Controlling Canada's swede midge problem

So what's the problem?

The swede midge (Contarinia nasturtii), a pest of Eurasian origin, was first detected in Ontario (Canada) in 2000. It causes severe damage to a wide variety of important cabbage crops such as broccoli, cabbage, cauliflower, turnips, radish, and canola. Swede midge larvae feed actively on the growth points and leaf stalks of cabbage plants, resulting in deformed plants, decreased seed production and reduced crop yield. Damage can reach up to 80% if crops are left untreated. In 2012, the swede midge was present in Quebec, Nova Scotia, Manitoba, and Saskatchewan, as well as five American states: New York, Massachusetts, New Jersey, Connecticut, and Ohio. Since arrival of the swede midge in the main cabbage growing areas of eastern Canada, pesticide applications in cabbage crops have increased, threatening already existing biological control programs against other cabbage pests.

What is this project doing?

Between 2008 and 2011 we comprehensively surveyed and identified potential classical biological control agents in Europe for introduction into North America. Levels of attack, however, were typically less than 10%. Since parasitoids do not seem to regulate the pest efficiently, we initiated life-table studies in Europe to identify other important biotic and abiotic mortality factors for the swede midge. Allowing mortality from a natural enemy to be compared with other sources of mortality, life-tables also allow the contribution to population regulation of a pest by a natural enemy to be assessed.

Results so far

Two different methods for studying life-table characteristics for swede midge were developed in 2012. The preliminary results of our first life table experiments indicate that swede midge suffers from high egg mortality. Studies in Switzerland will be continued in 2013.

Project Executive

Ulrich Kuhlmann

Address: Rue des Grillons 1, CH-2800 Delemont, Switzerland

Tel: +41 (0)32 421 4882

Email: u.kuhlmann@cabi.org

Project Manager

Tim Haye

Address: Rue des Grillons 1, CH-2800 Delemont, Switzerland

Tel: +41 (0)32 4214883

Email: t.haye@cabi.org

Senior Supplier

Matthew Cock

Address: Bakeham Lane, Egham, Surrey, TW209TY, United Kingdom

Tel: +44 (0)1491 829037

Email: m.cock@cabi.org