INSECT CRYOPRESERVATION, DORMANCY, GENETICS AND BIOCHEMISTRY
Location: Insect Genetics and Biochemistry Research
Title: Sugar feeding improves survival of nondiapausing cold stored Culex pipiens
Submitted to: Journal of Medical Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: August 30, 2012
Publication Date: November 1, 2012
Citation: Rinehart, J.P., Yocum, G.D., Robich, R.M. 2012. Sugar feeding improves survival of nondiapausing cold-stored Culex pipiens. Journal of Medical Entomology. 49(6):1347-1354.
Interpretive Summary: The maintenance of laboatory insect cultures is a major expense in many entomology laboratories, both in terms of resources and time expended. In addition to operational costs, there can be biological costs as well, leading to the gradual reduction in insect quality. Previously, our research group reported that the northern house mosquito Culex pipiens could be stored as adults for up to two months, and that the colony could be quickly restored after cold storage. The current study investigates the benefits of sugar feeding adults during cold storage. Providing ready access to a sugar meal significantly improved storage survival, with 50% of the stored insects survivng almost 6 months of cold storage. These findings substantially improve the benefits of cold storage laboratories interested in maintaining colonies of this species.
The continuous culture of mosquitoes is a costly endeavor for vector biology laboratories. In addition to the resources that must be committed to colony maintenance, biological costs including genetic drift and accidental colony loss can also occur. While alternatives do exist, their application to mosquitoes is limited. Mosquito cryopreservation remains elusive, and many important species lack a well defined diapause. Previously, we demonstrated that cold storing nondiapausing mated adult females of the northern house mosquito, Culex pipiens resulted in a nearly four-fold increase in longevity when measured at the LT50, allowing for cold storage for up to ten weeks. In the present study, we used sugar feeding during cold storage to significantly improve cold storage longevity. At 6°C, the LT50 of cold stored females was 23 weeks, and 100% mortality was not realized until 43 weeks. Cold stored females did exhibit reduced fecundity, but egg production returned to normal levels within two generations. These results suggest that cold storage without diapause induction is a viable option for Cx. pipiens, and with the addition of sugar feeding, a colony could be maintained with less than two generations per year.