Defensive compounds of <i>Blissus pulchellus</i> (Hemiptera: Blissidae) as a barrier against infection by entomopathogenic fungi

Abstract Defensive secretions produced by certain hemipterans are known to deter natural enemies and play a crucial role in reducing microbial infections. In this study, we investigated the protective mechanisms of the chinch bug Blissus pulchellus against entomopathogenic fungi and we explored the relationship between the major volatile compounds produced by B. pulchellus and their potential role in enhancing its resilience to disease. Both adults and nymphs exhibited low susceptibility to infection by various strains of Metarhizium anisopliae and Beauveria bassiana . The close and continuous contact of conidia with antimicrobial substances on the insect's integument significantly inhibited germination rates. Conidia washed from insects after 4 h of contact with their integument exhibited germination rates of less than 20% on culture media. Chemical analyses of body extracts from adults and nymphs revealed both qualitative and quantitative differences in their defensive compound profiles. Our findings suggest that the aldehydes are the primary compounds responsible for fungal inhibition, effectively protecting the insect from infection. Identifying fungal strains capable of overcoming the fungitoxic compounds produced by B. pulchellus is crucial for advancing mycopesticide development to manage chinch bug populations in pastures.