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Wolbachia bacterium may boost livestock pest control

It’s less than one-hundredth the size of a pinhead and sounds like a character from Star Wars. But for western cattle producers it could reduce pest problems that cost an estimated $7 million each year in Alberta alone.

Wolbachia is a bacterium under study at Agriculture and Agri-Food Canada’s Lethbridge Research Centre, where new DNA studies are shedding light on its unique role in nature and its dramatic potential to improve biological pest control strategies.

Early research has shown that wasps infected with Wolbachia can, under certain conditions, produce a much higher percentage of female offspring than uninfected wasps, says Dr. George Kyei-Poku, an insect pathologist and microbiologist studying Wolbachia along with biocontrol researcher Dr. Kevin Floate. The scientists are investigating the potential of the bacterium to cause female-biased sex ratios in species of tiny wasps that are natural enemies of the house fly and the stable fly, two economically-important pests of cattle. Both the bacterium and the wasps occur naturally in Alberta.

Female wasps lay eggs in fly pupae. The eggs hatch and the wasp larvae feed on the developing fly. These wasps eventually emerge as adults from the dead fly pupae and go on to repeat the cycle, killing more developing flies. Because only females lay eggs, the effect of Wolbachia in producing more female wasps could provide increased fly control, explains Kyei-Poku. The researchers are now using molecular techniques to isolate and classify different strains of Wolbachia DNA, to find the ones with the best potential.

“It’s really taking the battle with livestock pests down to the molecular level,” says Kyei-Poku. “Once we identify the strains of Wolbachia by their DNA, we can pinpoint the effects that each might have on an insect, and pick the best ones for targeted and effective pest control strategies.”

Biocontrol is an important tool for integrated pest management (IPM), which involves the use of sanitation, chemicals and natural enemies in varying combinations, to give producers long-term, safe and cost-effective pest control, says Floate. Because Wolbachia is widespread in many insect pests throughout the globe, this fundamental DNA research has broad implications.

“Wolbachia is thought to infect 20 to 70 percent of all known insect species, and research into the bacterium has just started to develop in the last 10-15 years,” says Floate. “It’s an exciting time, because we’re only now beginning to learn what Wolbachia can do and how widespread it is.”

Kyei-Poku has already identified one strain of Wolbachia as causing female-biased sex ratios in parasitic wasps. The researchers hope to eventually find a strain that causes all-female offspring. A “quirk” of wasp biology would allow all-female populations of wasps to persist generation after generation, explains Kyei-Poku.

“If we could use Wolbachia to produce a strain of wasps that produces only females, we could save a great deal of time and money,” Floate explains. “Our ultimate goal is to use Wolbachia to produce all-female populations of wasps that then could be released to control flies.” He notes that the wasps attack only flies, and do not sting people or animals.

Research on biological control conducted at Agriculture and Agri-Food Canada’s Lethbridge Research Centre illustrates the government’s commitment to support research that minimizes environmental impacts as proposed in the new Agriculture Policy Framework. The framework should help increase and improve the use of farm management systems that enhance efficiency and performance, and secure the long-term sustainability of producers’ operations.

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