C9 Aliphatic Aldehydes: Possible Sex Pheromone from Male Tropical West African Shield Bug, Sphaerocoris annulus

Introduction Sphaerocoris annulus (F.) is a 1 cm long, distinc­ tively patterned, tropical West African shield bug. Linnavuori [1] places the genus Sphaerocoris in the subfamily Scutellerinae within the family Pen­ tatomidae in the Hemiptera-Heteroptera. Concern­ ing the biology of S. annulus not a great deal seems to be known. Food plants include species of Vernonia (Compositae). The life cycle probably involves an adult reproductive diapause. It is a peculiarity of the scent gland system of S. annulus that the uniquely divided abdominal dor­ sal first scent gland (DG1) is well developed and biochemically active in the male adults. Only a ves­ tige of DG1 is to be seen in nymphs and female adults. A sex dimorphism in DG1 in the adults in Pentatomidae has been reported previously only in certain Asopinae [2—6] and one other species (Hotea gambiae) within the Scutellerinae [7]. In Podisus maculiventris (Asopinae) observation has shown that the volatile multicomponent emission from male adult DG1 functions in Nature as a precopulatory aggregation pheromone [6].