Insect surveillance was conducted in winter canola in Ontario for the 2020-2021 season to monitor the type and number of insects that inhabit this crop. There were 13 fields surveyed in Wellington, Huron, Grey, Chatham-Kent and Middlesex counties. Sweeps were taken from 10 different areas of each field both at the perimeter of the field and in the interior. A sweep consisted of a 180° movement from shoulder to shoulder across the tops of the plants and this was done 10 times in each area during the full flower stage. The most abundant insects that were found include cabbage maggot flies, seedcorn maggot flies, Hydrobaenus midges and flea beetles towards the end of the flowering period.
The cabbage maggot fly (Delia radicum) and the seedcorn maggot fly (Delia platura) are pests of Brassicaceae crops such as canola, broccoli, cabbage and kale that can reduce yield by crop root feeding. Cabbage maggot flies affect Brassicaceae crops specifically while seedcorn maggot flies target a wide variety of crops including Brassicaceae, corn, soybean and more. The larvae of these flies can cause yield-impacting damage when they feed on roots and burrow into emerging seedlings, creating extensive tunneling in the roots of the plants. This may result in stunting of plant growth through reduced branching or killing the plant. It is important to check the roots of canola plants for tunneling when there is an abundance of these flies. Though these flies were one of the most common insects found in this surveillance, the lack of tunneling in the roots indicated that there wasn’t significant damage caused by them.
Midges of the Hydrobaenus species was another abundant type of insect found in this survey. It is a very small insect not specific to canola or Brassicaceae crops and it is not a pest of canola.
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