Australian cattle breeders, especially those from the northern part of the continent, have to face a serious threat, namely the buffalo flies. Now that the famous insect is moving south, governments are relying on bacteria to stop this southward expansion.
Led by Dr. Peter James, a senior researcher at the Center for Animal Science and Postgraduate Coordinator with the Queensland Alliance for Agricultural and Food Innovation (QAAFI), a joint effort involving academia, industry and the Queensland government will rely on bacteria Wolbachia to stop the fly breeding cycle.
(Photo: CSIRO via Wikimedia Commons) CSIRO develops buffalo fly traps. The buffalo fly, Haematobia irritant exigua, is a blood-sucking fly that remains on cows during its adult life, with a brief absence by the female to lay eggs in new cow dung. The numbers of buffalo flies exceed 200 per head for most of the summer in northern Australia and cause heavy production losses.
The buffalo fly problem is a costly concern for the health of Australian cattle, and subsequent meat production in the area. Article from QAAFI puts this problem at about $ 100 million per year, going to maintenance and production losses. The use of insecticides also remains a potential contested solution, facing local resistance coupled with the need to protect the “clean green” reputation known as Australian beef.
The researchers also noted that the buffalo fly has continued to move south over the past 100 years, moving through Queensland to northern New South Wales. In addition, the data model suggests that this climate change-driven expansion will reach South Australia and southwestern Western Australia by 2030.
Fighting the Buffalo Fly
The buffalo fly (Haematobia exigua) is an invasive species introduced to Australia’s Northern Territory in the late 1830s, coming from Asia. It uses two separate mouth parts, splits the skin of the mammal and sucks blood, with cows being the most common victims. This causes large and painful wounds, with the affected animal experiencing severe distress, affecting their diet and affecting the growth and health of the affected animal. The only rest Australian mammals get is when winter arrives, weakening the buffalo flies and forcing them to go into local pockets to survive the winter.
Wolbachia, a solution proposed in the study published in Parasites & Vectors, is a type of intracellular bacteria that mainly attacks insects. It has been used successfully in mitigation dengue fever, which is transmitted by mosquitoes. However, it requires an injection of the bacteria into the fly because Wolbachia is not transmitted sideways between flies but from mother to offspring. This was a challenge for the team because, as Dr. James, the buffalo fly eggs are very hard.
“When we started micro-injecting eggs, like mosquitoes do, we blunted the needle and broke the eggs like you wouldn’t believe it. The needles even burst,” explains Dr. James.
Introducing Wolbachia Through Adults and Pupa
“So from there we looked at adult flies or pupae that inject micro, the idea is that bacteria will still spread through insects and enter the female germ tissue,” added Dr. James. The project leader explained that the main thing was to introduce bacteria into the fly population. Researchers are looking for ways to use male flies as an alternative solution, as Wolbachia are microbes transmitted from mothers passing through eggs.
Researchers are now looking at three possible solutions. If infected males mate with healthy females, they may not have offspring. Furthermore, if a healthy male mates with an infected female and produces infected offspring, that will spread the bacteria to a large part of the population. The final option is to breed and release sterile male buffalo flies, using them to influence weakened flocks during winter.