King tides have created ideal conditions for new year mosquito population boom

A complex ecosystem: Dr Cameron Webb found that there had been a steady increase in wetland predators since the Hexham floodgates were opened a decade ago.
A complex ecosystem: Dr Cameron Webb found that there had been a steady increase in wetland predators since the Hexham floodgates were opened a decade ago.

The Hunter coast is set for a new year mosquito boom thanks to improved breeding conditions created by a several Christmas king tides.

Sustained periods of hot, dry weather in recent months has helped keep mosquito numbers down, however, tidal inundation in parts of Hexham, Port Stephens and Lake Macquarie has laid the foundation for their return. 

 “We’re expecting to see an increase in mosquitoes to greet us early in 2019,” University of Sydney medical entomologist Cameron Webb said. 

“It is difficult to predict what the mosquitoes will be like over the summer holidays but just because we’ve seen the arrival of hot weather, it doesn’t mean an end to mosquitoes,” 

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Lower Hunter mosquito hots spots  include Hexham, Callaghan, Shortland, Blackbutt Reserve and Carrington.

Saltmarsh mosquitoes lay their eggs in wetland mud and can survive for long periods in dry conditions. 

“Once covered by tides, these hatch, complete development within a week, and emerge in very large numbers to fly kilometres away into nearby communities to bite and spread disease-causing pathogens such as Ross River virus,” Dr Webb said.

Another breading ground is uncovered stocks of fresh water in backyards. 

A mosquito trap

A mosquito trap

“If your rainwater tank isn’t properly screened or you’re keeping uncovered bins and buckets around the backyard filled with water, you’ll be providing a home for mosquitoes,” Dr Webb said.

Saltmarsh mosquitoes in coastal areas can be carriers of Barmah Forest infection, while freshwater breeding mosquitoes inland can transmit the Ross River virus.

Symptoms of Barmah Forest or a Ross River virus infection include fever, skin rash, painful joints and tiredness.

Dr Webb began studying mosquito populations in Hexham Swamp as part of a project to monitor the impact of the reopening of the Ironbark Creek floodgates.

The study found there was a steady increase in mosquito predators such as birds and fish since the staged opening of the gates in 2008. As a result, the swamp's mosquito population has started to decline.

Dr Webb said Newcastle used to have one of the largest mosquito eradication programs in the country however, but it was discontinued due to its unintended consequences on other wildlife.  It was also considered inefficient.