Submitted to: Journal of Cryobiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/6/2000
Publication Date: 9/30/2000
Citation: Wang, W., Leopold, R.A., Freeman, T.P. 2000. Cryopreservation of Musca domestica (Diptera: Muscidae) embryos. Journal of Cryobiology. 41(2):153-166. Interpretive Summary: Methods to store insects on a long-term basis as an aid to mass rearing systems that are part of bio-control and sterile insect release programs are currently not available for certain flies that are pests of livestock and the fruit industry. A method designed to preserve embryos of the vinegar fly, Drosophila melanogaster, was found to be not suitable for these other insect pests. This study used the common house fly as a model insect to develop a method for cryopreservation of embryos in liquid nitrogen which has a temperature of -196 deg. C. Substantial advances were made when solutions that protect the embryos from freezing injury were developed. Approximately 20% of the house fly embryos hatching into larvae were able to develop on to fertile adults. This level of survival was high enough to regenerate a colony of flies that had been stored in liquid nitrogen. This method for long-term storage of insect embryos is now being tested for use on other flies such the screwworm fly and the Caribbean fruit fly.
Technical Abstract: Prior studies on cryopreserving embryos of several non-drosophilid flies established that a Drosophila melanogaster embryo cryopreservation protocol was not directly suitable for use with these species. This paper describes our work on developing a protocol for cryopreservation of embryos of the house fly, Musca domestica. Significant progress was made when a vitrification solution containing ethylene glycol, polyethylene glycol and trehalose was formulated and when cooling and recovery of the cryopreservation protocol included a step which passed the embryos through liquid nitrogen vapor. More than 70% of house fly embryos withstand treatments of dechorionation, permeabilizaton, loading with cryoprotectant and dehydration in vitrification solution, but the cooling and warming steps still cause some reduction in embryo viability. Up to 57% of vitrified M. domestica embryos hatch into larvae and further development of these larvae into pupae and fertile adults was observed.