Determination of Different Diseases and Preventive Measures of Mulberry Silkworm

The present study deals with the determination of different disease and preventive measures of mulberry silkworm, (Bombyx mori). Epizootiology, development of immunodiagnostic kit, fluorescent antibody technique and use of ideal disinfectant, chemotherapy and thermo-therapy techniques and management strategies have been addressed for identification, destruction, prevention and control of disease causing micro-organisms. Three years survey was conducted on the incidence of silkworm diseases namely, Grasserie, Flacherie, Muscardine and pebrine, the data revealed that grasserie and flacherie incidence were maximum in summer season and minimum in winter season whereas muscardine was observed high in winter.


I. INTRODUCTION
Diseases are the behavioral and physiological changes induced by pathogens in an organism. All diseases have specific symptoms and characteristics. Similarly, silkworms are also affected by various types of diseases caused by protozoa, fungi, bacteria and viruses. Since they cause substantial financial loss to the industry, their prevention and control assumes utmost importance [1].The mulberry silkworm is prone to infection of various pathogenic organisms. Infections of the disease ranging from chronic to highly virulent can result in heavy loss to the sericulture industry. Several strains and species of various micro organisms have since been isolated from the infected silkworms, and the disease is becoming increasingly more and more complex.

II. RELATED STUDIES
Dasgupta classified the major diseases affecting silkworm, Bombyx mori are flacherie, grasserie, muscardine and pebrine [2]. Seventy percent loss due to flacherie in sericulture industry was reported by [3] observed 30-40 per cent cocoon crop loss in silkworm is due to flacherie caused by bacteria were restricted to intestine and haemolymph. Savanurmath reported that the flacherie as the most predominant (47.9 percent) among the disease of B. mori followed by grasserie (42.6 percent) and kenchu [4].

Study Area
Present work was carried out at Government Resham Kendra, Ashoknagar and Mhow (M.P.)

Experimental Species
Productive bivoltine silkworm hybrid (CSR2 × CSR4) is obtained from Central Sericulture Research and Training Institute (Mysore, India) was used as a study material. This hybrid is suitable to rear during favourable season (August-February).

Determination of different diseases.
The following diseases were determined in present study and identified by following scientist methods:

Symptoms and effects of Grasserie:
(i) In such case of infection the larvae lose its appetite and become pale. (ii) The body becomes swollen and shiny. (iii) The blood of the larvae becomes turbid like pus and when the skin is broken, milky pus flows out which is known as jaundice of the silkworm.

Prevention and Control of Grasserie:
(i) The diseased larvae should be isolated from the rearing tray. (ii) Suitable leaves, proper ventilation and spacing should be selected for the rearing of silkworm.

 BACTERIAL DISEASES Flacherie
This disease generally occurs in the mature larvae and caused mainly by bacteria like Streptococcus and Staphylococcus.

Symptoms and effects of Flacheria:
Flacherie infected silkworm (i) In this case there is loss of appetite in the larvae.

 PROTOZOAN DISEASE Pebrine
It is a dangerous disease to the silkworms and the causative organism is the Nosemabombyc is belonging to the phylum protozoa. During the year 1865-70, this disease is first diagnosed by the great Bacteriologist Louis Pasteur. This silkworm disease is transmitted through the egg of the mother silkworm and also through ingestion of contaminated food.
[10] Reported that the flacherie as the most predominant (47.9 per cent) among the disease of B. mori followed by grasserie (42.6 per cent) and kenchu (9.5 per cent) and also investigated that Streptococcus and Staphylococcus are primarily responsible for flacherie in silkworm. [11] Investigated that loss of appetite, sluggishness, flaccidity of silkworms, rapid pulsation of dorsal vessel, vomiting of brown fluid, soft excreta, decomposition of gut contents and diarrhoea are the symptoms of diseases in B. mori.
In the present investigation healthy larvae and diseased larvae of silkworm were treated with optimum concentration of different synthetic and herbal drugs (methoprene, fenoxycarb, thiadiazole, bovine milk, amla extract). The survival rate of diseased untreated (control) silkworm was 20.The maximum survival rate of silkworm was 48 and 40 for healthy and diseased larvae treated by bovine milk respectively.
Many researchers' worked on the control and prevention of disease of silkworm (flacherie, grasserie, muscardine and pebrine) during silkworm rearing helps to increase the silk productivity by preventing the mortality to a great extent. Various treatments in practice are of synthetic chemicals but no natural product has been commercialized yet. Earlier, several plants such as Lantic acid purified from Lantana camera L. had shown antibacterial activity against Bacillus cereus [12]. Garlic purified allicin also showed antibacterial action along with basil and Emblica officinalis extracts. Our study showed that the synthetic and herbal drugs have a positive effect on the health, survivability and production of B. mori larvae. The present study indicates that the treatment of silkworm with the synthetic and herbal drugs affects the growth, health, development of silkworm and silk productivity in comparison with the untreated ones. Thus, the results of present study also corroborated with previous researchers.

VI. CONCLUSION
The control and prevention of various infections during silkworm rearing helps to increase the silk productivity by preventing the mortality to a great extent. In a view, use of amla extract during rearing improves the larval survival by preventing the infections and also improves the productivity of the silk.
Conclusively, use of synthetic (Methoprene, fenoxycarb and thiadiazole) and herbal drugs (bovine milk and amla extract) proves to be an growth promoter, growth enhancer and prolong the larval period of silkworm which results in the high quality of silk and good reeling performance as compared to the control ones.