SELECTIVE OVIPOSITION BY AEDES-AEGYPTI (DIPTERA, CULICIDAE) IN RESPONSE TO A LARVAL PARASITE, PLAGIORCHIS-ELEGANS (TREMATODA, PLAGIORCHIIDAE)

A series of biological assays was performed in the laboratory to examine the oviposition response of Aedes aegypti (L.) to sites containing, or which had previously contained, conspecific larvae parasitized by the digenean, Plagiorchis elegans (Rudolphi). Waters containing parasitized larvae received significantly fewer eggs than waters containing unparasitized larvae. Larval holding waters that had previously contained unparasitized larvae received significantly more eggs than either waters that had previously contained no larvae or parasitized larvae. Waters that had contained no larvae received significantly more eggs than larval holding waters that had contained parasitized larvae. When these waters were boiled, treated with antibiotics to curb bacterial growth, or filtered sterilized, larval holding waters that had contained parasitized larvae continued to receive significantly fewer eggs than larval holding waters that had contained unparasitized larvae. We propose that gravid A. aegypti are deterred from ovipositing in response to a chemical found in waters containing parasitized larvae. The ecological implications of this selective oviposition are discussed.