Budget cuts a buzz kill

Concerns have been raised about the effectiveness of mosquito control after the Department of Health cut the budget for aerial spraying. The department, in partnership with the Peel Mosquito Management Group and Peel Contiguous Local Authorities Group, which includes the City of Mandurah and Shire of Murray, helps deliver the largest mosquito management program in WA.

Mosquito management is primarily done through aerial larvicide treatments via a Department of Health-contracted helicopter provider. A report to the City of Mandurah said this method of treatment was “essential” given the regional disease risk, extensive breeding habitat, time sensitivity, and “prolific” mosquito breeding cycles.

However, earlier this year the budget for the helicopter service was cut and it was not available during May, June and July. The City of Mandurah council voted at its October 28 meeting to push the State Government to provide funding for the treatments to continue. The report said there was a higher risk of disease when aerial treatments had been restricted to September to April.

“Whilst helicopter treatments during the winter months are inherently more difficult to plan and align with windows of suitable weather and breeding activity, the impact they have at the end or beginning of the season cannot be underestimated,” it said. The report said the decision to cut funding for the aerial services was made without any consultation.

Camera Icon Aerial treatments are considered "essential". Credit: City of Mandurah “Despite strong opposition to the decision and multiple requests for the matter to be reconsidered at officer level, the change came into effect as of May 2026,” it said. Cr Jenny Green said without mosquito management there was a risk of an increase in cases of Ross River virus, the Barmah forest virus and Japanese encephalitis.

“At the moment we’re seeing some really positive results,” she said. “This is the time now that you don’t fall back; if you take your foot off the pedal, you’re going to see a lot more of mosquitoes affecting people. “I think that we should continue to apply that pressure because what we don’t want to see is by going backwards, that we’re going to then see an increase in these particular diseases.” Cr Green said the risk was also heightened by the area’s population growth.

“We’re getting a lot of people wanting to live near the waterways, our estuaries and our oceans and our bays,” she said. “The estuary ... (has) a lot of low-lying vegetation which is a great breeding ground for the mosquitoes. “Although some adults can provide cover to stop the the mosquito bite, there are a lot of children also who love playing around early evening and I’d hate to think that a lot of them change their mind or are excluded from outdoor activity because of the mosquito plague.” In WA, mosquitoes can transmit Ross River virus, Barmah Forest virus and Kunjin virus, as well as the potentially fatal Murray Valley encephalitis and Japanese encephalitis viruses.

While there is a vaccine for JEV, there is no vaccine or cure for any of the other mosquito-borne disease acquired in WA. Cr Ryan Burns asked how much money the Health Department expected to save and if it had assessed the costs of other mosquito management activities and the risk to public health.

Executive manager development and compliance Brendan Ingle said they did not have detailed information due to the contract being between the department and helicopter provider. He said a review had shown winter treatments were effective in reducing larval numbers leading into spring.

“We see this as being a very important part of the continuation of what we have been doing that has been stopped,” Mr Ingle said. “There hasn’t been analysis of the disease risk. I guess we take the view intuitively that reduced mosquito numbers during high-risk periods will have an impact on potential disease risk but there’s no formalised data.” Mr Ingle said the city asked for an aerial treatment on June 16 but a helicopter was unavailable.

“In terms of how that translates into mosquito numbers, it’s too early really to tell because we weren’t able to treat the larvae that were within the aquatic environment,” he said. “Those larvae would have progressed to to adults, so again intuitively we would expect that that would lead to an increase.” Cr Dave Schumacher asked if the city had looked at using drones to replace the helicopter.

“I do know of one drone that can carry 25 litres or 25 kilos of lavacide, herbicide, fungicide,” he said. The meeting was told drones had potential to be used for surveillance or in areas with restricted flight paths or heavy tree canopies, but there were limitations. “We use large quantities of larvacide product and that (drone technology) has limitations for the scale of our program,” Mr Ingle said.

“The scale of the amount of drones that would be required to deliver — sometimes we have a day or two to complete the entire treatment — that would have to be factored in.” Cr Burns also asked if the city recorded where mosquito-related complaints came from, which he said could be used to help mosquito management and community education.

Camera Icon The Health Department's 'Fight the Bite' campaign. Credit: Department of Health Mr Ingle said complaints were tracked via GPS to try to target breeding areas. “Generally speaking, 1km from breeding sites is the hot zone for complaints that we get,” he said.

“There is value in tracking that information and over the years we have done analysis on that type of complaint data.” Cr Schumacher commended city staff for dropping the mosquito count from more than 16,000 mosquitoes per breeding cycle per person to just more than 3000. “You do a phenomenal job to curb mother nature’s wrath,” he said.

The Department of Health was contacted for comment. It runs a “Fight the Bite” campaign to help people prevent being bitten by mosquitoes, reduce breeding grounds and minimise the risk of mosquito-borne disease transmission. It also includes March fly bite prevention.

It also provides free repellent stations to eligible community organisations in high-risk locations to reduce the impacts of mosquito-borne disease in WA.