Mosquito Risk Assessment: Ballina Southern Cross Precinct Expansion, October 2015

Mosquito Risk Assessment: Ballina Southern Cross Precinct Expansion By Dr Cameron Webb, Medical Entomology October 2015

EXECUTIVE SUMMARY

. A Mosquito Risk Assessment (MRA) was commissioned by Ardill Payne & Partners for the proposed Southern Cross Precinct Expansion, Ballina Shire, NSW.

. No onsite mosquito surveys were conducted as part of this MRA. However, local data on pest mosquito populations was provided by NSW Mosquito Monitoring and Arbovirus Surveillance Program for Ballina Shire and additional reference sites at Byron Shire and Tweed Shire to provide a representative sample of mosquito populations within the region.

. The historical records identified over 30 mosquito species associated with the region that may impact the proposed development. The most abundant mosquitoes were those associated with the coastal swamp forest habitats that include a suite of species such as Aedes multiplex, Aedes procax and Verrallina funerea. However, the saltmarsh mosquitoes, Aedes vigilax, was considered the most important long-term pest species in the local area. These species have been identified as nuisance-biting pests and potential vectors of Ross River virus and Barmah Forest virus.

. Within the proposed development, the nuisance-biting impacts resulting from the mosquitoes associated with the coastal swamp forest will be minimized due to the substantial “buffer” created by the air strip and lack of substantial vegetation that would otherwise facilitate movement of mosquitoes across the site from the Ballina Nature Reserve.

. While analysis of recent monitoring periods has indicated that the abundance of Aedes vigilax is generally much lower than the abundance of Verrallina funerea and other species associated with the coastal swamp forests, Aedes vigilax remains the most important pest species likely to impact the development site. Given the abundance of potential habitats for this mosquito in the wetlands associated with North Creek and its tributaries, it is likely that Aedes vigilax will pose an annual pest risk with the severity of impacts highly dependent on prevailing environmental conditions (e.g. seasonal rainfall and tidal inundation of estuarine wetlands).

. Overall, there is no evidence that the proposed development, or future site users, will be impacted substantially or significantly more than any other in the region previously identified by Ballina Shire Council’s Development Control Plan (Chapter 2). Given the nature of the proposed development, it is not unreasonable to conclude that the nuisance-biting impacts within an industrial development are likely to be lower than those within a similarly sited residential development.

Mosquito Risk Assessment: Ballina Southern Cross Precinct Expansion, October 2015

INTRODUCTION

The far north coast of the NSW has experienced considerable growth in urban development in recent years. Residential, recreational and industrial developments have been designed to accommodate an expanding population but have the risk to increase potential exposure of the community to mosquitoes. Notwithstanding the potential nuisance-biting impacts, the potential public health risks associated with mosquito-borne pathogens such as Ross River virus and Barmah Forest virus are not insignificant. While not life threatening, the illness caused by these pathogens can have a substantial impact on the community through an adverse impact on tourism, property prices and public amenity of recreational facilities.

Mosquito risk assessments (MRA) are designed to provide information on local mosquito populations and provide comments on their significance. Based on this information, the assessment should provide comments and recommendations for mosquito management strategies if appropriate.

Local authorities in the far north coast of NSW have identified the importance of mosquitoes and their potential impact on their growing residential population and visiting tourists. Ballina Shire Council, as well as Tweed Shire Council and Byron Shire Council have addressed mosquito risks in their local regions with specific mosquito management plans or as components of their Development Control Plans. These strategies are designed to address the potential public health issues associated with mosquitoes by recommending and requiring various measures to reduce human contact with mosquitoes with respect to existing and proposed residential developments. Similarly, any developments that may influence the production of mosquitoes from local wetlands should be assessed.

The future mosquito and mosquito-borne disease risks faced by the region are varied and difficult to predict. Seasonal rainfall, temperature and sea-level rise associated with predicted climate change may all influence the abundance of mosquitoes as well as local wildlife that drive outbreaks of disease. The threat of introduced (or reintroduction) of mosquitoes capable of transmitting viruses such as dengue or chikungunya will be influenced as much by human activity as changes to climate. In addition, environmental conservation strategies and legislation may also play an influential role in the implementation of effective mosquito management strategies.

