Conspecific mortality cues mediate associative learning in crickets, Acheta domesticus (Orthoptera: Gryllidae)

Abstract

Many terrestrial and aquatic animals learn associations between environmental features and chemical cues of mortality risk (e.g. conspecific alarm pheromones or predator-derived cues), but the chemical nature of the cues that mediate this type of learning are rarely considered. Fatty acid necromones (particularly oleic and linoleic acids) are well established as cues associated with dead or injured conspecifics. Necromones elicit risk aversive behavior across diverse arthropod phylogenies, yet they have not been linked to associative learning. Here, we provide evidence that necromones can mediate associative olfactory learning in an insect by acting as an aversive reinforcement. When house crickets (Acheta domesticus) were forced to inhabit an environment containing an initially attractive odor along with a necromone cue, they subsequently avoided the previously attractive odor and displayed tolerance for an initially unattractive odor. This occurred when crickets were conditioned with linoleic acid but not when they were conditioned with oleic acid. Similar aversive learning occurred when crickets were conditioned with ethanol body extracts composed of male and female corpses combined, as well as extracts composed of female corpses alone. Conditioning with male body extract did not elicit learned aversion in either sex, even though we detected no notable differences in fatty acid composition between male and female body extracts. We suggest that necromone-mediated learning responses might vary depending on synergistic or antagonistic interactions with sex or species-specific recognition cues.Citation: Shephard AM, Aksenov V, Rollo CD (2018) Conspecific mortality cues mediate associative learning in crickets, Acheta domesticus (Orthoptera: Gryllidae). Journal of Orthoptera Research 27(2): 187-192. https://doi.

Appetitive and aversive social learning with living and dead conspecifics in crickets

“…4D). In house crickets, Acheta domesticus, it has been reported that oleic acid serves as a cue for recognition of dead conspecifics 32 and that crickets exhibited aversion to an odour after presenting it in compound with oleic acid for 24 hours 33 . Whether oleic acid or other chemicals are used for recognition of a dead conspecific in Gryllus bimaculatus remains to be studied.…”

Test of the prey-attraction hypothesis for the scorpion fluorescence

“…Perhaps detection is only possible when the scorpions move [20], and in that case, it should not lure the crickets but warn them. Evidence suggests multimodal communication in crickets since they also use non-visual signals in their communication like pheromones [21], tactile [22], chemical [23,24] and acoustic stimuli [25]; therefore, an isolated visual cue might not be enough to deceive crickets [11]. Our results also indicate that the response of the crickets towards the fluorescence was neither influenced by their sex nor the sex of the scorpion.…”