Polypodine-B (a phytoecdysone) as inhibitor to growth and moulting of Dysdercus cingulatus Fabr. (Hemiptera: Pyrrhocoridae)

Growth and moulting inhibiting effects of polypodine-B, applied topically as well as by injection on the advanced nymphal stages (4^th and 5^th instar) of Dysdercus cingulatus, were studied in the laboratory. The topical application @ 0.5, 1.0, 2.0, 4.0 and 8.0 μg polypodine-B to 4^th instar nymph (one day old) resulted in total nymphal mortality as 10, 19, 30, 39, and 52% respectively. When these doses were injected into 4^th instar nymphs the resulting mortalities were slightly higher. Furthermore, similar application of the aforesaid doses on 5^th instar nymphs proved relatively less fatal. Besides causing the mortalities, the application of polypodine-B also resulted in the development of wing abnormalities in adults. The application of hormone to 5^th instar nymphs produced wing abnormalities in more adults than the application on 4^th instar nymphs.