192 - Update on Preliminary Studies of the Southern California SIT Joint Pilot Project Using X-ray Sterilized Male Aedes aegypti

Since the arrival of Aedes aegypti (L.) in Los Angeles County in 2014 and Orange County in 2015, this mosquito species has proliferated throughout southern California. The species' rapid population growth and its synanthropic behavior have elevated the risk for autochthonous transmission of viruses that cause diseases such as Zika, chikungunya, and dengue. The Greater Los Angeles County Vector Control District (GLACVCD) and the Orange County Mosquito and Vector Control District (OCMVCD) partnered to develop a sterile insect technique (SIT) project, a tried and tested method for suppressing insect abundance, for use in southern California to combat Ae. aegypti. The SIT Joint Pilot Project plans to sterilize male Ae. aegypti using X-ray irradiation, releasing them en masse to compete with wild males for mating opportunities resulting in nonviable eggs, which reduces the local Ae. aegypti population over time. In contrast to SIT programs that apply ionizing X-ray radiation to sterilize mosquitoes at the pupal stage, this project is focused on developing a process to irradiate mosquitoes at the adult stage. Two mosquito strains were used in this project, a wild strain collected from the city of Mission Viejo in Orange County and a mixed population strain from both Los Angeles and Orange counties. This presentation will highlight the SIT Joint Pilot Project’s development of methods and preliminary findings, including cold-induced anesthesia (chilled) and compacting adults in preparation for irradiation, as well as the impacts of radiation dose on survival, sterility, and mating competitiveness. These and future studies aim to develop an area-wide SIT-based mosquito suppression program in southern California.