Reduction of Carpophilus freemani Dobson (Coleoptera : Nitidulidae) aggregation pheromone response by synthetic analogues

Analogues of (2E,4E,6E)-5-ethyl-3-methyl-2,4,6-nonatriene the major compone nt of the aggregation pheromone of Carpophilus freemani Dobson (Coleoptera: Nitidulidae), were synthesized and the potency of these compounds in suppr essing the response of C. freemani to its pheromone in a wind tunnel bioass ay was determined. The most potent compounds reduced behavioral response to pheromone 83-96% when the inhibitors were present in 10-fold excess. These compounds are (1Z,3E,5E)-1-methoxy-3-ethyl-5-methyl-1,3,5-heptatriene, (1E ,3E,5E)- 1-cyclopropyl-3-ethyl-5-methyl-1,3,5-heptatriene, and (1Z,3E,5E)-1 -cyclopropyl-3-ethyl-5-methyl-1,3,5-heptatriene. In the presence of ferment ing bread dough (a pheromone synergist), the most potent inhibitory compoun d, (IZ,3E,5E)-1-cyclopropyl-3-ethyl-5-methyl-1,3,5-heptatriene, was less ef fective in reducing mean landings (69% vs 99%) than when dough was absent. This inhibitory compound causes a reduction of response to pheromone but do es not cause a reduction of response to fermenting food-type volatiles such as fermenting bread dough. Analogues of pheromones that strongly reduce re sponse to pheromones by insects might be useful as biochemical probes to st udy the pharmacophoric (three-dimensional structure) requirements for phero mone perception.