Darwin, in the tropical north of Australia, is subject to high numbers of mosquitoes and several mosquito-borne diseases. Many of Darwin’s residential areas were built in close proximity to tidally influenced swamps, where long-term storm-water run-off from nearby residences into these swamps has led to anthropogenic induced ecological change. When natural wet-dry cycles were disrupted, bare mud-flats and mangroves were transformed into perennial fresh to brackish-water reed swamps. Reed swamps provided year-round breeding habitat for many mosquito species, such that mosquito abundance was less predictable and seasonally dependent, but constant and often occurring in plague proportions. Drainage channels were constructed throughout the wetlands to reduce pooled water during dry-season months. This study assesses the impact of drainage interventions on vegetation and mosquito ecology in three salt-marshes in the Darwin area. Findings revealed a universal decline in dry-season mosquito abundance in each wetland system. However, some mosquito species increased in abundance during wet-season months. Due to the high expense and potentially detrimental environmental impacts of ecosystem and non-target species disturbance, large-scale modifications such as these, are sparingly undertaken. However, our results indicate that some large scale environmental modification can assist the process of wetland restoration, as appears to be the case for these salt marsh systems. Drainage in all three systems has been restored to closer to their original salt-marsh ecosystems, while reducing mosquito abundances, thereby potentially lowering the risk of vector-borne disease transmission and mosquito pest biting problems.

Burnside Operations Pty Ltd plan to commence mining at the North Point and Princess Louise mine sites, located in the East Burnside Project Area approximately 130km south-east of Darwin. The mining method will be open cut, with ore to be transported to Union Reefs Gold Mine for processing. Workers are to be housed at the mine camp at Cosmo Village. Mine sites have the potential to create or exacerbate mosquito breeding, potentially from the creation of water dams, wetland filters, borrow pits, sediment traps, dry season water discharge, waste water disposal, as well as the construction of roads and mine waste dumps. Mine sites also have the potential to introduce new mosquito species into the Northern Territory, such as the dengue mosquito Aedes aegypti from North Queensland, if equipment was to be sourced from this area. As part of the environmental process, all major development in the NT is required to consider mosquitoes during the preparation of Environmental Impact Statements or Public Environmental reports, to ensure new development does not create new mosquito breeding sites, and also to protect the health of workers.

A Hazchem Storage Facility is proposed at Section 4239, Hundred of Bagot. Section 4239, Hundred of Bagot is located at Hidden Valley adjacent to extensive mangrove areas of Bleesers Creek and Reichardt Creek in Frances Bay, Darwin Harbour. Section 4239 is proposed to be subdivided in future, with the proposed Hazchem Storage Facility to be built within a 4ha site in Section 4239. The areas adjacent to the proposed development area were also identified as being subject to seasonal pest problems from the salt marsh mosquito Ochlerotatus vigilax (Whelan et al 1994). Other mosquito species of potential significance in the proposed development area include Culex annulirostris and Coquillettidia xanthogaster (Whelan et al 1994). Ochlerotatus vigilax is a vector of Ross River virus (RRV) disease and Barmah Forest virus (BFV) disease, while Culex annulirostris is a vector of RRV, BFV, Murray Valley encephalitis virus (MVEV) disease and Kunjin virus (KUNV) disease. The numbers of these species of mosquitoes in this area indicated there are seasonal risks for mosquito borne disease transmission in the development area. The Medical Entomology Branch (MEB) has been asked to identify any biting insect pest or potential human health problems in the development area, and provide advice on the magnitude of the problem. To do this MEB has referred to past biting insect investigations in the development area (Whelan et al 194), as well as examined the proposed plans for the potential of the development to create or exacerbate existing biting insect problems.

The Blacktip Project consists of both offshore and onshore components. The onshore components include the construction and operation of an onshore processing plant, construction and operation of 3km of buried onshore pipeline, and the construction of access roads and construction camp. There were potential biting insect concerns associated with these onshore components of the Blacktip Project. EcOZ Environmental Services was commissioned by Woodside Energy Limited (Woodside) to assist in the preparation of a Draft Environmental Impact Statement (EIS) for the Blacktip Project. EcOZ Environmental Services then commissioned the Medical Entomology Branch of the Department of Health and Community Services to provide information on biting insects likely to affect the Blacktip Project.

