Mosquito Research

The Foundation continues with its mosquito research. Recent achievements include an assessment of permethrin in work shirts using the mosquito Aedes aegypti for Central Safety & Workwear, completion of a study on "Residual and pretreatment application of Starycide Insect Growth Regulator (Triflumuron) to control Aedes aegypti in containers for Bayer Environmental Science and a statistical analysis for the BTI Misting Project for Valent BioSciences Corp.

In past years, work sponsored by The Dr Edward Koch Foundation has paid handsome dividends. A project funded by Australia Biosecurity, through the foundation, has confirmed that a new type of mosquito trap catches nearly seven times as many Japanese encephalitis mosquitoes as the traditional mosquito trap. Dr David Banks of Australian Biosecurity developed an updraft mosquito trap that incorporates a fan, a CO2 cylinder and a solar-powered 12 volt battery to collect mosquitoes. The CO2 attracts mosquitoes, much like your breath, which is composed of CO2, and draws them to you.

While there are many such mosquito traps on the market, the Banks trap differs by using a powerful fan to suck mosquitoes up into a collection cage using an updraft of air situated just above the CO2 gas. Mosquitoes, when they feel that they are being "swept away", engage in evasive action by flying up, right into the updraft and into a collection cage. Most traps use downdraft fans, and thus are fighting against mosquito urges to fly away.

In trials conducted in Cairns by Ian Walsh of the Tropical Public Health Unit and Paul Zborowski (funded by The Dr Edward Koch Foundation), this trap collected nearly seven times as many Japanese encephalitis mosquitoes as the standard mosquito trap. In 2004, the foundation trialled the Banks trap in the Torres Strait as a new system to monitor for Japanese encephalitis in Australia.

Dr Scott Ritchie also conducted research with the staff of the National Institute of Hygiene and Epidemiology (NIHE) in Vietnam in a project partially funded by the foundation. The sticky ovitrap, developed at the Tropical Public Health Unit, consists of a 1.2 litre plastic bucket containing 500 mls of stagnant water. Dengue mosquitoes, looking for a container of water to lay their eggs in, are attracted to the bucket. But inside, a plastic strip has been placed containing a powerful adhesive that catches the unwary mosquito.

Sticky ovitraps were set in a Vietnamese village not far from Hanoi, with the aid of Tessa Knox, a PhD student of the Queensland Institute of Medical research, and the staff of NIHE. Large numbers of Asian tiger mosquitoes, Aedes albopictus, were collected, along with some dengue mosquitoes (Aedes aegypti). Because the Asian tiger mosquito, also a vector of dengue, is not currently found in Australia, Australian Quarantine and Inspection Services (AQIS) carefully monitor for its presence at all Australian ports. Results clearly demonstrate that the sticky ovitrap is an excellent way to monitor for this high risk mosquito.

Under the guidance of Professor Vu Sinh Nam of NIHE, director of the dengue control program in Vietnam, Scott has been shown the highly successful and novel dengue control program. This program, initiated in collaboration with Professor Brian Kay of QIMR, utilises small shrimp-like planktonic animals called copepods to ingest newly hatched mosquito larvae. The copepods are reared at NIHE's laboratory then posted on moist sponges to district health offices. Health officials then distribute the "mosquito-bomb" sponges to villages where a small sponge cube is dropped into rainwater tanks. Within weeks, no mosquitoes. The program was shown to Scott in a small village in NW Vietnam. Many water tanks were sampled, finding no mosquito larvae but plenty of copepods. So far, dengue has been eliminated from these villages.

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