ECODA project number: B.4
Principal investigator: Geneviève Labrie
Insect pests can cause serious damage to crops and significantly reduce yield. The insect species attacking canola in Eastern Canada are not as well documented as in Western Canada. New exotic invasive insects such as the cabbage seedpod weevil (Ceutorhynchus obstrictus have been found to attack canola in Eastern Canada since 2000. The impacts of flea beetles (Phyllotreta crucifera and Phyllotreta striolata) and, recently, European corn borer (Ostrinia nubilalis) are not well documented in this part of Canada. Climatic growing conditions in Eastern Canada are different, which results in different levels of insect pressure on canola. Knowledge on their incidence and economic threshold in relation to these conditions is lacking.
The overall objective of this project was the development of integrated pest management strategies for insect pests of canola in Eastern Canada. Resistant lines of canola were tried against cabbage seedpod weevil and root maggot, with some lines showing good resistance. Management practices such as late seeding dates were effective in reducing flea beetle and cabbage seedpod weevil numbers. However, yield was better at the earliest seeding dates, even with the presence of high numbers of cabbage seedpod weevil. Fertilization and tillage did not have major impacts on populations of insect pests of canola. Biological control of cabbage seedpod weevil increased in the two years of the project and parasitoids were observed in Northern areas. Low populations of European corn borer observed in the two years of this study did not cause yield losses in canola.
Insecticides were, however, effective in reducing damage by this species and could be used, if populations are high in some years. Insecticides are efficient to reduce populations of cabbage seedpod weevil. However, no differences in yield were observed in any trials in producers’ treated fields. Furthermore, introduction of high numbers of cabbage seedpod weevil in cages with canola did not allow calculation of threshold levels against this pest as there was no relationship between yield losses and the percent of pods damaged in either year of this study. More experiments with higher levels of infestation are necessary to calculate these thresholds. This project resulted in improved understanding of the major pests of canola in Eastern Canada and strategies which can be uses to reduce their impact on canola yield. More years of study, with different environmental conditions and different levels of insect pressure are needed to give strong recommendations to producers.