Milingimbi is an Aboriginal community in Arnhem Land, 206 km West from Nhulunbuy. The population is 920 (NT government intranet, 30/6/2003). The community is located on Milingimbi Island. Near the end of February 2003 the Milingimbi community council expressed concerns over increased mosquito numbers to Environmental Health, who requested the Medical Entomology Branch to visit the community, assess the situation and advise on strategies to reduce mosquito problems. Two MEB officers visited Milingimbi on 7-9 April 2003 and carried out a comprehensive biting insect survey, including biting insect trapping, larval mosquito surveillance and a receptacle survey. The results of this survey and the assessment are presented in this report. A mosquito survey had previously been carried out in Milingimbi in 1983, and was documented in a MEB branch report.

There are many examples of development in the Darwin region that have led to enormous populations of a range of mosquito species, severely effecting residents in nearby areas and requiring costly rectification. To aid planners in their design of the proposed Newton development, the Medical Entomology section of the department of Health and Families has made collections of biting midges and mosquitoes form march 1984 to April 1985 in and around the proposed development area between the Elizabeth and Blackmore Rivers, south-west of Palmerston. Additional surveys of biting midge breeding areas were made in late 1987. This report analyses the result and suggest methods of minimising the adverse effects of the biting insect present in the proposed development area, and outlines some construction guidelines to avoid exacerbating the problem.

Compass Resources NL is proposing the development of the Browns Oxide mine, located in the Northern Territory approximately 65km south of Darwin and 7km north-west of Batchelor (Figure 1).The project is currently under construction. Compass Resources NL proposes to utilise open cut mining methods and a conventional hydrometallurgical process to extract approximately 3.9 million tonnes of oxide ore and produce copper, cobalt and nickel over a four year period (Public Environmental Report (PER) - Enesar Consulting Pty Ltd 2005). Mine sites have the potential to create or exacerbate mosquito breeding, from the creation of water dams, wetland filters, borrow pits, sediment traps, pit water discharge, waste water disposal, as well as the construction of roads and mine waste dumps. Mine sites also have the potential to introduce new mosquito species into the Northern Territory, such as the dengue mosquito Aedes aegypti from North Queensland, if equipment is sourced from this area. Therefore, all major development in the NT is required to consider mosquito breeding during the Environmental Assessment process, to ensure development does not create new mosquito breeding sites.

There have been many instances of construction in or near tidal areas in the Top End of the Northern Territory that have resulted in ecological disturbance and subsequent mosquito breeding. Many of the deleterious disturbances have been the result of little or no recognition of the ecological consequences of construction practices, either during the construction period or on completion of the project. Much of the deleterious ecological disturbance can be avoided or minimized by consultation between engineers or construction authorities and people with ecological expertise.

Phillips Petroleum Company Australia Pty Ltd (now ConocoPhillips Australia Pty Ltd) were given approval by both the NT and Commonwealth environmental ministers in 1998 for the construction and operation of a proposed 3 Million Tonnes Per Annum (MTPA) LNG facility at Wickham Point, in Middle Arm of Darwin Harbour. This project was deferred, and in March 2002 Darwin LNG Pty Ltd (a subsidiary company of ConocoPhillips) submitted a Public Environmental Report for an expanded 10MTPA LNG plant. Post construction inspections were carried out by MEB in January and March 2006. Sites of particular interest were stormwater drains, stormwater drain end points, stormwater pits, sediment basins and discharge points, disturbed tidal areas and landscaped areas. As this report is based on the post construction inspection only, discussion on mosquito species is limited to the major potential pest and vector species. For further information on mosquito species mentioned in this report readers should refer to the Wickham Point Baseline Biting Insect Report (Warchot and Whelan 2004).

Drains are generally constructed structures to convey stormwater, waste water, or other sources of water by a flow path or formal channel from a catchment or source to a discharge point. Drains can be part of an organised drainage system or a specific measure to drain depressions or temporary flooded areas. Generally drains in small catchments in undeveloped areas only convey water during or for a few hours after rain, and if they have adequate slope, dry up soon after the rain ceases. However drains with larger catchments or from perennial or artificial sources of water, contain water for relatively long periods and can be significant sources of mosquitoes.

Territory Iron Limited proposes to develop an open cut iron ore mining operation at Frances Creek, 180 kilometres south-east of Darwin. The proposed operation will be on the site of the previous Frances Creek Iron Ore Mine, which operated from 1967 to 1974. It will use remaining infrastructure from the previous operation. Three of five pits will be extensions of existing pits (Frances Creek Project PER, MBS Environmental August 2006). As the proposed mine site contains various water holding features such as dams and pits, as well as being located adjacent to ephemeral creek lines, there was the likelihood that pest and disease carrying mosquito species would be present at the mine site. Mining operations have the potential to create new mosquito breeding sites through the excavation of pits, construction of sediment ponds and dams, waste water disposal, construction of waste dumps, pit dewatering activities and the construction of roads. Mine operations also have the potential to introduce new mosquito species into the Northern Territory, such as the dengue mosquito Aedes aegypti from North Queensland, if equipment was to be sourced from this area.

