A Lethbridge entomologist is trying to eliminate males.
“Males are unnecessary,” says Kevin Floate, who is talking about small parasitic wasps used to control flies in feedlots. “Wasps don’t need males to reproduce.”
Only the female wasps can lay eggs, thereby killing developing flies and reducing the number in a feedlot.
Wasps lay their eggs in the flies’ pupae. The pupae are killed when the wasp eggs hatch.
Floate, who works at Agriculture Canada’s research centre in Lethbridge, Alta., said infecting wasps with the Wolbachia bacterium will result in all the offspring being female.
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“When we mass produce wasps as biological control agents, about 40 percent of all wasps we produce are males. That is essentially a waste of energy because males don’t lay eggs and can’t kill the flies,” he said.
The Lethbridge scientists want to know if they can manipulate the wasps to produce only the beneficial female wasps.
Wolbachia research is in its infancy, Floate said. The bacteria are believed to infect as many as 10 percent of all known insect species.
Preliminary DNA detection found Wolbachia bacteria in wasps in Alberta feedlots, giving the scientists a clue that it does occur naturally in the area.
Scientists hope to control stable flies and house flies.
Stable flies take painful bites when they’re getting blood from cattle to reproduce.
The housefly is mostly a nuisance. It vomits every time it rests, leaving little brown spots over buildings, fences and homes.
Stable flies are estimated to cost Alberta feedlot operators $7 million in lost production each year from lost weight gain in cattle and poor feed conversion.
Floate said feedlot operators’ opinions of flies range from nuisance to obsession.
“Some feedlot operators have a very low tolerance for flies.”
Floate said feedlot operators should use a three-step approach to control.
Flies breed in areas where there is rotting silage, and wet manure, or low-lying areas where it is wet most of the time. These areas should be drained and allowed to dry to eliminate a breeding site.
Chemical fly spray should target areas where adult flies congregate, such as the sides of barns and fences.
Parasitic wasps should be used to target areas where eggs are laid and immature flies congregate.
Floate said there is still a lot of research left to find out how the bacterium will affect different types of wasps. The goal is to use the female Wolbachia-infected strains to produce biocontrol agents for repeated release throughout the summer.
