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Title: Insecticide resistance management in B-biotype Bemisia tabaci
Authors: Gunning, Robin
Keywords: silverleaf whitefly
B-biotype Bemisia tabaci
disease of cotton
toxicological, biochemical molecular and genetic techniques
resistance insecticide management strategies
piperonyl butoxide synergism
insect growth regulators
Issue Date: 30-Jun-2005
Publisher: NSW Department of Primary Industries
Series/Report no.: ;DAN162C
Abstract: The silverleaf whitefly, B-biotype Bemisia tabaci, first detected in Australia in 1999, has become a major pest on cotton in central Queensland. The silverleaf whitefly is also found, albeit in low numbers, in most other cotton districts in Australia. The silverleaf whitefly represents a considerable threat to cotton production in Australia. The objectives of this project were: • To monitor whitefly species distribution on cotton. • To use toxicological, biochemical molecular and genetic techniques to continue investigate insecticide resistance mechanisms in B-biotype B. tabaci. • To continue a resistance monitoring programme for B- biotype, B. tabaci. • To devise and test resistance insecticide management strategies for management of Bemisia tabaci in Australia. The project has tracked the expansion of silverleaf whitefly into most cotton areas of New South Wales and Queensland. Resistance monitoring has exposed serious insecticide resistance problems in the silverleaf whitefly, including resistance the insect growth regulators. Studies have demonstrated cross-resistance between the two insect growth regulators that have been used on cotton in Australia. Resistance mechanism and synergism studies, however, have provided the means to overcome most resistances in the silverleaf whitefly. The research project has been an instrumental part of the central Queensland, silverleaf whitefly, resistance management strategy, which, so far, has prevented “sticky cotton” problems. Major Outputs of this project have been: • Results of this project have given a knowledge of the distribution and abundance of whitefly species on cotton in Queensland and New South Wales. While the silverleaf whitefly has expanded into most cotton areas, data show that Greenhouse whitefly, silverleaf whitefly and native B. tabaci can co-exist on cotton. • Insecticide resistance levels in the silverleaf whitefly can be very high and resistance is easily selected for, thus emphasising the need to rotate chemistry. Resistance to the insect growth regulator pyriproxyfen is of particular concern, because of the industry’s dependence on use early season, to prevent silverleaf whitefly population build-ups Post insect growth regulator use, pyriproxyfen resistance levels are so high, as to suggest that consecutive generations of silverleaf whitefly are receiving pyriproxyfen. It is therefore likely that the threshold based initiation of pyriproxyfen use, is giving a longer use period in the area than is desirable. In 2004, post insect growth regulator use, pyriproxyfen resistance was extreme and coincided with reports of poor control at Emerald.. Piperonyl butoxide synergism studies with pyriproxyfen, however, showed complete suppression of resistance and piperonyl butoxide synergism may become a very valuable tool in prolonging the life of pyriproxyfen on cotton. 24 • This project has also developed technology for more effective insecticide synergism in the field, for the control of resistant silverleaf whitefly. Using our patented concept (Gunning, R. V and Moores, G. D. Method and Composition for Combating Pesticide Resistance UK Patent no. 0309773.0, PCT/GB2003/001861),of microencapsulation of insecticides to delay insecticide release until piperonyl butoxide has effectively inhibited the esterase enzymes causing resistance, we have been able to overcome resistance. Field trials demonstrated outstanding control with pyrethroids, against highly resistant silverleaf whitefly. This resistance control technology can be applied to a number of esterase mediated resistances in the silverleaf whitefly, such as insect growth regulators, imidacloprid, the pyrethroids will lead to greatly improved control options for the silverleaf whitefly.
Appears in Collections:2005 Final Reports

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