Mosquito Control and Coastal Development: How they Have Coexisted and Matured in Florida and Australia.

The aims of this review were to compare planning for both mosquito control and land use in east-central Florida, USA, and in New South Wales, Queensland, and the Northern Territory, Australia. Saltwater mosquito production in mangroves and salt marsh is the predominant mosquito control concern in all the areas. Urban encroachment towards saltwater mosquito habitats is a problem in both Florida and Australia. In east-central Florida and the Northern Territory, mosquito control is supported by comprehensive source reduction programs, whereas in Queensland and New South Wales, larviciding is the main method of control. The long-term control by source reduction programs reduces vulnerability to mosquito issues as population encroaches towards wetlands, whereas larviciding programs have to respond repeatedly as problems arise. Problems from urban encroachment are exacerbated if mosquito control and land-use planning are not integrated. Further, urban planning that is not informed by mosquito management can lead to increased mosquito problems by inadvertent design or allowing residential development close to mosquito habitats. This increases the need for mosquito control and related resourcing. At the regional level of governance, Florida and the Northern Territory generally have greater integration between planning for development and mosquito control than at the local government level in New South Wales and Queensland, where there is a lack of integration between mosquito agencies and planners. It is concluded that coordination of planning and mosquito control is more effective at higher government levels than at local levels, which have less connectivity between management areas and/or insufficient resources. The lesson is that collaboration can assist in avoiding or resolving conflicts.

Using Present Value as a Simple Approach to Compare Mosquito Larval Control Methods.

Simple economic-based comparisons of source reduction and larvicide treatment are generally lacking in the mosquito control literature. The aim is to address this by developing an Excel tool that calculates the total present value (PV) of control methods. We use 15 years as the time frame, but this can be varied. Total PV is calculated based on the cost of each method at the start. A 3% discount rate is applied to recurring costs, and one-off costs are included throughout because they are part of the total PV. The data are based on information provided by mosquito control agencies in southeast Queensland, Australia. Values in the tool can be simply edited to reflect specific program characteristics. The outcome for the data used showed that source reduction is an appropriate option if maintenance is minimal. When major maintenance is needed, then larviciding may be the better option, particularly if money is the main consideration. However, if the frequency of applying larvicides increases, then source reduction becomes an increasingly attractive option.

Four degrees of latitude: mosquito control on the "right" coasts of Australia and Florida, USA.

This study compares mosquito control within similar environments between 26 and 30 degrees of latitude on the east central coasts of Florida and of Australia. It describes and compares the relevant mosquito-producing environments, the development of mosquito control, legislative framework, funding arrangements, and organizational differences between the areas, including the international interactions that have facilitated good practices. The article identifies some strengths and weaknesses of the programs in each area. Significant strengths include some aspects of funding and administration; collaborations with other organizations; the roles of national and state organizations, including research agencies; and commitment of individuals. Potential weaknesses in programs that are part of larger organizations include their relatively low position in the organizational hierarchy and the need to compete for resources. Programs that are independent districts may lack opportunity to interact with other land management units. Other weaknesses include the relatively high turnover of staff in state environmental resource agencies and the potential loss of institutional memory when long-term mosquito control staff members leave. The case comparison highlights similarities in product use at the individual program level (Indian River Mosquito Control District and Gold Coast Pest Management Unit) and differences in practices including aerial adulticiding being used in Florida but not in Australia.

Habitat characteristics and eggshell distribution of the salt marsh mosquito, Aedes vigilax, in marshes in subtropical Eastern Australia.

Research at 10 locations in coastal subtropical Queensland, Australia, has shown that salt marshes contained heterogeneous distributions of eggshells of the pest and vector mosquito Aedes vigilax (Skuse) (Diptera:Culicidae). The eggshell distribution was related to specific vegetation assemblages, with a mix of the grass, Sporobolus virginicus (L.) Kunth (Poales: Poaceae), and the beaded glasswort, Sarcocornia quinqueflora (Bunge ex (Ung.-Stern) A.J. Scott (Caryophyllales: Chenopodiaceae), as significantly higher in eggshells than any other vegetation. There were also high numbers in the mix of S. virginicus with the arrowgrass, Triglochin striata Ruiz & Pavón (Alismatales: Juncaginaceae). Both mixed types are found in relatively wetter areas, despite very few eggshells being found generally in the low marsh. Most sites contained S. virginicus and eggshell locations were variable for this species alone. This was probably related to its life form variability in response to salinity and location on the marsh. Location on the marsh was important for eggshell distribution with most eggshells around the edges of pools and depressions, followed by, but to a significantly lesser extent, the marsh surface. Eggshells were fewest in the low marsh. Partition analysis resulted in a tree that simplified and summarised the factors important for eggshell distribution confirming the individual analyses. The potential effects of climate, sea level and other change are also briefly discussed in the context of likely changes to land cover and relative location on the marsh. For example, increased sea level may lead to low marsh conditions extending into higher marsh area with implications for oviposition and numbers of eggshells.

Constructed wetlands for sewage effluent treatment and mosquito larvae at two sites in subtropical Australia.

This study of 2 wetlands in subtropical Australia, constructed to treat sewage effluent, examined the relationships between dips positive for mosquito larvae and water quality, operational status of the system, vegetation, and nontarget macroinvertebrates. One site is inland and the other is close to the coast. Larvae of disease vector mosquitoes were present at various times in the wetlands, especially in summer and autumn. The proportion of early instars (1st and 2nd) was greater than that of later ones (3rd and 4th). Dissolved oxygen was negatively, and temperature was positively, associated with the proportion of dips containing larvae. For the coastal site we noted that larvae were more common during draw-down of water for maintenance and also as the system started to come online. Vegetation associated with larvae included dense Typha orientalis and algae. Where there were several types of plants, such as at the coastal site, plant density and water depth were not significantly related to larval presence. Where there were several types of macroinvertebrates there were fewer dips positive for larvae. To provide water treatment capacity and minimal mosquito production we concluded that design should include a variety of plant types, discouraging low dissolved oxygen (for example, by aeration) and ongoing maintenance should be carried out in winter or spring, when mosquitoes are fewer than in summer.