Record Details

INFLUENCE OF CERTAIN PHYSICAL AND CHEMICAL FACTORS ON THE BACTERIAL FLACHERIE DISEASE OF SILKWORM (Bombyx mori L.)

KrishiKosh

View Archive Info
 
 
Field Value
 
Title INFLUENCE OF CERTAIN PHYSICAL AND CHEMICAL FACTORS ON THE BACTERIAL FLACHERIE DISEASE OF SILKWORM (Bombyx mori L.)
 
Creator PARAMASIVA, I
 
Subject INFLUENCE, CERTAIN, PHYSICAL, CHEMICAL, FACTORS, BACTERIAL, FLACHERIE, DISEASE, SILKWORM
 
Description Investigations on instar and breed susceptibility of silkworm,
Bombyx mori L. to bacterial flacherie disease were conducted during
2004-2005. Morphological and biochemical changes that occur due to
flacherie incidence, histopathological changes that reflect in the larvae
of silkworm infected with Bacillus thuringiensis were documented.
Simultaneously the effect of ecological factors like temperature and
humidity, leaf maturity, larval starvation and leaf preservation on the
development of bacterial flacherie disease were observed. The impact of
antibiotics in preventing the bacterial flacherie were also carried out in
the sericulture unit in Department of Entomology, S.V. Agricultural
College, Tirupati, Acharya N.G.Ranga Agricultural University,
Hyderabad.
In all the three races of silkworm, later larval instars were seen
to be more tolerant to bacterial flacherie, than the early instars,
indicating that susceptibility of silkworm to flacherie decreased with
the advancement of the stage of the larvae. Among three breeds used,
PM race was found to be more tolerant to flacherie than CSR2 and PM
x CSR2 races. Marked morphological changes, like darkening of the
eggs, shrinkage of the larval body, malformed pupae and adults with
crinkled wings were observed in the silkworm when they were infected
with Bacillus thuringiensis. Total proteins, carbohydrates and lipid
content in the haemolymph of infected larvae were found low when
compared to the normal larvae. However, the reduction in protein,
carbohydrate and lipid contents in the haemolymph of infected larvae
was conspicuously low in PM race than CSR2 and PM x CSR2 indicating
its tolerance to flacherie.
Thirty minutes after ingestion of spores of B.thuringiensis by the
larvae, the midgut epithelial cells became detached from the wall of the
midgut and deep infoldings of columnar cells became irregular. Cavity
of goblet cells became enlarged. Vacuoles were observed in the
columnar cells. The maximum growth and sporulation of the bacteria
were observed at 35°C temperature and 90 per cent relative humidity.
The bacterial flacherie infected larvae showed higher mortality
when they were fed with tender leaves without shade drying. The lower
mortality was low in the larvae fed with medium mature leaves that
were shade dried for 3h. The larval and cocoon parameters were higher
when the larvae were fed with medium mature leaves without shade
drying. Whereas lowest values were obtained with the coarse leaves
that were shade dried for 3 h. The fourth and fifth instar larvae
showed higher mortality, lower larval weight and cocoon parameters
when the bacterial flacherie infected larvae starved for 36 h. Whereas
lower mortality and higher larval and cocoon parameters were recorded
when the infected larvae were reared without starvation.
The bacterial flacherie infected fifth instar larvae reared with
leaves without preservation, showed higher mortality and higher larval
and cocoon parameters. Whereas the larvae reared with 24 h preserved
leaves showed lower mortality and lower larval and cocoon parameters.
Among the different antibiotics, evaluated and methods of
applications involved, “norfloxacin” applied by the method of spraying
at a concentration of 1500 ppm was found to be very effective in
reducing the mortality of silkworm larvae due to bacterial flacherie.
This treatment also significantly increased the larval weight and
cocoon parameters like cocoon weight, shell weight and shell
percentage.
 
Date 2016-08-17T14:35:18Z
2016-08-17T14:35:18Z
2005
 
Type Thesis
 
Identifier http://krishikosh.egranth.ac.in/handle/1/72794
 
Language en
 
Relation D7713;
 
Format application/pdf
 
Publisher ACHARYA N.G. RANGA AGRICULTURAL UNIVERSITY, RAJENDRANAGAR, HYDERABAD