Response of Doru luteipes (Dermaptera: Forficulidae) to insecticides used in maize crop as a function of its life stage and exposure route

Abstract

The present study aimed to evaluate insecticide toxicity to Doru luteipes (Scudder), a major predator of corn pests. Lethal (reduction in survival) and sublethal effects (prey consumption, adult tibia length and walking distance) of compounds were assessed on earwig nymphs and adults. Insects were exposed to the compounds through contact (exposure to insecticide residue on corn leaves) and ingestion (consumption of insecticide-treated prey) routes. Tested insecticides included a biopesticide (Spodoptera frugiperda multiple nucleopolyhedrovirus - SfMNPV), and modern (flubendiamide and metaflumizone) and older neurotoxins (imidacloprid + β-cyfluthrin). The imidacloprid/β-cyfluthrin mix was highly toxic (100% mortality) to the predator, regardless of the exposure route and predator stage. Metaflumizone caused mortality superior to 95% and 45% of nymphs and adults, respectively. Flubendiamide and SfMNPV were the least toxic compounds, not differing from the untreated control in any of the assessed endpoints. Adult tibial length did not differ among treatments. Overall, the insecticides caused a more pronounced effect on D. luteipes nymphs than on adults and were more toxic by the contact route. From these findings, flubendiamide and SfMNPV are safer for D. luteipes and should head insecticide choice in integrated pest management programs in corn.