australian mosquitoes take a bite out of california
TRANSCRIPT
An Australian mosquito in California: Public health risks and control options
Dr Cameron E. WebbDepartment of Medical Entomology
University of Sydney & Pathology West – ICPMR WestmeadEmail: [email protected] Twitter: @mozziebites
Greater Los Angeles County Vector Control District, California, Wednesday 15 November 2014
During an expanded search in the summer of 2014 for the invasive
Asian tiger mosquito, staff from the San Gabriel Valley Mosquito and
Vector Control District (SGVMVCD) and the Greater Los Angeles
County Vector Control District (GLACVCD) collected unusual
specimens from a couple of Californian homes.
.
After some initial research, photographs of the mosquito were sent to
Dr. Cameron Webb and John Clancy with the Marie Bashir Institute of
Infectious Diseases and Biosecurity at the University of Sydney,
Australia and they confirmed it to be the Australian backyard mosquito,
Aedes notoscriptus.
Aedes notoscriptus
Where is it?
Source: Landcare Research http://www.landcareresearch.co.nz
Natural and artificial water-holding containers Rock pools, tree holes and water-holding plants Artificial containers From bird baths to blocked roof gutters Rainwater tanks Rubbish and “backyard junk” Not subterranean
Habitat associations
Approximately 200m Brisbane study in 2000
reported: Mean 105.2 and 179.9m Max 195 and 238m
Compared to Ae. aegypti study in 2005 reporting: Mean 78m Max 200m
Vegetation critical Human assisted movement
Dispersal
Host Feeding
Host Bullians & Cowley
2001
Jansen et al 2005
Derraik et al 2007
Kay et al 2007
Johansen et al 2013
Human Yes Yes Yes Yes
Dog Yes Yes
Cat Yes
Possum Yes Yes Yes Yes Yes
Rodent Yes
Horse Yes
Flying fox Yes
Bird Yes Yes
Vector competence: Laboratory studiesPathogen Infection Transmission Reference
Ross River virus Yes Yes (No?) Watson & Kay 1998, Ryan & Kay 2000
Barmah Forest virus Yes Yes Watson & Kay 1999, Kramer et al 2011
Murray Valley encephalitis virus No No Kramer et al 2011
Japanese encephalitis virus No No van den Hurk et al 2003, Kramer et al 2011
West Nile virus Yes Yes Jansen et al 2008
Dengue virus No No Watson & Kay 1999, Kramer et al 2011
Chikungunya virus Yes Yes (No?) van den Hurk et al 2003,Kramer et al 2011
Yellow Fever virus Yes Yes Van den Hurk et al 2011
Rift Valley Fever virus Yes Yes Turell & Key 1998
Whataroa virus Yes Yes Holder et al 1999
Dog heartworm Yes Yes Russell & Geary 1997
Field isolations RRV, BFV plus other “minor risk” arboviruses
Brisbane 1994 13/63 RRV isolations from Aedes notoscriptus
Western Sydney 1999 Small cluster RRV cases Kangaroo populations but no substantial wetlands Aedes notoscriptus most common mosquito No RRV from field collected mosquitoes Subsequent isolation BFV Southern Sydney Small cluster RRV cases Aedes notoscriptus along with estuarine species Isolation of RRV, BFV
Surveillance and outbreak investigations
Surveillance options
Adult populations Carbon dioxide baited traps BG Sentinel traps Ovitraps (sticky or paddle) Human bait (afternoon) Gravid not effective
Larval surveys
Control options
Education Source reduction
Cleanup Screening
Methoprene Bti Monomolecular film
Endemic and exotic mosquito interactions
How does Aedes notoscriptus interact with other species? Aedes aegypti
No competitive exclusion in laboratory studies, minor advantage to Ae.notoscriptus in temperate climates (Russell 1986)
No competitive displacement in field studies but (?) Ae.notoscriptus selects non-Ae.aegypti containers (Tun-Lin et al 1999)
Aedes albopictus No significant impact on survivorship or population
performance indices (Nicholson et al 2015)
Russell (1986) Australian Journal of Zoology 34: 527-534Tuni-Lin et al (1999) Dengue Bulletin 23: 73-79
Nicholson et al (2015) Journal of Medical Entomology [in press]
How many species of Ae. notoscriptus?
Endersby et al (2013) Infection, Genetics and Evolution, 18: 191-201Foley et al (2004) Medical and Veterinary Entomology, 18:180-190
High levels of genetic divergence (Foley et al 2004)
Complex of species, some showing strong genetic isolation in two lineages (Endersby et al 2013)
Supportive of inconsistent vector competence studies?
More research required
Summary
Does Aedes notoscriptus pose a public health risk? Minor risk compared to Ae.aegypti and Ae.albopictus Comparable geographic spread to Ae.albopictus Unlikely to displace other container-inhabiting species “Collateral damage” associated with current control Reminder of ease of exotic mosquito spread Great example of international networks of expertise
Thank you!
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