SECRETORY MECHANISMS FOR THE MALE-PRODUCED AGGREGATION PHEROMONE OF THE PALM WEEVIL RHYNCHOPHORUS-PALMARUM L (COLEOPTERA, CURCULIONIDAE)

Histological and chemical analyses of different corporal segments of t he palm weevil Rhynchophorus palmarum, revealed the presence of two sy mmetrical glands (modified salivary glands) in the prothorax of males, but absent in females. Using gas chromatography and mass sepectrometr y, we demonstrated the presence of rhynchophorol (aggregation pheromon e) in extracts of this gland, as well as in the rostrum and digestive tract (rectum) of males. Olfactometric experiments showed that the rel ease of the aggregation pheromone starts approximately 10 min after th e insect detects ethyl-acetate and continues for several hours. The ph eromone is secreted through the feces and more concentrated through th e mouth to a depression on the dorsal part of the rostrum where, via h airs and the surface tension of the secretion, it collects in a comple x structure consisting of various types of hairs, which help disperse the pheromone. Copyright (C) 1996 Elsevier Science Ltd