## 4 Host-Marking Pheromones
### Chemical Identity, Production and Analytical Approaches to Their Characterisation
\begin{table}
\begin{tabular}{c c c c} \hline \hline
**Genus** & **Species** & **Chemical Identity** & **References** \\ \hline _Anastrepha_ & _A. suspensa_ & - & [376] \\ _A. sororella_ & - & [377] \\ _A. f. fellerulus_ & - & [378] \\ _A. pseudoparallela_ & - & [379] \\ _A. bistrigata_ & - & [380] \\ _A. grandis_ & - & [381] \\ _A. ludens_ & 2-(2,14-Dimethylpentadecanoylamine)pentane-dioic & [123; 382] \\ _A. striata_ & - & [97] \\ _A. obligua_ & - & [132] \\ _A. serpentina_ & - & [132] \\ \hline _Bactrocera_ & - & - & - \\ \hline _Cenatitis_ & _C. capitata_ & - & [111; 126] \\ _C. cosgra_ & Glutathione & [33] \\ _C. rosa_ & Glutamic acid & [34] \\ \hline _Rlugoletis_ & _R. pomonella_ & - & [112; 374; 383; 384] \\ _R. cerasi_ & _N-[15(\(\beta\)-Glucopyranosyl)-oxy-8-hydroxypalmitoyl]- & [30; 385; 386] \\ _R. completa_ & - & [135] \\ _R. fustata_ & - & [387] \\ _R. cingulata_ & - & [388] \\ _R. carnivora_ & - & [388] \\ _R. indifferens_ & - & [388] \\ _R. mutdax_ & - & [388] \\ _R. helellaria_ & - & [388] \\ _R. basiola_ & - & [130] \\ _R. zephyria_ & - & [131] \\ _R. alternata_ & - & [389] \\ \hline _Zengodacus_ & - & - & - \\ \hline \hline \end{tabular}
\end{table} 
Table 3: List of tephriti species for which host-marking behaviour has been identified. Later, the HMP [2-(2,14-dimethyl)pentadecanoyllamino)pentanedioic acid (or \(N\)-[2,14-dimethyl-1-oxopentadecyl)glutamate acid)] of _A. ludens_ has been chemically characterised and synthesised [382; 400]. It presented a relatively simple structure containing an isopalmitic fatty acid chain substituted by methyl at the C-2 position and coupled to glutamic acid (GA) as a single diastereomer [382; 400]. The HMP of _A. ludens_ exhibited not only intraspecific but also interspecific oviposition deterring activity to _A. obliqua_ and _A. serpentina_[132]. Of note, the HMPs of _R. cerasi_ and that of _A. ludens_ display similarities in structure (i.e., both contain a long fatty acid residue attached to an amino acid). Recently, the HMP of _C. cosyra_ and _C. rosa_ have been isolated and both chemical structures have been determined [33; 34]. The _C. cosyra_ and _C. rosa_ HMP identified are the tripeptide glutathione (GSH) (consisting of glycine, cysteine, and GA [33]), and GA [34], respectively. Interestingly, GSH and GA levels were 5-10 and 10-20 times higher in the faecal matter than in the ovipositor or haemolymph extracts of the respective females. These results suggest that the HMPs may be transferred from the gut into the ovipositor through the haemolymph and the excess amount may be expelled with the faecal matter. GSH was shown to express pheromone and allomone action respectively, reducing the oviposition in individuals of the same species and in those of different species, such as _C. rosa_, _C. fascicentris_, _C. capitata_, _Z. cucurbiae_. Interestingly, the GSH acts as kairomone inducing arrestment behaviour in the egg parasitoid _Fopius arisanus_ (Sonan) (Hymenoptera: Braconidae). On the other hand, GA perception resulted in oviposition reduction in _C. rosa_ and _C. fascicentris_, but not in _C. cosyra_. It is noteworthy that the HMPs of the two _Ceratitis_ species are highly distinct from the HMPs identified in the other fruit flies. However, they appear to be more closely related to the HMP of the Mexican fruit fly, which contains GA, than of _R. cerasi_ that is a fatty acid glucoside. Taken together, these findings may indicate that closely related species may utilise a similar pathway for HMP synthesis. Host marking through HMP deposition is noticeably absent in the _Bactrocera_ genus, even if contrasting results have been reported [35; 139]. To prevent other females from ovipositing on the same fruit, _B. oleae_ females do not depose an HMP but use their labella to spread olive juice leaking from the oviposition wound, with the main compounds responsible for this repulsion being (_E_)-hex-2-enal and oleuproein derivatives, such as the hydroxytyrosol [143; 401].