A Novel Form Of Aversive Learning In Honeybee: Devaluation Of Olfactory Memory Via Conditioning Taste Aversion

Honey bees constitute a robust model for the study of appetitive learning and memory as they easily associate and memorize multiple sensory cues with a reward of sucrose solution.but aversive learning has rarely been investigated in honeybee because lacking of a well-established aversive learning protocol,so we were trying to establish a novel conditioned taste aversion learning in honeybee.Conditioned taste aversion(CTA)learning induces the devaluation of a preferred food through its pairing with a stimulus inducing internal illness.In invertebrates,it is still unclear how this aversive learning impairs the memories of stimuli that had been associated with the appetitive food prior to its devaluation.Here we studied this phenomenon in the honey bee and characterized its neural underpinnings.We first trained bees to associate an odorant(conditioned stimulus,CS)with appetitive fructose solution(unconditioned stimulus,US)using a Pavlovian olfactory conditioning.We then subjected the bees that learned the association to a CTA training during which the antennal taste of fructose solution was contingent or not to the ingestion of quinine solution,which induces malaise a few hours after ingestion.Only the group experiencing contingent fructose stimulation and quinine-based malaise exhibited a decrease in responses to the fructose and a concomitant decrease in odorspecific retention in tests performed 23 h after the original odor conditioning.Furthermore,injection of dopamine-and serotonin-receptor antagonists after CTA learning revealed that this long-term decrease was mediated by serotonergic signaling as its blockade rescued both the responses to fructose and the odor-specific memory 23 h after conditioning.Our results introduce a novel form of aversive learning in honey bees,and we found the impairment of a prior CS memory by subsequent CTA conditioning confirms that bees retrieve a devaluated US representation when presented with the CS.Our findings further highlight the importance of serotonergic signaling in aversive learning in the bee and uncover mechanisms underlying aversive memories induced by internal illness in invertebrates.