This paper outlines the various elements of an integrated mosquito control program in Katherine, involving public awareness, larval mosquito control, adult mosquito control and engineering control methods. The program has provided a number of lessons for improved mosquito control following floods which are applicable to other areas in Australia.

Darwin, the northern gateway to Australia, is both vulnerable and receptive to a range of exotic and endemic mosquito borne diseases, including malaria, dengue, epidemic polyarthritis and Australian encephalitis. The Medical Entomology Branch has developed an integrated mosquito control program.

The upper tidal reaches of the various arms of Ludmilla Creek in Darwin have been historical breeding sites for pest and disease carrying mosquitoes. Most of the historical mosquito breeding in the Ludmilla Creek catchment was a direct result of urban development and associated stormwater discharge. The major mosquito breeding sites associated with Ludmilla Creek were targeted in 1984 under the combined Northern Territory Government and Darwin City Council mosquito engineering program, which was supervised by Medical Entomology. These included constructing suitable drains in the Coconut Grove, Fannie Bay and East Point areas of Ludmilla Creek.

The upper tidal reaches of the various arms of Ludmilla Creek in Darwin have been historical breeding sites for pest and disease carrying mosquitoes. Most of the historical mosquito breeding in the Ludmilla Creek catchment was a direct result of urban development and associated stormwater discharge. The major mosquito breeding sites associated with Ludmilla Creek were targeted in 1984 under the combined Northern Territory Government and Darwin City Council mosquito engineering program. Mosquito breeding areas were identified by Medical Entomology (ME), with construction supervised by Darwin City Council (DCC). This included constructing drains in the Coconut Grove, Fannie Bay and East Point areas of Ludmilla Creek from suburban areas to the central section of the creek. The construction of the drains removed the dry season ponding and associated mosquito breeding, although the northern salt marsh mosquito Aedes vigilax does still breed in some tidally affected drains and the Kulaluk rice field during the late dry season/early wet season.

Terra Gold Mining Pty Ltd, a wholly owned subsidiary of GBS Gold Australia Pty Ltd proposes to commence mining activities at the previously worked Maud Creek Mine site near Katherine, Northern Territory. The operation will involve construction of an underground decline, stockpile area, and associated infrastructure. Extracted ores will be transported to Union Reefs Gold Mine for processing (URS 2008). Mine sites have the potential to create or exacerbate mosquito breeding, from the creation of water dams, wetland filters, borrow pits, sediment traps, pit water discharge, waste water disposal, as well as the construction of roads and mine waste dumps. Mine sites also have the potential to introduce new mosquito species into the Northern Territory, such as the dengue mosquito Aedes aegypti from North Queensland, if equipment is sourced from this area. Therefore, all major development in the NT is required to consider mosquito breeding during the Environmental Assessment process, to ensure development does not create new mosquito breeding sites.

The McArthur River Mine (MRM) is situated approximately 50 km south west of Borroloola in the Northern Territory. The objective of the project is to mine the silver-lead-zinc deposit adjacent to the McArthur River. The ore will be transported by truck along the Carpentaria Highway, through Borroloola, to a barge loading facility at Bing Bong Station situated on the shore of the Gulf of Carpentaria. This report summarises the results of the first 12 months of baseline monitoring and discusses the implications of the mosquito species, their relative numbers, and the spatial and temporal distribution of the mosquito species in the area. The results of a follow up field inspection on 19-20 September 1995 are also presented.

The Medical Entomology Annual Report 2008/09 is intended to present an overall picture of DHF mosquito surveillance and control activities carried out in the Northern Territory in 2008/09. In addition, specific figures and tables for regional towns that are not presented in this report, have been produced for Alyangula, Nhulunbuy, Jabiru, Katherine, Tennant Creek and Alice Springs to provide local officers with the detailed information from local programs. These tables and figures are available on request.

The Medical Entomology Annual Report 2009-10 is intended to present an overall picture of DHF mosquito surveillance and control activities carried out in the Northern Territory in 2009/10.

The Medical Entomology Annual Report 2011/12 is intended to present an overall picture of DoH mosquito surveillance and control activities carried out in the Northern Territory in 2011/12.