SOUTH AUSTRALIAN MOSQUITO INTELLIGENCE REPORT No. 35

1. SOUTH AUSTRALIAN MOSQUITO INTELLIGENCE REPORTNo. 35 RELEASE DATE: 21thof May 2014 MOSQUITO TRAPPING AND ABUNDACE SUMMARY River Murray (RM): Trapping for this season started on September 3rd 2013 and includes the seven district councils of the Murray River. The final trip for this monitoring season commenced on April 24 2014. In total, eleven trips have been completed during this monitoring season and 390 traps have been set. Over all, the mosquito abundance in 2013-2014 at the seven different locations follows a similar pattern as the one for the previous monitoring season in 2012-2013. However, a trend towards a slightly lower overall abundance can be seen in Berri-Barmera and Loxton-Waikerie for the 2013-2014 season (Figure 1.). 2640.7 1455.1 Figure 1: The average number of mosquitos per trap caught each months during the trapping season 2013-2014 (green) and season 2012-2013 (blue) at each of the locations . Note the average number of mosquitos caught in September in Coorong was 2630.7 in 20013 and 1455.1 in 2012.

2. SOUTH AUSTRALIAN MOSQUITO INTELLIGENCE REPORTNo. 35 North Western Adelaide (NWA): The monitoring season, for the City of Salisbury council commenced on September 16th 2013 and includes the two locations, St Kilda and Globe Derby Park (GDP). During this trapping season, September 2013 to April 2014, has a total of 96 traps have been set over 16 trips. A similar trend in adult female mosquito abundance can be seen for the monitoring season 2013-2014 as that for monitoring season 2012-2013 (Figure 2). RELEASE DATE: 21thof May 2014 From his most recent trips, Stephen Fricker has commented that “The surveillance season ended with mosquito populations along the River Murray being mostly higher than long term averages in the southern councils and lower in the more northern councils. Rainfall in the second week of April is the probable cause of this late season increase in mosquito activity. The effects of this rain was variable, with the upswing in mosquito numbers in Coorong council being primarily Cx. molestus, probably coming from the problematic nearby drain. This indicated that this drain requires reapplication of S-methoprene Briquettes. In Murray Bridge and Mid-Murray councils the increase in mosquito numbers was due to an increase in the late cool weather mosquito Ae. camptorhynchus despite comprehensive treatment of problem sites on council land, this increase could be expected due rain probably filling unknown larvae sites on private land. In the upper river mosquito numbers were low compared to historic means. It is interesting to note that Berri Barmera Council had a higher number of mosquitoes than other upper river councils, this was due to what appears to be a local foul water problem at Glossop with a high number of Cx. quinquefasciatus recorded and some high numbers of Cx. australicus at Cobdogla.  The Glossop catch may be an issue that may cause some problem biting, and could be due to an issue like a septic tank or drain.” Figure 2: The average number of adult mosquitos per trap caught each months during monitoring season 2012-2013 (blue) and season 2013-2014 (green) for the City of Salisbury To date 10929adult female mosquitoes have been trapped for this season. Ae. camptorhynchus and Ae. vigilaxcomprised the majority of females caught in April 2014. Throughout the season have the 20 permanent methoprene bait stations been continuously monitored for quality assurance with other larval breeding sites being spot treated. Early in the season were six methoprene bait stations put in place in the intertidal areas of St Kilda. This in anticipation of Aedesvigilax, a saltmarsh mosquito known as a Ross River virus vector,becoming more prevalent later in the season. During November and December 2013 were additional 26 permanent treatment stations put in place across the various sites of GDP and St Kilda, to allow more effective control for the remaining season, and seasons to follow. All already existing treatment stations were refilled. In April, the average number of adult mosquitos per trap caught in Murray Bridge and City of Salisbury appear to be slightly higher than the same period last year. Over all the mosquito abundance was generally lower during the season 2012-2013 than during monitoring season 2013-2014 (Figure 1 and 3).

3. SOUTH AUSTRALIAN MOSQUITO INTELLIGENCE REPORTNo. 35 RELEASE DATE: 21thof May 2014 172 Figure 3: The average number of mosquitos per trap caught each months during the trapping season 2013-2014 (green) and season 2012-2013 (blue) at each of the eight locations . Note the average number of mosquitos caught in April at Unity park was 172.

4. SOUTH AUSTRALIAN MOSQUITO INTELLIGENCE REPORTNo. 35 RELEASE DATE: 21thof May 2014 WEATHER FORECAST: March was warmer than average across the state. Rainfall across the state was 76% below average. In April 2014, the approximate mean river height at Morgan was 3.4m. Overall the summer 2013-2014 saw multiple heat waves and rainfall tended to be average to above average across the state with a record breaking rainfall events in mid-February. The weather forecast for the North Western Adelaide and River Murray regions for April through to June shows no deviation from expected average rainfall for the respective regions. The likelihood of exceeding the median maximum temperature is 65-70% and the likelihood of exceeding the median minimum temperatureis 80% for the two regions (www.bom.gov.au). ROSS RIVER VIRUS RISK FORECASTS FOR April-June from RR Forecaster: The next three months are predicted to be NOT ABOVE AVERAGE RISK period for Ross River virus activity for all RM regions: Upper RM risk for April-June: The predicted incidence rate for autumn in the upper Valley in SA is 19 per 100,000 population. The predicted number of notifications for the region for the next three months is 6, (95% confidence 0-50). This does not constitute above-average risk. Mid RM risk for April- June: The predicted incidence rate for autumn in the middle Valley in SA is 37 per 100,000 population. The predicted number of notifications for the region for the next three months is 10, (95% confidence 0-65). This does not indicate above-average risk. Lower RM risk for April-June: The predicted incidence rate for autumn in the lower Valley in SA is 0 per 100,000 population. The predicted number of notifications for the region for the next three months is 0, (95% confidence 0-12). This does not indicate above-average risk.

5. SOUTH AUSTRALIAN MOSQUITO INTELLIGENCE REPORTNo. 35 RELEASE DATE: 21thof May 2014 MOSQUITO VIRUS TESTING: The most recent results from the FTA cards have been received from ICPMR, Westmead Hospital in NSW. In addition to the January ones fifteen more detections of arboviruses (Ross River, Barmah Forest and Stratford) from February and March field collections have been reported. The total virus detections for 2014 are listed below: Table 1: Total number of virus detections during the period January 2014-March 2014. Compiled by S. Orre-Gordon, G. Mincham, C.R. Williams and from UniSA Sofia.Orre@unisa.edu.au, Craig.Williams@unisa.edu.au, Gina.Mincham@unisa.edu.au phone: 08 8302 1906 or 08 8302 1813