WATER-DEPRIVATION AND LIGHT AFFECT RESPONSES OF CULEX TARSALIS (DIPTERA, CULICIDAE) TO OVIPOSITION SITE CUES

Responses of blood-fed gravid Culex tarsalis Coquillett mosquitoes to visual and chemical cues associated with oviposition sites were affect ed by water deprivation but not by sugar deprivation. Gravid mosquitoe s deprived of water for 24 h before bioassay were more responsive to o viposition cues and laid the majority of their egg rafts around dusk, whereas mosquitoes not deprived of water laid similar numbers of eggs around dusk and dawn. Ambient light levels also affected responses to oviposition cues, with mosquitoes using visual cues more under dim lig ht than in full darkness. These results indicate that oviposition beha vior is flexible, depending on the types of cues that are available. O viposition behavior is mediated by physical, chemical, and biological cues, and our results suggest that in the absence of a particular cue, the entire suite of behaviors which culminate in oviposition may stil l be triggered by the remaining cues present.