Potential for a biopesticide bait to control black beetle, Heteronychus arator (Coleoptera: Scarabaeidae)

Background: Yersinia entomophaga is an entomopathogenic bacterium that is active against scarab beetles, among other insects. In New Zealand, the African black beetle, Heteronychus arator (Coleoptera: Scarabaeidae), is a major pest of pastures and arable crops but very few control options exist and no insecticides are registered for use in established pastures. Results: In laboratory bioassays, H. arator adults were susceptible to a bait containing Y. entomophaga at low doses. This bait was more effective against H. arator adults during spring than autumn in small‐scale field plots (320 mm diameter). A large‐scale field trial (40 × 40 m plots) reduced adult numbers substantially: approximately twice as many beetles were captured in pitfall traps from untreated plots compared with plots treated with the Y. entomophaga bait at 70 kg ha−1. This single bait application in spring also reduced subsequent larval populations in summer. Conclusions: Heteronychus arator is a difficult pest to manage using chemical insecticides. This biopesticide with Y. entomophaga as the active ingredient offers a new solution for New Zealand pastures, with potential for application to other crops affected by H. arator and for control of other pests. © 2020 Society of Chemical Industry