Biosci. Biotech. Res. Comm. 6(2):
A preliminary survey on incidence of seasonal diseases in commercial crops of silkworms in Akola and Washim districts of Maharashtra
Rashmi P. Joshi, I. A. Raja* and A. P. Bagde†
*Research Laboratory of Zoology, Shri Shivaji College, Akola, India
†Central Silk Board, Usmanabad, Maharashtra, India
In the present study a survey of silkworm Bombyx mori for seasonal diseases in Akola and Washim districts were conducted during
KEY WORDS: WORDS:BOMBYX MORI, FIFTH INSTAR LA VA, G ASSE IE, FLACHE IE, MUSCARDINE
The silkworm Bombyx mori, is a commercially important insect, produces the silk. Akola and Washim district though known as cotton producing districts, farmers in villages, are now encouraged for opting sericulture, taking commercial crops throughout the year, using CSR2 and Kolar gold breeds. However there is great deal of loss every harvest as silkworm is susceptible to a number of diseases during rearing. In tropical countries like India, almost all the major pathogenic microbes infect and cause disease to silkworm (Rajsekhar et al., 1992: Doreswamy et al., 2004).
The most common diseases of silkworm are Grasserie caused by a virus: nuclear polyhedrosis, Flacherie, caused by
*Corresponding Author Received 22nd October, 2013
Accepted after revision 20th December, 2013 BBRC Print ISSN:
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bacteria: Streptcoccus and Staphylococcus in association with Flacherie virus, Muscardine, Aspergilosis, caused by fungal infection, and Pebrin, a protozoan disease caused by a para- sitic
These infections vary seasonally, and greatly affect, the economic performance of these worms. According to Sivapra- kasam and Robindra (1995) commercial silkworm rearing units are to be regularly surveyed for incidence of such diseases. Such surveys were earlier, conducted by Christi and Schaf (1990) in Jammu and Kashimir State, Samson et al., (1990) in Karnataka, Reddy and Rao, (2009) in Andhra Pradesh, and by Isaiarasu et al., (2011), in Virudhunagar district of Tamilnadu. Such study however has not been carried out in Akola and Washim, the new districts on the sericulture map of Vidarbha
region in Maharashtra. Therefore attempts are being made to know the seasonal silkworm diseases and their incidence lev- els, in the commercial silkworm crops in Akola and Washim districts. The results of the study will make local silk growers aware about the diseases and help them to take due control measures.
MATERIAL AND METHODS
Akola and Washim are districts in the Indian state of Mahar- ashtra, which forms central part of Amravati Division. Washim was earlier a part of Akola. These study districts were surveyed and the information of the leading commercial silk growers located in Wadegoan, Deulgaon, Khanapur, Patur and Balapur in Akola district, Sawad, Kalamba, Risod, Maihsaldoh, Male- goan in Washim district was collected. With due consent of the farmers, a Season wise survey of the silkworm diseases was conducted during the year
RESULTS AND DISCUSSION
The survey in Akola and Washim districts revealed that the common breed of silkworm in the area is dominated by CS 2 and by Kolar gold in summer. The data regarding the seasonal diseases in silkworm occurred during the year
The figures revealed that all the major diseases of the silk- worm namely, Grasserie, Flacherie, Muscardine are reported to infect the silkworm in all studied commercial crops from Akola and Washim districts. Same disease pattern has also reported by Reddy and Rao, (2009) in the districts of adjoining state of Andhra Pradesh. Worms infected with Grasserie were sluggish, with swollen
As depicted in the table 1, our first survey
Joshi et al.
7.0- 9.0%, Grasserie was 6.0 - 9.5% and Muscardine was
0.5- 2.5. In winter season, the Flacherie was 2.0 - 4.0%, Grasserie was 5.0 - 7.0% and Muscardine was 19.0 - 22.0%. While in summer season the Flacherie was 7.0 - 9.0%, Grasserie was 6.0 - 9.5% and Muscardine was lacking.
Survey during 2011 - 12, found that in rainy season Flach- erie was 2.5 - 3.8%, Grasserie was 3.0 - 5.0% and Muscardine was 0.0 - 1.0%,.In winter season Flacherie was 0.0 - 1.0%, Grasserie was 1.5 - 3.6% and Muscardine was nil. In summer season Flacherie was 4.0 - 6.8%, Grasserie was 3.5 - 6.8% and Muscardine was nil.
As per the data, collected during
Winter conditions in the region are dry and more suitable for fungal growth; therefore encourage the spread and trans- mission of Muscardine fungus (Miyajima, 1978). Accordingly in the present study too Muscardine infection was reported higher during winter season, but very much reduces during rainy season and lacking in summer.
The table also revealed that, there was reduction in inci- dence of diseases in year,
TABLE 1: Survey of silkworm diseases (%) in the commercial crops from Akola and Washim district, during year
Joshi et al.
silkworm help a great deal in protecting the commercial silk- worm crop from the seasonal incidence of Grasserie, Flacherie, and Muscardine in the region.
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