Neuroendocrine control of cocoon production in native earthworm Perionyx ceylanensis subjected to seasonal variation

Abstract

Aim: The aim of the present study was to observe the role of cerebral ganglionic neurosecretory cells (NSCs) during cocoon production in native earthworm species Perionyx ceylanensis subjected to amputation and seasonal variations. Methodology: Histological studies (using Aldehyde Fuchsin and Chrome Alum Haematoxylin Phloxin stain) were carried out on brain NSCs in the two groups of earthworms (Group I and Group II) maintained in earthen culture pots (2L) with cowdung as food. Group I comprised of brain amputed earthworms was subjected to observe the role of brain NSCs in production of cocoon and Group II earthworms subjected to seasonal changes in the cerebral NSCs during cocoon production. Five replications were kept for Group I (1 individual per pot) and Group II (1 pair per pot). Results: Group I debrained earthworms started to lay cocoons from the 31st day following regeneration of cerebral ganglionic type A NSCs. In group II worms the highest neurosecretory activity was registered in the cerebral type A cells, especially during monsoon coinciding with the hike of cocoon generation. Interpretation: Appearance of type A NSCs in regenerated brain and peak of type A neurosecretory cell activity during peak reproductive period of earthworm species (as indicated by peak of cocoon production) indicates the possible role of cerebral type A NSCs in cocoon laying.