Methods for High‐Throughput Screening of Novel Plant Protection Agents Against the Maize Pest, Diabrotica virgifera virgifera (Coleoptera: Chrysomelidae)

ABSTRACT The western corn rootworm, Diabrotica virgifera virgifera , poses a significant threat to maize production in North America and Europe. With recent bans on key insecticides and concerns about overuse of remaining options, there is an urgent need for the development of novel, effective, and little disruptive crop protection agents. This requires accessible and comparable screening methods. We propose comparative high‐throughput screening methods against the eggs, larvae, and adults of this pest, emphasizing the importance of suitable positive controls tailored to the specific bioassay types. We evaluated seven common insecticides (imidacloprid, clothianidin, acetamiprid, novaluron, cypermethrin, chlorpyrifos‐methyl, and spinosad) against eggs, larvae, and adults as potential positive controls for each of the proposed assay methods. Dipping assays with ready‐to‐hatch eggs revealed several ingredients to cause mortality, but imidacloprid and clothianidin might be most suitable due to a robust concentration‐response in reducing egg hatching as well as causing mortality of hatching neonates. Larval bioassays using artificial diet overlays revealed mortality caused by all insecticides, with imidacloprid exhibiting best mortality response curves as well as sublethal effects. Adult bioassays using artificial diet‐core overlays revealed mortality caused by all insecticides tested, with acetamiprid exhibiting best mortality response curves. The provided lethal concentrations of each insecticide, as well as equations for concentration‐response models, offer insights for researchers in selecting appropriate positive controls for screening new crop protection agents or assessing resistance levels against different life stages of this pest.