PERFORMANCE OF FIFTH INSTAR SILKWORM Bombyx mori L. ON TENDER SHOOTS
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Date
2001-08-09
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UNIVERSITY OF AGRICULTURAL SCIENCES GKVK BANGALORE
Abstract
Studies on the effect of feeding tender shoots on fifth instar silkworm,
Bombyx mori L. were conducted at the Department of Sericulture, University
of Agricultural Sciences, Dharwad during 1997-98. The experiment was
conducted by using Pure Mysore (PM), NB4D2 -and PM x NB4D2 over three
different seasons.
Among different treatment combinations, feeding tender shoots to fifth
instar silkworms upto third day and subsequently matured shoots
significantly increased larval and cocoon parameters (viz., full grown larval
weight, effective rate of rearing, cocoon yield, productivity, cocoon weight,
shell weight, shell ratio, pupal weight, silk filament length and weight) of
silkworm breeds when compared to matured shoot feeding (control).
During all the three rearings, the larval and cocoon parameters were
significantly higher in NB4D2; for the parameters viz., cocoon yield by weight,
productivity and shell ratio, NB4D2 was on par with PM x NB4D2. The
survival parameters viz,, effective rate of rearing, cocoon yield by number,
pupation rate and moth emergence were significantly higher in Pure Mysore,
which was on par with PM x NB4D2 when tender shoots were fed to fifth
instar silkworms upto third day and subsequently matured shoots. The
larval and pupal duration remained unaltered by tender shoot feeding. But,
fecundity was highest in PM x NB4D2 during winter when fifth instar
silkworms were fed with tender shoots upto three days and subsequently
matured shoots. Grasserie and Flacherie were lowest in PM when the fifth
instar silkworms were fed with tender shoots during winter. However
grasserie incidence was highest in NB4D2 when silkworms were fed with
tender shoots for entire fifth instar during summer.
Irrespective of season and breed when the fifth instar silkworm larvae
were fed with tender shoots upto three days and subsequently matured
shoots gave better performance for most of the economic traits in bivoltine
breed NB4D^nd the survival parameters were better in multivoltine breed,
Pure Mysorejxhe combination of economic as well as survival parameters in
multi x biovltine hybrid, PM x NB4D2.
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