Imidacloprid Movement into Fungal Conidia is Lethal to Mycophagous Beetles

Abstract

O_LIApplications of systemic pesticides can have unexpected direct and indirect effects on nontarget organisms, producing ecosystem-level impacts. C_LIO_LIWe investigated whether a systemic insecticide (imidacloprid) could be absorbed by a plant pathogenic fungus infecting treated plants and whether the absorbed levels were high enough to have detrimental effects on the survival of a mycophagous beetle. Beetle larvae fed on these fungi were used to assess the survival effects of powdery mildew and imidacloprid in a factorial design. Fungal conidia were collected from treated and untreated plants and were tested for the presence and concentration of imidacloprid. C_LIO_LISurvival of beetles fed powdery mildew from imidacloprid-treated leaves was significantly lower than that of beetles from all other treatments. C_LIO_LIImidacloprid accumulated in fungal conidia and hyphae was detected at levels considered lethal to other insects, including coccinellid beetles. C_LIO_LIWater-soluble systemic insecticides may disrupt mycophagous insects as well as other nontarget organisms, with significant implications for biodiversity and ecosystem function. C_LI