Identification between Schistocerca gregaria (Forskal) and Locust Migratorioides (Riech &Farmaire) in Relation to Phase Polymorphism

Abstract

Cross pheromone-mediating releaser effects between the desert locust, Schistocerca gregaria gregaria, and the African migratory locust, Locusta migratoria migrator_ioides, were investigated in olfactometer bioassays. These were compared with responses of gregarious individuals of the two locust species to their own air-borne volatiles. Similar to previous reports, nymphal and adult stages of S. gregaria responded strongly to their own volatiles; inunature and mature adults responded to mature adult, but not to nymphal volatiles; nymphs did not respond to mature adult volatiles. The responses of both nymphal and adult stages to their respective volatiles were dose dependent. In L . migratoria, nymphal and adult stages also responded strongly and in a dose-dependent fashion to their own volatiles. Immature adults responded to volatiles of mature adults, but both immature and mature adults did not respond sufficiently to nymphal volatiles. Nymphs also responded to volatiles of mature adults, but not to those of inunature adults. The two locust species cross-responded to each other's volatiles in a dose-dependent fashion. Both nymphal and mature adult stages of S. gregaria were less responsive to the voJ.atile emj_ssi.ons of the corresponding stages of L. migratoria.(continue from the attached PDF)