Substitutes for Pupae busting - targeting larvae moths
Abstract
The Australian cotton industry depends heavily on genetically engineered Bt cotton (currently in the form of Bollgard II®) which provides resistance to the key pests of cotton, larvae of the moths Helicoverpa armigera and H. punctigera. Bt cotton has enabled substantial reductions in the use of insecticides, provided greater flexibility on cotton farming systems, and made the crop easier to grow. However, as with most pest management tactics, there is potential for the pests to develop resistance, and to counter this the Australian cotton industry has developed comprehensive Resistance Management Plans (RMPs), observance of which is mandatory for growers of Bt cotton.
A traditional component of RMPs, dating from resistance management of conventional insecticides, is pupae busting, or cultivation of the soil to destroy overwintering (and potentially resistant) pupae. However, pupae busting incurs financial, agronomic and environmental costs. It restricts the implementation of minimum tillage techniques which can help prevent erosion, conserve soil moisture and enhance soil carbon. Moreover, we have demonstrated through modelling studies in this project that in modern Bt cotton systems, with high fruit retention and early maturation, many potentially resistant insects are emerging before overwintering diapause is initiated, and are thus not vulnerable to pupae busting. There is a need to develop tactics for RMPs that can fill this gap.
One potential tactic is to target moths instead of pupae, using the attract-and-kill technology Magnet® which was developed by the researchers in this project during early work in successive Cotton CRCs. Magnet® consists of a mixture of plant volatile compounds which, when combined with small quantities of insecticide, can attract and kill adult Helicoverpa spp. moths. It has impacts beyond the area in which it is applied, but with careful placement it might be able to kill proportionately more potentially resistant moths from cotton than susceptible moths from refuge crops and other sources, thereby enhancing the genetic dilution effect provided by refuge crops which are another component of RMPs. A farm scale trial conducted during this project indicated the feasibility of this approach, and helped develop techniques to be used in a larger, area-wide trial of the approach to be conducted over the next three years. If successful, this trial could lead to the development of more robust RMPs, and the reduction of elimination of the requirement for pupae busting.
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- 2012 Final Reports
CRDC Final reports submitted 2012