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Modelling the impact of an insecticide treatment on codling moth populations
- Cormier, D., Pelletier, F., Chouinard, G., Vanoosthuyse, F., Joannin, R.
- Acta horticulturae 2017 no.1160 pp. 307-312
- Calypso, Cydia pomonella, acetamiprid, adults, apples, eggs, fruits, growers, heat sums, larvae, larvicides, methoxyfenozide, models, mortality, novaluron, orchards, pests, residual effects, thiacloprid, toxicity, toxicity testing
- Most codling moth development models are based on degree-days and adult catches obtained in orchards. These models accurately predict the first developmental stages of the codling moth but become imprecise in commercial orchards subjected to repeated applications of insecticides that affect the survival of the pest. In order to develop an interactive bio-climatic model for the development of codling moth populations in apple orchards, we conducted insecticide toxicity tests. Six insecticide treatments were applied topically to eggs and larvae, and mortality was assessed 7-10 days after application. The highest mortality rate of eggs on fruits (ca. 80%) was achieved with the neonicotinoids Assail (acetamiprid) and Calypso (thiacloprid). The growth regulators Intrepid (methoxyfenozide) and Rimon (novaluron) were the only other insecticides more toxic than the control, causing near 50% mortality, but only for eggs. As for larvae, the highest mortality rates (90 and 75%) were achieved with Delegate (spinetoram) and Intrepid, respectively. The Calypso, Altacor (chlorantraniliprole) and Assail treatments had a significant topical larvicidal effect when compared to the control, but the Rimon treatment did not. These data, combined with those evaluating the residual effects of the same insecticides on eggs and larvae, were implemented into an interactive platform included in the model. The platform allows the user to visualize the predicted impact of a specific insecticide treatment sprayed on codling moth populations. This model is available online and is used by more than one hundred apple growers and advisors.