Non-target effects of two insecticidal sunflower seed treatments on Orius insidiosus and Chrysoperla carnea

Abstract

The use of systemic insecticides as seed treatments is generally considered safer for natural enemies than other modes of application. However, the potential for contamination of plant products, such as extrafloral nectar, has raised concern about the possible impacts of these products on non-target organisms, because many beneficial insects use these products to supplement their diet. Therefore, the aims of the present study were to assess whether either chlorantraniliprole or thiamethoxam cause negative effects on the development and reproduction of (1) Orius insidiosus (Say) (Hemiptera: Anthocoridae) or (2) Chrysoperla carnea (Stephens) (Neuroptera: Chrysopidae) when various life stages of these predators are exposed to sunflower seedlings grown from seed treated with these insecticides. Thiamethoxam caused both lethal and sublethal effects on O. insidiosus, whereas chlorantraniliprole was not lethal to any life stage, although sublethal effects were evident. The nymphal stage was most susceptible and insecticidal toxicity diminished with plant development. In C. carnea, both chlorantraniliprole and thiamethoxam adversely impacted adults when they fed on extrafloral nectar of seedlings grown from treated seed. These insecticides reduced adult survival and female fecundity, especially thiamethoxam. Offspring of chlorantraniliprole-exposed adults had lower survival than those of controls. Both chlorantraniliprole and thiamethoxam had no effect on any life history parameter of C. carnea when larvae were exposed to sunflower seedlings grown from treated seed, but the sex ratio of resulting adults was lower in the thiamethoxam treatment than in the chlorantraniliprole treatment.