Effect of mating duration on reproductive parameters and its impact on larval growth and quality of cocoons of eri silkworm, Samia ricini Donovan
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Date
2018
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Publisher
AAU, Jorhat
Abstract
The current investigation on effect of mating duration on reproductive
parameters and its impact on larval growth and quality of cocoons of eri silkworm,
Samia ricinia Donovan, was carried out in the laboratory of Department of Sericulture,
Assam Agricultural University, Jorhat in autumn and spring season during the year
2017-2018. The findings revealed that mating duration had significant effect on
fecundity/ female/ day, total fecundity, weight of eggs, total weight of eggs and average
hatchability percentage and non-significant effect on total oviposition duration and
incubation period of eri silk moth. In almost all mating durations and seasons the egg
laying percentage was maximum in the first day which gradually decreased with
succeeding number of ovipositing days. Irrespective of season, five hours of mating
duration was found to be better in total fecundity, weight of eggs and total weight of
eggs which was at par with four hours mating duration. Four hours of mating duration
was found to be better in both fecundity/ female/ day and average hatchability
percentage regardless of season. Season also had significant effect on total oviposition
duration, fecundity/ female/ day, total fecundity, weight of eggs, incubation period and
average hatchability percentage. Total oviposition duration and incubation period of eri
silk moth was recorded longer in spring season than autumn season. Fecundity/ female/
day, total fecundity and weight of eggs of eri silk moth were recorded better in autumn
season. But, average hatchability percentage was better in spring season. Mating
duration had no significant effect on larval growth and cocoon parameters. However,
season had significant effect on larval duration, weight of full grown larvae, weight of
matured larvae, ERR (%), cocoon weight, shell weight and pupal weight. Larval
duration of eri silk moth was recorded shorter in autumn than spring season. Weight of
full grown larvae, weight of matured larvae, ERR (%), cocoon weight, shell weight and
pupal weight of eri silk moth was recorded better in autumn season than spring season.
But, shell ratio (%) was better in spring season. Interaction effect between mating
duration and season was significant in total oviposition duration, weight of eggs/
female/ day, larval duration, cocoon weight and pupal weight.
Thus, from the present investigation it may be inferred that a period of
three to five hours coupling duration is optimum for maximum egg laying of eri silk
moth. In addition to this, though the fecundity and weight of eggs was registered better
in autumn, with shorter incubation period and hatching percentage of eggs of the silk
moth performed better in spring season. Larval and cocoon parameters showed better
performance in the autumn season than spring season.