Stylotermitidae appear peculiar among all termites, feeding in trunks of living trees in South Asia only. The difficulty to collect them limits the ability to study them, and they thus still belong to critically unknown groups in respect to their biology. We used a combination of microscopic observations, chemical analysis and behavioural tests, to determine the source and chemical nature of the trail-following pheromone of Stylotermes faveolus from India and S. halumicus from Taiwan. The sternal gland located at the 5th abdominal segment was the exclusive source of the trail-following pheromone in both S. faveolus and S. halumicus, and it is made up of class I, II and III secretory cells. Using gas chromatography coupled mass spectrometry, (3Z)-dodec-3-en-1-ol (DOE) was identified as the trail-following pheromone which elicits strong behavioural responses in workers at a threshold around 10- 4 ng/cm and 0.1 ng/gland. Our results confirm the switch from complex aldehyde trail-following pheromones occurring in the basal groups to simpler linear alcohols in the ancestor of Kalotermitidae and Neoisoptera.

• Keywords
• (3Z)-dodec-3-en-1-ol, Neoisoptera, Semiochemicals, sternal gland,
• MeSH
• Pheromones * chemistry   MeSH
• Animal Communication * MeSH
• Gas Chromatography-Mass Spectrometry MeSH
• Cockroaches * MeSH
• Animals MeSH
• Check Tag
• Animals MeSH
• Publication type
• Journal Article MeSH
• Names of Substances
• Pheromones * MeSH

Termite colonies are almost always founded by a pair of winged dispersers, in spite of the high costs and low success rates inherent in independent colony foundation. The dispersal flights of imagoes from natal colonies are followed by mate search, mediated by sex-pairing pheromones. Here, we studied the chemistry of sex-pairing pheromones and the related aspects of mate search in winged imagoes of two facultatively parthenogenetic species, Embiratermes neotenicus and Silvestritermes minutus, and an additional species from the same subfamily, Silvestritermes heyeri. All three species are widespread in the Neotropics, including the rainforests of French Guiana. After the dispersal flight and spontaneous loss of wings, females expose their hypertrophied tergal glands situated under abdominal tergites VIII - X. The females are attractive to males and, upon direct contact, the two sexes form characteristic tandems. Chemical analyses indicated that the females secrete species-specific combinations of unbranched, unsaturated C12 primary alcohols from the tergal glands, (3Z,6Z,8E)-dodeca-3,6,8-trien-1-ol (approx. 200 pg per female) and (3Z)-dodec-3-enol (185 pg) in E. neotenicus, (3Z,6Z)-dodeca-3,6-dien-1-ol (3500 pg) in S. heyeri, and (3Z,6Z)-dodeca-3,6-dien-1-ol (300 pg) and (3Z)-dodec-3-enol (50 pg) in S. minutus. (3Z,6Z,8E)-Dodeca-3,6,8-trien-1-ol and (3Z,6Z)-dodeca-3,6-dien-1-ol act as major pheromone components in the respective species and mimic the function of female tergal gland extracts in electrophysiological and behavioral experiments. Biologically relevant amounts of the third compound, (3Z)-dodec-3-enol, elicited non-significant reactions in males of E. neotenicus and S. minutus, and slight synergistic effects in males of S. minutus when tested in combination with the major component.

• Keywords
• Embiratermes neotenicus, Sex-pairing pheromones, Silvestritermes heyeri, Silvestritermes minutus, Syntermitinae, Tergal glands,
• MeSH
• Alcohols chemistry   isolation & purification   MeSH
• Species Specificity MeSH
• Exocrine Glands metabolism   pathology   MeSH
• Isoptera physiology   MeSH
• Solid Phase Microextraction MeSH
• Gas Chromatography-Mass Spectrometry methods   MeSH
• Sexual Behavior, Animal physiology   MeSH
• Sex Attractants analysis   chemistry   isolation & purification   MeSH
• Stereoisomerism MeSH
• Animals MeSH
• Check Tag
• Male MeSH
• Female MeSH
• Animals MeSH
• Publication type
• Journal Article MeSH
• Names of Substances
• Alcohols MeSH
• Sex Attractants MeSH

A great diversity of defensive chemicals has been described in termite soldiers equipped with a unique defensive organ, the frontal gland. Along with the functional diversity of these compounds, reflecting the evolutionary history of particular lineages and their defensive strategies, a considerable degree of chemical variability often occurs among species and populations. Thus, the chemistry of termite defense may provide information on the phylogeny and geographic dispersal of species and populations. In this paper, we report on the anatomy of the frontal gland and on the diversity of soldier defensive chemicals in the sand termite, Psammotermes hybostoma, from nine colonies and five different localities in Egypt. Using gas chromatography-mass spectrometry, a total of 30 sesquiterpene hydrocarbons, or their oxygenated derivatives, were detected, and the chemical identity of most of them identified. In addition, a ketone, an ester, and a diterpene were identified in some colonies. Within colonies, the chemical composition was stable and did not differ among soldier size categories. However, there were pronounced quantitative and qualitative differences in frontal gland chemicals among colonies and geographic locations. The findings are discussed in a broader comparison with other termite taxa.

• MeSH
• Isoptera anatomy & histology   chemistry   MeSH
• Gas Chromatography-Mass Spectrometry MeSH
• Sesquiterpenes chemistry   isolation & purification   MeSH
• Animals MeSH
• Check Tag
• Animals MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH
• Geographicals
• Egypt MeSH
• Names of Substances
• Sesquiterpenes MeSH