In animal societies, chemical communication plays an important role in conflict and cooperation. For ants, cuticular hydrocarbon (CHC) blends produced by non-nestmates elicit overt aggression. We describe a sensory sensillum on the antennae of the carpenter ant Camponotus japonicus that functions in nestmate discrimination. This sensillum is multiporous and responds only to non-nestmate CHC blends. This suggests a role for a peripheral recognition mechanism in detecting colony-specific chemical signals.

We identified cis-jasmone as a potent attractant in mulberry leaves for silkworms and provide evidence that a highly tuned receptor, BmOr-56, may mediate this behavioral attraction. The current study sheds light on the mechanism of the correlation between olfactory perception in folivore insects and chemotaxis behavior to a natural volatile emitted by green leaves.

Here we report direct evidence that cuticular hydrocarbons are responsible for nestmate recognition in Formica japonica distributing in Southern Honshu in Japan. Workers showed aggressive behavior against foreign workers but not against nestmates. A similar response was observed when a glass dummy was treated with isolated hydrocarbons from foreign workers or nestmates. Among the isolated hydrocarbons, ten hydrocarbon components were identified: five nalkanes and five (Z)-9-alkenes with odd number of carbons from 25 to 33, in different ratios in different colonies. When synthetic hydrocarbons blended in the same ratio as natural blends were presented to workers, they showed aggressive responses against foreign blends but paid less attention to those of nestmates. Neither n-alkane nor (Z)-9-alkene blends, however, caused aggression response in foreign workers. Thus, both n-alkanes and (Z)-9-alkenes are necessary to discriminate nestmates from foreign conspecifics.

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Lady beetle can walk on a vertically smooth surface such as a glass plate in the same manner as on a horizontal one. It was reported that the insect probably released a non-volatile lipid secretion from the spatulate ends of the tenent hairs and this secretion was essential to the adhesion process on smooth surfaces against the force of gravity. We have studied footprint chemicals which were secreted from the tenent hairs of the three species of lady beetles Epilachna vigintiocotomaculta, Epilachna vigintioctopunctata and Coccinella septempunctata. The component of footprints was species specific and consisted of hydrocarbons and true waxes. The footprint chemicals were just identical with those of the cuticular waxes. The waxes of footprints were secreted larger amount from the tarsus than that from cuticular surface.

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SUMMARYIn ants, including Formica japonica, trophallaxis and grooming are typical social behaviors shared among nestmates. After depriving ants of either food or nestmates and then providing them with either food or nestmates, a behavioral change in type and frequency of social interactions was observed. We hypothesized that starvation and isolation affected levels of brain biogenic amines including dopamine (DA) and octopamine (OA) -neuromediators modifying various insect behaviors -and tested the relationship between brain biogenic amines and social behaviors of stressed ants. Ants starved for 7days contained lower brain DA levels and they did not perform trophallaxis toward nestmates. Feeding starved ants sucrose solution re-established trophallaxis but not brain DA levels. The performance of trophallaxis induced recovery of brain DA content to the level of untreated ants. Ants that were isolated for 2days displayed markedly increased OA levels, which following nestmate interactions, returned to levels similar to those of control (non-isolated) ants and ants isolated for 1h. We conclude that: (1) starvation reduced brain DA level but had no significant effect on brain OA (trophallaxis recovered the brain DA levels), and (2) isolation increased brain OA level but had no effect on brain DA (trophallaxis and grooming events recovered the brain OA levels). We suggest that social interactions with nestmates influenced brain biogenic amine homeostasis in stressed F. japonica.

The alarm pheromone of the ant Camponotus obscuripes (Formicinae) was identified and quantified by gas chromatography (GC) and gas chromatography-mass spectrometry (GC-MS). Comparisons between alarm pheromone components and extracts from the major exocrine gland of this ant species revealed that the sources of its alarm pheromone are Dufour's gland and the poison gland. Most components of Dufour's gland were saturated hydrocarbons. n-Undecane comprised more than 90% of all components and in a single Dufour's gland amounted to 19 microg. n-Decane and n-pentadecane were also included in the Dufour's gland secretion. Only formic acid was detected in the poison gland, in amounts ranging from 0.049 to 0.91 microl. This ant species releases a mixture of these substances, each of which has a different volatility and function. When the ants sensed formic acid, they eluded the source of the odor; however, they aggressively approached odors of n-undecane and n-decane, which are highly volatile. In contrast, n-pentadecane, which has the lowest volatility among the identified compounds, was shown to calm the ants. The volatilities of the alarm pheromone components were closely related to their roles in alarm communication. Highly volatile components vaporized rapidly and spread widely, and induced drastic reactions among the ants. As these components became diluted, the less volatile components calmed the excited ants. How the worker ants utilize this alarm communication system for efficient deployment of their nestmates in colony defense is also discussed herein.