New pest species found in Prairie canola
Researchers at Agriculture and Agri-Food Canada’s Saskatoon Research and Development Centre (SRDC), along with colleagues at the University of Guelph, Alberta Agriculture and Forestry, and the Canadian Food Inspection Agency have found a new insect damaging canola in northeastern Saskatchewan and east-central Alberta. The new species, a midge that has yet to be named and scientifically described, belongs to the genus Contarinia. It is similar in appearance to the swede midge (Contarinia nasturtii) commonly found in Ontario.
Currently, the only confirmed symptom of damage by this insect are “bottle”-shaped galled flowers that form as a result of larval feeding inside flowers. Damaged flowers do not produce pods or seeds.
How the new species was confirmed
For years there have been accounts of differences between swede midge populations in Saskatchewan and Ontario, including adult size, the number of generations per year, and the type and amount of damage reported. These hints, combined with extremely low capture rates of adult swede midge in pheromone-baited traps in Saskatchewan despite apparently high rates of adult swede midge emergence caught the attention of Boyd Mori, a trained chemical ecologist and new biologist at the SRDC.
Mori collected adult midges from soil emergence cages and reared larvae found in infested flowers. The resulting adult midges were sent to Rebecca Hallett and James Heal, preeminent North American swede midge researchers at the University of Guelph, who immediately noticed differences between the midge from Saskatchewan and swede midges from Ontario: midges from Saskatchewan were more robust, had hairier wings and had slight differences in the antennae and genitalia compared to the swede midge.
These differences were confirmed by midge expert Bradley Sinclair with the Canadian Food Inspection Agency in Ottawa. Sinclair also found several other physical differences. Using morphological differences and DNA sequencing, the researchers concluded the Saskatchewan midges were a separate species from the swede midge.