Ecology, Environment and Conservation Paper

EFFECT OF REARING SEASONS AND FOOD PLANT COMBINATIONSON ECONOMIC TRAITS OF COCOONS AND YARN OF MUGASILKWORM (ANTHERAEA ASSAMENSIS HELFER)

P. Borpuzari, M.R. Das and A. Rahman

Abstract

Muga silkworm, Antheraea assamensis Helfer (Lepidoptera: Saturniidae) is a multi-voltine polyphagousinsect which produces golden yellow muga silk. Muga silkworm feeds on leaves of many tree plant speciesbut primarily the leaves of Persea bombycinaKost. (Som) and Litseamonopetala Roxb. (Soalu). The farmersrear the silkworm mainly in two seasons for commercial purposes although the silkworm can be reared sixtimes (crops) in a year. Productivity of silkworm rearing is dependent on cocoons and yarn characteristicswhich are affected by the type of food plants at the time of rearing. In this study, an attempt was made toevaluate the economic characters of cocoons and yarn of muga silkworm reared in different combination ofprimary food plants in different seasons. Two primary food plants P. bombycina and L. monopetala wereselected in four combinations (T1 –T4) for rearing in two commercial crop seasons namely Kotia (V1), Jethua(V2) and two seed crop i.e. Bhodia (V3) and Chotua (V4). Cocoon weight and pupal weight were higher inthe cocoons harvested from the silkworm reared in L. monopetala only and mainly in Kotia (October-November) seasons followed by Jethua (April-May), Bhodia (August-September) and Chotua (February-March)seasons. Shell weight, shell ratio, filament weight, filament length and non-breakable filament length (NBFL)were higher in the silkworms reared in P. bombycina (T1) irrespective of seasons followed by treatmentcombination T4 (L. monopetala up to 3rd instar then P. bombycina). Benefit cost ratio (BCR) was higher in T1combination during Kotia (10.61:1) seasons followed by Jethua, Bhodia and Chotua crop seasons. As such, P.bombycina is the preferred food plant for commercial rearing of muga silkworm, however the silkworm canbe reared in L. monopetala up to 3rd instar and thereafter in P. bombycina till maturation for higher productivityin terms of cocoon and yarn characteristics.