Chemoecology 15:1–6 (2005) 0937–7409/05/010001–6 © Birkhäuser Verlag, Basel, 2005 DOI 10.1007/s00049-005-0285-9 CHEMOECOLOGY Neocembrene A, a major component of the trail-following pheromone in the genus Prorhinotermes (Insecta, Isoptera, Rhinotermitidae) David Sillam-Dussès 1 , Etienne Sémon 2 , Céline Moreau 2 , Irena Valterová 3 , Jan Šobotník 3 , Alain Robert 1 and Christian Bordereau 1 1 Université de Bourgogne, UMR CNRS 5548, Développement-Communication chimique, 6 Bd Gabriel, 21000 Dijon, France 2 INRA, Unité mixte INRA/ENESAD de recherches sur les Arômes, 17 rue Sully, 21000 Dijon, France 3 Institute of Organic Chemistry and Biochemistry, Flemingovo nám.2, Praha 6, CZ-166 10, Czech Republic Summary. The diterpene neocembrene A or (1E,5E,9E,12R)-1,5,9-trimethyl-12-(1-methylethenyl)- 1,5,9-cyclotetradecatriene, known as the trail-following pheromone of the advanced Termitidae Nasutitermitinae Nasutitermes exitiosus and Trinervitermes bettonianus, has been identified after SPME-GC/MS as the major component of the trail-following pheromone of the Rhinotermitidae Prorhinotermitinae, Prorhinotermes canalifrons and P. simplex. In all the other Rhinotermitidae studied until now, the major component of their trail pheromones is dodecatrienol ((3Z,6Z,8E)-dodeca-3,6,8-trien-1-ol). This biochemical data further add to the anatomical and mole- cular characteristics that give a special status to the taxon Prorhinotermes among Rhinotermitidae. In Prorhinotermes canalifrons and P. simplex, neocembrene A was the only secretory compound specific to the sternal gland surface that could be detected after SPME. It elicited orientation as well as recruitment behavioral effects. However, the com- parison of the respective biological activities triggered by neocembrene A and by sternal gland secretion suggests that minor components of the latter are acting in synergy with neocembrene A. Key words. Termites – Prorhinotermitinae – P. canalifrons – P. simplex – Neocembrene A – Phylogeny Introduction Data on the chemical nature of termite trail pheromones are relatively scarce but suggest very low species-specificity and chemical parsimony (Pasteels & Bordereau 1998; Peppuy et al. 2001a), unlike the high diversity and species- specificity of ant pheromones (Billen & Morgan 1998; Ayasse et al. 2001). Subterranean termites of the family Rhinotermitidae have mostly been investigated. The first ter- mite trail pheromone was identified in the Heterotermitinae Reticulitermes virginicus as (3Z,6Z,8E)-dodeca-3,6,8-trien- 1-ol (dodecatrienol) (Matsumura et al. 1968). Subsequently, the same compound was found to be the trail-following pheromone of R. flavipes (Tai et al. 1969), R. speratus (Tokoro et al. 1991), R. santonensis (Laduguie et al. 1994), R. lucifugus grassei (Wobst et al. 1999), Heterotermes tenuis (unpublished results), Coptotermes formosanus (Tokoro et al. 1989) and Coptotermes gestroi (unpublished results). These species belong to the subfamilies Heterotermitinae and Coptotermitinae, but the three genera Reticulitermes, Heterotermes and Coptotermes form only one clade according to recent molecular phylogenetic studies (Ohkuma et al. 2004; Lo et al. 2004). Within the framework of research on the evolution of chemical communication among Isoptera, we have analyzed the trail pheromone in the genus Prorhinotermes, a taxon occupying a particular position among the Rhinotermitidae. Quennedey and Deligne (1975) isolated this genus from the Rhinotermitinae to form the monotypic subfamily, Prorhinotermitinae, based on specific anatomical characte- ristics of the soldier head. Furthermore Vrkoc and Ubik (1974) and Prestwich (1983) identified an exceptional nitro compound in the defensive secretion of P. simplex. Roisin (1988) showed that the caste system of Prorhinotermes with pseudergates was analogous to that of the Kalotermitidae and Termopsidae and much more ancestral than those of the other Rhinotermitidae. Although lacking true workers, P. inopinatus was however capable of extranidal foraging activities (Roisin et al. 2001). Parmentier and Roisin (2003) underlined that Prorhinotermes occupied a basal position in the Rhinotermitidae phylogeny. Recent molecular studies confirmed that Prorhinotermes branched deeply from the Rhinotermitinae and well supported the Prorhinotermitinae subfamily (Ohkuma et al. 2004; Lo et al. 2004), but only weakly its basal position (Okhuma et al. 2004). According to other molecular phylogenetic analyses, Prorhinotermes would be a sister group to Rhinotermidae with an inter- mediate position between Rhinotermitidae and Termitidae (Austin et al. 2004). We report here the results obtained on the trail- following pheromones of the Malagasy P. canalifrons. Com- parative analyses have been carried out on the Neotropical P. simplex. Correspondence to: Christian Bordereau, e-mail: christian.borderau @u-bourgogne.fr Research papers