Allometry of Ingestion Among Habitat Mimicking Praying Mantises

Ingestion is the process of consuming a resource and is a component of an organism's handling time, which can limit the acquisition of additional resources and decrease predation rate. If a predator spends more time handling prey, it will have less time to seek out additional prey. Variation in ingestion may therefore impact energy fluxes and ecosystem stability. Body size has been proposed to affect ingestion, with larger organisms predicted to have a reduced handling time, potentially scaling like metabolic rate. The goal of this study was to examine the allometric relationships of ingestion, a proxy for handling time, among praying mantis species with different camouflage strategies in a phylogenetic context. We measured the time it takes adult female mantises to ingest a standard prey using time-lapse photography in 1-8 individuals among 14 species of Mantodea 3-5 times, resulting in 324 trials from 66 individuals. We examined the scaling of ingestion in relation to mantis body size using both a phylogenetic general linear mixed model to account for within-species variation, as well as a phylogenetic generalized least-squares approach on species means. We also compared the scaling of our praying mantis ingestion allometry to other allometric relations of other organisms from a larger database (e.g., other insects, arachnids, and vertebrates). We found that the ingestion rate and time scale with a power-law function regardless of the camouflage strategy. We also found that mantis prey-mass-specific ingestion scaled more like arachnids than insects when compared to the larger database. Comparing our scaling of ingestion to published values of metabolic scaling, we found a higher slope for ingestion. Together, our results suggest that larger praying mantises can ingest more resources than may be needed based on their metabolic rate, which may influence their role in the ecosystem.