Choice behavior of the generalist pentatomid predator Podisus maculiventris when offered lepidopteran larvae infected with an entomopathogenic fungus

To understand the practical application of entomopathogenic fungi and predatory insects in an integrated pest management program, it is necessary to investigate the compatibility of biocontrol agents occupying the same niche. The objectives of our research were to understand the response behavior of the predatory spined soldier bug, Podisus maculiventris (Say) (Hemiptera: Pentatomidae) exposed to volatiles from the entomopathogenic fungus Beauveria bassiana (Bals.-Criv.) Vuill. (Hypocreales: Cordycipitaceae). We assessed the predator’s behavior when presented with B. bassiana-infected lepidopteran prey and determined the volatile profile of B. bassiana spores. Choice behavior of P. maculiventris nymphs towards B. bassiana-infected (non-sporulating and sporulating) versus uninfected larval fall armyworm, Spodoptera frugiperda (J. E. Smith) (Lepidoptera: Noctuidae), was determined in choice arenas. The predator nymphs more frequently chose the uninfected prey and avoided fungus-infected prey. Of five P. maculiventris nymphs that fed on non-sporulating fungus-infected prey, four molted to adulthood, and the time required to molt to adult was similar to that of nymphs that fed on uninfected prey. In Y-tube olfactometer choice assays, 65% of the nymphs (26/40) avoided potato dextrose agar plugs containing B. bassiana and preferred clean agar plugs. Gas chromatography-mass spectrophotometry analysis showed that the primary volatile chemicals emitted from B. bassiana spores were 2-ethylhexanol and 2-methyl-1-butanol. Applications of B. bassiana combined with releases of P. maculiventris may be a viable option for pest management in the field.