Residual activity of insecticides against adult Systena frontalis (Coleoptera: Chrysomelidae) under semi-field conditions.

Systena frontalis (Fabricius) (Coleoptera: Chrysomelidae) is a serious insect pest in nursery production. Insecticides are an important control tactic for S. frontalis adults to reduce economic losses associated with its injury. Because densities and activity of S. frontalis adults are influenced by many biotic (e.g., adult emergence timing) and abiotic (e.g., fluctuating temperatures) factors in the nurseries, it is challenging to reliably determine the efficacy and residual activity of insecticides under field conditions. Thus, the objective was to determine the residual activity of common and alternative insecticides on adult S. frontalis under semi-field conditions. Field-collected S. frontalis adults were exposed to 0-, 7-, 14-, and 21-d-old, field-aged residue of 13 insecticides applied on panicled hydrangea (Hydrangea paniculata Siebold) shoots and maintained in the field. The fresh residues of tetraniliprole, cyclaniliprole, and sulfoxaflor + spinetoram were the most effective against S. frontalis adults, whereas only tetraniliprole and cyclaniliprole elicited evidence of efficacy when their residues were aged for a week. Fourteen- and 21-d-old residues of tetraniliprole were still effective on S. frontalis adults and reduced the injury. Based on the results, tetraniliprole, cyclaniliprole, and sulfoxaflor + spinetoram were effective for immediate management, cyclaniliprole can provide short-term efficacy, and tetraniliprole provides longer-term efficacy.