Sublethal pesticide exposure improves resistance to infection in the Asian corn borer

Abstract

1. Diverse environmental factors contribute to the evolution of host immunity and host–parasite interactions. However, the effect of insecticides on the insect immune system is less well understood.2. This study investigated the variation in haemocyte density, phenoloxidase (PO), and total PO activities in the Ostrinia furnacalis larvae following sublethal treatment of tebufenozede and their susceptibility to Escherichia coli infection.3. Surprisingly, it was found that O. furnacalis larvae exposed to the insecticide have significantly higher haemocyte density, and active and total PO activities than those not exposed. Moreover, when infected with E. coli, O. furnacalis larvae treated with tebufenozide survive much better with lower bacterial load than those not treated.4. This study demonstrates that insecticide may change the immunity of insects and potentially have an impact on their interactions with parasites.