Comparison of applying multiple pesticide within generation or in alternating generations
Simulation models were used to evaluate whether the application of multiple pesticides within the generation or in alternating generations is the optimal management strategy to retard the appearance of insecticide-resistant insect pests. A series of simulations involving multiple insecticides, mating behavior of insect pest accompanying migration, and the timing of exposure to insecticides showed that application within generation is often more effective in delaying the development of resistance. Currently, verification experiments are being conducted to determine whether the simulation results are actually effective in the field. It is expected that this study will contribute to the usage standard of pesticides that delays longer and more effectively the resistance of insect pests to the existing or coming active components.
- When the same pesticide (insecticide) is used continuously, resistant insect pests in which the insecticide has no effect will appear and eventually account for the majority. Different action mechanisms are required for controlling resistant pests. However, developing insecticides usually requires huge amount of time and cost, so it is essential to develop a technology that utilizes active components longer and effectively for addressing the pesticide resistance.
- Past theoretical studies have advocated two different combination methods: the application of multiple insecticides within the generation of the main pest (mixture use or pyramiding), and the application in alternating generations using different insecticides for each generation (rotation).
- Therefore, the research group from the Institute for Agro-Environmental Sciences, NARO (NIAES) performed a series of simulations involving multiple insecticides, mating behavior of insect pest accompanying migration, and the timing of exposure to insecticides in order to determine which method can reduce the development of pesticide resistance over a longer period of time. It is clearly evident from the results that application within the generation is more effective in delaying the development of resistance in many cases than currently popular method of application in alternating generations.
- For example, in a simulation using Lepidopteran insect pests, where the insecticides are used only to larvae and adults experience the inter-patch migration before mating, application of two kinds of insecticides within the generation can delay the development of resistance from several to 100-fold as compared to application in alternating generations.
- This result was published on November 2, 2017 in the online edition of the international scientific journal Evolutionary Applications.
- Currently, verification experiments are being conducted to determine whether the simulation results are actually effective in the field. It is expected that this study will contribute to the development of active components of pesticides that delays the occurrence of resistance longer and more effectively.
- Sudo M, Takahashi D, Andow DA, Suzuki Y, Yamanaka T (2017) Optimal management strategy of insecticide resistance under various insect life histories: heterogeneous timing of selection and inter-patch dispersal. Evolutionary Applications
- Takahashi D, Yamanaka T, Sudo M, Andow DA (2017) Is a larger refuge always better? Dispersal and dose in pesticide resistance evolution. Evolution 71: 1494-1503
Application of multiple insecticides with different action mechanisms within generation and alternating generations of insect pests.
Summary of the simulation results, showing the optimal management strategies which maximize the waiting time to the resistance development (resistance-allele-frequencies > 0.5) in the variety of insect life-history components and pest control regimes.