Chemical ecology of astigmatid mites. LXIV. The alarm pheromone neral functions as an attractant in Schwiebea elongata(Banks)(Acari: Acaridae).

Abstract

Although neral [(Z)-3,7-dimethyl-2,6-octadienal] has been known as the alarm pheromone of Schwiebea elongata, reinvestigation of the pheromone resulted in recognition of another function as an attractant. The alarm pheromone activity was confirmed at a dose of one female equivalent of the hexane extract, whereas the attractant pheromone activity was observed at 0.1 female equivalent. Although no attractant activity was recovered in fractions of the silica gel (SiO2) column eluate, the synthetic neral manifested both activities; the attractant activity at 3 ng and 1 ng with a convex dose-response relationship, and the alarm pheromone activity at 30 ng. A female contained 30.4 ng of neral on average and a male 0.7 ng on average. This is the first example among astigmatid mites demonstrating that a single mite compound emitted from the opisthonotal gland exhibits two pheromonal functions, alarm pheromone and also attractant, at different doses.