. It’s concluded that, the symbiotic bacteria associated with Steinernema sp. Kalro is Xenorhabdus sp. strain Kalro Genbank Accession MW245845. The bacteria is a potential biological control agent against Tuta absoluta larvae. Further classification of the bacteria to species level and pathogenicity trials in the screen house and field are recommended.

Globally, vegetable production including tomato is constrained by pests and diseases. The tomato leafminer, Tuta absoluta (Meyrick.), is a major pest of tomato, mainly managed using chemical pesticides. There is a need for integrated pest management (IPM), approaches that are human and environmentally friendly. The study aimed at molecular identification and virulence evaluation of four entomopathogenic nematodes (EPNs) against T. absoluta larvae. The DNA was extracted, sequenced, and phylogeny analyzed. The EPNs virulence was evaluated using the insect baiting technique at different nematode concentrations (0-Control, 100, 150, 200, and 250 infective juveniles/ml of distilled water). Larval mortality data were collected for five days. Molecular identification resulted in nucleotide sequence lengths of 877-895 base pairs (bp). All the isolates were found to be Steinernema species of EPNs. The % similarity of the isolates and their close relatives ranged between 82-100%. The isolates closely matched Steinernema spp. AY230184 (Sri Lanka); AY230186 (Kenya), JN651414 (Ethiopia), and MW151701 (Kenya). The sequences were deposited to Genbank as Steinernema sp. Isolate Kalro 75 (MW150871), Steinernema sp. Isolate Kalro S86 (MW150872), Steinernema sp. isolate Kalro97 (MW150873) and Steinernema sp. Isolate KalroR52 (MW150874). All the EPN isolates were virulent against T. absoluta. Isolate Kalro R52 and Kalro S86 recorded the highest mortality of 76±7.5%; 72±15.0% respectively in the 48 h. There was a significant difference (P < 0.001), between all the isolates and the Control. The four EPNs were virulent and have bio-control potential against, T. absoluta. Research on their virulence against T. absoluta in the field is recommended.

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.

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.

Plant parasitic nematodes cause up-to 5% yield losses to a wide range of economic crops. In Kenya vegetables yield loss attributed to plant parasitic nematodes is estimated to 80%. Over the years, nematode control has heavily on the use of chemical nematicides which unfortunately leads to biological magnification and elimination of the beneficial microorganisms in the soil. This has triggered a growing interest in search of 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 self-sustaining system for management of plant parasitic nematodes. Soil samples were collected from five vegetable production zones in Kenya which were Kinare, Kabete, Athi-river, Machakos and Kibwezi and transported to the laboratory for extraction of the nematode destroying fungi. Soil sprinkle technique as described by Jaffee et al., (1996) was used to isolate the fungi from the soil while identification was done using identification keys described by Delgado et al.,(2001). From the study a total of 171 fungi isolates were identified as nematode destroying fungi. The highest population was recorded at Kabete area recording 33.9% of the total record, followed by Machakos, Kibwezi, Athi-river and the least in Kin are with 24.6, 22.2, 11.7 and 7. 6% of the total population in that order. Arthrobotrys was the most frequent genera with a 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 zones with the highest occurrence being recorded in Kabete and the least in Athi-river. The highest diversity index and species richness of nematode destroying fungi was recorded in Kibwezi while the least was recorded in Athi-river. The genera Arthrobotrys had the highest number of trapped nematodes with a total population of 57, followed by Monacrosporium and least was Stylopage with 45 and 36 respectively, within a period of 104 hours. From the study, it is evident that agricultural practices affect the occurrence and diversity of nematode destroying fungi and Arthrobotrys can be developed as a bio-control agent for management of plant parasitic nematodes.