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Please note this concern for resistanct to two organically allowed pesticides (pyrethroid as a natural botanical pesticide) is restircted (allowed following NOP rule)and Spinosad (allowed). If you have expereince with this insect pest or these pesticides please reply to the [log in to unmask] and to Tony Shelton from Cornell University at [log in to unmask] Sincerely, Vicki Morrone ________________________________ From: Tony Shelton [mailto:[log in to unmask]] Sent: Tuesday, July 22, 2008 11:04 PM To: Great Lakes Vegetable WG Subject: Resistance in ECB Has anyone done tests to determine if European corn borer is becoming resistant to pyrethroids and spinosad? A local extension educator in New York says that his sweet corn farmers are telling him that they are experiencing resistance. A few years ago we published a paper that indicated a dramatic decrease in efficacy for pyrethroids and spinosad against ECB with increased temperature after some growers claimed 'resistance'. So now we are wondering if anyone has done some actual lab test for resistance. Musser, F. P and A. M. Shelton. 2005. The influence of post-treatment temperature on insecticides to Ostrinina nubilalis. Pest Management Sci. 61:508-510 Abstract: The influence of post-treatment temperature on the toxicities of two pyrethroids (lambdacyhalothrin and bifenthrin), a carbamate (methomyl) and a spinosyn (spinosad) to Ostrinia nubilalis (H¨ubner) larvae was evaluated in laboratory assays. From 24 to 35 ?C, the toxicities of the pyrethroids decreased 9.5- and 13.6-fold while spinosad toxicity decreased 3.8-fold. The toxicity of methomyl did not change significantly. The results demonstrate that the most effective insecticide against a pest may vary with environmental conditions. In situations where comparable products frommultiple insecticide classes are available, temperature should be included as a factor in the decision-making process. -- --- Tony Shelton: [log in to unmask] Professor, Department of Entomology International Professor; Associate Director International Programs Cornell University/NYSAES, 630 W. North St., Geneva NY 14456 PH 315 787-2352 FAX 315 787-2326 http://www.nysaes.cornell.edu/ent/faculty/shelton/index.html If you would like to access previous postings to the Mich-Organic listserv you can copy and paste the following URL into your browser address bar http://list.msu.edu/archives/mich-organic.html