Question

Discuss moulting in silkworms

Answer 1

Answer:

Silkworm rearing is an extensive month-long exercise starting from egg stage and terminating in adults laying eggs and dying their natural death. During this course, they pass through five larval instars intervened by four moults, cocoon and pupal stage. Silkworm rearing effectively means the culturing of five larval instars as other stages like egg, pupa and adults are non-feeding stages. Whole life cycle spans through 45-55 days with 10-12 days of egg stage, 25-30 days of larval stage, 2-3 cocoon spinning days, 5-7 days as pupal duration and 4-5 days in adult stage. Prevailing environmental conditions especially, temperature and relative humidity conditions are vital in determining silkworm physiology as it is a cold-blooded organism. Hence, maintenance of recommended temperature, relative humidity (RH), light and ventilation conditions for every stage of rearing are of utmost importance for successful silkworm rearing. Dark condition, room temperature and 65% RH is required for incubation of silkworm eggs. 27-28 °C and 80-85% RH is required for first and second instar larvae (Chawki silkworm rearing), while 24-25 °C and 60-65% RH is required for third, fourth and fifth instar larvae (late-age silkworm rearing). During the intervening moulting stage of 24 hour each between two instars, temperature of 25-26 °C and RH 60% is recommended for the smooth integument change over. Room temperature and 65% RH is required during spinning, cocoon preservation, moth emergence, coupling, decoupling processes. Dark conditions with room temperature and 75-80% RH is required for oviposition process. A day in silkworm culture consists of various activities like harvesting of mulberry leaves, food preparation, feeding, bed cleaning etc. Silkworms are fed four times in a day – morning (9-10 A.M.), afternoon (1-2P.M.), evening (4-5P.M.) and night (9-10P.M.). Leaves after harvesting from plantations are first washed with plain running water and then treated with mild KMnO4 for general disinfection.

Answer 2

Answer:

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