Provincial officials are calling on area crop producers to help them control and study wireworm populations by sending in samples of local specimens.
Since the ban of Lindane – an insecticide that kept wireworm levels low for several decades – Dr. Bob Vernon has been heading a research team that is investigating new approaches to keep wireworm populations in check, says Neil Whatley from the Alberta Ag-Info Centre.
“Wireworm populations and their damage to crops are increasing, and (producers) can help to find a solution for your distinct farming area,” said Whatley, noting that wireworms are the larval stage of click beetles.
“A silver bullet approach (Lindane) has disappeared, and wireworm is not like other insect pests where dealing with only one species makes control measures relatively easy.”
There are some 30 different wireworm species that exhibit variable life cycles and behaviours, and the species vary from region to region.
A single field may contain more than one species and therefore, more than one type of wireworm behaviour, he added.
“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,” he said.
Wireworm losses are generally greater in crops grown on medium-textured (silt) soils, and continuously-irrigated fields are at higher risk.
Crop injury is less likely in fine textured (clay) soils but heavy infestations do occur in light textured (sand) soils, he said.
Wireworm damage shows up early as crop thinning during stand establishment and most loss occurs during the earlier part of the growing season before larvae burrow deeper in the soil to escape warm summer temperatures.
While some seed treatments – like Cruiser Maxx and Raxil WW – can protect crops for a growing season by repelling the wireworms, these products don't kill wireworms, 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,” he said.
This integrated approach involves producers baiting wireworms and submitting samples for review, he said.
“By sending wireworm samples to Dr. Vernon and his technician, Dr. Wim van Herk, you contribute to finding a solution for your unique grain growing region,” he noted.
“The research team needs to know which specific wireworm species dominate in your area so the correct control option (or options) are selected.”
To obtain live wireworms producers may need to bait them by burying whole potatoes or bait balls – gauze packets containing about one cup of wheat seeds, bran, or another cereal-based product.
The bait should be buried about four to six inches deep, at random marked locations in a field. Or, if the crop is up, the bait should be placed in thin or patchy areas.
The best time during the season is in either early spring or early- to mid-August when the worms are nearer to the soil surface, he added.
Dig the bait up 10 to 14 days later – no longer or the bait becomes repulsive – and search 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,” he said.
The samples should be sent to Dr. Vernon at:
Agriculture and Agri-Food Canada
6947 #7 Hwy
P.O. Box 1000
Agassiz, B.C.
V0M 1AO
Information to be included in the package should list where the sample was gathered, what crops the worms were found in, and any previous crop rotations in the past four years in that particular field.
There should also be contact information, as once the species are identified, the producer will be contacted with results.
Please 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.
“As damage to field crops escalates, please consider playing a part of the wireworm control solution for your area by submitting samples from your farm to the wireworm research team,” he said.
