Observations on the morphology and secretory activity of the thoracic glands in Chrysocoris stollii Wolff (Heteroptera: Pentatomidae).

Abstract

There is a pair of thoracic glands, one on each side, lying superficially on the thoracic fat body and connected with the prothoracic tracheal trunk at one end and the salivary gland at the other. Each gland consists of eight to ten beaded strings of cytoplasm, containing single rows of large nuclei and covered with a prominent cytoplasmic sheath. The glands show cyclic secretory activity in each nymphal instar. They are much reduced and contain smaller nuclei and clear cytoplasm in freshly moulted nymphs. As the nymphs grow, the nuclei enlarge, the cytoplasm becomes granular, and finally, when the nuclei have reached their maximum size, the cytoplasm shows vesicles filled with secretion. About 48 hours before the next moult, secretory material is discharged, vesicles are replaced by vacuoles and the glands shrink. In adults, about 12 hours after the last moult, the gland is much attenuated, degeneration begins, after 24 hours it has disa appeared.