Does timing of post-stressor exposure mating matter for parental effect?

Abstract

Stress and harsh environmental conditions affect an organism's life-history traits and may impact the following generation/s features and stress resistance by parental effect. However, it is unknown which time point after stressor exposure is better for mating and subsequent parental effect transfer to future generation/s. We assessed post-stressor exposure mating to evaluate whether early mating (an hour) or late mating (24 h) post stressors exposure would affect the parental effect. To address this issue, we used seed beetle Callosobruchus maculatus and mint and rosemary essential oils as environmental stressors to evaluate biological parameters, including immature development time, adult emergence, sex ratio, longevity, egg number, egg hatch, and copulatory behaviors. Results showed that the interval between stress exposure and mating affected parents' fitness. Thus, early-mated post-stressor-exposed females lived longer than late-mated females. However, mating timing did not influence male adult longevity. In the late-mated group, stress did not affect insects' mating behaviors, whereas adverse effects were recorded in early-mated beetles. Parents' stress exposure also did not alter biological parameters in the unexposed F1 generation. Then we let the F2 generation experience the same stressor as F0. Rosemary essential oil exposed late-mated grandparents produced grand offspring that laid more eggs with higher hatching rates than grand offspring of the control in response to rosemary essential oil. In other words, late-mated grandparents generated grand offspring who could better cope with the same stressor as F0. This study indicated that the interval between stress exposure and mating is important in the quality of parental effects. Parents having enough time for recovery could produce offspring and subsequently grand offspring more capable of coping with the same stressor.