D3210: Influence of relative humidity and diet on Podisus maculiventris growth and survival

Limited water availability may be one of the greatest challenges for organisms to survive, grow, and reproduce under future climate change scenarios. Insects can respond to such challenge by reducing water loss (e.g., closing spericacles), and/or by increasing water intake. Increasing water intake, however, may be particularly difficult for carnivorous insects, given the relatively low water content of prey items and the water requirements for predation. Insect predators can increase their water intake by also feeding on plants, which provide little energy but larger amounts of water. Here, we examined whether a generalist predator, Podisus maculiventris, prioritize water over energy intake by shifting to a plant diet when experiencing dry environments. We provided two different food sources to P. maculiventris, plant material and Lepidoptera larvae. Using stable isotopes, we tracked the proportion of plant vs. prey material consumed when experiencing either a dry or wet environment. Our results indicate that the feeding behavior of terrestrial predators is tightly dependent on changes in relative humidity. Given that P. maculiventris feeds on a variety of pest insects, our results provide new insight into how stressful environments may alter their role in regulating crop pests.