Background

The diamondback moth (DBM), Plutella xylostella, is a destructive pest of Brassica oilseed, vegetable and forage crops, which has developed resistance to more than 80 insecticides globally.

Insecticide resistance in DBM evolves through repeated use of insecticides in local areas, creating selection pressure. In some regions, summer-active brassicaceous plants provide a refuge habitat for DBM, which allows insecticide-resistant populations to persist locally. Resistance levels are similar in DBM populations across canola-growing areas due to the insect’s widespread dispersal. This poses a threat to production. The more frequently growers use a certain type of insecticide, the more likely resistance will occur. Additionally, migration of resistant DBM from intensively sprayed brassica vegetable crops poses a threat to canola production.