STUDIES ON THE RESPONSE OF THERMOTOLERANT BIVOLTINE HYBRIDS OF Bombyx mori L. TO Beauveria bassiana (Bals.-Criv.) Vuill. INFECTION
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Date
2019-08-30
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UNIVERSITY OF AGRICULTURAL SCIENCES GKVK, BENGALURU
Abstract
The study on the response of thermotolerant bivoltine hybrids of Bombyx mori L.
to Beauveria bassiana (Bals.-Criv.) Vuill. Infection was conducted at the Department
of Sericulture, UAS, GKVK, Bengaluru. Four parents viz., B1, B4, B6 and B8 and 12
hybrids viz., B1 × B4, B1 × B6, B1 × B8, B4 × B1, B4 × B6, B4 × B8, B6 × B1,
B6 × B4, B6 × B8, B8 × B1, B8 × B4 and B8 × B6 were used in the experiments. The
hybrid B1 × B8 showed highest LC50 value (9.04 × 104
spores/ml) for Beauveria
bassiana infection and significantly highest LT50 value at all the fungal spore
dilutions. Further, B8 breed and B1 × B8 hybrid performed significantly better at all
fungal dilutions for six out of twelve traits studied. When inoculated with fungal
spores at LC50 of B1 × B8, per-se performance was found better in B8 breed and
B1 × B8 hybrid for ten out of twelve traits studied. Under high temperature treatment
(36 ± 1 ºC, 6 hr every day for five days in fifth instar), per-se performance revealed
that B1 and B8 breeds were better for five traits each and B1 × B4 hybrid for eight
out of twelve traits. Significantly highest positive relative heterosis under muscardine
inoculation was recorded in the hybrid B4 × B6 for ten characters and under high
temperature treatment in B1 × B4 hybrid for five traits. However, heterosis scoring
over all the traits under muscardine inoculation and high temperature treatment
revealed that the hybrid B4 × B6 was better under both the conditions. Thus, B1 and
B8 among parents and B1 × B8 and B4 × B6 among hybrids could be selected for
dual stress tolerance against high temperature and muscardine disease.