What Happens on Islands, doesn't Stay on Islands: Patterns of Synchronicity in Mosquito Nuisance and Host-Seeking Activity between a Mangrove Island and Adjacent Coastal Development

Coastal development is expanding globally in response to mass human migration, yet urban planning guidelines often overlook the problems that human encroachment on or near coastal mosquito habitat may cause. This study aimed at elucidating the frequency and magnitude of dispersal of highly vagile saltmarsh mosquitoes from productive off-shore bay islands to adjacent coastal human developments. Inter-population dynamics and daily host-seeking activity of saltmarsh mosquitoes were monitored daily at 15-min intervals within a productive bay island and adjacent coastal development in southeast Queensland, Australia, using emerging smart trap technology over a 2-month period of high mosquito activity. The regulation of mosquito dispersal and host-seeking activity by local environmental factors, e.g. temperature, relative humidity and hourly wind patterns, were also investigated. The data show that the primary saltmarsh mosquitoes Aedes vigilax (Skuse) and Culex sitiens (Wiedemann) disperse from offshore breeding sites to neighboring mainland areas in high numbers and in highly synchronized waves despite unfavorable wind patterns and the need to traverse a considerable expanse (ca. 1.4 km) of open water. Patterns of host-seeking activity within each site were also remarkably similar despite notable differences in the local environment demonstrating a consistency in host-seeking activity across disparate habitats. These findings demonstrate that distant saltmarsh habitats, including offshore breeding sites, are likely to be primary sources of mosquito nuisance for coastal housing developments. This observation highlights the need to develop new planning and regulatory guidelines that alert urban planners to the risks of encroaching on habitats close to sources of highly vagile mosquito species.