Pheromone study on acarid mites IV : Citral : composition and function as an alarm pheromone and its secretory gland in four species of acarid mites

Abstract

Through bioassay and biological investigations on the alarm pheromone of five species of acarid mites, Aleuroglyphus ovatus, Carpoglyphus lactis, Lardoglyphus konoi and Dermatophagoides farinae, following results were obtained. Citral and neryl formate were more or less active as an alarm pheromone and not strictly species-specific within five species. Along with T. putrescentiae, two more acarid mites, C. lactis and L. konoi, were concluded to possess the alarm pheromone and citral was identified as their pheromone. Citral was emitted to the environment and the quantity of this discharge was 10 to 50 times larger when mites were disturbed than when undisturbed. Furthermore the composition of citral differed significantly between the disturbed (74-86% of neral) and undisturbed conditions (54-66% of neral), that is, the percentage of neral increased when disturbed. The original composition of extracted citral under 1-min soaking consisted of more than 90% of neral in the three species except L. konoi (75% of neral). Therefore the initial composition of citral when discharged from glands is supposed to consist of more than 90% of neral in three species, L. konoi, A. ovatus and D. farinae. Secretory gland of citral was identified as the latero-abdominal gland or the oil gland in all species of mites.