Taking a Hit: Resistance to Handling in Model-Mimic Insect Complexes

Aposematism has been hypothesised to co-occur with an improved ability to survive being handled by a predator with negligible damage. The current literature on this "resistance to handling" is reviewed, including anecdotal accounts, experimental evidence and bio-physical considerations. The relationship between resistance to handling and Batesian mimicry is tested through two experiments on field-caught specimens. The first evaluates the ability of specimens to survive a given amount of compressive force using the successive application of increasing weights, comparing mimics (Diptera: Syrphidae) to non-mimics (non-syrphid Diptera) and their models (Hymenoptera). The second experiment measures the force required to deform an insect by a given proportion. Hymenopterans were the most resistant group, syrphid flies the least, and non-syrphid dipterans intermediate between the two. In all groups, both larger body size and a greater resistance to deformation were correlated with higher kill weights, while mimicry status and mimetic fidelity were not.