P08 - Container size influences oviposition performance in a novel forced oviposition method for Culex quinquefasciatus and Aedes aegypti

Abstract: Research in mosquito vector control relies heavily on live specimens, with wild populations playing an essential role in surveillance, field-based product evaluation, and improving the overall efficacy and accuracy of studies. However, establishing and maintaining wild mosquito colonies in laboratory settings remains a persistent challenge. Here, we present a modified forced oviposition technique developed for two major mosquito vectors, Aedes aegypti and Culex quinquefasciatus. The method was tested using both laboratory-reared and field-collected females placed individually in oviposition tubes consisting of 1.5 mL containers lined with moistened cotton and a strip of germination paper. To evaluate the effects of container size on oviposition success, additional trials were conducted using tubes of four volumes: 1.5, 5, 15, and 50 mL. Overall, the modified method was highly effective, yielding eggs from both laboratory and field strains. Aedes aegypti exhibited the highest success, with over 80% of females ovipositing, compared to 50–60% for Cx. quinquefasciatus. Culex quinquefasciatus also required a longer holding period (3–7 days) prior to oviposition, whereas Ae. aegypti females typically laid eggs within 24 hours of transfer. In Cx. quinquefasciatus laboratory strains, egg hatch rates varied depending on whether egg rafts remained intact or were broken, although this factor had little effect on wild strains. Both species displayed a marked preference for smaller, confined spaces, showing “claustrophilic” oviposition behavior, as higher egg-laying rates occurred in the 1.5 and 5 mL tubes. These findings demonstrate that this adapted forced oviposition technique is both versatile and effective for generating F₁ offspring from diverse mosquito vectors, facilitating key advances in vector control research.