(1R,2S,6R)-Papayanal: a new male-specific volatile compound released by the guava weevilConotrachelus psidii(Coleoptera: Curculionidae)

Abstract

The guava weevil, Conotrachelus psidii is an aggressive pest of guava (Psidium guajava L.) that causes irreparable damages inside the fruit. The volatile compounds of male and female insects were separately collected by headspace solid-phase microextraction or with dynamic headspace collection on a polymer sorbent, and comparatively analyzed by GC-MS. (1R,2S,6R)-2-Hydroxymethyl-2,6-dimethyl-3-oxabicyclo[4.2.0]octane (papayanol), and (1R,2S,6R)-2,6-dimethyl-3-oxabicyclo[4.2.0]octane-2-carbaldehyde (papayanal) were identified (ratio of 9:1, respectively) as male-specific guava weevil volatiles. Papayanal structure was confirmed by comparison of spectroscopic (EIMS) and chromatographic (retention time) data with those of the synthetic pure compound. The behavioral response of the above-mentioned compounds was studied in a Y-tube olfactometer bioassay, and their role as aggregation pheromone candidate components was suggested in this species.

Profile of Terpenoid Compounds Mediating a Plant‐Herbivore Interaction: Screening by Static Headspace Solid‐Phase Microextraction‐Gas Chromatography/Q‐ToF Mass Spectrometry

“…Although the taxonomically related species C. psidii and C. dimidiatus have the same eating habits, the compounds P-OL [36] and P-AL [10] were identified only in males of C. psidii while we found P-OL both in males and females of C. dimidiatus. Then, we directed additional efforts of our research to confirm the release of P-OL by both females and males of the weevil under study, to find differences at a biochemical level between C. dimidiatus and C. psidii.…”

“…[39] P-OL and P-AL were identified in males from field captures and unknown mating status. [10,36] It is possible that the mating status of the studied C. dimidiatus influenced on the production of P-OL and P-AL, although a convincing effect on responsiveness was not detected for C. nenuphar and Tribolium castaneum under unmated and mated conditions. [40,41] Further, to avoid controversy the experiments performed during 2019 included only mated insects and the results confirmed the release of P-OL both by female and male C. dimidiatus as depicted in representative chromatographic peaks in Figure 3 in the analysis performed in polar and non-polar columns.…”

“…A comparison with the P-AL peak intensity in the current work and in the male microextractions from C. psidii and Heilipus lauri is not possible because the intensity scale of the chromatograms is omitted in those publications. [10,12] It is known that in many insect species, mating status influences production and response to sex pheromones. [38] For example, only virgin female D. armandi produces frontalin as the mated male.…”

“…[10 -13] Romero-Frías, for example, obtained the same information about the presence of two insect pheromones by using SHS-SPME-GC/MS and the classical dynamic aeration (dynamic headspace DHS) method. [10,12] Chemical ecology is concerned, among other things, with the study of the relationship between an insect and its host plant and balances pest control strategy with research into insect interactions, requiring first the knowledge of the identity of the metabolites and then, the amounts released by them. Authors reported β-caryophyllene, limonene, and copaene as the main volatile organic compounds involved in the signalization between Conotrachelus psidii Marshall and its host, the Colombian guava.…”

“…On the other side, papayanol and papayanal were identified as volatile compounds released by C. psidii that play the role of aggregation pheromone. [10,15] There are no formal identification studies of the VOCs released by C. dimidiatus. Contreras-Montañez and Tafoya explored the extraction of chemical compounds by DHS and SHS-SPME methods in 2008.…”