New Zealand Journal of Crop and Horticultural Science abstracts

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Base levels of resistance to common control compounds by a New Zealand population of Varroa destructor

R. M. GOODWIN
M. A. TAYLOR
H. M. MCBRYDIE
H. M. COX

The Horticulture and Food Research Institute
 of New Zealand Limited
Private Bag 3123
Hamilton, New Zealand
email: mgoodwin@hortresearch.co.nz

Abstract  Base levels of Varroa destructor resistance to four synthetic chemicals were established in New Zealand during May through August 2003. The four chemicals-amitraz, coumaphos, flumethrin, and fluvalinate are currently used, or may in the future be registered for use, in New Zealand. Resistance was measured by placing mites on paraffin wax impregnated with the chemicals. The LC50 estimate, adjusted for natural mite mortality, for amitraz was 110 µg/g, and >200 µg/g for coumaphos, 12 µg/g for flumethrin, and 1269 µg/g for fluvalinate. A comparison with international data indicates that New Zealand populations are not currently resistant to flumethrin. The LC50 for two Italian locations with mites resistant to fluvalinate was 385 and 857 µg/g, and 16-17 µg/g for non-resistant varroa (Milani 1995). Whether the adjusted LC50 for fluvalinate in this trial (1269 µg/g) would be observed as resistance in the field in New Zealand is unknown. Because this is the first time these tests have been conducted in New Zealand it is not known whether this level of resistance was present when varroa arrived in New Zealand or whether it has since developed. 

Keywords  Varroa destructor; fluvalinate; flumethrin; amitraz; coumaphos; resistance

New Zealand Journal of Crop and Horticultural Science, 2005, Vol. 33: 347-352
0014-0671/05/3304-0347      © The Royal Society of New Zealand 2005

H04052; Online publication date 1 November 2005
Received 31 May 2004; accepted 11 July 2005
 
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