Abstract
Hexane extract derived from Histiostoma laboratorium HUGHES, possibly the opisthonotal gland secretion, contained hydrocarbons and monoterpene as major components. The monoterpene fraction indicated the alarm pheromone activity and consisted of a mixture of neral (10%, 3, 7-dimethyl-(Z)-2, 6-octadienal) and geranial (90%, 3, 7-dimethyl-(E)-2, 6 octadienal). The synthetic geranial was active at 1 ppm, while corresponding neral was inactive at 10 ppm. The alarm pheromone of Histiostoma laboratorium was, then, concluded as geranial. This is the first example that geranial is the active compound as the pheromone, although neral which is the other component of citral is well known as mite's alarm pheromone in at least 5 species.
