Influence of Endocrine Activity on Larval Development in Busseola fusca (Fuller) (Lepidoptera:Noctudine)

Abstract

The present study investigated the role of juvenile and moulting hormones in development of Busseola fusca. Morphometric measurements were used to distinguish differences in endocrine activity between non-diapause and diapause development with regard to the prothoracic glands and the corpora allata. The corpora allata of non-diapause larvae were similar in size to those of diapause larvae. The critical period for the prothoracic glands to produce the required titer of ecdysone for further development was by the third day after ecdysis to the last larval instar. Juvenile hormone extracts from haemolymph of Busseola fusca larvae in non-diapause and diapause development had morphometric effects on last instar nymphs of Dysdercus cingulatus. The extent of juvenilization of nymphs by these extracts was a measure of relative titer of juvenile hormone present. Extracts of JH from the fifth instar larvae of Busseola fusca and larvae in early diapause gave higher juvenilizing scores than JH from non-diapause sixth instar larvae.