The eucalyptus weevil, Gonipterus spp. Schoenherr, 1833 (Coleoptera, Curculionidae) is considered a major pest of eucalyptus plantations. In regions where control is achieved, success is usually brought by the action of the solitary egg parasitoid Anaphes nitens (Girault, 1928) (Hymenoptera, Mymaridae). Research was conducted to ascertain which cues might mediate female wasp host location and selection. In Petri dish arenas, females were attracted to Gonipterus platensis Marelli, 1927 egg capsules, to G. platensis mated female faeces and to leaves of Eucalyptus globulus Labillardiere, 1799. Gas chromatography-mass spectrometry electroantennographic detection analysis was conducted using extracts obtained from leaves of E. globulus, from G. platensis egg capsules, as well as from adults of both sexes and their faeces, in order to detect and identify compounds perceived by the wasp's olfactory system. The parasitoids were shown to detect a wide range of compounds emitted by each one of these sources, and for 31 compounds, antennal response was confirmed by dose-response tests. Further behavioural trials were conducted in Petri dishes in order to decode the effect, on parasitoid behaviour, of selected compounds emitted by E. globulus and of the pheromones, emitted by the weevils on parasitoid behaviour. Attraction was observed to two compounds emitted by E. globulus, namely 1,8-cineole and gamma-terpinene, and to the main component of the male sex/aggregation pheromone, cis-verbenol. To our knowledge, this is the first report of attraction of a parasitoid from the family Mymaridae to a component of its host's sexual/aggregation pheromone. Similarly, to other egg parasitoid species, A. nitens females are likely to use the host plant volatiles as long-range host location cues and to adopt the `infochemical detour' strategy in order to get in the vicinity of their hosts.

The eucalyptus weevil, Gonipterus platensis (Coleoptera, Curculionidae), is a major pest of eucalyptus plantations worldwide. To date, no pheromones have been identified for this species, despite their valuable potential as tools in monitoring or control strategies. Here we report the detection and identification of pheromones candidates of G. platensis. The weevil's volatile compounds were collected by solid phase micro extraction (SPME) and monolithic material sorption extraction (MMSE). Using Gas Chromatography coupled to Mass Spectrometry (GC/MS) analysis, eleven insect specific compounds were detected and identified: verbenene, cis-verbenol, trans-verbenol, verbenone, 2-oxo-1,8-cineole, 9-hydroxy-1,8-cineole, 2-alpha-hydroxy-1,8-cineole, 3-oxo-1,8-cineole, 2-beta-hydroxy-1,8-cineole, 3-alpha-hydroxy-1,8-cineole and 7-hydroxy-1,8-cineole. Three of these compounds, verbenene, cis-verbenol and trans-verbenol, were shown to be male-specific. Antennal sensitivity towards ten compounds emitted by G. platensis was detected using Gas Chromatography-Mass Spectrometry/Electroantennographic Detection (GC-MS/EAD). Extracts from virgin males proved to be attractive to virgin females in olfactometer bioassays. Further behavioural bioassays showed that both virgin females and virgin males were attracted to the male-specific compound cis-verbenol and that virgin females were attracted to trans-verbenol. Verbenone was attractive to mated females. Regarding 2-alpha-hydroxy-1.8-cineole and 2-oxo-1,8-cineole, which are produced by both sexes, the alcohol was attractive to virgin males and both the alcohol and the ketone were repellant to mated females. This is, to our knowledge, the first identification of pheromones candidates in Gonipterus spp. and also the first evidence of cineole metabolites acting as semiochemicals.