PHASE-INDEPENDENT RESPONSES TO PHASE-SPECIFIC AGGREGATION PHEROMONE IN ADULT DESERT LOCUSTS, SCHISTOCERCA-GREGARIA (ORTHOPTERA, ACRIDIDAE)

Volatiles from solitary-reared (solitarious) and crowd-reared (gregari ous) adult male desert locusts, Schistocerca gregaria (Forskal) (Ortho ptera: Acrididae), were quantitatively and qualitatively different. In particular, solitarious males did not emit phenylacetonitrile, a key component of the aggregation pheromone produced by gregarious adult ma les. In laboratory bioassays, solitarious and gregarious adults of bot h sexes responded similarly to the natural aggregation pheromone blend , the major pheromone component phenylacetonitrile, and a synthetic ph eromone blend comprising benzaldehyde, guaiacol, phenylacetonitrile an d phenol. EAG measurements showed significant differences in the respo nsiveness of adults of the two phases to the four synthetic components at high doses; however, the general response patterns were similar, T hese results suggest that the gregarious adult male aggregation pherom one may play a role in the arrestment and subsequent recruitment of so litarious individuals into gregarious or gregarizing groups during the early stages of a locust outbreak.