Identification of Male-Produced Aggregation Pheromone of the Curculionid Beetle Sternechus subsignatus

Abstract

Analyses of the headspace volatiles produced by males and females of Sternechus subsignatus Boheman (Coleoptera: Curculionidae) revealed seven male-specific compounds. The major component was (E)-2-(3,3-dimethylcyclohexylidene)-ethanol, and the minor components were 1-(2'-hydroxyethyl)-1-methyl-2-isopropenylcyclobutane (grandisol), 7-methyl-3-methyleneoct-6-en-1-ol, (Z)-2-(3,3-dimethylcyclohexylidene)-ethanol, (Z)- and (E)-2-(3,3-dimethylcyclohexylidene)-acetaldehyde, and (E)-2-(3,3-dimethylcyclohexylidene) acetic acid. The latter compound is described for the first time as a natural product. Only four of the seven identified compounds showed electrophysiological activity. Enantioselective gas chromatography showed that the natural grandisol is the (1R,2S)-stereoisomer. The major component, (E)-2-(3,3-dimethylcyclohexylidene)-ethanol, attracted S. subsignatus in olfactometer bioassays. Studies are in progress to evaluate the biological activity of the major component and the EAD-active mixture under field conditions.

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

“…Aggregation pheromones have been studied and applied in field to monitor or as support control strategy to control several Curculionidae species. [3][4][5][6] These kind of pheromones offers a promising method for direct insect control through mass trapping. 7,8) In addition, previous studies have shown that host plant volatiles are attractive to both sexes of C. psidii.…”

“…H NMR (400 MHz, CDCl 3 ) of the synthetic compound: δ [ppm] = 1.12 (s, 3H, CH 3 C-11); 1.16 (s, 3H, CH 3 C-10); 1.32 (ddd, 1H, 2 J = 14.0 Hz, 3 J = 2.0/2.0 Hz, He C-5); 1.43-1.50 (m, 1H, H endo C-7); 1.55-1.62 (m, 1H, H exo C-7); 1.57-1.65 (m, 1H, H exo C-8); 1.73-1.79 (m, 1H, CH C-1); 1.90 (ddd, 1H, 2 J = 14.0 Hz,3 J = 13.3/5.1 Hz, Ha C-5); 1.94-2.04 (m, 1H, H endo C-8); 3.23 (d, 1H, 2 J = 10.9 Hz, CH 2 OH); 3.42 (d, 1H, 2 J = 10.9 Hz, CH 2 OH); 3.53 (ddd, 1H, 2 J = 12.0 Hz, 3 J = 13.3/2.2 Hz, Ha C-4); 3.63 (ddd, 1H, 2 J = 12.0 Hz, 3 J = 5.2/2.1 Hz, He C-4); 13 C NMR (100 MHz, CDCl 3 ): δ [ppm] = 18.0 (C-8); 20.2 (C-10); 28.1 (C-11); 33.6 (C-7); 34.1(C-5); 35.8 (C-6); 45.1 (C-1); 57.5 (C-4); 68.9 (C-9); 72.9 (C-2). ½a 25 D = −34.4°(C = 1.00, n-hexane).…”

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

“…The less intense peaks in Figure 1 b and 1c correspond to the C 10 terpenoids marked as peaks a–g: GI, GII, GIII, GIV, P‐OL, and GA were detected only when the insects are fed with immature fruit. The elution order of the geometric isomers GIII and GIV was assigned according to the reported retention indices on a low‐polarity column [23,24] . The detection limit (in TICs) of GI‐IV and P‐OL was in the range of 95 to 240 ng L −1 .…”

“…The elution order of the geometric isomers GIII and GIV was assigned according to the reported retention indices on a low-polarity column. [23,24] The detection limit (in TICs) of GI-IV and P-OL was in the range of 95 to 240 ng L À 1 . quantified the six C 10 terpenoids normalizing per insect and per day of a one-day (08/31/2017) SHS-SPME experiment using the peak areas representing the average emission of 19 females and 26 males.…”

“…GI has been isolated from other curculionid beetles, such as papaya weevil Pseudopiazurus obesus (Boheman), [27,28] bark weevil Pissodes spp., [29] and the soybean stalk weevil Sternechus subsignatus. [24] Grandlure II is also a pheromone of the strawberry blossom weevil. [23] Grandlures III + IV are aggregation pheromones of the cranberry weevil.…”