Study of bacterial court (rangi) disease (streptococcus faecalis) infection during rearing of mulberry silkworm in different meteorology

Silkworm Lepidoptera insect is of immense economic importance for the production of silk which is vulnerable to a various microorganisms resulting in crop losses to sericulture industry. It is infected by various disease viz., Pebrine (Fungal disease), Flacherie (Bacterial disease), Grasserie (Viral disease) and Muscardine (fungal disease). Among these, Bacterial court (Rangi) disease caused by Streptococcus faecalis and is commonly observed in all the meteorology but during the summer and winter meteorology, its infection level is more. It is a spore forming obligate intracellular contamination of damaged skin or oral feeding of mulberry leaves that causes the irresistible court rangi disease in silkworm which are transmitted by either horizontal or vertical or transobacterial transmissions. We evaluated the performance of biological and commercial parameters of meteorology in silkworm fed on mulberry leaves. The disease free eggs of Baharaich sericulture grainage Uttar Pradesh were reared in Sericulture Research Laboratory.

The silkworm eggs were incubated at standard conditions for control. Larval rearing was maintained at standard rearing conditions of temperature (26±1°C), Relative Humidity (80±5%), and photoperiod (12hrs light: 12hrs dark). The experiment was laid out in the Completely Randomized Design with six replications. Observation showed significantly greater variations were observed in the mean larval weight (gm) and mean larval length (cm) during all instars i.e. maximum larval weight i.e. 0.076gm, 0.52gm, 3.10gm, 4.10gm, and 6.10gm in 1st, 2nd, 3rd, 4th, and 5th instars, respectively. A similar trend in the mean larval length (P < 0.05) was also observed. Significantly greater fecundity (497 no. of eggs), were recorded in the rainy meteorology which were significantly higher as compared to winter and summer meteorology. Similarly, cocoon weight (1.28gm), cocoon shell weight (0.22gm), cocoon shell percentage (18.74 %) was recorded found in the rainy meteorology which was significantly greater (P < 0.05) than other winter and summer meteorology. We documented that the rainy meteorology is promising and has great potential to perform on mulberry under prevailing meteorological conditions. We also suggest that popularizing sericulture as the allied sector of the agricultural economy needs to exploit the potential of the rainy meteorology for the production of silk yield.