Classical biological control: an important tool to manage invasive alien insect pests in Canadian oilseed rape

摘要

Oilseed rape is an important arable crop in Canada, grown on over 5.4 million ha. Within the last four years, rapeseed production has increased tremendously, from 4.5 to 8.3 million tonnes. The crop is damaged by a wide range of native and exotic insect pests, many of which are of considerable economic importance. Historically, such pests have been controlled mainly by the use of insecticides; however, concerns over problems associated with chemical control of insect pests, particularly contaminationof the environment, increasing development of resistance by insects to pesticides, destruction of natural enemies, and the damage to human health, are increasing. The need to reduce reliance on insecticides has led to intensive investigation to developpotential biological control methods. Although biological control is generally regarded as safe, the challenge facing scientists and regulators alike is to ensure that classical biological control agents do not impact on non-target organisms. Among others, major targets for classical biological control in Canadian oilseed rape are currently the cabbage root fly (Delia radicum) (in Canada known as the cabbage maggot), the cabbage seed weevil (Ceutorhynchus assimilis) (in Canada known as the cabbage seedpod weevil) and plant bugs (Lygus spp.).