Ardill Payne & Partners commissioned this MRA in association with the Southern Cross Precinct Expansion proposal. The objective was to identify the potential mosquito risks associated with the proposed development site with respect to the regional mosquito and mosquito-borne disease risk.

This Mosquito Risk Assessment has been prepared in accordance with the brief provided by Ardill Payne & Partners and is for the use only by this client. The Department of Medical Entomology, Pathology West – ICPMR Westmead, accepts no responsibility for its use by other parties. The use of brand names and any mention or listing of commercial products or services in this article does not imply endorsement by the Department of Medical Entomology, or discrimination against similar products or services not mentioned.

Mosquito Risk Assessment: Ballina Southern Cross Precinct Expansion, October 2015

PROPOSED DEVELOPMENT SITE

The development, Southern Cross Precinct Expansion, will include a proposal for rezoning of the land from RU2 – Rural Landscape and SP2 –Infrastructure – Air Transport Facility to part IN1 – General Industrial and part IN2 – Light Industrial under the Ballina LEP 2012.

The area covered by the proposed development had been identified previously as a potential site for commercial and industrial development in the 2012 Ballina Shire Growth Management Strategy and 2008 Southern Cross Precinct Master Plan.

The site is located to the north of the Ballina township and is within 1km of two wetlands that have the potential to produce pest mosquito populations, North Creek and Ballina Nature Reserve (Figure 1). The proposed layout of the development, highlighting the Southern Cross Rezoning Study area is provided in Figure 2.

Preliminary assessments identified a number of potential environmental, social and economic impacts of the proposed development. One of these was mosquitoes and that an entomological assessment would be required.

Ballina Shire Council has been one of the more proactive local governments in Australia in responding to the threat of mosquitoes and mosquito-borne disease in the local area. They have been a participant in the NSW Mosquito Monitoring and Arbovirus Surveillance Program (a program coordinated by NSW Health) and Council was one of the first local authorities to put a Development Control Plan in place that includes requirements for developers to consider mosquito risk and engage professional entomological expertise in developing responses to those risks.

The risk of mosquitoes is currently outlined in Development Control Plan (DCP) - Chapter 2, Item 3.6 (Mosquito Management) with the objective to minimise nuisance and health risk associated with mosquitoes and minimise human contact with mosquitoes.

This section of the DCP includes reference to Ballina Shire Council Development Control Plan – Mosquito Management Map (South) in which the proposed Southern Cross Precinct Expansion development sits within the “coastal plains and lowlands” and has been designated as a zone of “high mosquito risk”.

In providing expert advice on the future mosquito risks to future users of the proposed development, consideration should be given to the nature of the development and the provision of strategies that may reduce the relative mosquito impacts as outlined in the DCP.

Mosquito Risk Assessment: Ballina Southern Cross Precinct Expansion, October 2015

FIGURE 1: Relative location of the Southern Cross Industrial Estate rezoning study area. The extensive wetland areas of the Ballina Nature Reserve to the north and estuarine wetlands associated with North Creek to the east of the site are notable locations of suitable mosquito habitats.

Mosquito Risk Assessment: Ballina Southern Cross Precinct Expansion, October 2015

FIGURE 2: Southern Cross Industrial Estate rezoning study area.

Mosquito Risk Assessment: Ballina Southern Cross Precinct Expansion, October 2015

FIGURE 3: Ballina Shire Council Development Control Plan – Mosquito Management Map (South).

Mosquito Risk Assessment: Ballina Southern Cross Precinct Expansion, October 2015

MOSQUITO BIOLOGY

Mosquitoes are small blood sucking insects that belong to the family of flies called Culicidae (Order Diptera) and there are more than 300 different species in Australia with each species closely associated with particular habitats. There are likely to be close to 100 species that may be found in the far noth coast region of NSW.

