Gregory Shobert

Spotted wing drosophila (Drosophila suzukii) is a global agricultural pest responsible for substantial agricultural losses worldwide. Recent genetic engineering advances in this species show promise for effective genetic pest control solutions in the future. A current challenge to developing these genetic solutions exists, however, in the loss of transgenic elements due to meiotic recombination and genetic drift. The lack of balancer chromosomes available for D. suzukii leaves only time and labor intensive screening methods to ensure the homogeneity of transgenic lines in the face of this challenge. One promising alternative to balancers is the cryopreservation of homozygous D. suzukii embryos, achieved through rapid freezing and rewarming of embryos chemically protected from water crystallization. This approach allows for indefinite storage of revivable fly lines, thereby preventing both meiotic recombination and genetic drift. In addition to substituting for balancers, cryopreservation also reduces the considerable labor associated with maintaining large fly populations by eliminating the need for keeping live flies. Cryopreservation also constitutes a tool for preserving genetic diversity at a given time point in wild populations, and could potentially facilitate improved sharing and storage of useful D. suzukii lines amongst research groups. An effective cryopreservation protocol has been demonstrated for Drosophila melanogaster, but efforts to replicate this protocol in D. suzukii have resulted in high embryo mortality. Accordingly, optimization of existing cryopreservation methods is required to achieve success with D. suzukii embryos. To assess the viability of cryopreservation as a tool for genetic engineering, diversity preservation, and research collaboration, we demonstrate an effective method for cryopreserving D. suzukii embryos, cataloging success metrics at each procedural step to expose targets for further optimization.