Predatory mite mothers prime their offspring to behave more optimally in intraguild predation environments

Abstract: Predation risk is a strong selective force shaping prey morphology, life history and behavior. Anti-predator behaviors may be innate, learned or both but little is known about the transgenerational behavioral effects of maternally experienced predation risk. We examined intraguild predation (IGP) risk-induced maternal effects on offspring anti-predator behavior, including learning, in the predatory mite Phytoseiulus persimilis. We exposed predatory mite mothers during egg production to stressful and benign conditions (presence or absence of the IG predator Amblyseius andersoni) and assessed whether maternal stress affects the anti-predator behavior, including learning, of their offspring as protonymphs and adult females. Individuals emerging from stressed or unstressed mothers and having experienced IGP risk as larvae or not, were subjected to binary choice situations with/without IG predator traces. Predation risk-mediated maternal effects were more pronounced in protonymphal than adult female offspring. Predator-experienced protonymphs from stressed mothers were the least active and acted the boldest towards predator cues. While adult females of all treatments deposited their eggs preferentially in the site without IGP cues, females originating from stressed mothers fed the most on the site without predator cues. Considering that every anti-predator behavior incurs costs, we argue that the attenuated response to predator traces alone is adaptive. A strong response was not necessary because no predator was physically present. Experienced females originating from stressed mothers were the most selective in avoiding IGP environments and deposited their first egg later than others, probably reflecting the time needed for information processing and decision-making. Since larval IGP risk is largely determined by the oviposition site preference of their mothers, selective egg placement is highly important to increase the survival chances of offspring. Overall, our study suggests that P. persimilis mothers experiencing IGP risk may prime their offspring to behave more optimally in IGP environments.Extended abstract