Quantifying the Drivers of Larval Density Patterns in Two Tropical Mosquito Species to Maximize Control Efficiency

Abstract

Understanding the contributions of environmental variation and density feedbacks to changes in vector populations is essential for designing effective vector control. We analyzed monitoring datasets describing larval densities over 7 yr of the two dominant mosquito species, Aedes vigilax (Skuse) and Culex annulirostris (Skuse), of the greater Darwin area (Northern Territory, Australia). Using generalized linear and linear mixed-effects models, we tested hypotheses regarding the environmental determinants of spatio-temporal patterns in relative larval abundance in both species. The most important spatial drivers of Ae. vigilax and Cx. annulirostris larval densities were elevation and water presence. Ae. vigilax density correlates negatively with elevation, whereas there was a positive relationship between Cx. annulirostris density and elevation. These results show how larval habitats used by the saltwater-influenced breeder Ae. vigilax and the obligate freshwater breeder Cx. annulirostris are separated in a tidally influenced swamp. The models examining temporal drivers of larval density also identified this discrimination between freshwater and saltwater habitats. Ae. vigilax larval densities were positively related to maximum tide height and high tide frequency, whereas Cx. annulirostris larval densities were positively related to elevation and rainfall. Adult abundance in the previous month was the most important temporal driver of larval densities in both species, providing a clear dynamical link between the two main life phases in mosquito development. This study shows the importance of considering both spatial and temporal drivers, and intrinsic population dynamics, when planning vector control strategies to reduce larval density, adult population density, and disease transmission effectively.

Foraging Ranges of Insectivorous Bats Shift Relative to Changes in Mosquito Abundance

“…vigilax during March 2010 was significantly lower in saltmarsh than in February 2010. This result was in line with expectations as the lack of extensive tidal flooding of saltmarsh in the weeks preceding the March 2010 radio-tracking period did not provide suitable conditions for mosquito development [33]. However, there was no significant difference in the mean abundance of Ae.…”

Mosquito distribution in a saltmarsh: determinants of eggs in a variable environment

“…Moisture is an essential component in saltmarsh mosquito egg conditioning (Knight and Baker , Kay and Jorgensen ) and hatching (Andreadis , Rydzanicz et al , Cardo et al ) and many studies correlate Aedes spp. with wet, lower regions of saltmarshes that are periodically flooded by tide (De Little et al , Jacups et al , Cardo et al ). We found that soil moisture was greatest in bare soil and runnel habitat than shrubby glasswort and samphire, but there was no relationship between soil moisture and elevation.…”

Ecological Suitability and Spatial Distribution of Five Anopheles Species in Amazonian Brazil

“…5,6 Knowledge of the influence of habitat factors on larval production is critical for understanding the spatial and temporal distribution patterns of mosquito vector species and for planning and implementing appropriate larval control strategies. 7,8 Despite five decades of intensive control efforts, Brazil continues to report the greatest proportion of malaria cases in the Americas. 9,10 Within Brazil, the incidence of malaria is almost exclusively (99.8% of the total number of cases) restricted to the Amazon Region, where a number of combined factors favor disease transmission and impair the use of standard control procedures.…”