Flexible color learning in an invertebrate predator: Habronattus jumping spiders can learn to prefer or avoid red during foraging

Understanding the design of prey defenses, such as aposematic colors, involves considering perceptual and cognitive abilities of predators that drive their evolution. Research has focused on avian predators, with little attention to small invertebrate predators. Jumping spiders are abundant and voracious; here, we examined their ability to learn, remember, and generalize color from interactions with aposematic prey. First, we demonstrated that Habronattus pyrrithrix can learn to avoid red, aposematic milkweed bugs. Then, we asked whether exposure to either palatable or unpalatable red prey can drive generalized color biases. Spiders were assigned to one of 3 diets that included exposure to 1) distasteful red milkweed bugs (fed milkweed seeds), 2) palatable red milkweed bugs (fed sunflower seeds), or 3) white-eyed Drosophila only (control). After exposure, we tested spiders for red biases using artificially colored crickets. In our first color-learning experiment, field-collected adult spiders did not exhibit generalized color biases. However, in a second (similar) experiment with lab-raised juveniles, we found evidence of generalized color learning: Group 1 demonstrated red aversion, Group 2 demonstrated red preference, and Group 3 showed no bias. Finally, we examined persistence of memory and found that learned aversions to milkweed-fed bugs lasted less than 2 weeks if they were not continuously reinforced. We discuss our findings in the context of predator psychology and suggest that jumping spider color generalization may differ from that of avian predators. Such invertebrate predators should be considered more when thinking broadly about the evolution of prey color.