Ecological risk assessment of the effects of neonicotinoid insecticides on northern bobwhites (<i>Colinus virginianus</i>) in the South Texas Plains Ecoregion

Abstract

Abstract Neonicotinoid insecticides are among the latest class of insecticides that can have harmful effects on birds. Approximately 30 000 kg of neonicotinoid insecticides are applied annually to 429 100 ha of row-crop fields within the South Texas Plains Ecoregion, Texas, USA. Various studies have demonstrated that treated seeds can be highly toxic to northern bobwhites, with the consumption of only 20 corn seeds causing a fatality. Similarly, other studies have indicated that neonicotinoid insecticides can reduce arthropod populations—a substantial prey base for northern bobwhites, especially during the breeding season—by approximately 60%. Our objective was to conduct an ecological risk assessment of neonicotinoid insecticides' impact on northern bobwhite (Colinus virginianus) populations in the South Texas Plains Ecoregion. We estimated that juvenile and adult northern bobwhites could intake from 7.32 to 27.0 mg/kg/day and from 10.0 to 37.5 mg/kg/day of neonicotinoid insecticides, respectively, which can cause adverse effects on growth, reproductive output, and long-term survival. Our study determined that the application of 30 000 kg of neonicotinoid insecticides annually in the South Texas Plains Ecoregion harms the region's northern bobwhite that are exposed to neonicotinoids. Integr Environ Assess Manag 2022;18:488-499. © 2021 SETAC KEY POINTS Approximately 30 000 kg of neonicotinoids are applied annually on row crop fields in the South Texas Plains Ecoregion, USA. Juvenile and adult northern bobwhites could intake from 7.3 to 27.1 mg/kg/day and from 10.1 to 37.6 mg/kg/day of neonicotinoids a day, respectively. Treated seeds contain a high concentration of neonicotinoids. Through the consumption of treated seeds and other contaminated food, bobwhites are expected to reach LOAEL levels for five adverse effects.

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