In laboratory and field bioassays, Gnathotrichus sulcatus responded to sulcatol (6-methyl-5-hepten-2-ol) only when both enantiomers were present. Response was greater to racemic sulcatol than to a mixture (65 : 35) of S-(+) and R-(-) enantiomers, the naturally occurring isomeric ratio. Enantiomer-specific active sites on receptor proteins in the same or different cells are implicated.

No abstract

The aggregation pheromone of the ambrosia beetle, Trypodendron lineatum (Olivier), was isolated by MacConnell et al. (1977), identified as one of two isomeric, tricyclic acetals, and given the trivial name, lineatin. One of the isomers, 3,3,7-trimethyl-2,9-dioxatricyclo [3.3.1.0 4,7] nonane (4,6,6-lineatin), was synthesized in µg quantities by three different syntheses, assessed to be structurally identical to the isolated pheromone, and demonstrated to be highly attractive in field tests (Borden et al. 1979; Vité and Bakke 1979). The other structural isomer, 3,3,7- trimethyl-2,9-dioxatricyclo [4.2.1.0 4,7] nonane (4,5,6-lineatin), was not tested for biological activity. The enantiomeric composition of natural lineatin was not determined by MacConnell et al. (1977).

Field experiments tested lineatin, the aggregation pheromone of Trypodendron lineatum (Olivier), in combination with either S-(+)- or (±)-sulcatol, the pheromones of Gnathotrichus retusus (LeConte) and G. sulcatus (LeConte), respectively. Beetles of each species responded maximally to their own pheromone alone or in a binary combination. Slight, but significant cross attraction between Gnathotrichus spp. was evident, and G. retusus was slightly attracted to lineatin. Both Gnathotrichus spp., but not T. lineatum, responded to α-pinene with ethanol. These two compounds had no effect on the allelochemic activity of the pheromones. While mutually inhibitory communication would be of adaptive advantage in bark beetles which compete for an essentially 2-dimensional host, the phloem tissue, little selection pressure would occur among ambrosia beetles which share a more bountiful host, the 3-dimensional sapwood; hence the lack of mutual inhibition between Gnathotrichus spp. and T. lineatum. On the other hand, enantiomer-based specificity in pheromone communication between Gnathotrichus spp. may have been at least a partial basis for speciation. Compatibility of lineatin with either S-(+)- or (±)-sulcatol indicates that in pheromone-based pest management, 2-binary pheromone stimulus release systems can be used instead of 3 single ones.

Can, Enr. 116: 51-56 (1984) The chemicals cis (Z) and trans (E)1 1-tetradecenyl acetate (1 1-14:Ac), trans 1 l-tetradecen-1-01 (El 1-14:OH) and trans 1 1-tetradecenal (El 1-14:Ald) were isolated from unmated female Choristoneura orae Freeman and shown to be highly attractive when used as lures in sticky traps. The identification of these components of the sex pheromone facilitates the separation of C. orae from other Pinaceae-feeding Choristoneura in the same area. ResumeOn a is016 de la femelle non accouplCe de Choristoneura orae Freeman les composCs chimiques cis (2) et trans (E) 1 I-acCtate tktradecenyl (1 1-14:Ac) trans Il-tCtradecen-1-01 ( E l 1-14:OH) et trans 1 1-tetradecenal (El 1-14:Ald) qui se sont rkvC1Cs tres attractifs comme appits dans des pibges engluts. L'identification de ces composCs de la pheromone sexuelle facilite la distinction de C. orae d'autres especes de Choristoneura infCodCes aux Pinaceae dans la meme rkgion.