Established populations of Northern Corn Rootworm have been found in additional locations, as reported in the most recent Manitoba Insect & Disease Update – August 17, 2016. The following is provided by John Gavloski, Provincial Entomologist with Manitoba Agriculture.
When corn is grown in the same field for several years in a row, it becomes more susceptible to various potential pests. One such pest is northern corn rootworm (Diabrotica barberi). Until last year only the occasional specimen of northern corn rootworm had been found in Manitoba, and not at levels that appeared to be an established population in a corn field. Last year we did find a well established population in a field in the Souris area. This year we are looking more intensively for them, and have found established populations in corn fields near Morden and Winkler. All fields where they have been found so far have had a long history of consecutive corn being grown in the same field.
This time of year you will see the adult beetles (Figure 1), often on the silks of the corn plants. These adult beetles are generally not of concern, and will lay eggs in the soil of the corn field they are in. When larvae hatch from these eggs the next spring, if there is corn in the field again they will feed on the corn roots. If corn is not in the field they will starve to death. Thus crop rotation is the easiest and cheapest way of dealing with them.
If anyone finds corn rootworm on their corn, or insects they think may be corn rootworm, we are trying to verify the range of this insect in Manitoba. So samples would be welcome and can be sent to John Gavloski, Manitoba Agriculture, Box 1149, 65-3rd Ave. NE, Carman, MB, R0G 0J0.
Visit the Insect Pages of Manitoba Agriculture’s website at: http://www.gov.mb.ca/agriculture/crops/insects/index.html