Differential oviposition by Aedes hendersoni and Aedes triseriatus (Diptera: Culicidae) in response to chemical cues associated with treehole water.

The oviposition behavior of Aedes hendersoni Cockerell and Aedes triseriatus (Say) was examined in the laboratory by offering gravid females oviposition sites containing water from different treehole types and by varying the physical characteristics of oviposition sites. Ae. hendersoni females oviposited more frequently in containers with water from treeholes in which they are found commonly in nature (maple "deep rotholes") than in containers with water from holes in which they are found rarely (beech "pans"). In contrast, Ae. triseriatus eggs were distributed uniformly in containers holding the two types of treehole water. There were no differences between species in response to oviposition container height or orientation of the entrance hole (vertical or horizontal). Females of both species laid nearly all their eggs in containers with horizontal openings, and most were deposited at the higher of two levels. We suggest that the adaptive value of the oviposition behavior of Ae. hendersoni is to maximize fitness by reducing interspecific contact with Ae. triseriatus.