|RAJAMOHAN, ARUN - North Dakota State University|
|Rinehart, Joseph - Joe|
Submitted to: Cryobiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/19/2015
Publication Date: 4/1/2015
Publication URL: http://handle.nal.usda.gov/10113/61207
Citation: Rajamohan, A., Rinehart, J.P., Leopold, R.A. 2015. Stage selection and restricted oviposition period improves cryopreservation of Dipteran embryos. Cryobiology. 70(2):143-149.
Interpretive Summary: The continuous rearing of insect colonies is an expensive endeavor, both in terms of the time and effort required as well as the increased likelihood of accidental loss. Alternatives, such as cryopreservation, exist, but nuances in the required protocols inhibit widespread acceptance. One of the most difficult challenges inhibiting successful cryopreservation is the precise selection of the optimal developmental stage prior to initiation of the process. Even slight variations in developmental stage can drastically affect success. This study presents a method by which the timing of cryopreservation can be optimized, thereby reducing the difficulties encountered during this pivotal step in the process.
Technical Abstract: Embryos of two dipteran species (Musca domestica, and Lucilia sericata) were assessed for an effective sampling time that would result in the highest post cryopreservation hatch proportion. Additionally, the effects of cryopreservation pretreatment viz. permeabilization, on the embryonic age and the proportion of embryos amenable to various treatments were assessed versus the length of egg collection time. Permeabilization treatment at any stage of development did not significantly reduce the embryo viability. Longer periods of embryo collection significantly reduced the number of embryos available in the developmental stage amenable to cryopreservation. This is turn translated to - shorter durations of egg collection result in higher hatch percentage after cryopreservation. Even higher proportion of larval hatch could be obtained by selection of specific stages of the embryos prior to the treatment with cryoprotectants. Cryopreservation of stage selected embryos in M. domestica resulted in 86.5±5.5% larval hatch compared to 33.3±4.5% obtained with cryopreservation of embryos staged by visual confirmation. In the case of L. sericata, the hatch percentages were 79.0±11.1 for stage selected embryos compared to 17.0±3.9% for samples cryopreserved without selection.