Features Agronomy Insect Pests
Producers asked to collect wireworms for research

Aug. 13, 2013 - Wireworm populations and their damage to crops are increasing, and farmers are being encouraged to help find a solution.

Dr. Bob Vernon with Agriculture and Agri-Food Canada at Agassiz, B.C., is heading a research team investigating new approaches to keep wireworm problems in check. To do that, the team needs to know which specific wireworm species dominate in various areas, so the correct control option(s) are selected. So they are asking producers to send them samples of wireworms they find in their crops.

According to Neil Whatley, crop specialist with Alberta Agriculture and Rural Development, since the ban of lindane in 2004, a "silver bullet approach has disappeared. Wireworm is not like other insect pests where dealing with only one species makes control measures relatively easy," he says "There are some 30 different wireworm species that exhibit variable life cycles and behaviours.

Wireworm species vary from region to region and a single field may contain more than one species and, therefore, more than one type of wireworm behaviour. Instead of persisting for only one season like some insect pests, a single worm-like larva can feed on plant roots and germinating seeds in the soil for three to five years, depending on the wireworm species, before developing into the adult click beetle stage.

Larvae burrow higher or lower in the soil profile in response to soil temperature and moisture conditions," notes Whatley. "While some seed treatments (e.g., Cruiser Maxx and Raxil WW) can protect crops for a growing season by repelling the wireworms, these products do not cause wireworms to die and their populations can continue to increase to the point where crop protection with seed treatment eventually fails. The effectiveness of these seed treatments also varies with different wireworm species. Clearly, this new generation of wireworm control requires a more integrated approach."

When wireworms complete their life cycles and adult click beetles are formed in a year when a cereal crop is planted, the conditions are optimal for a huge, single-year increase in wireworm populations in that field. "This increased threat will persist for the next 3-5 years until the adult click beetle generation is eventually formed again," notes Whatley. "This scenario may account for situations where wireworm populations are reaching epidemic proportions in some areas and in some fields."

To assist Vernon and his team in their research, producers can obtain live wireworms and send them to Vernon and his team. To bait wireworms at this time of year, bury whole potatoes or bait balls (gauze packets containing about one cup of wheat seeds, bran or other cereal-based product) about four to six inches deep in thin patchy areas of the crop when the worms are nearer to the soil surface (early to mid-August, or in early spring). Dig these baits up 10 to 14 days later, searching for wireworms and their tunnels. Collect wireworms, along with some of the field soil that is not too wet, and put them in a hard plastic container for shipping. There may be more than one species present, so collect as many as possible.

Mail these wireworm samples to Dr. Bob Vernon, Agriculture and Agri-Food Canada, 6947 #7 Hwy, P.O. Box 1000, Agassiz, B.C., V0M 1AO.

Include a brief description of where the sample was collected (nearest town or address), what crop the wireworms were found in, any information about previous rotations in that field over the past four years, your name and phone number. Once identified, you will be contacted with the results.

August 13, 2013  By Janet Kanters