The 2005 ESA Annual Meeting and Exhibition
December 15-18, 2005
Ft. Lauderdale, FL

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Thursday, December 15, 2005 - 9:42 AM

Susceptibility of imidacloprid-resistant Colorado potato beetles to alternative insecticides

Andrei Alyokhin, andrei.alyokhin@umit.maine.edu1, Galen P. Dively, gd7@umail.umd.edu2, Matthew Mahoney, matt.mahoney@bayercropscience.com3, David Rogers,, and John Wollam, john.wollam@bayercropscience.com3. (1) University of Maine, Biological Sciences, 5722 Deering Hall, Orono, ME, (2) University of Maryland, Department of Entomology, 4112 Plant Sciences Building, College Park, MD, (3) Bayer Corporation, 4773 Sailors Retreat Rd, Oxford, MD, (4) Bayer CropScience, Product Development, P.O. Box 12014, Research Triangle Park, NC

Although insecticide mode of action rotation is a commonly recommended resistance management technique that is often adopted by growers, the repeated use of neonicotinoid insecticides in certain areas has resulted in geographically isolated hotspots of increased Colorado potato beetle tolerance to imidacloprid. In the laboratory we determined susceptibility of the imidacloprid-resistant Colorado potato beetles from a population in Southern Maine to other insecticides currently registered for use on potato. This population was about 30-fold resistant to imidacloprid and could not be effectively controlled by its applications. Resistant larvae exhibited significantly less mortality than susceptible larvae when exposed to concentrations of cyfluthrin, carbaryl, azinphosmethyl, and methamidophos. Their susceptibility to oxamyl was also somewhat reduced, although it did provide nearly 100% mortality at the highest concentration tested. Disulfoton was highly toxic to the resistant larvae. Oxamyl killed about 40% of the adults in greenhouse assays with potted potato plants, altered their feeding behavior (fewer adults up on plants), and reduced defoliation by more than 90%. Disulfoton was not lethal to adults, but significantly suppressed their feeding. In field trials with the resistant population, oxamyl and spinosad provided the best beetle control, distantly followed by disulfoton. Novaluron was somewhat of a disappointment, although it did reduce the number of large larvae. There was little difference between the plots treated with imidacloprid or thiamethoxam and untreated control, except for a slight delay in peak beetle abundance on treated plots.

Species 1: Coleoptera Chrysomelidae Leptinotarsa decemlineata (Colorado Potato Beetle)
Keywords: Neonicotinoids, Insecticide Resistance

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