Insect of the Week – Natural enemies of the canola flower midge

This week’s Insects of the Week are two parasitoid wasps, an Inostemma sp. (Hymenoptera: Platygastridae) and a Gastrancistus sp. (Hymenoptera: Pteromalidae). These parasitoids are natural enemies of the canola flower midge (Contarinia brassicola, Diptera: Cecidomyiidae), a newly discovered fly species that uses canola as its host plant. The parasitoids have been found throughout the Prairies emerging from infested galls created by the canola flower midge. Little is known about these two species, but parasitism rates as high as 30% have been noted in northeast Saskatchewan.

Gastrancistrus sp. (Hymenoptera: Pteromalidae)
(c) 2016 Boyd Mori, AAFC
Inostemma sp. (Hymenoptera: Platygastridae)
(c) 2016 Boyd Mori, AAFC

Submitted by Dr. Boyd Mori and Dr. Meghan Vankosky

Find out more about the natural enemies of the canola flower midge and more at the Insect of the Week page!

Insect of the Week – The new canola flower midge (Contarinia brassicola, Diptera: Cecidomyiidae)

This week’s Insect of the week is a new find on the prairies, tentatively called the canola flower midge, Contarinia brassicola (Diptera: Cecidomyiidae). The canola flower midge has been found throughout central Alberta, Saskatchewan, and the Swan River Valley in Manitoba. The female lays eggs on developing canola flower buds. Upon hatching, the larvae feed within the developing flower and cause the formation of a “pop-bottle”-shaped gall. To date, this is the only damage associated with the midge, and it has been minimal across the prairies.

Adult canola flower midges appear similar to swede midge (Contarinia nasturtii). They are tiny, delicate flies, 2-5 mm in size. They can be differentiated from swede midge based on the appearance of the female antennae, the damage symptoms they produce and genetically.

Many thanks to Scott Meers and Shelley Barkley (Alberta Agriculture and Forestry) for organizing the Alberta surveys for the canola flower midge.  

Submitted by Dr. Boyd Mori and Dr. Meghan Vankosky

Find out more about the insect pests that plague your crops and the natural enemies that keep them in check at the Insect of the Week page!

“Pop-bottle”-shaped galls created by the canola flower midge.
(c) 2016 Boyd Mori, AAFC