New Zealand Journal of Crop and Horticultural Science
abstracts
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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