## 3 Volatile Pheromones
### Composition of Volatile Pheromones  
In rebritidis, the volatile pheromone is a mixture of diverse chemical compounds with different isomers [167]. These chemicals are either newly synthesised or produced from precursors acquired from the diet. Plant-borne chemicals introduced with the diet become integrated into the pheromone mixture and contribute to male mating success. Diet-derived chemicals can unmodified be incorporated into the pheromone blend (e.g., raspberry ketone (RK) in _Z. cucurbate_[168; 169]) or can go through conversion in other compounds that are then used in the pheromone (e.g., ME in _B. dorsalis_ that is converted in 2-allyl-4.5-dimethoxyphenol and _trans_-coniferyl alcohol [68; 69; 170; 171]). _Bactrocera dorsalis_  
Figure 3: Tissues involved in semiochemicals’ production in rebritidis. Diagrammatic representation of a male (left) and female (right) generalized tephritid showing the tissues/body compartments involved in pheromone production. Reproductive tracts and rectum are shown in upper left (male) and right (female) boxes. Bottom left and right boxes show the abdomen of a calling male, showing the expanded rectal epithelium (pae, pleural abdominal expansion), and the ovipositor of a female. Abbreviations: Male reproductive system: tes (testes), ves (vas deferens), acg (accessory glands), ejd (ejaculatory duct), eja (ejaculatory apodeme), acd (adeagus). Female reproductive system: ova (ovaries), ovr (ovariable), ovd (oviduct), spm (spermatheca), acg (accessory glands), cgd (coliterial gland duct), ovp (ovipositor). rectum: rev (rectal valve), rep (rectal papilla), res (reservoir containing pheromone), ant (anal tube). males are attracted to ME, and feeding on this compound was shown to directly benefit mating success [171; 172]. The pheromone mixture comprises both major, minor and trace compounds, with the complete blend displaying stronger effects than individual compounds or a mix of a subset of compounds. Indeed, medfly females respond differentially to mixtures of major male pheromone compounds than to the complete blend [173]. In _B. oleae_, olean (1,7-dioxaspiro[5.5]undecane) is the major component of female sex pheromone, and it is more attractive to males than the other identified components (e.g., \(\alpha\)-pinene, nonanal, and ethyl dodecanoate) [174]. However, the combination of all chemicals is more attractive than olean alone (see [171] for a review). The composition of the pheromone mixture has been investigated using two main approaches: (i) sampling the headspace of calling males (or females in the case of Bactrocera species), (ii) extracting the chemicals from the rectal glands. Volatiles captured in the headspace have been so far collected and characterised in 18 tephritid species (Table 1; Table S1), while gland extracts have been obtained from 26 species (Table 2). \begin{table}
\begin{tabular}{c c c c} \hline
**Genus** & **Species** & **Male/Female-Borne** & **References** \\ \hline _Anastrepha_ & _A. fraterculus_ & Male & [175; 176; 177; 178; 179] \\  & _A. ludens_ & Male & [87; 180; 181; 182; 183; 184; 185; 186] \\  & _A. obliqua_ & Male & [187; 188; 189; 190; 191; 192] \\  & _A. serpentina_ & Male & [193] \\  & _A. suspena_ & Male & [149; 180; 185; 194; 195; 196; 197; 198; 199; 200; 201; 202; 203] \\ \hline _Bactrocera_ & _B. carambolae_ & Male & [72] \\  & _B. dorsalis s.s._ & Male/Female & [68; 204; 205; 206] \\  & _B. musae_ & Male/Female & [76] \\  & _B. oleae_ & Male/Female & [80; 174; 207; 208] \\  & _B. tryoni_ & Male/Female & [209; 210; 211; 202; 212] \\  & _B. zonata_ & Male/Female & [213] \\ \hline _Zeugodacus_ & _Z. cucurbite_ & Male/Female & [204; 205] \\ \hline _Ceratitis_ & _C. anonae_ & Male & [214] \\  & _C. capitata_ & Male & [166; 217; 218; 219; 220; 221; 222; 223; 224; 225] \\  & _C. fascicentris_ & Male & [214] \\  & _C. rosa_ & Male & [214] \\ \hline _Rlagoletis_ & _R. batava_ & Male & [61] \\  & _R. cerasi_ & Male & [226] \\ \hline \end{tabular}
\end{table}