A new method for producing a synthetic pheromone identical in composition to the natural aggregation pheromone of beetles of the genus Tribolium and its testing in laboratory conditions

The natural aggregation pheromone of beetles of the genus Tribolium is 4,8-dimethyldecanal and is a mixture of the stereoisomers (4R, 8R), (4R, 8S), (4S, 8R), and (4S, 8S) in a ratio of 4:4:1:1. Synthesizing a mixture of such a composition is quite problematic. A new method for producing natural tribolure by mixing 2 parts of the racemate 4,8-dimethyldecanal and 3 parts of (4R, 8RS)-dimethyldecanal is proposed. The synthesis of racemates is simpler and less expensive than the synthesis of optically active compounds. (4R, 8RS)-dimethyldecanal exhibits optical activity only at the 4-position, simplifying the task compared to synthesizing substances with two optically active centers. This article presents methods for synthesizing these components of the pheromone mixture. The synthesis of the substances was carried out using known schemes, to which we introduced a number of significant improvements. Laboratory comparative tests in an olfactometer showed that the racemate of 4,8-dimethyldecanal actively attracts Tribolium castaneum beetles. A mixture of stereoisomers was tested for T. castaneum. The “optically active” tribolure mixture exhibited attractiveness at a lower concentration than the racemate in experiments on T. castaneum. Under the experimental conditions, the racemate attracted T. castaneum starting at a dose of 50 ng, and began to repel insects at a dose of 10,000 ng. A mixture of stereoisomers, identical to the natural pheromone, attracted insects at a minimum dose of 2 ng.

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