New Zealand Journal of Crop and Horticultural Science abstracts
Development of resistance to fenvalerate in Helicoverpa armigera
(Lepidoptera: Noctuidae) in New Zealand
P. J. CAMERON
G. P. WALKER
T. J. B. HERMAN
New Zealand Institute of Crop & Food
Research Limited
Private Bag 92169
Auckland, New Zealand
Abstract A programme to monitor
Helicoverpa armigera
(Hübner) for resistance to fenvalerate was initiated in 1991. Bioassays
that exposed individuals to insecticide residues in glass vials were carried
out on pheromone-trapped adults and on F1 larvae reared from insects collected
in the field. These assays assessed changes in susceptibility to fenvalerate
during each cropping season and from year to year.
H. armigera for
assays were collected from processing tomato, sweet corn, and lucerne crops,
mainly from the Gisborne and Hawke's Bay regionsof New Zealand. Comparison of
LD50s showed significant increases in resistance of 69-fold for adults and
47-fold for third instar larvae within a season. A diagnostic dose of 1 ug
(LD95 for susceptible populations) showed a significant trend of declining
mortality from 1992 to 1994 for adults, but trends were unclear for larvae.
Assays with a diagnostic dose of 10 ug (LD99 for susceptible populations)
showed decreasing mortality from 1992 to 1994, and at 90 ug c. 1% survival of
field-collected adults was detected in 1994. Comparison with Australian data
and lack of control failure suggests that New Zealand populations are still
widely susceptible to the insecticide, but that the frequency of resistance to
pyrethroids is increasing. A reduction in the rate of decrease in
susceptibility within the 1994 cropping season suggests that integrated pest
management procedures have reduced selection for fenvalerate resistance in
H. armigera.
Keywords insecticide resistance; Helicoverpa armigera;
fenvalerate; bioassays; tomatoes; sweet corn; lucerne; integrated pest
management
New Zealand Journal of Crop and Horticultural Science, 1995, Vol. 23:
429-436
0114-0671/95/2304-0429 $2.50/0 (c) The Royal Society of New Zealand
1995
PDF file of entire paper: medium quality (584K); (scanned from paper original: notes about this process)
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