Mosquitoes have a relatively short but complex life cycle consisting of eggs, four aquatic larval stages (instars), an aquatic pupal stage and a terrestrial adult stage. Mosquitoes are dependent on water, with the immature stage totally aquatic, and without access to free-standing water of some kind, the larvae cannot complete their development to the adult phase.

Adult female mosquito will typically lay eggs either on the water surface (usually with eggs in the form of a floating raft) or on a frequently inundated substrate (usually singularly or in small groups). The ‘oviposition sites’ may include frequently inundated soil or vegetation at the edge of a wetland, soil or leaf litter where temporary pools form after rainfall or inside water holding containers (e.g. tins, tyres etc).

While some mosquito eggs (such as those laid by Aedes or Verrallina species) can be desiccation resistant and remain unhatched for many months before being inundated by tides or rainfall, most eggs (particularly those laid by Culex and Anopheles species) will hatch within 2-3 days. On hatching, the young larvae (commonly called wrigglers) feed continuously on aquatic particulate matter and grow through four different instars or moults. The larvae of some mosquito species have developed specialised mouthparts and are predatory, feeding on other mosquito larvae and aquatic invertebrates. The final larval stage (4th instar) develops into a pupa (commonly called tumbler) from which the adult mosquito emerges approximately 2 days later. During summer, it generally takes seven to ten days from the hatching of larvae to the emergence of adults.

On average, a female mosquito may live approximately 2-3 weeks but the male's lifespan is much shorter. Adult mosquitoes are most active from dusk until dawn, seeking refuge during the day in cool and humid habitats such as well-vegetated areas or under houses. Some pest species, however, can be active during the day and disperse many kilometres from larval habitats.

Within their lifetime, both adult male and female mosquitoes will feed on nectar and plant fluids, but it is only the female that will seek a blood meal required to provide protein for egg development. While many mosquitoes are generalist feeders, some specialise in feeding on humans, mammals, birds or amphibians. Host seeking females respond to a range of stimuli, the most important being carbon dioxide.

Mosquito Risk Assessment: Ballina Southern Cross Precinct Expansion, October 2015

MOSQUITOES AND PUBLIC HEALTH RISKS

Over 30 mosquito species have been identified from the north coast region of NSW. The majority of these species pose little or minor pest or public health risk due to their relatively low abundance, non-human biting preferences or association with less common habitats. Much of our understanding of local mosquito populations comes from data collected by the NSW Mosquito Monitoring and Arbovirus Surveillance Program (Table 1). In addition, a number of short mosquito surveys have been conducted in the Ballina Shire region in recent years but while these studies may provide some site-specific mosquito data, these shorter surveys have supported the data provided by the NSW Mosquito Monitoring and Arbovirus Surveillance Program as a suitable representation of local mosquito risks.

The species of greatest concern, due to likely nuisance biting impacts and potential public health risks, are Anopheles annulipes, Coquillettidia linealis, Culex annulirostris, Culex quinquefasciatus, Aedes alboannulatus, Aedes multiplex, Aedes notoscriptus, Aedes procax, Aedes vigilax and Verrallina funerea. A summary of the key local mosquito species is provided in Table 2. These species are associated with a range of different habitats including freshwater, brackish water and estuarine wetlands as well as urban environments. The actual impacts of these species is expected to vary considerably throughout the region as the relative abundance of populations is dependent on factors such as the quantity and distribution of rainfall, tidal inundation of wetlands, flooding events, species specific dispersal patterns, prevailing winds and the distribution of appropriate refuge sites.

The most important pest mosquito in the region is the saltmarsh mosquito, Aedes vigilax. The larvae of this species are typically associated with tidally influenced saltmarsh and mangrove habitats found within the estuarine wetlands of the region. During the months between November and April, there can be exceptionally large populations of the mosquitoes and the adults can disperse great distances (>5km) from wetlands. The mosquito is a severe nuisance biting pest and an important vector of Ross River and Barmah Forest viruses in NSW.

