2020 ESA Annual Meeting (August 3 - 6)

COS 210 Abstract - Is a good place to be a larva a good place to be an adult mosquito?

Melissa H. DeSiervo, Ecology Evolution Ecosystems & Society, Dartmouth College, Hanover, NH, Matthew P. Ayres, Biological Sciences, Dartmouth College, Hanover, NH, Ross A. Virginia, Environmental Studies Program, Dartmouth College, Hanover, NH and Lauren Culler, Institute of Arctic Studies, Dartmouth College, Hanover, NH
Background/Question/Methods

A central question in population dynamics is why some populations vary greatly in space and time while others remain stable. This is further complicated for organisms with complex life cycles, such as mosquitoes, where resource requirements vary across life stages, and only adults can disperse. Here we ask, what drives spatial and temporal heterogeneity in the abundance of Arctic mosquitoes (Aedes nigripes)? If adult dispersal is limited and most females lay eggs near their natal pond, then variation in larval habitat would be a key factor for heterogeneity in the adult population. Alternatively, variation in the abundance of vertebrate blood meals could be a central driver of population dynamics. To address this question, we surveyed the mosquito population near Kangerlussuaq Greenland during summers of 2017 - 2019. We collected scoop samples from ponds to track larval density and mortality following egg hatch and quantified emerging adults with emergence traps. Around these same ponds we sweep netted to estimate adult density and proportion of gravid females. Lastly, we established five pairs of carbon dioxide (CO2) baited traps to capture host-seeking females. One set in each pair was established at a focal pond while the other was placed in a nearby area with less larval habitat within 1 km.

Results/Conclusions

Ponds varied by more than tenfold in their densities of hatching larvae, and ponds with more hatching larvae had more emerging adults, but also more per-capita mortality and negative population growth rates. Although actual densities varied among years, the ponds with the most larvae remained consistent across year. From sweep net samples, we collected 3386 mosquitoes in 2018 of which 2.9% were gravid (compared to 3.8% in 2017). In both years, the highest proportion of gravid females were collected in a sandy area that is a nesting ground for ringed plovers. Our CO2 data indicated that adult abundance was unimodal and peaked approximately 4 weeks after ice thaw. Adults were somewhat aggregated in areas with more larval habitat and there was little evidence that the population became less aggregated throughout the season. In conclusion, our results indicated that sites with high densities of hatching larvae tended to have more adults, but a lower proportion of gravid females. This indicates that a good place to be a larva and a good place to be an adult are places with low conspecific density, and that spatial heterogeneity is largely driven by oviposition tendencies.