Embryonic exposure to heat impacts development time, adult morphology, and fecundity in pea aphids

Stress experienced during embryogenesis can have long-lasting effects. These effects may be particularly pronounced in hemimetabolous insects, given that they do not undergo body reorganization prior to adulthood. Here, we examined the effects of maternal exposure to different temperatures (19 °C, 22 °C, 25 °C, 28 °C, 31 °C) in live-bearing, asexual female pea aphids (Acyrthosiphon pisum). Specifically, we reared pea aphid mothers at these different temperatures, transferred their offspring to a common permissive temperature of 19 °C, and subsequently measured offspring developmental time, adult morphological traits, and fecundity. We found that pea aphids largely did not survive to adulthood at 31 °C, so we were not able to examine their offspring. For the remaining temperatures, offspring whose mothers were raised at 19-25 °C had largely similar trait values, while those whose mothers were raised at 28 °C developed significantly more slowly, had smaller body parts, and had lower fecundity. Our results demonstrate that in this hemimetabolous insect, the effects of embryonic exposure to temperature (either indirectly via the mother or directly from the environment) persist into adulthood.