The influence of aquatic predators on mosquito abundance in animal drinking troughs in New Zealand

Abstract

The occurrence and abundance of mosquito populations may be associated with the abundance of predators. We examined the relationship between aquatic predators and populations of mosquitoes in animal water troughs in Waikanae, New Zealand. We also investigated the effects of water volume and environmental factors (temperature, rainfall, wind speed, humidity, and pressure) in order to further understand factors influencing mosquito and predator populations. Logistic regression indicated that the presence or absence of mosquitoes was primarily affected by three factors: predator abundance, week of observation, and water volume. Pearson's correlation indicated that the presence of predators had a positive correlation with water volume (r² = 0.176, p< 0.05). Otherwise, the presence of mosquito larvae in water troughs was negatively correlated with water volume (r² =-0.159, p=0.022) and wind speed (r² =0.142, p=0.041). We established a translocation experiment in which predators or mosquitoes were moved between troughs in order to examine the prey survival rate after exposure to Anisops wakefieldi predators. The survival rate of mosquitoes was not significantly different, between 0-0.1%, irrespective of the number of predators translocated (1-9) or the initial mosquito density (20-70 larvae). Our results suggested that A. wakefieldi predators may have the potential to be a promising biological control tool for the control of mosquito populations by altering mosquito population dynamics.