Comparisons of ecorational and chemical insecticides against crucifer flea beetle (Coleoptera: Chrysomelidae) on canola

Abstract

Studies were done comparing the insecticides SpinTor (spinosad), BotaniGard ( Beauveria bassiana ), Neemix (azadirachtin), and Surround (kaolin, a clay) with conventional chemical insecticides Capture (bifenthrin) and Helix XTra (thiamethoxam), all applied at seven rates in a 7-d assay to assess their impact on adult crucifer flea beetle, Phyllotreta cruciferae (Goeze) (Coleoptera: Chrysomelidae). Lethal time (LT) required for 25, 50, and 75% mortality (LT 25 , LT 50 , and LT 75 ) and relative potencies for the insecticide concentration groupings (0, 1X–1.5X, and 2X–4X) were estimated for each treatment by using survival functions. P. cruciferae mortality increased in response to increasing concentrations, especially for Helix XTra, Capture and SpinTor. After 2 d of exposure in 2002, mortality ranged from 54 to 78% for Helix XTra, from 60 to 94% for Capture, and from 66 to 92% for SpinTor across concentrations. In 2003, flea beetle mortality ranged from 37 to 60%, from 29 to 63%, and from 23 to 52% on exposure to Helix XTra, Capture, and SpinTor, respectively, for 2 d. The LT 50 and relative potencies of the insecticides were in the order of Helix XTra, Capture, and SpinTor > BotaniGard, Neemix, and Surround. In 2002, LT 50 values were 1 and 2 d for Capture and SpinTor, 2 d for BotaniGard, and 3 d for Neemix and Surround. In 2003, LT 50 values occurred between 2 and 4 d after exposure to Helix XTra, Capture, and SpinTor, with LT 50 values of 5–7 d on exposure to BotaniGard, Neemix, and Surround. SpinTor seems to be a suitable ecorational insecticide in canola, Brassica napus L., for P. cruciferae management.