CROSS INFECTIVITY OF PATHOGENS OF DIAPHANIA PULVERULENTALIS (HAMPSON) TO BOMBYXMORIL.
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Date
2007-08-02
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UNIVERSITY OF AGRICULTURAL SCIENCES GKVK, BANGALORE
Abstract
Fortnightly survey was conducted in three villages of Sidlagatta Taluk of Kolar
District in Karnataka from August 2006 to February 2007 to record the incidents of leafroller,
Diaphania pulverulentalis (Hampson) on mulberry and also the incidents of its
diseases. The seasonal incidence and rate of infestation of D. pulverulentalis were
significantly maximum during January (91.00 and 18.87% , respectively). The incidence
of pathogens of D. pulverulentalis such as, Beauveria bassiana (Bals.) Vuillernen and
Aspergillus sp. was noticed from October to January, while the other two
pathogens, Microsporidian and DpNPV were prevalent from August to February. The
ET50 for expression of symptoms and ET50 for mortality in the test population of B. mori
were maximum in silkworms inoculated with 10-2 dilution of B. bassiana, Aspergillus sp.
and Microsporidian, but decreased as the dilutions increased. However, no disease
expression or mortality were observed in silkworms infected with DpNPV. The
silkworms infected with the NPV isolated from caterpillars of D. pulverulentalis
performed as those of control batches with regard to larval parameters [viz., fourth larval
duration(98.00h), fourth moult duration (25.33h), rate of fourth moult (100%), duration
of fifth instar (168 .00h) , fourth and fifth instar larval weight (0.90g and 2.35g ,
respectively)], cocoon parameters [viz., rate of cocoon spinning (l00%), cocoon weight
(1.74g), pupal weight (1.46g)] and post cocoon parameters [viz., shell weight (0.28g) ,
shell ratio (16 .27%) , silk productivity (3.95cg/day)] and grainage parameters [viz.,
pupation rate (100%), rate of moth emergence (l00%), cocoons to layings ratio (71.33%)
and fecundity (440.33 eggs/moth)] , indicating specificity of DpNPV. However, the
economic traits of silkworms were significantly affected when infected with B. bassiana,
Aspergillus sp. and Microsporidian, which were isolated from the caterpillars of D.
pulverulentalis. Hence, the DpNPV can be evaluated and . utilize <as a potential biocontrol
agent in the management of D. pulveru e tali in mulberry
ecosystem.
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