Male-produced aggregation pheromone of Carpophilus mutilatus (Coleoptera: Nitidulidae)

Males of Carpophilus mutilatus Erichson produce an aggregation pheromone to which both sexes respond. The pheromone includes two hydrocarbon components, (3 E,5 E,7 E)-5-ethyl-7-methyl-3,5,7-undecatriene (1) and (3 E,5 E,7 E)-6-ethyl-4-methyl-3,5,7-decatriene (2). These were emitted in a 10:1 ratio and in a total amount of ca. 5 ng per feeding male per day. All tested doses of 1 and 2, from 0.03 to 30 ng, were more attractive than controls in wind-tunnel tests, but there was no evidence of synergism between these trienes. Dramatic synergism between the pheromone and a food-type coattractant occurred in the field, however. In a date garden in southern California, traps with a combination of synthetic 1 and fermenting whole-wheat bread dough attracted 22 times more beetles than dough by itself and 295 times more than 1 by itself. Volatile collections from males also contained three oxygenated compounds that were absent from females. One of these was tetradecanal (ca. 5 ng per male per day), but the structures of the other two are presently undetermined (0.8 and 1.1 ng per male per day). No function for these was demonstrated. One compound originating in the artificial diet, 2-phenylethanol, was particularly attractive in the wind-tunnel bioassay, as was the chromatographic solvent, methanol.