Species survey and testing of resistance to chlorpyrifos in Delia species in brassica vegetable growing areas in Canada

Project Code PRR15-020

Project Lead

Josée Owen    Agriculture and AgriFood Canada

Objective

(1) Survey the species of Delia flies found in vegetable Brassica crops across Canada, and determine which of these cause damage to the crop plants; (2) Survey chlorpyrifos resistance in Delia flies in vegetable Brassica growing regions across Canada

Vegetable Brassicas, such as cabbage, broccoli, cauliflower, and rutabaga, are grown in every province in Canada. The cabbage maggot, Delia radicum (Diptera: Anthomyiidae), is one of the most chronic and challenging pests attacking these crops.

The prevalence of other Delia species and their role in causing damage to these crops is relevant to Integrated Pest Management (IPM) decision-making. Species such as D. platura, D. floralis, D. planipalpis, and D. florilega have also been found in fields exhibiting cabbage maggot damage. Some are recognized as primary pests on certain crops while others move into damaged crops as secondary pests. The information about their regional distribution, however, is incomplete and largely outdated.

Chlorpyrifos is the only remaining insecticide registered in Canada for cabbage maggot control; however, insect resistance to this pesticide is increasing. In 2013, 75% of populations tested in British Columbia were found to be chlorpyrifos-resistant. The status of resistance in other provinces is unknown.

In this two-year project the team will establish provincial and grower-group partnerships and develop protocols for collecting specimens in the field. Specimens will be identified by using recently-revised taxonomic keys. Chlorpyrifos resistance will be determined by a series of toxicological bio-assays in the lab. Feeding studies will be carried out to assess which of the species present in a field also cause crop damage. The project will provide up-to-date information on the species involved in the cabbage maggot complex and the current status of chlorpyrifos resistance in all Brassica vegetable growing regions in Canada.

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