Cross Infectivity of Nucleopolyhedrosis virus (SoNPV) in silkworm, Bombyx mori L.

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Date
2022-07
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Sher-e-Kashmir University of Agricultural Sciences and Technology of Jammu
Abstract
Nucleopolyhedrosis viruses (NPVs) are well-thought-out lethal bio-pesticides to managethe Spilosomaobliqua and are found naturally in S.obliqua(SoNPV). They are often claimed to be species-specific and are expected to show less or no cross infectivity to other insect species of the same order, thus making them ideal candidates as biopesticides against certain insect pests of economically important crops. Based on this perception, a study entitled “Cross Infectivity of Nucleopolyhedrosis virus (SoNPV) in silkworm, Bombyxmori L.” was carried out inthe Division of Sericulture, SKUAST-Jduring 2021. The naturally SoNPV exhibiting larvae of S. obliqua were collected from the field to extract SoNPV and the latter wereinoculated to laboratory reared, disease freeS.obliqualarvae so as to obtain pure culture of SoNPV. After second moult, healthy B. mori larvae were transferred to clean containers for the cross-infectivity evaluation of SoNPV. The results of our investigation showed that 3rd, 4th and 5th instar larvae of B. moridid not developed any symptoms of mortality due to SoNPVeven at the concentration of 1.0×107 OBs/ml.The effect of SoNPV on larval weight from 3rdinstar till the end 5th instar showed that there occurred a significant decrease in weight at concentration 1.0×107 OBs/mlcompared to lower concentrations and control. The lower cocoon and shell weight (0.63±0.01 and 0.08±0.00)gwere found at1.0×107 OBs/mlwhile as highest shell ratio (21.34%) was found at1.0×102 OBs/ml compared to 1.0×107 OBs/ml (12.69%). No significant differences in the sex ratio were found from treatment 1.0×102 to 1.0×105 OBs/ml, however, post 1.0×105 OBs/ ml, sex ratio start fluctuating showing significant decrease in number of males(16.00±0.00) compared to females (22.00±0.00). Significant differences were observed in fecundity due to effect of SoNPV on B. mori.Our results suggested that SoNPVcan be effectively employed for management of S.obliqua in mulberry fields at lower concentrations.
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Preferred for your work. Attri. K., 2022, Cross Infectivity of Nucleopolyhedrosis virus (SoNPV) in Silkworm Bombyx mori L.
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