Sugar feeding improves survival of nondiapausing cold-stored Culex pipiens

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, also can occur. Although 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 L. resulted in a nearly four-fold increase in longevity when measured at the LT50, allowing for cold storage for up to 10 wk. In the current study, we used sugar feeding during cold storage to significantly improve cold storage longevity. At 6 degrees C, the LT50 of cold stored females was 23 wk, and 100% mortality was not realized until 43 wk. 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.