Male-produced aggregation pheromone of Colopterus truncatus:: Structure, electrophysiological, and behavioral activity

A male-produced aggregation pheromone was demonstrated in Colopterus truncatus Randall (Coleoptera: Nitidulidae) by gas chromatographic comparisons of male and female volatile emissions. Male-specific compounds were identified with coupled gas chromatographic-mass spectrometric (GC-MS) analysis and GC and MS comparison of authentic standards. Physiological activity was evaluated by coupled gas chromatographic-electro-antennographic (GC-EAG) recordings, and electroantennographic (EAG) assays of standards. The mole-produced volatiles eliciting responses from malt: and female antennae (and relative abundance) were (2E,4E,6E)-3,5-dimethyl-2,4,6-octatriene (1) (1.8), (2E,4E,6E)-4,6-dimethyl-2,4,6-nonatriene (2) (100), and (2E,4E,6E,8E)-3,5,7-trimethyl-2,4,6,8-decatetraene (3) (3.3). A fourth male-specific compound, (2E,4E,6E,8E)-4,6,8-trimethyl-2,4,6,8-undeca-tetraene (4) (0.6) was not EAG-active. EAG dose-response studies showed that the antennae were most sensitive to 2 followed by 3 and 1. Synthetic 2, binary blends or 1 and 3, and tertiary blends of 1, 2, and 3 were highly attractive in the field when synergized with fermenting whole-wheat bread dough. In the field, cross-attraction to the C. truncatus pheromone components was observed for Carpophilus lugubris Murray, C. antiques Melsheimer, and C. brachypterus Say.