6th International Congress of the Society for Vector Ecology

Culex_molestus_Photo_StephenDoggettThis month, medical entomologists from across the globe will come together in California for the 6th International Congress of the Society for Vector Ecology. With thanks to a travel grant provided by the Bill and Melinda Gates Foundation, two of my (recently completed) PhD students will be attending and presenting work on the role of mosquitoes in urban environments and mosquito-borne disease risk.

The Society for Vector Ecology was established in 1968 to bring together individuals interested in the management of vector-borne disease. This includes professionals mostly involved in mosquito research, mosquito control and surveillance operations and communications. Every four years, the society holds a congress either in North America or Europe. The couple of congresses that I’ve attended have been fantastic and I’m greatly disappointed not to be able to attend this year’s meeting.

The 6th International Congress of the Society for Vector Ecology is being held 22-27 September in La Quinta, California, USA. You can have a look at a PDF of the program here.

Although I won’t be able to make it, two of my PhD students will be attending after being awarded travel grants by Bill and Melinda Gates Foundation. They will be presenting some of the work they completed as part of their PhD candidature.

The titles and abstracts of their presentations are below.

Understanding the ecological importance of mosquitoes to insectivorous bats and the implications for mosquito-borne disease management in coastal Australia

Leroy Gonsalves, Bradley Law, Cameron Webb, Vaughan Monamy and Brian Bicknell

Manangement of mosquito-borne disease risk in coastal Australia faces many challenges. Urbanisation is increasing the size and proximity of the community to productive mosquito habitats. Coastal wetlands are also the focus of conservation and rehabilitation efforts. Mosquitoes associated with these wetlands, in particular the saltmarsh mosquito, Aedes vigilax, are abundant, widely dispersing and key vectors of Ross River and Barmah Forest viruses. These mosquitoes may also represent an abundant prey resource for threatened and endangered insectivorous bat species and local authorities are reluctant to approve broadscale mosquito control programs due to concerns regarding indirect impacts on local bat populations. A combination of diet analysis, radio-tracking and prey abundance studies were undertaken. Analysing prey DNA within guano collected from 52 individuals representing five local bat species demonstrated that bats consumed a diverse range of prey dominated by lepidopterans. Consumption of Ae. vigilax was restricted to two species, Vespadelus pumilus and V. vulturnus. Radiotracking of 13 V. vulturnus individuals during periods of relatively large and small population abundances of Ae. vigilax, together with monitoring of prey abundance, revealed that foraging ranges of bats shifted in response to mosquito abundance (and no other prey). These findings suggest that there are species-specific relationships between bats and mosquitoes and that there may be site-specific strategies required to balance mosquito management and bat conservation.

The biology, distribution and genetics of Culex molestus in Australia?

Nur Faeza A Kassim, Cameron E Webb & Richard C Russell

The Culex pipiens subgroup of mosquitoes includes some of the most important vector species involved in mosquito-borne disease transmission internationally and four species within this subgroup are found in Australia. One of these species, Culex molestus, is thought to have been introduced into Australia in the 1940s. Closely associated with subterranean urban habitats, this mosquito has the potential to cause serious nuisance biting impacts but also may cause significant public health risks through the transmission of endemic arboviruses. Exotic pathogens, such as West Nile virus, may also pose a potential threat to biosecurity of Australia. Our review of the literature has confirmed that the current Australian distribution of Cx. molestus is limited to areas south of latitude -28.17ºS. However, given that the mosquito is established in habitats south of the corresponding zone in the northern hemisphere, there is potential for Cx. molestus to spread north into QLD and NT. Molecular analysis of the mosquito indicated that Australian Cx. molestus shared stronger genetic similarity with specimens from Asia than specimens from Europe or North America. Laboratory and field studies have shown that the mosquito is uniquely adapted to urban environments through the expression of autogeny (ability to lay their first batch of eggs without a blood meal) and stenogamy (ability to mate in confined spaces). Culex molestus is active throughout the year and the current trend towards increased water storage in urban areas of Australia has raised concerns of increased nuisance-biting and public health risks in the future. However, the results of our studies indicate that there may be biological and ecological barriers that may lessen the importance of this mosquito in urban mosquito-borne disease cycles. A delay in blood feeding resulting from their obligatory autogeny, combined with limited access to potential reservoir hosts, may reduce the likelihood of them playing a significant role in pathogen transmission.