First evidence for an aposematic function of a very common color pattern in small insects

This paper presents the first experimental investigation of the aposematic (warning coloration) function of the black-orange-black (BOB) color pattern found in many small parasitoid wasps across 23 families of Hymenoptera. Through controlled behavioral experiments using jumping spiders (Lyssomanes jemineus) as predators, we tested four wasp genera representing both BOB and all-black morphospecies. The study combined predator-prey behavioral observations, spectral analysis of wasp coloration relative to spider vision, and acute toxicity tests using Daphnia magna and Vibrio fischeri. Key findings demonstrated that spiders never consumed BOB-patterned wasps but did ingest some black wasps, and BOB wasps showed significantly higher toxicity in bioassays compared to black morphospecies. Field-experienced spiders showed greater discrimination against BOB patterns than laboratory-reared individuals, suggesting both learned and innate components to predator avoidance. Spectral analysis revealed that the perceived contrast between black and orange components varied among genera and correlated with predator behavioral responses. This interdisciplinary work bridges behavioral ecology, sensory biology, and chemical ecology to demonstrate how a widespread color pattern functions as an honest signal of toxicity to invertebrate predators, contributing to our understanding of aposematism in small arthropods.

Recommended citation: Mora-Castro, R., Alfaro-Córdoba, M., Hernández-Jiménez, M., Fernández Otárola, M., Méndez-Rivera, M., Ramírez-Morales, D., et al. (2021). "First evidence for an aposematic function of a very common color pattern in small insects." PLOS ONE. 16(2): e0237288.
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