نوروفیزیولوژی و رفتار حس بویایی در مورچه‌های جهنده‌ی Harpegnathos saltator

In order to maintain colony integrity ants need to cooperate with each other. This cooperation is regulated by communication through olfactory cues, known as odorants. Compounds of one important odorant group, known as cuticular hydrocarbons (CHCs), are part of the lipid surface of the cuticle. Olfactory detection in insects involves interactions between odorants and diverse groups of olfactory receptors expressed in the dendritic branches of the olfactory sensory neurons housed within individual hair-shaped structures, known as sensilla, that are predominately, present on antennae. However, our knowledge about the detection and discrimination of these odorants is meager. We investigated this problem in the ant Harpegnathos saltator. Here, female workers act as helpers and raise brood, or, in the absence of the queen, may undergo a transition period and become reproductive individuals, called gamergates. In contrast, the male ants’ sole function is to mate with queens or workers. We employed extracellular recording technique to measure and compare electrophysiological responses from the female-specific sensilla basiconica of the non-reproductive workers and reproductive workers (gamergates) using a panel of 45 compounds (CHCs and non-HC stimuli). We found that responses to several long-chained hydrocarbons were significantly lower in gamergates. Subsequent age- and reproductive status-specific recordings showed that sensillum responses to a panel of long-chained hydrocarbons significantly and consistently decreased within the four months of gamergate maturation after the transition from worker status. However, 36-month-old gamergates did not show a further decline in response over time. Interestingly, this effect was hydrocarbon-specific and responses to non-HCs did not change. The responses to CHCs did not change in non-reproductive workers, which indicates that the reduced response to long-chained hydrocarbons seen in gamergates is specific to their transition to reproductive status. Since the reproductive-specific blend of long-chained hydrocarbons may have an inhibitory effect on worker, and potentially gamergate, ovarian development, a reduction in sensitivity to hydrocarbons may reduce mutual and self-inhibition in gamergates. In a search for CHC-responding sensilla in males we found that, unlike workers and gamergates, males’ sensilla are not broad spectrum detectors of CHCs as only some sensilla responded to CHCs from virgin queen postpharyngeal glands which may be used for close range mate recognition.Olfactometric bioassays verified that the male ants display behavioral responses to the electrophysiologically active non-HC stimuli which correlate with the life habits of male ants. We discuss how the peripheral olfactory detection of male ants is correlated with their life habits.