Aedes aegypti and Aedes albopictus, like many aquatic insects, feed and grow in an aquatic environment, but reproduce in the aerial environment. Observations and experiments indicate that A. albopictus may be superior in resource competition in the aquatic environment, yet these species coexist in south Florida, and A. aegypti remains dominant in containers in the Florida Keys. Mean temperature and seasonal drought differentially affect mortality of eggs and are correlated with the distributions of these species in Florida. I investigated whether differential mortality of eggs can alter the competitive outcome or facilitate coexistence of these competitors. The model, developed using Stella 5.1.1®, includes: detritus input to the aquatic environment, growth of a resource population (bacteria) on that detritus, resource competition among larvae, persistent eggs, and mortality of eggs determined by moisture in the aerial environment. The model postulates that the species that is the superior resource competitor as a larva also lays eggs that have greater daily mortality under dry conditions. This model predicts that: 1) For constant environments defined by moisture levels, all of which can support either species alone, decreasing moisture shifts the outcome from exclusion of the inferior competitor, to competitive equivalence, to exclusion of the superior competitor. 2) In environments with dry and wet seasons, increasing amplitude of change in moisture level can produce stable coexistence between the competitors. Thus, this model predicts that although competition does not occur in the aerial environment, physical conditions in the aerial environment can determine both whether competitors can coexist, and which species will be excluded. Seasonality appears to be critical for stable coexistence. The model suggests that distributions of these Aedes are not only correlated with climate, but may be causally related to effects of climate on competition.
Species 1: Diptera Culicidae Aedes albopictus (Asian tiger mosquito)
Species 2: Diptera Culicidae Aedes aegypti (yellow fever mosquito)
Keywords: desiccation, seasonality
The ESA 2001 Annual Meeting - 2001: An Entomological Odyssey of ESA