An Australian mosquito species, Aedes notoscriptus, has been found for the first time in California. It is able to spread viruses like Ross River virus and Barmah Forest virus under laboratory conditions. Aedes notoscriptus lives in natural and artificial containers near human habitats. It can travel up to 200 meters and be spread greater distances through human transport. While a minor public health risk compared to Aedes aegypti and Aedes albopictus, it is a reminder of how easily exotic mosquitoes can spread. More research is needed to understand interactions with existing species and whether it consists of complex of cryptic species. Controlling mosquito habitats through education, source reduction and larviciding offers options

1. Greater Los Angeles County Vector Control District, California, Wednesday 15 November 2014
An Australian mosquito in California:
Public health risks and control options
Dr Cameron E. Webb
Department of Medical Entomology
University of Sydney & Pathology West – ICPMR Westmead
Email: Cameron.Webb@health.nsw.gov.au Twitter: @mozziebites

2. 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.

3. Aedes notoscriptus

5. Where is it?
Source: Landcare Research http://www.landcareresearch.co.nz

6. Habitat associations
 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

8. Dispersal
 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

9. 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

10. Vector competence: Laboratory studies
Pathogen 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

11. Surveillance and outbreak investigations
 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

12. Surveillance options
 Adult populations
 Carbon dioxide baited traps
 BG Sentinel traps
 Ovitraps (sticky or paddle)
 Human bait (afternoon)
 Gravid not effective
 Larval surveys

13. Control options
 Education
 Source reduction
 Cleanup
 Screening
 Methoprene
 Bti
 Monomolecular film

14. 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: 527-534
Tuni-Lin et al (1999) Dengue Bulletin 23: 73-79
Nicholson et al (2015) Journal of Medical Entomology [in press]

15. How many species of Ae. notoscriptus?
 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
Endersby et al (2013) Infection, Genetics and Evolution, 18: 191-201
Foley et al (2004) Medical and Veterinary Entomology, 18:180-190

16. 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

17. Thank you!
Join the conversation
Visit my website: http://cameronwebb.wordpress.com
Email: Cameron.Webb@health.nsw.gov.au
Follow me on Twitter: @mozziebites