Controlling the cabbage seedpod weevil in Canada

Overview

Results

The team

Related information

So what's the problem?

The cabbage seedpod weevil, Ceutorhynchus obstrictus, is a widely distributed pest of cruciferous crops in Europe and North America. Accidentally introduced from Europe, the weevil was first discovered in British Columbia, Canada, about 80 years ago, and has since spread to other parts of western and eastern North America. Since its arrival in North America, the weevil has caused substantial economic losses in canola crops in the Canadian prairie provinces of Saskatchewan and southern Alberta. In eastern Canada, the occurrence of C. obstrictus is regarded as a threat to canola seed production.

Yield loss results from adults feeding on the flower buds and larvae feeding within the seedpods. Current control measures for the cabbage seedpod weevil still rely on applying broad-spectrum insecticides. Although never intentionally released in eastern Canada, the most effective natural enemy of C. obstrictus in Europe, the parasitic wasp Trichomalus perfectus, was first recorded in Ontario and Quebec in 2009. To date, it remains unclear whether the parasitoid has the potential to spread and establish throughout the canola growing areas of Canada.

What is this project doing?

Bioclimatic simulation models, also known as bioclimate envelope or ecological niche models, have been applied successfully to predict the distribution and the extent invasive insect pests have managed to establish in new environments. To a much lesser extent bioclimatic models have been developed to predict the potential areas where insects considered for classical biological control may be successful against invasive pests. The objective of our study is to collect European distribution data for Trichomalus perfectus to develop bioclimatic models, predicting the potential distribution and abundance of the parasitoid in North America.

Results so far

In 2011/12 surveys for cabbage seedpod weevil parasitoids were conducted in France, Italy, Spain, Switzerland, Germany, Denmark, Hungary and Romania to determine the distribution and abundance of T. perfectus in Europe. In total, more than 15,000 weevil larvae and 7,000 parasitoids emerged from our collections. The most common parasitoids were: Trichomalus perfectus, Mesopolobus morys, Stenomalina gracilis and Eurytoma spp. Trichomalus perfectus was found at 121 locations, and our preliminary data suggest that T. perfectus is dominant in the northern parts of Europe, whereas M. morys is more common in the South. In 2013, surveys will be expanded to additional European countries.

Recent publication:

Haye, T., Mason, P.G., Dosdall, L., Kuhlmann, U. (2010) Mortality factors affecting the cabbage seedpod weevil, Ceutorhynchus obstrictus (Marsham), in its area of origin: A life table analysis. Biological Control 54, 331-341.

You may be interested to refer to our book 'Biological Control Programmes in Canada 1981-2000', which is published by CABI.

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