RESPONSE OF INSECT PESTS AND BOMBYX MORI L. TO MULBERRY GENOTYPES AND ENRICHMENT OF MULBERRY LEAVES FOR ENHANCED PRODUCTIVITY OF COCOON AND SILK
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Date
2009-09-20
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University of Agricultural Sciences, Bangalore
Abstract
In the present investigation18 insects pests were recorded on mulberry; further,
the seasonal occurrence and damages caused to four mulberry genotypes namely V1,
S36, S54 and Mysore local by insect pests such as wingless grasshopper
(Neoorthacris acuticeps nilgriensis Uvarov), Bihar hairycaterpillar (Spilosoma
obliqua Walker), leaf-roller (Diaphania pulverulentalis Hampson), spiralling whitefly
(Alerodicus disperses Russell), pink mealybug (Maconellicoccus hirsutus Green) and
thrips (Pseudodendrothrips mori Niwa) were studied. The wingless grasshopper was
most active during rainy season. The activity was least during winter and summer on
V1; Bihar hairy caterpillar occurs in more numbers from April to September.
Infestation of leaf-roller was severe during winter months, moderate in rainy seasons,
while mild in summer on all varieties at all locations. The incidence of spiralling
white fly, mealy bug and thrips incidence was noticed on all mulberry varieties
throughout the year at all locations with varying degrees.
The varieties/genotypes exhibited significant differences in respect of nutrient
contents at all the growth periods and maturity levels. The tested mulberry varieties
(V1, S54, S36 and Mysore local) recorded maximum leaf moisture, moisture retention
capacity and highest protein content at 30 and 45 days growth periods of tender
leaves, which gradually declined with increased maturity level and advancement of
growth period and V1 showed better nutrient parameters followed by S54, S36 and
Mysore Local. All the races (G and PM; CSR2 and NB4D2; CSR2 X CSR4 and CSR18
X CSR12) tested for enrichment of mulberry leaves for enhanced productivity of
cocoons and silk, showed good performance on feed additives with respect to the
quantitative traits of silkworm. Silkworms fed with calcium at 1:10 showed maximum
improvement with respect to larval weight, pupal weight, shell weight, silk
productivity, filament length, denier, fibroin and ERR followed by ascorbic acid at
1:10 ratio for polyvoltine, bivoltine and hybrid races with lower disease incidence.
The cost benefit ratio without new feed additive (NEWFA) was 1:21 while the
same with NEWFA was 1:3. This may benefit sericulturists as well as researchers to
increase cocoon and silk yield.
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