Evaluating the efficacy of Podisus maculiventris and Isaria fumosorosea as biological control agents of Microtheca ochroloma

The yellow-margined leaf beetle (YMLB), Microtheca ochroloma Stål, a native of South America, is a pest in cruciferous crops. Little information is available in the literature about natural enemies of this pest. Therefore, the objective of this study was to evaluate the efficacy of the predator Podisus maculiventris (Say) and the fungus Isaria fumosorosea Wize to control YMLB. Preliminary results demonstrated that Podisus maculiventris preyed in all stages of the YMLB. Consumption rate studies showed that the nymphal stage of the P. maculiventris can prey on an average of 67 3^rd instar of the YMLB in 18 days in the laboratory at 25^o C. A field cage experiment showed that densities of 10 and 16 nymphs of P. maculiventris per 6 turnips plants can reduce 75 and 84% of the YMLB population, respectively. In laboratory observations, the larvae of the YMLB are susceptible to I. fumosorosea. Infectivity of 31% by I. fumosorosea was recorded on 4^th instars of the YMLB. These results suggest that P. maculiventris and I. fumosorosea may be promising biological control agents.