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Initiation and maintenance of cocoon spinning behaviour by saturniid silkworms
Author(s) -
LOUNIBOS L. P.
Publication year - 1976
Publication title -
physiological entomology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.693
H-Index - 57
eISSN - 1365-3032
pISSN - 0307-6962
DOI - 10.1111/j.1365-3032.1976.tb00961.x
Subject(s) - biology , antheraea pernyi , anatomy , midgut , instar , botany , larva , biochemistry , gene
Larvae of Antheraea pernyi and Hyalophora cecropia terminate the feeding phase of the fifth instar by purging the alimentary tract. This occurs in the morning under artificial illumination schedules and precedes the initiation of spinning by a species‐specific time interval. Infusion of β‐ecdysone into H. cecropia late in the feeding phase may, under certain conditions, provoke premature gut purging or terminate spinning by causing premature metamorphosis. Experiments in which spinning A. pernyi were stripped of their cocoons at various stages of construction confirmed that caterpillars initiated the spinning of a second cocoon at the same point in the behavioural repertoire where they had been interrupted. The rapid turning involved in cocoon impregnation behaviour was executed only in the confines of a cocoon, and required that the hindgut be both distended by exudate and free to expel it. Severance of the ventral nerve cord anterior to the terminal ganglion also eliminated impregnation behaviour. Cyclic turning of the cat́erpillar in the cocoon persisted after spinneret occlusion or silk gland excision, but at a markedly depressed frequency.