FECAL VOLATILES AS PART OF THE AGGREGATION PHEROMONE COMPLEX COMPLEX OF THE DESERT LOCUST, SCHISTOCERCA-GREGARIA (FORSKAL) (ORTHOPTERA, ACRIDIDAE)

Olfactometric bioassays showed that nymphs of crowded desert locusts, Schistocerca gregaria, aggregated in response to volatiles derived fro m their feces and to volatiles emitted from the feces of young adults, but were indifferent to volatiles emitted by older adult feces. On th e other hand, young and older adults were not only responsive to their own fecal volatiles but also cross-responsive to each other's and tha t of the nymphs. Charcoal-trapped volatiles from the feces and synthet ic blends of the fecal volatiles also elicited similar responses. Youn g adults responded moderately to a blend of nymphal volatiles and thos e derived from nymphal feces. GC-EAD and GC-MS analysis of the trapped volatiles revealed the presence of guaiacol and phenol as predominant electrophysiologically active components of nymphal and young adult f eces. Fecal volatiles of older adult contained phenylacetonitrile in a ddition to guaiacol and phenol, which were present in relatively lower proportion. These results suggest that fecal volatiles are part of th e aggregation pheromone complex of the desert locust, which includes t he pheromone blends produced by nymphs and older adults, respectively.