In vitro culture of polyembryonic wasp embryos

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Media suitable for culturing the 2-cell embryos of a polyembryonic wasp, Litomastix maculata, were exploited on more than 50 modified MGM-450 media. Bovine plasma albumin levels of more than I % was required as a component of the medium for the embryos to develop up to the complete morula. Ovalbum in and conalbumin also supported some development of the embryos, whereas lactalbumin was rather detrimental. The modifications of MGM-450 medium by changing the carbohydrates and the minerals to 0.2 5 % suct-ose alone and D-20's minerals, respectively, was required for the embryos to develop into Polygerms beyond the morula stac, . e. Experiments on the effect of supplementing- : the medium with insect hormones indicated that exogenous juvenile hormone(JH)supported the development of embryos into polygerms, which was a developmental- event specific to the polyembryonic insects. JH I was the most e erective !iorinone followed by 'H 11 and 'H Ill. On the other hand, 20-hydroxyecdysone did not. The composition of amino acids also was important for culturing 2-cell embryos up to polygerms ; amino acid composition of MGM-450 medium was the most suitable among those of several insect cell culture media. Supplementation of fetal bovine serum into the medium caused the higher percentage of Polygerm formation.There were not clear effects of albumin and juvenile hormone where the culture was started at the morula stage ; 80-90 % of morulae cultured in either MGM-450 medium or modified MGM-450 medium mentioned above developed into polygermis.