Insecticide resistance and cross-resistance development in Colorado potato beetle Leptinotarsa decemlineata Say (Coleoptera: Chrysomelidae) populations in Canada 2008-2011.
Scott, I.M., Tolman, J.H., and MacArthur, D.C. (2015). "Insecticide resistance and cross-resistance development in Colorado potato beetle Leptinotarsa decemlineata Say (Coleoptera: Chrysomelidae) populations in Canada 2008-2011.", Pest Management Science, 71(5), pp. 712-721. doi : 10.1002/ps.3833 Access to full text
Background: A survey of insecticide resistance in over 150 Canadian populations of Colorado potato beetle was completed between 2008 and 2011. Three neonicotinoid and two anthranilic diamide insecticides were tested at a discriminating concentration (DC) with second-instar larvae in a leaf-disc bioassay. Results: The mean mortality for the imidacloprid (Admire) DC was 46–67% between 2008 and 2011 respectively. Over the 4 years, 10–46% and 26–40% of the populations were classified as resistant or showed reduced susceptibility to imidacloprid. The mean mortality for thiamethoxam (Actara) and clothianidin (Poncho/Titan) ranged from 56–76% in 2008 to 81–84% in 2010 for each insecticide respectively, indicating continuous susceptibility to clothianidin but reduced susceptibility to thiamethoxam. In 2008 and 2009, susceptibility to chlorantraniliprole (Coragen) was observed in 85% of populations. Similarly, cyantraniliprole (Cyazypyr) affected 93% of the 2009 and 74% of the 2010 populations. There was a significant (P < 0.05) and high positive correlation (R = 0.4–0.84) between the three neonicotinoids, indicating the potential for cross-resistance. Conclusions: The trend observed in decreasing susceptibility for thiamethoxam and clothianidin will continue unless resistance management practices are followed.
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