The battle against wireworms on the Prairies is hindered by the need for more research and a lack of effective control measures, says a researcher studying the pest.
Bob Vernon, who works for Agriculture Canada in Agassiz, B.C., told the Agronomy Update Conference in Lethbridge Jan. 18 that research is progressing but few remaining insecticides kill both resident wireworms and neonates, which are the recently hatched larvae.
Lindane, Furadan and Lorsban, no longer used in Canada, provided some control.
Vernon said research now focuses on neonicotinoids and their combination with phenyl pyrazoles such as fipronil. However, the latter is not yet registered for use on wireworms in Canada and may never be registered at high enough rates to be effective on its own.
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Cruiser Maxx and Raxil will control prairie wireworms in the current season but don’t reduce populations. Numbers appear to be increasing, Vernon said.
Surveys conducted since 2004 show Canada has 30 species of wireworms, which are the larval stage of click beetles.
Seventy-four percent of prairie species are Hynoides bicolour, followed by Selatosomus destructor. Both species are often found in the same field and prefer non-irrigated land. Cereal crops and pastures are their preferred targets, although Vernon said they will also attack pulses, forages and almost anything else.
“It’s very important to know what species you have on your farm because that might in the future dictate what sort of control you’re going to be using,” Vernon said.
Surveys will continue with the help of prairie farmers and researchers.
“What we would like is, if any growers are putting bait balls out in the field, if you happen to find enormous numbers in your field, please contact me.”
Collected worms are tested to determine the effectiveness of insecticides. Researchers have found neonicotinoids only slow them down.
“They are almost dead and they look dead, but they come back to life and they’re hungry as heck,” he said.
“We get zero kill of neonates with neonicotinoids. You get great crop establishment and yield, under optimum conditions, but you get little reduction in resident wireworms and no reduction in neonates.”
Research points toward a blend of insecticides that will kill neonates and older wireworms, providing several years of control.
Wireworms live for three to five years in the soil. Click beetles overwinter and lay eggs in May or June. The eggs hatch into neonate larvae, which remain in the soil for three to five years. They then pupate and become adults.