Other key local pest species include a group of mosquitoes collectively referred to as “coastal swamp forest” or “floodwater” mosquitoes. These include Aedes multiplex, Aedes procax and Verrallina funerea amongst others but Verrallina funerea is the most important. This mosquito is associated with estuarine to brackish-water habitats and can be a significant nuisance-biting pest. However, unlike Aedes vigilax, this species does not disperse far from local wetlands and is thought to travel no more than 100m from forest habitats.

It is difficult to quantify both the impact of nuisance biting resulting from Aedes vigilax and other mosquitoes within the Ballina region due to the spatial and temporal fluctuation in mosquito abundance and the mix of different mosquito species, their respective habitats and the environmental and/or climatic conditions that trigger population increases. While the actual impact of

Mosquito Risk Assessment: Ballina Southern Cross Precinct Expansion, October 2015

mosquitoes on the community can also vary with the tolerance level of individuals and their previous personal experiences with mosquitoes.

Notwithstanding the local nuisance-biting impacts associated with mosquito populations, the far north coast of NSW has experienced outbreaks of mosquito-borne disease in recent years.

Ross River virus (RRV) and Barmah Forest virus (BFV) are the most common disease-causing pathogens spread by mosquitoes in Australia. There are approximately 5,000 cases of illness caused by Ross River virus each year across the country with around 500 reported from NSW. Over the past ten years, there have been between 10-60 confirmed cases per year of Ross River or Barmah Forest virus infection within the Ballina Shire region. The activity of these pathogens naturally varies from year to year with seasonal climatic conditions as well as ecological factors influencing the populations of wildlife (particularly macropods) that are the natural reservoirs of the pathogens.

While the symptoms of disease caused by RRV and BFV can vary greatly between individuals and include fever and rash, infection with either of these viruses may result in a condition known as polyarthritis with arthritic pain in the ankles, fingers, knees and wrists. Generally, the rash tends to be more florid with BFV infection but the arthritic pain is greater with RRV infection. The presence of specific antibodies showing infection with RRV and BFV can be determined with a blood test. Under the NSW Public Health Act 1991, both viruses are classified as a notifiable infectious disease.

There are also other arboviruses transmitted by mosquitoes, including Stratford (STRV), Sindbis virus (SINV) and Edge Hill virus (EHV), that are occasionally isolated from mosquitoes in coastal regions of NSW but these viruses rarely cause disease in Australia. There is no local activity of dengue viruses or malaria parasites in the Ballina region.

Mosquitoes and mosquito-borne disease are often discussed as a major concern should climate change result in increased temperatures and/or sea level rise. There are many factors besides temperature (including the availability of suitable habitats, short term changes in rainfall and tidal heights, urbanisation and mosquito control programs) that influence the distribution and abundance of mosquitoes as well as the incidence of human disease.

It is difficult to predict how mosquito risk will change in the future but while one group of mosquitoes may benefit from some changes, there may be others that are reduced in their abundance. For example, sea level rise may increase the frequency of tides that penetrate into coastal swamp forests and provided enhanced conditions for mosquitoes such as Verrallina funerea but these same conditions may result in persistent tidal flooding of saltmarsh environments that could result in them being less productive for Aedes vigilax.

The risks of ‘tropical’ diseases are unlikely to rise with predicted climate change, there may be a local increase in the risk of arboviruses, including

Mosquito Risk Assessment: Ballina Southern Cross Precinct Expansion, October 2015

Ross River or Barmah Forest viruses resulting from an extension of the “mosquito season” into early spring or late autumn.

Assessing the impact of climate change is a complex process (with much debate surrounding the potential magnitude of temperature, rainfall and sea level change) but the pest and public health impacts of mosquitoes in the future may be determined as much by urbanisation, wetland construction and rehabilitation, wildlife management strategies and mosquito control programs as any change to the climate of the region. It is highly unlikely that any rise in temperature or sea-level will result in a significant change to the mosquito fauna (either the species composition or abundance) in the short-term.

