Saskatoon, Saskatchewan
January 29, 2003

A European parasitic beetle, Aleochara bipustulata, may represent a solution to a pest problem that in some years costs Prairie canola producers $100 million.

A new research project supported in part by the Endowment Fund, administered by Western Grains Research Foundation, is investigating the potential of this beetle to help control the cabbage root maggot, a common pest of canola and other cruciferous crops.

The project could lead to introductions of the beetle for biocontrol of the maggot within five years, says project leader Dr. Neil Holliday, an entomologist at the University of Manitoba.

"In the past, cultural control methods and insecticide application have proven unsuccessful in the battle against the maggot," says Holliday. "But this beetle looks very promising."

Cabbage root maggots attack plant roots in mid-season, which makes the delivery of insecticide to the affected area difficult, he says. Some producers have tried cultural control methods, such as high density seeding or longer crop rotations, but these often conflict with economic objectives.

Because the cabbage root maggot is not a major crop pest in its native Europe, researchers have expected it has a competitive natural European enemy. Three species of parasitic beetle, Aleochara verna, Aleochara bilineata and Aleochara bipustulata, are all present in Europe, but Aleochara bipustulata is not found in North America.
 
The University of Manitoba project has several key objectives. The first is to test and evaluate the potential of Aleochara bipustulata as a targeted biocontrol agent, with minimal impact on non-target plant species and the environment. Field testing for this component will take place in Switzerland, where all three beetle species are native.

"Before introducing Aleochara bipustulata into Canada, we need to assess its interaction with the other species found in Canada - namely, Aleochara verna and Aleochara bilineata," says Holliday. "At the same time, we want to ensure that introducing this species will lead to better control, as opposed to simply replacing the control level achieved by other parasites."

A second objective is to investigate whether Aleochara bipustulata is well suited to the spring emergence of cabbage root maggot in Canada. For this purpose, overwintering insects from the Switzerland plots will be transported to Manitoba. Researchers plan to rear groups of the beetle at five different constant temperatures, in controlled rearing facility environments to assess the insects' emergence time under Canadian Prairie field conditions.

In a third component, researchers will evaluate the ability of mustard seed meal spread in crop fields to attract the beetle. This method of attracting the beetle for biocontrol purposes has worked well in fields in Sweden, says Holliday. "We plan to verify this finding in Prairie canola. If a simple chemical cue is involved, we may eventually be able to work that into the canola genome."

If the research produces favourable answers, researchers hope to begin large-scale introductions of Aleochara bipustulata in Canada in about five years. Successful biocontrol agent introductions usually start to take effect within three or four years, but it will take several more years to reach full biocontrol capability, says Holliday. "Annual economic benefits to producers within 10 years could be equal to
current levels of annual loss."

The Endowment Fund has allocated over $17 million to more than 200 research projects since its inception in 1983. The Fund is administered by Western Grains Research Foundation.