## 4 Discussion  
In Buprestidae, host and mate-seeking behavior is suggested to be ruled by complex signals that integrate visual and olfactory cues at both long and short range [23; 24; 25; 26]. In terms of olfaction, the deciphering of host kairomones has been successfully addressed in numerous studies [18; 19; 24; 27; 28; 29; 30], in contrast to the isolation and characterization of jewel beetle pheromones. To date, identification of pheromones in this family has been only achieved in _A. planipennis_, in which the female-released (\(Z\))-3-dodec-12-olide is considered as a short-range sex pheromone that attracts males [31; 32]. In the congeneric species _Agrilus bilineatus_ ([PERSON]), the presence of females increases the attraction of males towards cages baited with host logs, suggesting the existence of female-released compound(s) with pheromonal activity [33]. In addition to volatile pheromones, scant works have aimed to the identification of contact chemical cues [29; 34; 35]. Here, we report for the first time the release, and the electroantennographic and behavioral activity, of olean on both sexes of the FOB. This spiroacetal compound has been previously detected only in fruit fly species (Diptera: Tephritidae), and in the stingless bee _Partamona cupira_ ([PERSON]) (Hymenoptera: Apidae) [36; 37; 38]. Biologically active spiroacetals have been also described as part of the pheromonal communication system of some bark beetles (Coleoptera: Curculionidae), such as (2S,5S)-chalcogram [(2S,5S)-2-ethyl-1,6-dioxaspiro[4.4]nonane] in the genus _Pitygenes_ [PERSON] [39; 40; 41], and (5S,7S)-conophthorin [(5S,7S)-7-methyl-1,6-dioxaspiro[4.5]decane] in _Pityophthora carmeli_ [PERSON] [42], among others. Our laboratory assays demonstrated that virgin male and female FOB more than seven days from emergence positively responded to racemic olean in behavioral tests, whereas this attraction was not mediated in insects younger than seven days old, and a repellent effect was even detected in these females. These age-related differences in response to the compound may suggest that olean has a role in the chemical communication of the insect according to its sexual maturity. After trunk emergence, new FOB may migrate to the canopy in search of fresh leaves, as other bark-boring beetles behave in maturation feeding [43; 44]. Hence, young FOB would not find these chemical cues related to intraspecific communication attractive. A similar response pattern related to  
Figure 5: Reproductive system of a female from trap captures (**A**); close-up of the genitalia of a trapped (**B**) and virgin female (**C**). Legend: ov, ovaries; bc, bursa copulatrix; Sp, spermatophore; sp, spermatheca; mo, median oviduct. sexual maturity has been observed, for instance, in _A. planipennis_ when responding to kairomonal cues for host selection, with immature females not being responsive to those host chemical cues [(_Z_)-3-hexen-1-ol and bark sesquiterpenes] that are highly attractive for mature conspecifics [45]. Even though the chirality of naturally-occurring olean in _C. undatus_ was not elucidated, the racemate was proven to significantly attract both males and females in behavioral assays. To date, in two of the tephritid species known to use the compound as an intraspecific cue, namely _Bactrocera oleae_ (Gmelin) and _Bactrocera acuminata_ (Hering), it has been determined that olean is biosynthesized as its racemic form [46; 47]. In the olive fruit fly _B. oleae_ both sexes produce and release the racemic mixture [47; 48], with males being attracted to (_R_)-olean in laboratory and field assays, and females only responding to (_S_)-olean under laboratory conditions [47]. Although speculative, the hypothesis that _C. undatus_ produces the racemic form of olean should not be ruled out, taking into consideration that the biosynthetic pathway of olean in fruit flies species is suggested to follow a general paradigm [49].