To skip or not to skip: exploring the connections between orviposition behavior and density –dependence in Aedes albopictus mosquitoes

Taryn Waite, a student at Colby College, collaborated with REU student Courtney Schreiner, Nicole Solano, Dr. Craig Osenberg, and Dr. Courtney Murdock.

Abstract: Conspecific density in larval habitats is an important factor affecting adult fitness in Aedes albopictus mosquitoes, as it drives competition for food and space. We conducted a larval density experiment wherein mason jars containing leaf infusion and varying numbers of larvae were placed in a field enclosure, developmental stage was recorded daily, and emerged adults were collected. Nonlinear regressions were performed on the data for survival to adulthood, sex ratio of adults, and wing length of females, and fecundity was inferred from wing length. Using these regressions, an equation was created to predict short-term population dynamics in habitats with varying conspecific densities. What determines the densities that will actually occur in various larval habitats is where females choose to lay their eggs. Female mosquitoes have the ability to skip-oviposit, which entails spreading their eggs out among multiple habitats instead of dumping them all in one habitat. The population dynamics equation was used to evaluate the theoretical consequences of skip- versus non-skip- oviposition, using scenarios with varying numbers of egg-laying females and a fixed number of available larval habitats. We found that at low densities of ovipositing females, skip-oviposition produces more short-term population growth than non-skip-oviposition. At higher densities, non-skipping becomes more productive than skipping, though there is less divergence between the outcomes. This simulation demonstrates a way in which patterns of density-dependence could act as a link between oviposition behavior and population dynamics. Due to the effects that we found of density dependence in larval habitats, individual females’ oviposition behavior could have consequences for short-term population dynamics.