Assessing the threats and strategic responses to exotic mosquito threats in temperate Australia

Assessing the threats and strategic responses to exotic mosquitoes

(1) Department of Medical Entomology, Pathology West – ICPMR Westmead; (2) Marie Bashir Institute of Infectious

Disease and Biosecurity, University of Sydney; (3) Medical Entomology, Environmental Health Hazards Unit, Department of Health, Western Australia Government; (4) Virology, Public and Environmental Health, Forensic and Scientific Services,

Department of Health, QLD Government

Cameron E Webb (1,2), Jay Nicholson (3)

Andrew F van den Hurk (4) and Stephen L. Doggett (1)

Australia has annual activity of endemic mosquito-borne pathogens

Exotic vectors and pathogens have potential to shift disease risks from the swamps to the suburbs

Mosquito surveillance and control strategies will need to adapt to new threats….

…this shifts requires a review of financial and operational resources.

Existing surveillance focused on “wetland” mosquitoes and enzootic pathogens

Mosquito control focused on “wetland” mosquitoes and their (relatively) well defined and mapped habitats

A shift to included “exotic” mosquitoes requires strategies targeting container-inhabiting species (financial constraints)

Authorities in tropical Australia well resourced and experienced……what about temperate regions?

Initial stages of a plan for NSW to strategically respond to exotic mosquito threats are underway and a multi-agency team has been formed

Stephen Doggett (Medical Entomology, Pathology West – ICPMR Westmead)

Yellow Fever Mosquito (Aedes aegypti) is a day-biting pest and vector in tropical regions

Images: Stephen Doggett (Medical Entomology, Pathology West – ICPMR Westmead)

Asian Tiger Mosquito (Aedes albopictus) is an

invasive, severe day-biting species of tropical

and temperate regions

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Knope et al. 2013. Increasing notifications of dengue in Australia related to overseas travel 1991-2012. CDI 37: 55-59

Australian travellers and mosquito risk (home and abroad)

Newcastle Morning Herald and Miners' Advocate (NSW),31 December 1927

Assessing future mosquito risk with an eye on the past

Climate change no “game changer” for Aedes aegypti

Russell, Lee and Stanislas (1984). Aedes aegypti (L.) (Diptera: Culicidae) in New South Wales. General and Applied Entomology, Vol. 16: 9-16.

Surveys in 1976-1980 failed to detect exotic mosquitoes in northern regions of NSW

Surveys in 2008 of far north coast NSW failed to detect exotic mosquitoes

But they identified issues with surveillance…

Webb, Clancy, Sullivan, Lloyd and Russell (2009) Is Aedes aegypti in NSW? Mosquito Bites, 4: 34-40.

Hill, M. P., Axford, J. K. and Hoffmann, A. A. (2014), Predicting the spread of Aedes albopictus in Australia under current and future climates: Multiple approaches and datasets to incorporate potential evolutionary divergence. Austral Ecology, 39: 469–478.

Temperate climate no barrier to Aedes albopictus

Nicholson, Ritchie, Russell, Zalucki and van den Hurk (2014) Ability for Aedes albopictus (Diptera: Culicidae) to Survive at the Climatic Limits of Its Potential Range in Eastern Australia. Journal of Medical Entomology 51:948

Immature mosquitoes may not survive a Sydney or Melbourne “winter”…but eggs will survive and hatch in spring…

“Summer” and “winter” dynamics of Aedes albopictus

Are there ecological barriers to exotic mosquito spread?

How does Aedes notoscriptus interact with other species?

Aedes aegypti No competitive exclusion but

minor advantage to Ae.notoscriptus (Russell 1986)

No competitive displacement but Ae.notoscriptus selects non-Ae.aegypti containers (Tun-Lin et al 1999)

What about Aedes albopictus?Russell (1986) Australian Journal of Zoology 34: 527-534

Tuni-Lin et al (1999) Dengue Bulletin 23: 73-79Stephen Doggett (Medical Entomology, Pathology West – ICPMR Westmead)

Local mosquitoes no barrier to establishment or spread of Ae.albopictus

Growing consensus that there is little negative interspecific competition between endemic and exotic container-inhabiting mosquitoes

Nicholson, Webb , Ritchie and van den Hurk (2015). Effects of cohabitation on the population performance and survivorship of the invasive mosquito Aedes albopictus and the resident mosquito Aedes notoscriptus (Diptera: Culicidae) in Australia. Journal of Medical Entomology, 52: 375-385..

Endemic mosquitoes no barrier to Aedes albopictus

Asian Tiger Mosquito provides the tinder in temperate zones waiting for the spark provided by an infected traveller…

Japan experienced the biggest outbreak of dengue in 70 years in 2014

Webb (2014) What can the outbreak of dengue in Japan tell us about future mosquito-borne disease risk? https://cameronwebb.wordpress.com/2014/09/15/what-can-the-outbreak-of-dengue-in-japan-tell-us-about-future-mosquito-borne-disease-risk

Future mosquito-borne disease risk will be determined by more than just temperature, tides and rainfall (or exotic mosquitoes)

Drivers of outbreaks may include wildlife conservation, wetland rehabilitation and urban developments

Ross River virus disease outbreak in 2015?

Claflin and Webb (2015) Ross River Virus: Many Vectors and Unusual Hosts Make for an Unpredictable Pathogen. PLoS Pathog 11(9): e1005070

Webb (2015) “Is climate change to blame for outbreaks of mosquito-borne disease?” The Conversation

Authorities must respond to a shift in the mosquito and mosquito-borne disease

“playing field” posed by exotic mosquitoes but they should split funding and reduce focus on endemic public health threats and strategic responses they require

Thank you!

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The illustration used on the title slide by Golly Bard http://gollybard.blogspot.com.au/