Cryopreservation of embryos of Culicoides sonorensis (Diptera: Ceratopogonidae).

The successful long-term storage of insects that are used for research purposes can eliminate the need for ongoing colony maintenance on a large scale. In addition, rare and valuable genotypes of insects can be preserved. This study was conducted to determine whether cryopreservation is a suitable means of storing embryos of Culicoides sonorensis Wirth & Jones, an important vector of animal pathogens. We determined that eggs of C. sonorensis can withstand vigorous treatments of dechorionation, permeabilization, and loading with the cryoprotectant, elthylene glycol. Although their viability was reduced, an average of 80.3% of the embryos developed into larvae. Dehydration in vitrification solution caused a much greater reduction in egg viability (42.7% survival), and freezing in liquid propane further reduced the number of eggs that developed into larvae (40.1%), pupae (22.9%) and adults (18.8%). This work demonstrated that this procedure may prove useful for the cryopreservation of standard laboratory colonies and genetic lines of C. sonorensis.