There is unlikely to be a significant change in the abundance of local mosquitoes or activity of mosquito-borne pathogens. However, if the abundance of reservoir hosts (i.e. macropods) is reduced through continuing urbanization of the region, health risks may be reduced. It is important to note that the general risk of mosquito-borne disease within the Ballina Shire is expected to remain at a comparable level as documented in the previous ten years of human notification data.

A growing concern for local authorities is the introduction, or reintroduction, of “exotic” mosquitoes. There are two key mosquito species that play an important role in the transmission of dengue and chikungunya viruses internationally and both are closely associated with water-holding containers found in urban areas. One of these mosquitoes, Aedes aegypti is only found in northern QLD. Historically it was found along the coast of NSW but has not been recorded in the Ballina region since the 1950s. Surveys in recent times specifically searching for this mosquito have not detected it. However, there is growing concern by QLD authorities that the mosquito may be spreading south toward Brisbane with movement facilitated through human movement and transport of live mosquitoes and objects containing eggs.

Another mosquito of concern is the Asian tiger mosquito, Aedes albopictus. This species is not currently established on mainland Australia but authorities across the country are concerned that this pest species could easily become established along the east coast. As well as being a severe nuisance-biting pest, the mosquito is responsible for triggering outbreaks of dengue and chikungunya viruses in temperate regions of the world (e.g. Europe, Japan).

Given the nature of the Southern Cross Industrial Estate, that is likely to be a key hub of transport, it is important that the risk of these mosquitoes is considered. Notwithstanding the risks associated with the locally abundant container-inhabiting mosquito, Aedes notoscriptus, opportunities for species such as Aedes aegypti and Aedes albopictus should be minimised.

Such strategies will require that water holding structures (e.g. rainwater tanks) are suitably screened and any other permanent or temporary structures/objects are carefully managed. It would be beyond the scope to include detailed discussion of these aspects of future developments within this document but may be considered in the future.

Mosquito Risk Assessment: Ballina Southern Cross Precinct Expansion, October 2015

TABLE 1. Mosquitoes recorded from far north coast (NSW Arbovirus Surveillance and Mosquito Monitoring Program 2008-2009 through 2013- 2014.)

1 Lennox 3 Ocean Mosquito species Ballina 2 Byron Bay 3 Head Shores

Aedes aculeatus + + + + Aedes alternans + + + Aedes burpengaryensis + + + Aedes gahnicola + + Aedes kochi + + + + Aedes multiplex + + + + Aedes notoscriptus + + + + Aedes palmarum + + Aedes procax + + + + Aedes quasirubithorax + Aedes sp. Marks 51 + Aedes vigilax + + + + Aedes vittiger + An. annulipes + + + + Coquillettidia linealis + + + + Coquillettidia variegata + + + + Coquillettidia xanthogaster + + + + Culiseta antipodea + Culex annulirostris + + + + Culex australicus + + + Culex bitaeniorhynchus + + Culex edwardsi + + + Culex halifaxii + + + + Culex orbostiensis + + + + Culex postspiraculosus + Culex pullus + + Culex quinquefasciatus + + + + Culex sitiens + + + + Culex sp. Marks No. 32 + + + Culex squamosus + + + Mansonia uniformis + + + + Tripteroides marksae + + Tripteroides tasmaniensis + Uranotaenia lateralis + Uranotaenia nivipes + Verrallina funerea + + + + Verrallina sp. Marks No. 52 + + + +

Total number of species 27 24 27 30 1Trap site location has move over the sampling period but most frequently located adjacent to North Creek 2Trap site location has move over the sampling period but most frequently located at Pacific Pines 3Note that Byron Shire Council did not participate in the 2013-2014 monitoring period

Mosquito Risk Assessment: Ballina Southern Cross Precinct Expansion, October 2015

TABLE 2. Larval habitat, pest status and period of peak activity of the most common mosquitoes in the region covered by Ballina Shire Council.

