Laboratory evalutation of
Beauveria bassiana (Bals.) Vull. on larval
development and cocoon production of mulberry silkworm.
Lohani B. N., Y. D. GC, R. B. Thapa and S. M. Shrestha. 2007.
IAAS Research Advances Vol. 1. Institute of Agriculture and Animal Sciences, Rampur,
Chitwan,
Nepal. pp.
135-139.
Keywords:
Beauveria bassiana, Bombyx mori,
mortality, shell ratio
Laboratory experiment was conducted to observe the effects of different
indigenous fungus B. bassiana on
Mulberry silkworm (Bombyx mori, L.)
at the Institute
of Agriculture and Animal
Science (IAAS), Rampur
in 2005. A virulent strain (B2)
of Beauveria bassiana was tested by
dipping the fourth instar silkworm larvae at different concentrations of 107,
106, 105 and 104 conidia per ml including
control. Mortality of silkworm larvae due to fungus effect started only after 13th
day of treatment. The mean mortalities on 17th day after treatment
were 39.58%, 31.20%, 23.12% and 19.5% with 107, 106, 105
and 104 conidia per ml, respectively. Shell ratios did not show
any significant variation between the highest concentration and control;
however, other dosage showed lower shell ratios than control. The highest good
cocoons were recorded in control (91.66%) followed by 104 (55.83%),
105 (55.83%), 107 (28.33%) and 106 (34.17%)
conidia per ml. Similarly, poor quality cocoons were high in 106
(32.5%) followed by 107 (30%) 104 (21.66%), 105
(18.33%) conidia per ml whereas in control it was only 5%. Except on 7th
and 10th day of treatment, there was no difference in larval body
weight due to fungus treatment.
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