Effects of microbial, organically acceptable, and reduced risk insecticides on Anthonomus signatus (Curculionidae: Coleoptera) in strawberries (Fragaria × ananassa)

Anthonomus signatus, the strawberry bud weevil, is active in early spring coinciding with the bloom period of host plants and when managed and unmanaged pollinators are active. Female A. signatus cause injury to the host plant during egg laying when they deposit a single egg inside an unopened flower bud and then girdle or “clip” the bud at the pedicel. Past efforts to control A. signatus populations have relied on the use of broad spectrum insecticides. Fields are either treated at the first signs of damage, or precautionary treatments may be applied prophylactically in fields with a history of damage. Because A. signatus damage occurs during bloom, there is concern about the potential harm to pollinators caused by these treatments. In order to identify materials more compatible for use during bloom, the efficacy of reduced risk pesticides against A. signatus was tested in semi-field bioassays over two years. Beauveria bassiana, cyantraniliprole, novaluron, and pyrethrins were assessed in the first year, and none caused significant A. signatus mortality. Acetamiprid, flonicamid, and spinosad were compared in the second year, acetamiprid and spinosad had higher A. signatus mortality than an untreated control, and exposure to spinosad resulted in similar mortality to bifenthrin, an industry standard material.