|Spivak, Marla - UNIV. OF MN - ST. PAUL|
Submitted to: American Bee Journal
Publication Type: Popular Publication
Publication Acceptance Date: March 10, 1999
Publication Date: N/A
Technical Abstract: In late 1998, we initiated studies to investigate control of fluvalinate resistant Varroa (Varroa jacobsoni Oud.). A field test was conducted using plastic strips of Apistan, coumaphos or amitraz. Results showed that Apistan was completely ineffective, with an 89% increase in population after the treatment period. Coumaphos provided excellent control, with 97% %reduction of the populations tested. Amitraz, however, provided only 75% reduction of the population tested, significantly less than the expected 95% reduction seen in previous studies. A laboratory test conducted with amitraz on this Varroa population confirmed that these mites were beginning to show resistance to amitraz. This is the first known case of amitraz resistance of Varroa in North America.