LABORATORY AND FIELD EVALUATIONS OF OVIPOSITION RESPONSES OF AEDES-ALBOPICTUS AND AEDES TRISERIATUS (DIPTERA, CULICIDAE) TO OAK LEAF INFUSIONS

Organic infusions created by fermenting white oak (Quercus alba L.) le aves in water were evaluated as sources of attractant odorants and con tact oviposition stimulants for gravid Aedes albopictus (Skuse) and Ae des triseriatus (Say). Infusions were bioassayed in the laboratory by giving single females a choice of ovipositing in 1 container with infu sion and 7 containers with water. Ae. albopictus laid significantly mo re eggs in containers with infusion, regardless of concentration (dilu tions ranging from 10 to 100%) or age (fermentation periods of 7, 28, 60 d), than in containers holding water. The largest proportion of egg s (76.8%) was deposited in response to a 60% concentration of 7-d-old infusion. In contrast, lie. triseriatus exhibited variable oviposition responses but generally deposited the largest number of eggs in only a few concentrations of older age infusions. In binary ''sticky screen '' bioassays, there was no difference between the numbers of females a ttracted to infusion or water, indicating that oviposition responses t o infusion were mediated by contact chemostimulants rather than by att raction to odorants. Oviposition responses to infusions by field popul ations of Ae. albopictus and Ae. triseriatus in Raleigh, NC, were eval uated with pairs of oviposition traps, one containing infusion and the other containing water. Generally, Ae. albopictus laid significantly more eggs in ovitraps containing infusion regardless of its age (7, 28 , and 60 d old) or the mass of leaves fermented (126 g = 1x or 504 g = 4x) than in water. In contrast, Ae. triseriatus deposited an equivale nt number of eggs in traps containing water or 1x, 80% infusion regard less of its age; however, the oviposition response to ovitraps contain ing 4x, 7-d-old, 50% infusion was significant. Placement of an automob ile tire behind an ovitrap did not increase the number of Ae. albopict us eggs laid in ovitraps containing 4x, 7-d-old, 50% infusion or water relative to ovitraps without a tire. Our research indicates that bait ing ovitraps with oak leaf infusion would increase the sensitivity of surveillance efforts for Ae, albopictus and Ae. triseriatus.