Dolejsova, Klara

Fougeyrollas, Romain

Hanus, Robert

Krasulova, Jana

Roisin, Yves

Sillam-Dusses, David

English

Sydney eScholarship

Fertility-related volatiles in higher termites Klára Dolejšová1,2, Jana Krasulová1,2, Romain Fougeyrollas3, David Sillam-Dussès4,5, Robert Hanus1 & Yves Roisin6 1Chemistry of Social Insects, IOCB, Prague, Czech Republic 2Faculty of Science, Charles University in Prague, Czech Republic 3IEES Paris, Université Paris-Est Créteil, France  4IEES Paris, IRD, Bondy, France  5LEEC, Université Paris 13, France 6Evolutionary Biology and Ecology, ULB, Belgium Introduction Fertility signalling is at the heart of the debate on the evolution and maintenance of social hierarchy and reproductive division of labour in insect societies. While in social Hymenoptera, non-volatile cues on the body surface, the cuticular hydrocarbons, receive an increasing support, the situation in termites is less clear. In primitive termites, living in small societies with a direct contact among nestmates, the cuticular hydrocarbons are likely to be involved in fertility signalling as well. However, in populous colonies of advanced termites, the queens more probably announce their presence using volatiles, as evidenced by the recent discovery of the first termite queen pheromone1. Here, we report on identification of volatile compounds emitted by queens of three higher termites Embiratermes neotenicus, Silvestritermes holmgreni and S. minutus (Termitidae: Syntermitinae). Conclusions Primary and secondary queens of Embiratermes neotenicus produce large amounts of (E)-nerolidol, a sesquiterpene alcohol, which is absent in all other castes. The quantity of the compound emitted by the queens appears to be correlated with their reproductive status; it increases with the level of physogastry and thus fertility of the queens while it is absent in young non-breeding queens. Interestingly, we identified this same compound also in the extract of eggs. Our electrophysiological experiments suggest that the compound is perceived by E. neotenicus workers. We observed this same volatile to be produced by the queens of another syntermitine, S. holmgreni. The queens of the third studied species, S. minutus, also produce large amounts of a volatile compound, not yet fully identified, close but not identical in its structure with (E)-nerolidol. Multiple functions can be hypothesized for these queen- and egg-specific volatiles, ranging from queen and egg recognition signal to primer pheromone function preventing the nestmates from reproduction. These putative functions are not mutually exclusive and should all be considered in the future research. References 1 Matsuura, K., Himuro, C., Yokoi, T., et al. 2010. Identification of a pheromone regulating caste differentiation in termites. PNAS 107: 12963-12968. Acknowledgements We are grateful to the Czech Science Foundation (14-12774S), to the Charles University Grant Agency (580413) and to FNRS Belgium (FRFC grant 2.4594.12). Embiratermes neotenicus  Chemistry of body washes In solvent extracts of primary queens, secondary queens and eggs, we detected large quantity of a volatile compound.  Chemical identity Based on its retention characteristics and mass spectra, the volatile compound was identified as sesquiterpene alcohol (E)-nerolidol. The compound was completely absent in kings and in sterile castes.  1.67 2.17 2.67 1900 1400 900 400 RT (s) 1.67 2.17 2.67 1.67 2.17 2.67 1900 1400 900 400 RT (s) 1.37 1.87 2.37 1.37 1.87 2.37 1.37 1.87 2.37 HO (E)-nerolidol 1284 1184 1.35 1.55 RT (s) 1284 1184 1.35 1.55 RT (s) 1284 1184 1.35 1.55 RT (s) Headspace analysis In the next step, we analyzed headspace emanations of the queens and other castes. The same volatile proved to be present in the gaseous emissions of the queens. Fertility-related differences In young non-breeding queens this volatile was absent and its quantity increased with the level of physogastry of the queens. Antennal perception of (E)-nerolidol When searching for the function of (E)-nerolidol, we performed a series of electroantennographic analyses showing that the compound is perceived by the antennae and brain of workers.   1016 1116 1216 1316 1.32 1.42 1.52 1.62 1.72 RT (s) 1016 1116 1216 1316 1.32 1.42 1.52 1.62 1.72 RT (s) 1016 1116 1216 1316 1.32 1.42 1.52 1.62 1.72 RT (s) Air MeOH 50 ng 0.6 0.7 0.8 0.9 1.0 1.1 1.2 (E)-nerolidol 100 ng 200 ng EAG response (a.u.) Silvestritermes holmgreni  Chemistry of body washes To our surprise, we discovered the same compound, (E)-nerolidol, to be produced and emitted exclusively by queens of another syntermitinae, Silvestritermes (Armitermes) holmgreni. 0.83 1.83 2.83 1903 1403 903 403 RT (s) 0.83 1.83 2.83 1903 1403 903 403 RT (s) 0.83 1.83 2.83 1903 1403 903 403 RT (s) 0.83 1.83 2.83 1903 1403 903 403 RT (s) Silvestritermes minutus  Chemistry of body washes Another volatile compound, not yet fully identified, has been detected to be produced by the queens of a related species Silvestritermes (Armitermes) minutus. Its retention characteristics and mass spectra suggest that it differs, but not dramatically, in its structure from (E)-nerolidol. RT (s) 1900 1400 900 400 0.81 1.81 2.81 RT (s) 1900 1400 900 400 0.81 1.81 2.81 RT (s) 1900 1400 900 400 0.81 1.81 2.81 RT (s) 1900 1400 900 400 0.81 1.81 2.81 30 60 90 120 150 180 210  41   69   93   55   79   107   119   136   161   148   189   204   179   222  m/z Relative Abundance Embiratermes neotenicus Silvestritermes holmgreni Silvestritermes minutus Petit Saut, French Guiana 

Fertility-related volatiles in higher termites

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Fertility-related volatiles in higher termites

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