Egg production and embryo lethality for habrobracon from biosatellite II and associated postflight vibration experiments

Abstract

In the reproductive performance of female Habrobracon, striking contrasts were revealed between results from the actual biosatellite flight and those from experiments with the recovered vehicle subjected to forces of simulated launching and recovery. The conditions of the 2 types of experiments differ mainly in influences of orbital flight, of which weightlessness seems most notable. To summarize for the 3 criteria of damage studies: 1. (1) Orbital flight effectively cancelled the characteristic radiation-induced decrease in egg production. On the other hand, the forces of bibration and acceleration improved oviposition only slighty during the more radiosensitive period of the developmental sequence. 2. (2) Excepting metaphase-I results, the only evidence of low hatchability was obtained for an ordinarily invulnerable cell type giving rise to eggs deposited on the 3rd day after biosatellite recovery. Subsequently the hatchability of the haploid eggs was excellent even during the period ordinarily most radiosensitive. In contrast, hatchability data from the simulated flight showed the usual pattern of response except for a moderate alleviation of the senile decline after the 15th day. Death occurred in a variety of stages in eggs from wasps of the simulated flight, but no stage-1 ( i.e. cleavage failure) deaths were obtained during the periods of excellent hatchability of biosatellite wasp eggs. 3. (3) The survival and life span of adult females was excellent and attests to the somatic fitness of experimental wasps. An interpretation of the braconid response to space flight in the presence of chronic γ-ray exposures must explain the unimpaired survival of cell types providing a surprisingly high fecundity, plus the adequacy of these eggs in supporting embryonic development. Possibly under packaged inactivity and weightlessness a stasis of cytological structure provides an opportunity for biochemical mechanisms to repair presumptive radiation lesions. The same stasis may be deleterious to the oocyte-nurse cell complex engaged in vitellogenesis of units destined to be deposited as 3rd-day eggs.