Chemical composition of volatiles emitted from fresh mouse carcasses (laboratory mice, Mus musculus) was studied using solid sample injection technique (solid-phase micro-extraction), two-dimensional gas chromatography with time of flight mass spectrometric detection and gas chromatography with electroantennographic detection. Electroantennography (EAG) and laboratory olfactometric behavioural observations were used to study the antennal sensitivity to identified infochemicals and their attractiveness for burying beetles Nicrophorus vespillo and Nicrophorus vespilloides (Silphidae: Nicrophorinae). Chemical analysis showed that immediately after death, emitted volatiles did not differ from those emitted by a living organism. However, in the course of time, sulphur-containing chemicals, specifically methanethiol, methyl thiolacetate, dimethyl sulphide, dimethyl disulphide and dimethyl trisulphide appear. EAG measurements revealed antennal sensitivity to these compounds. Behavioural tests in laboratory olfactometer showed that dimethyl sulphide, dimethyl disulphide and dimethyl trisulphide are highly attractive to both studied species. The data suggest that sulphur-containing chemicals are involved in mediating the fresh carcass attractiveness for N. vespillo and N. vespilloides.

Insect cuticular hydrocarbons are usually species-specific mixtures and may serve for species and gender recognition. They are, therefore, widely used in the chemotaxonomy and zoogeography of various insect taxa. In order to provide a basic study for further comparative analyses of cuticular hydrocarbon (CHC) profiles of cryptic species hidden within the South American fruit fly Anastrepha fraterculus complex (Diptera: Tephritidae), we analyzed the composition of the CHCs and their production with respect to age and sex in a laboratory population from Tucuman, Argentina. Several techniques of gas chromatography with mass spectrometric detection have been used in order to develop a suitable method for CHC identification, i.e., GC-MS in EI mode, GC-MS in CI mode, and GC×GC/TOFMS. Our analyses revealed a complex profile of aliphatic hydrocarbons in both males and females, consisting predominantly of n-alkanes, methyl-branched alkanes, as well as of alkenes and alkadienes. In young individuals (up to about 5 days after emergence), the CHC profiles were similar in males and females. However, in older flies, these profiles diverged and became clearly sex-specific. The temporal dynamics of the CHC patterns in both sexes were evaluated using multivariate exploratory techniques.

Discrimination of particular species within the species complexes of tephritid fruit flies is a very challenging task. In this fruit-fly family, several complexes of cryptic species have been reported, including the African cryptic species complex (FAR complex). Cuticular hydrocarbons (CHCs) appear to be an excellent tool for chemotaxonomical discrimination of these cryptic species. In the present study, CHC profiles have been used to discriminate among three important agricultural pests from the FAR complex, Ceratitis fasciventris, Ceratitis anonae and Ceratitis rosa. Hexane body surface extracts of mature males and females were analyzed by two-dimensional gas chromatography with mass spectrometric detection and differences in CHC profiles between species and sexes tested through multivariate statistics and compared with species identification by means of microsatellite markers. Quantitative as well as qualitative CHC profile differences between sexes and species are reported. The CHC profiles consisted of a mixture of linear, internally methyl-branched and mono-, di- and tri-unsaturated alkanes. Twelve compounds were pinpointed as potential chemotaxonomical markers. The present study shows that presence or absence of particular CHCs might be used in the chemical diagnosis of the FAR complex. Moreover, our results represent an important first step in the development of a useful chemotaxonomic tool for cryptic species identification of these important agricultural pests.

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