The three criteria for resistance by plant carrion‐provisioning: insect entrapment and predator enrichment on Mimulus bolanderi

Abstract

1. Many sticky plants provision mutualistic scavenging arthropod predators with carrion, which in turn protect the plant from insect herbivores. While insect entrapment is a common trait across plants, which plants attract these predators and may derive protection is still largely unknown.2. Three conditions were proposed that must be satisfied for observational data to suggest this defensive strategy: (i) the consistent presence of scavenging predators, (ii) positive correlation between predator numbers and carrion, and (iii) suitability of these predators for controlling known herbivores.3. As a case study, we examined the fire‐following annual, Mimulus [Diplacus] bolanderi (Phyrmaceae), which is part of a well‐studied radiation of California monkeyflowers. Many monkeyflowers entrap insects, though attraction to predators has not been quantified in this genus.4. A guild of scavenging arthropod predators on M. bolanderi (condition #1) was found, which correlated positively with carrion abundance (#2) and could consume the primary herbivore (#3), suggesting a carrion‐mediated defensive strategy. Lastly, as M. bolanderi is variable in time and space, these interactions are facultative, and these predators are quick to adopt ephemeral carrion resources on novel host plants.