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United States Department of Agriculture

Agricultural Research Service

Title: Suspected Resistance to Amitraz by Varroa

Authors
item Elzen, Patti
item Baxter, James
item Wilson, William

Submitted to: American Bee Research Conference Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: April 1, 1999
Publication Date: N/A

Technical Abstract: Laboratory and field tests were conducted to measure amitraz efficacy in controlling the honey bee parastic mite, Varroa jacobsoni. The laboratory test involved the use of a single concentration of technical grade amitraz that was expected to kill 90% of exposed Varroa in a 24-hour period. The field test used formulated amitraz, impregnated into plastic strips, inserted into 51 bee hives; mortality was assessed by numbers of mites dropping onto sticky boards placed on the bottom of the hives. Results of the lab tests showed only ca. 33% mortality of mites tested, significantly less than the expected 90% mortality. The field test also showed decreased efficacy of amitraz with only ca. 70-80% mortality; previous experience with amitraz in the field was greater than 95% mortality. From these results it can be seen that at least one population of Varroa is beginning to show signs of amitraz tolerance.

Last Modified: 10/30/2014
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