Surveys for Resistance in Codling Moth Populations in Ontario

A codling moth (CM) insecticide-resistance survey in southwestern Ontario apple orchards found elevated levels of resistance to the organophosphate (OP) insecticide, Guthion, (azinphos-methyl) and the neonicotinoid, Calypso (thiacloprid).

Testing was conducted in 2008 on trapped male moths during the June and August flight periods. Sampling was conducted in Essex/Kent and Norfolk counties, with a total of 13 orchards surveyed. Male moths were attracted with pheromone lure-containing traps and captured on sticky sheets. The moth was dosed with either a solvent control or the technical grade insecticide.

The results of the survey indicated that OP and neonicotinoid resistance levels were higher in moths collected during the first flight in June in both regions. In several orchards, the OP's caused less than 10% mortality to treated moths. Abandoned orchard populations of CM were more susceptible to OP's and Calyspo with mortality typically greater than 90%.

Follow up studies with CM neonate larvae collected from both insecticide-managed and abandoned apple orchards will be used to confirm these results.

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