Salt Marsh mosquito infestation in Killcare\Hardy’s Bay area.
Huge numbers caught in Killcare trap during summer months.
400 residents signed petition calling on Gosford Council’s help for eco solution.
Mosquitoes
Out of 10 mosquito specimens caught in Killcare and examined by the Department of Medical Entomology in March 2004 for identification, all were identified as the saltmarsh mosquito, Ochlerotatus vigilax. (simply referred to as vigilax in future text).
Ochlerotatus vigilax breed in saline habitats on mudflats usually behind mangroves. Hatching of eggs is in response to inundation of mudflats through extremely high tides, although rainfall can initiate hatching and breeding.
The yearly ‘Arboviral Surveillance Program Reports’ generated by NSW Health Department, Public Health Unit (Central Coast Area Health) documents to Council the status of the ongoing state arboviral monitoring programs that monitors mosquito populations and species across the coast.
It states in the 2004 report given to Gosford Council that the vigilax species presents the greatest risk in the transmission of arboviral disease and says that it is widely accepted that vigilax is the major vector for the arboviral diseases “Ross River Virus” and “Barmah Forest” on the Central Coast.
Traps
The surveillance program incorporates monitoring traps in the Central Coast area that are intended to give an indication of changes in local mosquito populations.
The traps are located in Pearl Beach, Killcare, Empire Bay, Wyoming, Bateau Bay, Ourimbah, Tumbi Umbi, Tacoma, and Halekulani
Killcare yielded not only the highest total number of vigilax but also the highest averages on the coast, with an average weekly total of 356 of which 321 were vigilax. This level was similar to that of previous trapping seasons. Empire Bay’s average total was only 84 with 44 being vigilax and Ourimbah were 26.
Figure 1 - Weekly trappings from 4/11/03 to 22/4/04 (Killcare is yellow, Empire Bay pink)
The report states that the notification of arboviral diseases (Ross River Virus and Barmah Forest) increased toward the end of the season, with 12 notifications received by the Public Health Unit by mid May. This number was not dissimilar to previous years. It also states that sustained high number of vigilax of one or more sites is considered to be an indication of the potential for the spread of Ross River Virus, if the virus exists or is circulating in the mosquitoes.
Petition
Due to the infestation of mosquitoes in the Killcare area a petition was drawn up and placed in Killcare and Wagstaffe shops for 4 weeks. Over this time 400 people signed the petition. The petition asks “Gosford Council to support the residents in finding a solution that will protect their health and their lifestyle by controlling the mosquito infestation, using eco friendly controls that are recommended by Department of Medical Entomology and have been tested and implemented by the Sydney Olympic Authority.”
The petition was tabled on 22nd June 2004. As a result of this petition, Council asked their Health department for a report. Councillor Chris Holstein invited us (FAM – see details below) to ask for specific information to be address in this report. We asked for the following information to be sourced in the report.
1. We would like to know from Cameron Webb of Westmead Entomology what mosquito control they would recommend for our problem and an explanation of why there is a mosquito infestation in Killcare and not Empire Bay. Cameron confirmed that the prevalent mosquito caught in Killcare was the Salt Marsh mosquito.
Note: FAM have a copy of a letter dated January 1980 sent to a Killcare resident after complaining about the number of mosquitoes from the School of Public Health and Tropical Medicine confirming that the samples of mosquitoes caught in Killcare were of the same species. This evidence demonstrates that Killcare has had a salt marsh mosquito problem for many years. The author 24 years ago confirmed that a fresh water dam was not a breeding area for this mosquito and was not the cause of the mosquito problem as this mosquito breeds in salt water and can fly 10 to 20 miles!
2. We would like to know what controls other Councils such as Wyong and Newcastle Councils have used and the results of these controls.
3. We would like to receive information from the University of Sydney's Dept of Medical Entomology who have been monitoring the use of BTI (bacteria by the Sydney Olympic Park Authority about the success of the program and the implications on the environment by the use of this product.
4. We would like to receive graphical reports of the number of mosquitoes trapped in the Killcare trap over a 5 year period.
The report from Council’s Health department to Council will be tabled at Council on 7th September. We wait with interest.
Sandy Robinson
FAM (Fight Against Mosquitoes)
AH: 02 4360 2252
BH: 0419 215617