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).
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
The influence of post-treatment temperature on the toxicities of two
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
If you would like to access a searchable archive of the all the previous Mich-Organic listserv postings copy this URL and paste in your browser address field http://list.msu.edu/archives/mich-organic.html