1Laboratoire de Biologie Animale et Cellulaire CP 160/12, Université Libre de Bruxelles, 50 Av. F. Roosevelt, 1050 Bruxelles, Belgique.
2Laboratoire de Chimie Bio-organique CP 160/07, Université Libre de Bruxelles, 50 Av. F. Roosevelt, 1050 Bruxelles, Belgique.
3Departamento de Biologia, Universidade Estadual do Ceará, Av. Paranjana 1700, Campus do Itaperi, 60.740-000 Fortaleza-CE, Brazil.
The chemical analysis of the venom of 3 Crematogaster species from Brazil leads to the identification of new defensive compounds, including the first furanocembranoid diterpene isolated from insects. This is also the first report of the presence in the Dufour's gland of an ant of cembranoid diterpenes which act as defensive compounds. The comparison of these new substances with those previously described shows that the defensive compounds are highly variable in the genus Crematogaster. The toxicity of the venom is related both to its chemical composition and to the ant or termite species on which it was tested. The European species C. scutellaris seems to be resistant to its own secretion but this is not the case for at least 2 Brazilian species. When observed, lethal toxicity occured only after a few hours or days following topic application. The analysis of the agonistic behaviours between Crematogaster workers and other ant species suggests that the defensive compounds also have a more direct repulsive effect. This has been studied mainly in C. scutellaris. The defensive secretions of Crematogaster could provide useful chemotaxonomic tools since the classification of the species based on morphological characters is not evident in many cases. This is well illustrated by our results on 2 Brazilian "species". According to the current classification, these ants belong to the C. brevispinosa species. However, they S how different ecological traits and produce different furanocembranoid diterpenes, suggesting that they are two distinct species.