AGGREGATION PHEROMONE SYSTEM OF ADULT GREGARIOUS DESERT LOCUST SCHISTOCERCA-GREGARIA (FORSKAL)

Six electrophysiologically active aromatic compounds, viz., anisole, b enzaldehyde, veratrole, guaiacol, phenylacetonitrile, and phenol, were identified in the volatiles of older-adult male desert locust. Young adults and females of all age groups produced none or only trace quant ities of these compounds. Comparison of the aggregation responses of y oung and older adults to the crude, older-adult, volatile extract and different synthetic blends of the six compounds showed that the aggreg ation pheromone system of the adult gregarious locust consists of phen ylacetonitrile, guaiacol, phenol, and benzaldehyde. Like the crude vol atile extract of older males, neither the synthetic blend of the six c ompounds nor the adult pheromone blend evoked any significant aggregat ion responses from nymphs. These results confirm our previous report o f sexual differentiation in the production of adult aggregation pherom one in the desert locust and of the evidence of two distinct aggregati on pheromone systems in the two stages of the insect.