Repellent effects of insecticides on Stephanitis pyrioides Scott (Hemiptera: Tingidae) under laboratory conditions

Abstract

Stephanitis pyrioides Scott (Hemiptera: Tingidae) is an important insect pest of azalea plants (Rhododendron L. spp.) in the USA. The use of neonicotinoids in landscapes has been reduced because of consumer perceptions that they are not pollinator friendly. The reductions are due mostly to changes in the labels that restrict times these materials can be applied to ornamental plants based on plant phenology and bloom period. Pest management can be improved by using insecticides that repel S. pyrioides. A series of non-contact and contact laboratory assays were conducted with adult S. pyrioides to determine the repellency of insecticides. Insecticides with various modes of action were included in the assays. During the non-contact assay, significantly more S. pyrioides individuals were collected away from the insecticide source than closer to the source when cyfluthrin, bifenthrin, dinotefuran, clothianidin, cyclaniliprole and novaluron were used. During the contact assay, the number of visits was significantly lower for thiamethoxam, lambda-cyhalothrin + bifenthrin + imidacloprid, permethrin, tebufenozide and spinosad treatments than for dinotefuran, azadirachtin, spirotetramat and Chromobacterium subtsugae strain PRAA4-1 T. The adults spent significantly less time on leaves treated with cyfluthrin, permethrin and pyriproxyfen than the other treatments. In a mortality assay performed after 4 h of exposure, significantly more dead adults were found associated with acetamiprid, dinotefuran, thiamethoxam and flupyradifurone compared to chlorantraniliprole, cyantraniliprole, cyclaniliprole, azadirachtin, afidopyropen and flonicamid. After 24 h of exposure, a significantly lower number of fecal spots was observed in the acetamiprid, dinotefuran, thiamethoxam, flupyradifurone, lambda-cyhalothrin, cyantraniliprole, cyclaniliprole, pyrifluquinazon and afidopyropen treatments than chlorantraniliprole and azadirachtin.