Effect of Land Use on Abundance and Diversity of Nematode Destroying Fungi and Soil Nematodes in Embu County, Kenya

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.