Mosquito Species Larval Habitat Pest status Activity

Potential biting pest close Aedes alternans Estuarine & brackish wetlands Nov - Apr to breeding habitat

Aedes notoscriptus Urban water-holding containers Potential pest following Sep - May

Occasional biting pest Ephemeral brackish & Aedes multiplex close to breeding habitat Nov - Apr freshwater when populations large

Occasional biting pest Ephemeral brackish to Aedes procax close to larval habitat Dec - Apr freshwater bushland pools when populations large

Serious biting pest and Estuarine wetlands (esp. potential vector many Aedes vigilax saltmarsh) and brackish-water Nov – Apr kilometers from larval habitats habitat

Well vegetated, permanent Coquillettidia linealis freshwater wetlands (inc. Potential biting pest Nov - Mar constructed wetlands)

Potential biting pest and Well vegetated permanent and will pose greatest risk Culex annulirostris temporary freshwater wetlands Jan - Mar during periods of above (inc. constructed wetlands) average rainfall

Polluted freshwater wetlands Culex quinquefasciatus1 (inc. constructed wetlands) and Potential nuisance pest Sep - May urban habitats

Temporary brackish & Major biting pest and Verrallina funerea Dec - Apr freshwater vector

Mosquito Risk Assessment: Ballina Southern Cross Precinct Expansion, October 2015

MOSQUITO RISK ASSESSMENT: DEVELOPMENT SITE

With consideration given to the results of long term mosquito surveillance in the Ballina Shire region, and with reference to other regions on the far north coast of NSW, it can be concluded that there are a number of mosquito species present that may pose potential pest impacts to the proposed Southern Cross Industrial Estate. However, these risks are not considered to be significantly greater than any other development in the coastal plains and lowlands risk zone previously identified by Ballina Shire Council and documented in their DCP.

No mosquito sampling was undertaken in preparation of this assessment. However, as mentioned earlier in this report. Data available from NSW Mosquito Monitoring and Arbovirus Surveillance Program is sufficient to assess the likely mosquito risks associated with this development.

There is a range of species present in the local area that may cause potential pest impacts within the proposed Southern Cross Industrial Estate (Table 2). While each of these species has the potential to cause pest impacts within the site, the impacts will vary greatly depending on seasonal patterns of rainfall and tidal inundation. However, the two most likely critical pest species will be Aedes vigilax and Verrallina funerea.

The relative risk posed by Verrallina funerea is offset somewhat by the distances between the key habitats of this mosquitoes that will be associated with the Ballina Nature Reserve. This mosquito does not disperse far from the shaded and humid canopy of the coastal swamp forest and associated habitats in the nature reserve.

While this mosquito can cause nuisance-biting problems in residential developments adjacent to these habitats, particularly where residential allotments are in close proximity to the habitats and/or vegetative corridors provide dispersal routes for mosquitoes from the coastal swamp forest into the residential areas. The “buffer” between the Ballina Nature Reserve and the proposed Southern Cross Industrial Estate provided by the airstrip and associated areas clear of vegetation will greatly reduce any potential risk posed by this mosquito.

The mosquito most likely to impact the site will be Aedes vigilax and given the relatively small distances between the proposed development and estuarine wetlands associated with North Creek and its tributaries, it should be expected that this mosquito will cause some nuisance-biting impacts during periods of suitable environmental conditions.

In recent years, the abundance of Aedes vigilax at the North Creek trap site of the NSW Mosquito Monitoring and Arbovirus Surveillance Program has yielded relatively low populations for this species. In fact, the abundance has been overshadowed on many occasions by Verrallina funerea.

Mosquito Risk Assessment: Ballina Southern Cross Precinct Expansion, October 2015

During the 2013-2014 monitoring period there was a mean weekly abundance of Aedes vigilax recorded of 8.8 mosquitoes per trap (North Creek) and 20.6 mosquitoes per trap (Pacific Pines). This compared to mean weekly abundance of Verrallina funerea of 36.0 mosquitoes per trap (North Creek) and 46.9 mosquitoes per trap (Pacific Pines).

