Selectivity of insecticides to Harmonia axyridis (Coleoptera: Coccinellidae) under field and laboratory conditions
Tederson Luiz Galvan, email@example.com, Robert Koch, firstname.lastname@example.org, and William Hutchison, email@example.com. University of Minnesota, Department of Entomology, 219 Hodson Hall, 1980 Folwell Avenue, St. Paul, MN
The success of conservation biological control, particularly in agricultural systems, may depend on the selectivity of insecticides to natural enemies. Insecticide with new modes of action and narrow spectrum of activity, such as spinosad and indoxacarb, may be valuable for using in conjunction with biological control. Toxicity of insecticides to Harmonia axyridis (Coleoptera: Coccinellidae) was evaluated under field and laboratory conditions. In an in-field sweet corn trial, the abundance of H. axyridis was recorded following multiple applications of spinosad, indoxacarb, carbaryl, chlorpyrifos, bifenthrin, and lambda-cyhalothrin at labeled field rates. Larvae were more abundant than adults in the sweet corn field. Adults and larvae were more abundant in plots treated with spinosad than in plots treated with other insecticides. In a laboratory topical assay, the acute toxicity of the same insecticides was evaluated for eggs, first and third instars, pupae, and adults. Spinosad and indoxacarb were less toxic than carbaryl, bifenthrin, lambda-cyhalothrin, and chlorpyrifos to eggs, third instars, and adults. All of the tested insecticides, except spinosad, were highly toxic to first instars. Spinosad, indoxacarb, and carbaryl were not toxic to pupae. Sublethal effects of spinosad and indoxacarb were evaluated for first instars and mated adult females. Spinosad and indoxacarb showed chronic toxicity to H. axyridis. Spinosad and indoxacarb showed a reduction in the negative impacts on these predators in the field and topical assays. However, these insecticides may have sublethal effects on H. axyridis.
Species 1: Coleoptera Coccinellidae Harmoniaaxyridis (multicolored Asian lady beetle) Keywords: conservation biological control