Effects of Anti-Juvenile Hormone (Precocene II) Treatment on Phase Changes and Pheromone Production in the Desert Locust, Schistocerca gregaria (Forskal) (Orthoptera: Acrididae)

The roles of anti-juvenile hormone (precocene II) on phase changes and pheromone production were examined in laboratory-bred gregarious desert locust, Schistocerca gregaria. Precocene II was applied to last instar nymphs and newly emerged adults in gregarious phase. Generally, the 5 th instar nymphs exhibited a higher sensitivity to topical appli- cation of precocen II than the adults. In contrast, the adults exhibited a higher sensitivity to injection of precocen II in comparison to 5 th instar nymphs. Topical application or injection of precocene II inhibited pheromone production (as measured by the amount of phenylacetonitrile released). Both topical application to 5 th instar nymphs and injection to adults affected the external body coloration, sexual behavior and mating of gregarious adult males, S. gregaria in com- parison to control insects.