The difference was even more stark during the 2012-2013 monitoring period there was a mean weekly abundance of Aedes vigilax recorded of 10.0 mosquitoes per trap (North Creek) and 5.1 mosquitoes per trap (Pacific Pines). This compared to mean weekly abundance of Verrallina funerea of 172.2 mosquitoes per trap (North Creek) and 71.1 mosquitoes per trap (Pacific Pines).

Despite the overall mean weekly abundance of Aedes vigilax remaining relatively low over the previous two monitoring periods, there were occasions when over 200 mosquitoes were collected per trap during an individual trap night. Historically, there were also seasons when Aedes vigilax was consistently more abundant with collections during individual weeks exceeding 500 mosquitoes per trap.

There may be numerous explanations for these differences, it could be slight changes in the trapping locations, intentional or unintentional modification to local wetlands that may influence the productivity of Aedes vigilax and general climatic changes with differences in seasonal rainfall. For example, during periods dominated by La Nina weather patterns when summers are generally a little cooler and rainfall is above average, populations of Aedes vigilax are generally lower than during the hot and dry conditions associated with a prevailing El Nino weather pattern.

One of the most common mosquitoes in collections has been Aedes notoscriptus. This nuisance-biting pest is not associated with wetlands but rather natural and artificial water-holding containers (e.g. buckets, bird baths, rainwater tanks, discarded tyres, blocked roof gutters). The species is likely to be associated with future development.

In reviewing the abundance and diversity of local mosquito fauna, there are a number of other species identified that are occasionally abundant but these species are unlikely to disperse into the proposed development site. It is also important to note that one of the most abundant mosquitoes in the local area is Culex sitiens. This mosquito, regardless of abundance, is rarely a pest as it preferentially bites birds and not humans.

Overall. there is no evidence from the available data that nuisance-biting and/or potential public health risks within the proposed Southern Cross Industrial Estate development are significantly greater than those of comparable distance from estuarine wetlands in other areas of the Ballina Shire.

Mosquito Risk Assessment: Ballina Southern Cross Precinct Expansion, October 2015

MOSQUITO RISK ASSESSMENT: DEVELOPMENT PLAN

In the case of proposed residential developments, detailed plans of residential allotments, stormwater structures, constructed wetlands and landscaping are typically reviewed. Developments of an industrial nature, such as the Southern Cross Industrial Estate, are inherently likely to provided fewer opportunities for mosquito production and refuge.

The proposed zoning plan (Figure 2) outlines the proposed land uses within the Southern Cross Industrial Estate study area but this assessment is specifically discussing the risks within the Southern Cross Rezoning Study Area.

Without detailed plans of the building and landscaping plans associated with proposed developments, it is difficult to accurately assess future onsite nuisance-biting risks. However, it would be expected that there would be an absence of substantial vegetative corridors running across the site that would facilitate movement of mosquitoes. This lack of substantial vegetation, combined the industrial nature of the surrounding development (combined with the buffer created by the adjacent airstrip as discussed previously) would result in relatively fewer mosquitoes dispersing into the site compared to a comparably sited residential development.

There is no doubt that, on occasion, mosquitoes will cause nuisance-biting problems when environmental conditions are suitable. This is most likely to occur during the period November through March, particularly 10 days following any major rainfall event of tidal event in which spring tides inundate local wetlands. These environmental conditions provide the trigger for increased mosquito populations. Peaks in mosquito abundance will persist for around two weeks before natural mortality will result in declining mosquito abundance.

During these periods of peak mosquito activity, the extent of any nuisance- biting problems can be mitigated through a combination of building design and onsite water management. Water sensitive urban design (i.e. stormwater management and rainwater storage) can provide opportunities for mosquitoes (particularly Aedes notoscriptus and Culex quiquefasciatus). The construction of stormwater management devices ranging from gross pollutant trap through to bioretention swales may provide opportunities for mosquitoes to breed onsite and the installation of rainwater tanks may also provide additional habitats. Accurate assessment of mosquito risks associated with these structures requires the provision of detailed plans and may be considered at a later time. If substantial water storage (either permanent or temporary) structures are planned or that constructed wetlands or bioretention swales are proposed as part of the redevelopment, these systems should be assessed for potential to increase onsite mosquito risk in accordance with Ballina Shire Council DCP (Chapter 2).

