Dr Peter Ryan

Position: Laboratory Head, Mosquito Control Laboratory
Major area of interest: Mosquitoes, arboviruses

Dengue Control in Vietnam/Cambodia/North Queensland

1. Community based programs in dengue control in Vietnam (phase 2) with Brian Kay (QIMR), John Aaskov(QUT), National Institute of Hygiene and Epidemiology, Hanoi and Institute Pasteur, Nha Trang, Aust. Foundation of Peoples of Asia and the Pacific with AusAID funding;

2. Cambodia Regional Proposal for dengue control (to commence in September 2002 on AusAID funds) with Brian Kay (QIMR), Nat. Inst. Hygiene and Epidemiology, AFAP and National Malaria Centre (has responsibility for dengue control), WHO and Partners in Development (NGO);

3. The importance of subterranean breeding of Aedes and Ochlerotatus mosquitoes in North Queensland (NHMRC) with Brian Kay (QIMR), Bruce Russell (former PhD student) and in collaboration with the Tropical Public Health Unit, Townsville.

Queensland Local Government Mosquito Control

QIMR acts as the major technical resource to introduce new methods and products into, predominantly Local Govt. aerial salt marsh programs against the Ross River and Barmah Forest virus vector, Ochlerotatus vigilax. MARC (Mosquito and Arbovirus Research Committee) has approx. 20 subscribing members. Each year, the group sets research priorities against progress and new needs and provides approx. $140,000 / year for such activities. I have the responsibility of supervising these research projects, and the provision of technical information to local government officers and elected representatives. The close association between MARC and QIMR also provides an excellent training environment for our postgraduate research students.

1. Evaluation of new insecticides for control of Australian mosquitoes. Tanya Russell, a research assistant in the Mosquito Control Laboratory, is investigating a range of mosquito control agents, including insecticides, for use in saltmarsh and freshwater habitats. This includes the development of concentration-response data of target mosquitoes to different formulations and products in the laboratory and the field.

2. Non-target effects of insecticides used for mosquito control. Local Governments regularly spray mangrove and saltmarsh habitats with a range of chemical and biological insecticides in an attempt to control mosquito pests. Saltmarsh water is often sourced for aquaculture operations and there are growing concerns among farmers that this water may effect the survival and fecundity of farmed organisms, in particular tiger prawns. Tanya Russell will determine whether insecticides used for mosquito control (s-methoprene, Bacillus thuringiensis variety israelensis and Bacillus sphaericus) have any toxic effects on tiger prawns. This will extend our knowledge of the possible effects of insecticides on non-target organisms. This has already been determined for several native species of shrimp and fish.

3. Development and evaluation of age grading methods for mosquitoes. One of the goals of medical entomology is to understand the patterns of vector-borne disease in human populations. The survival of the mosquito has been shown to be one of the most important factors influencing the spread of mosquito-borne disease. Leon Hugo (PhD student, ACITHN) is evaluating several methods of age grading Oc. vigilax mosquitoes, one of the most important vectors of Ross River and Barmah Forest viruses in Queensland.

4. Evaluation of native Australian freshwater fishes for the biological control of mosquitoes. Tim Hurst (PhD student, ACITHN) is evaluating a range of native Australian fish species as predators of mosquito larvae. This is an example of a MARC funded project that has direct benefits to the local government mosquito control industry through the provision of technical information on the inclusion of native fish in their integrated pest management systems.

5. Investigation of a flying fox camp as a potential focus of Ross River virus and Barmah Forest virus transmission in Brisbane, Australia. Flying fox camps and the areas immediately surrounding them have recently been identified as having increased levels of Ross River virus activity. Katie Lee (Honours student, UQ Dept of Microbiology) and Scott Lyons (Research assistant) will determine whether there is evidence of arbovirus transmission between mosquitoes and flying foxes at Indooroopilly Island in Brisbane. We will also use spatial statistics to map the distribution of mosquitoes in areas around the flying fox colony to determine their pest range (principally Cx. annulirostris, Ve. funerea and Oc. vigilax), i.e., the distance over which the mosquitoes have an impact on the human population.

6. Local and regional variation in the risk of Ross River virus disease. With Brian Kay, Louise Kelly-Hope (QIMR) and Redland Shire Council, we have been able to demonstrate that there are spatial differences in the distributions and abundance of competent mosquito vectors and patterns of disease notification. Using a geographic information system (GIS) and new spatial statistical techniques, we have been able to incorporate risk assessment analysis into arboviral disease prevention. Using Redland Shire as a model, we have shown that areas with high numbers of adult mosquitoes and high numbers of mosquito biting complaints from residents, also have a higher than average risk of disease. This has lead to the identification of Cq. linealis, a mosquito not previously recognised as important in Redland Shire, as a potentially important vector of Ross River virus. We are also investigating the patterns of arboviral disease incidence at a broader scale. We are currently mapping 26,000 notifications of Ross River virus disease throughout Queensland. Again, using GIS and spatial statistics, we will be able to examine regional variation in the risk of Ross River virus disease and determine whether there is any relationship between disease incidence and local weather events.

7. Biology and control of fresh-brackish water mosquitoes in south east Queensland. Jason Jeffery (PhD student, ACITHN) and Scott Lyons (Research assistant). Coquillettidia linealis were recently identified as the second most abundant mosquito species on Russell Island in Redland Shire. An area with higher average risk of Ross River virus disease. Consistent with the risk assessment approach to arboviral disease prevention described above, Jason's research project aims to mediate the risk of Ross River virus disease through the development of effective control strategies to target Cq. linealis mosquitoes.

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