Submitted to: Journal of Agricultural and Food Chemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: December 23, 1998
Publication Date: N/A
Interpretive Summary: Due to customer concerns about the use of broad-spectrum pesticides and their effect on the environment, we are developing pest control strategies to specifically control a single target- insect pest in the presence of beneficial insects. The Freeman sap beetle is a pest of corn that can introduce and transmit damaging fungi from ear to ear. Males of this insect species produce a chemical substance, termed an aggregation pheromone, that attracts members of its own species. We have designed, prepared, and tested compounds similar in structure to the natural pheromone that substantially reduce the behavioral response of the Freeman sap beetle to its pheromone. These compounds should be useful biochemical probes which will enable scientists to study how this insect handles and responds to pheromone-based chemical information.
Technical Abstract: Analogs of pheromones that strongly reduce response to pheromones by insects might be useful as biochemical probes to study the mechanism of pheromone perception. Analogs of (2E,4E,6E)-5-ethyl- 3-methyl-2,4,6-nonatriene, the major component of the aggregation pheromone of Carpophilus freemani Dobson (Coleoptera: Nitidulidae), were synthesized and the potency of these compounds in suppressing the response of C. freemani to its pheromone in a wind tunnel bioassay 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 fermenting bread dough (a pheromone synergist), the most potent inhibitory compound, (1Z,3E,5E)-1-cyclopropyl- 3-ethyl-5-methyl-1,3,5-heptatriene, was less effective in reducing mean landings (69% vs 99%) than when dough was absent. This inhibitory compound causes a reduction of response to pheromone but does not cause a reduction of response to fermenting food type volatiles such as fermenting bread dough. The inhibitory compounds might be useful as biochemical probes to study the mechanism of pheromone perception in C. freemani.