With regard to building design, there are no strategies available that will completely remove all mosquito impacts. However, there are a number of

Mosquito Risk Assessment: Ballina Southern Cross Precinct Expansion, October 2015

strategies available that can be incorporated into the design and construction of the development that will assist in reducing mosquito impacts.

Mosquito activity should be expected in outdoor areas. Depending on the nature of the businesses operating in the proposed development, users of the site during dawn and dusk will be more likely to be exposed to mosquitoes. Minimising the entry of mosquitoes into buildings will be critical and the incorporation of insect screens of an appropriate mesh size should be fitted and regularly maintained. It should also be ensured that there are no entry points via air conditioning ducts, ventilation structures or other connections between indoor and outdoor areas.

Insect screens (made of aluminum, bronze or fiberglass) of an appropriate mesh size (mesh size of 1.2mm x 1.2mm is generally recommended) should be fitted to windows and doors where possible and maintained regularly (tears and loose fitting screens will allow mosquitoes entry to buildings). There is a wide range of options available for screening doors including sliding, spring loaded and pleated screens for doors and windows. Some retractable structures are available for wide openings with pleated and bi-folding options offering potential coverage of openings over 5m wide and up to 3m high. Adapting these screening options for industrial buildings will assist in reducing pest mosquito impacts.

In some locations within the site, consideration could be given to the provision of permanently screened outdoor areas. The provision of screened outdoor areas will provide protection from mosquitoes during the periods of peak activity and during the evening when mosquito activity is generally greatest.

Mosquito Risk Assessment: Ballina Southern Cross Precinct Expansion, October 2015

SUMMARY

This report provides an assessment of mosquito risks associated with the proposed Southern Cross industrial Estate development and, specifically, the nominated Southern Cross Rezoning Study Area. The report was undertaken in response to the gateway determination provided by NSW Department of Planning and Infrastructure recommending the provision of “entomological (mosquitoes)” information that should accompany the development planning proposal (DoP Reference: PP_2013_BALLI_005_00) prior to public exhibition.

The proposal is for the rezoning of the land from RU2 – Rural Landscape and SP2 –Infrastructure – Air Transport Facility to part IN1 – General Industrial and part IN2 – Light Industrial under the Ballina LEP 2012. Industrial redevelopment will generally bring inherently fewer mosquito risks as there is less likely to be substantial areas of vegetation to provide refuge for dispersing mosquitoes. However, given the location of the development, close to both the estuarine wetlands associated with North Creek and brackish- water habitats of the Ballina Nature Reserve, there is likely to be some nuisance-biting risks.

The potential risks of nuisance-biting mosquitoes and mosquito-borne disease were reviewed with respect to available data provided by the NSW Mosquito Monitoring and Arbovirus Surveillance Program on the mosquito fauna of the far north coast region of NSW. While this assessment did not included faunal surveys in the local area, it was considered appropriate to use historical data from nearby traps sites.

The finding is that, overall, the future users of this development will not be exposed to significantly more nuisance-biting risks or mosquito-borne disease risks than other developments within the region designated as a “high mosquito risk” zone within the “coastal plains and lowlands” as detailed in the Ballina Shire Council Development Control Plan (DCP) - Chapter 2, Item 3.6 (Mosquito Management).

Pending design reviews of any proposed substantial water storage structures associated with stormwater treatment and retention, rainwater storage or constructed wetlands, there is unlikely to be a significant onsite mosquito production. However, consideration should be given to mosquitoes adapted to urban habitats that may pose a risk if suitable habitats are created.

Mosquito Risk Assessment: Ballina Southern Cross Precinct Expansion, October 2015

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