Prey colour biases in jumping spiders (Habronattus brunneus) differ across populations

Abstract

Predators often avoid aposematic prey as a result of aversions to particular prey signals (e.g., bright colours and noxious odours). These aversions may be flexible, that is, they can be reinforced or extinguished with experience. As such, we might expect populations to differ in their biases against certain prey characteristics (e.g., colour or pattern) depending on the prey available in the community. Here, we tested whether the jumping spider, Habronattus brunneus(Salticidae), exhibits colour biases against red prey using choice tests with novel (artificially coloured) prey, and then went on to examine how these biases differ across four geographically distinct focal populations. We then conducted preliminary field surveys at each of these four sites to explore differences in habitat type and prey availability. Overall, we found that field‐caught H. brunneusexhibited a bias against the colour red (compared with black) when tested with artificially coloured prey in the laboratory. However, the degree of colour bias varied among our four focal populations (with two populations exhibiting strong biases against red and two showing no colour biases). Preliminary habitat and prey surveys suggest that these populations also differed in both habitat structure (percentage of grass, leaf litter and bare ground) and prey availability across many taxa, suggesting that the spiders from each population may have been exposed to, and had experiences with, different potential prey. We discuss how prey availability may influence colour biases in predators, as well as how predator experience may shape the evolution of prey colour signals.

Methods for independently manipulating palatability and color in small insect prey

“…If paint spread beyond the abdomen (e.g., onto the legs or thorax), the termite was discarded. Previous studies revealed no significant differences in movement rates between unpainted and painted termites [23,24] suggesting that this color manipulation does not inhibit their natural movement rates.…”

“…Because the DB solution is colorless, we needed a way to keep track of which termites in each experiment were DB-treated and which were controls. To do this, we randomly assigned each termite a particular color using a previously published method of termite color manipulation that uses flat oil-based enamel paints (Testors, Rockford, IL, USA) [23,24]. In this study, we were not interested in the spiders' color preferences per se, and so we strategically chose two colors that we expected to be neutral to the spiders and that they would readily attack: green (product #1164TT) and brown (product #1166TT).…”

“…Recent studies have emphasized the importance of considering a more diverse set of predators in this work [16,17], with a particular emphasis on considering terrestrial invertebrate predators [18][19][20][21][22][23][24], and such studies are revealing surprising insights. In some cases, there are remarkable similarities between arthropod predators and birds; for example, similar (but not identical) patterns of color aversion, learning, and generalization have been shown in jumping spiders [19][20][21]24], mantids [25], and predatory wasps [26,27]. Yet, there are also remarkable differences in the responses of some of these predators.…”

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

“…Furthermore, it has been shown that many predators are very conservative in their prey preferences, and avoid brightly colored prey even when they are edible [33]. Nonetheless, finding evidence for innate aversion of captive adult spiders to wasps with the BOB coloration does not rule out the possibility that learning is important in this predator prey interaction; indeed, aversions to particular prey colors can change with experience [38]. We found that spiders from natural conditions showed increased aversion over time, and this aversion coincides with the toxicity analyses and the aposematic pattern of the wasps.…”

Hemipteran defensive odors trigger predictable color biases in jumping spider predators

“…Like other jumping spiders, Habronattus are voracious predators 25 with exceptional visual acuity in their large forward-facing principal eyes 26 . Recent work suggests that spiders in this genus likely have the ability to distinguish a wide range of colors from UV to red 27 and behavioral work suggests that they attend to both color and odor cues while foraging 18 – 20 , 24 . They are common in a variety of habitat types 28 where they likely encounter potential insect prey with combinations of defensive odors and colors.…”