Evaluation of entomopathogenic fungus Metarhizium anisopliae var. anisopliae for integrated management of termites (Isoptera: Termitidae) in maize in Siaya County

Maize (Zea mays L) is one of the major staple crops in Africa contributing significantly to food security; however its production has been declining in the recent past. Termites are one of the major yield reducers accounting for 50-100% losses in maize. Chlorinated hydrocarbon insecticides used for their control have been restricted thus, the need for an alternative control measures. Recent studies have demonstrated the efficacy of the entomopathogenic fungus Metarhizium anisopliae for controlling termites, but little is yet known about practical and sustainable application of this bio control agent. This study was therefore conducted to evaluate different application rates of M. anisopliae and the effect of maize-based intercropping system on performance of fungus for integrated termite management in maize field and secondly to assess persistence of M. anisopliae in the soil. The fungi granules were mass produced in the laboratory at ICIPE Nairobi. Three application rates of the fungus granules at 40.0 kg/ha, 60.0 kg/ha 80.0 kg/ha plus untreated control were evaluated in the field under three cropping systems; maize monocrop, maize + soybean intercrop and maize + common bean intercrop. Treatments were replicated three times in a RCBD. Head count of lodged maize due to termite attack was recorded weekly; temperature and relative humidity at the base of the maize plant were recorded using hygrothermometer and yields per plot were taken at harvest. To assess persistence, four soil samples were picked at randomly per plot at planting and at harvest and fungus persistence test done in the laboratory. The number of colony forming units per gram of fresh soil was measured after seven days. Data were subjected to ANOVA analysis and means were compared by Turkeys' (P≤0.05) using Genstat software. Application of M. anisopliae of 60.0 kg/ha and 80.0 kg/ha significantly reduced maize lodging and increased maize yield. Maize yield was high in intercrop plots treated with M. anisopliae; application of 40.0 kg/ha of M. anisopliae in maize + soyabean intercrop increased maize yield to level comparable to 80.0 kg/ha of M.anisopliae in maize monocrop treatments. Spore density at harvest in all the treatments in the three cropping system differed significantly (P≤0.05) with application of M. anisopliae at 60.0 kg/ha and 80.0 kg/ha in maize intercrop having high conidia persistence compared to maize monocrop. The study demonstrates that application of M. anisopliae protects maize against termite attack and the use of legume intercrops enhances the efficacy and persistence of the fungus in the field. It is recommended that application of 60.0 kg/ha M. anisopliae granules in maize monocrop and 40.0 kg/ha M. anisopliae granules in maize soybean intercrop are effective for termite management.