Container surface area and water depth influence the population dynamics of the mosquito Culex pervigilans (Diptera: Culicidae) and its associated predators in New Zealand.

The density of larval mosquitoes in containers is related to adult mosquito ovipositional preferences and to other factors such as the abundance of predators. We examined the effects of anthropogenic container size and water depth on the population dynamics of mosquitoes and their macroinvertebrate predators in Wellington, New Zealand. Culex pervigilans was the only mosquito species observed in these containers. With the exception of one sampling date, throughout the year Cx. pevigilans larvae, egg rafts, and pupal exuviae were observed. The highest densities of Cx. pervigilans were observed in the containers with the smallest surface area. A multiple regression analysis was used to analyze the effects of container surface area and depth on the mean density of mosquito larvae in each container. This analysis showed larval densities significantly decreased with increasing container surface area, for two-thirds of the year. Although fewer Cx. pervigilans were generally observed in similarly sized containers with greater depths, this effect was not statistically significant. The significant effect of container surface area appeared to be related to adult ovipositional preferences, as few observations of predators were made in any of the container treatments. Of the predators that were observed, damselfly larvae and diving beetles tended to be more common in the larger containers. Our results suggest that mosquitoes may have strong preferences based on container size alone that influence larval population dynamics, irrespective of the abundance of aquatic predators.