Aggregation pheromone of the German cockroach, Blattella germanica (L) (Dictyoptera: Blattellidae): Controlled release of attractant amines by salt formation

The aggregation attractant pheromone of the German cockroach comprises highly volatile 1-dimethylamino-2-methyl-2-propanol and alkylamines, and their release from the substrate was controlled by acidic components. Ion chromatographic analysis showed that hydrochloric acid was the major constituent, accounting for 81% of the total equivalent of anions. Methylated organic acids analysed by CC-Ms comprised 4-(methylsulfinyl)-butanoic, oxalic and lactic acids and other dibasic and hydroxyl acids. The attractiveness of each amine mixed individually with hydrochloric, nitric, sulfuric and the three major organic acids was evaluated by olfactometer assay. The mixtures with hydrochloric acid showed almost the same attractiveness as those with the natural acidic fraction. The most active mixtures were those with 4-(methylsulfinyl)-butanoic acid, and the activity was retained irrespective of the increase in the amount of acid. The attractiveness of trimethylamine hydrochloride assayed at various humidities indicated that the release of an amine from salt is modulated by humidity and reduced in moist conditions.