Urban population structure and dispersal of an Australian mosquito (Aedes notoscriptus) involved in disease transmission

Abstract

AbstractDispersal is a critical factor in designing successful pest control measures as it determines the rate of movement across target control areas and influences the risk of human exposure to the species and its pathogens. Here we used a fine scale spatial population genomic approach to investigate the dispersal ecology and population structure ofAedes notoscriptus, an important disease transmitting mosquito, on the Mornington Peninsula near Melbourne, Australia. The species is suspected to be involved in the transmission ofMycobacterium ulcerans, the bacterium that causes Buruli ulcer, in this area. We sampled and rearedAe. notoscriptuseggs at two time points from 170 traps up to 5 km apart and generated genomic data from 240 individuals. We also produced a draft genome assembly from a laboratory colony established from mosquitoes sampled near the study area. We found low genetic structure (Fst) and high coancestry throughout the study region. Using genetic data to identify close kin dyads, we found that mosquitoes had moved distances of >1km within a generation, which is further than previously described for this species. A spatial autocorrelation analysis of genetic distances indicated genetic dissimilarity at >4 km separation, a fourfold higher distance than for a comparable population of the dengue mosquito,Ae. aegypti, from Cairns, Australia. These findings point to high mobility ofAe. notoscriptus, highlighting the challenges of localized intervention strategies targeting this species. Further sampling within the same area at two time points 6 and 12 months after initial sampling showed that egg counts were relatively consistent across time, and that spatial variation in egg counts covaried with spatial variation in Wright’s neighbourhood size (NS). As NS increases linearly with population density, egg counts may be useful for estimating relative density inAe. notoscriptus. The results highlight the importance of acquiring species-specific data when planning control measures.