Reduction of the dependence on organophosphorus pesticides to control insect pests of apple in the post-bloom stage

Project Code : BPI06-330

Project Lead

Gérald Chouinard - Institut de recherche et de développement en agroenvironnement

Objective

To isolate and formulate a pheromone for use in traps for monitoring plum curculio

Summary of Results

In Canada, current programs for controlling the most harmful pests to apples rely on the use of organophosphorus insecticides. These are indispensable tools in apple production throughout Canada, but because of the associated health and environmental risks, their use must be reduced, while at the same time ensuring that this does not compromise the future of this horticultural crop.

The purpose of this project is to develop a strategy to control insect pests of apples in the post-bloom stage, based on a combination of a new approach to watching for plum curculio and a real-time decision support system for insecticide intervention. Post-bloom insecticide applications are still used preventively and systematically, mainly because there is no reliable and effective way to detect the plum curculio - the main enemy of apple trees - at this point.

The main component of the new detection method involves the use of a pheromone (grandisoic acid) that attracts the plum curculio. Using this pheromone in insect traps would help to better estimate the number of plum curculios, and thereby to decide on the proper treatment only when the population sizes so warrant, which would avoid sometimes unnecessary preventive treatments with organophosphorus insecticides.

One of the main objectives of this project is to isolate the plum curculio pheromone, identify its chemical structure, and measure its effectiveness through laboratory tests.

The attractive properties of grandisoic acid, the main component of the plum curculio, have been tested in laboratories with an olfactometer. The grandisoic acid was obtained through chemical synthesis and divided into its two components (enantiomer + and enantiomer -). Tests were conducted to determine the optimal attraction concentration of enantiomer + (the pheromone's bioactive component). At the doses tested, grandisoic acid enantiomer + did not change the behaviour of the male and female plum curculio, and no preference was noted when the adults were exposed to the pheromone blending different proportions of the bioactive enantiomer.

The process of separating the two enantiomers is currently underway, and once the purified form of the pheromone is obtained, testing in the laboratory and orchards will proceed to clarify the roles of the two components (enantiomer + and -) of the plum curculio pheromone. In addition, identifying the secondary components of the pheromone released by the males (which could be tested mixed with grandisoic acid) could be a way to develop an effective trap for catching plum curculios.

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