Predicting variation in behavioral, physiological, and developmental responses to predation risk

Background/Question/Methods

We seek a predictive framework for when non-consumptive effects of predators on prey will be strong. Here I will consider how both environmental conditions and traits of prey may influence prey responses to predation risk, and that individual prey can deploy multiple behavioral, physiological and developmental responses to maintain growth while avoiding predation. We measured phenotypic variation in Colorado potato beetles in response to predation risk and how these responses are altered by host plant resistance. Specifically, eggs from Colorado potato beetle sibships were reared in predation risk or control environments on high or low resistance plants. We used potato plants treated with a foliar application of jasmonic acid to enhance plant resistance. On each plant-type we exposed Colorado potato beetle larvae to predaceous stink bugs (Podisus maculiventris), including either ‘lethal’ predators or sham predators with their mouthparts surgically altered to prevent killing. We measured CPB responses to the predator over their lifetime and fitness.

Results/Conclusions

We found 3-fold phenotypic variation between sibships in consumption and growth rate in the control treatment. Sibships varied in their type of response to predation risk, with 9 of 14 sibships reducing feeding and 5 of 14 sibships increasing assimilation efficiency in the predation risk treatment compared to controls. Mean sibship growth rate in the absence of predation was strongly correlated with their behavioral response to predation risk. Beetles on high resistance plants had a weaker response to predation risk. Beetles whose siblings grew the most quickly in the absence of predators were the ones that reduced feeding the most in the presence of predators. Increasing assimilation efficiency in the predation risk treatment was not associated with growth rate. Overall, environmental conditions and prey traits that promote rapid growth are associated with stronger responses to the predator.