Factors affecting pheromone release by Scyphophorus acupunctatus (Coleoptera: Curculionidae)

Scyphophorus acupuncatus Gyllenhal is considered to be the most significant pest of cultivated agaves in the world. Recent studies on the chemical ecology of this weevil have shown that males release a pheromone that attracts both sexes. In this study, we investigated the effect of feeding, aging, photoperiod, and time of day on pheromone release by S. acupuncatus males under laboratory conditions. The pheromone released by individual males was sampled using solid-phase microextraction and analyzed by gas chromatography-coupled mass spectrometry. Our results show that food is an important factor because weevils deprived of plant material did not release any pheromone. In addition, we found that males fed with apple, a nonhost plant, released less pheromone than weevils fed with agave. Host odor does not seem to be important in stimulating pheromone release. We found that males as young as 1 mo were able to release pheromone, although the numbers of individuals releasing pheromone increased with age. Older males released more pheromone than younger males. We found that S. acupuncatus males released pheromone during the photophase and scotophase; there was, however, no significant peak in pheromone release. Also, the pheromone released by S. acupunctatus was not affected by the length of the photoperiod.