GROWTH AND ECONOMIC PARAMETERS OF ERI SILKWORM

REARING FED ON DIFFERENT VARIETIES OF CASTOR LEAVES

A Case study of Bhergaon Sub-Division, Udalguri, BTAD, Assam

INTRODUCTION

Eri silkworm, Samia ricini (Donovan) is a multivoltine insect and largely reared by the farmers of North Eastern India, particularly in Assam.

However, Kesseru is considered as another major perennial food plant. Besides these two, eri silkworm being polyphagous feeds on several alternative host plants, viz., Tapioca (Manihot esculanta), Kesseru (Ailanthus excelsa), Barpat (A. grandis), Gulancha (Plumeria acutifolia), Gamari (Gmelina arborea) and many more.

Eri silkworm feeds primarily on Castor leaves (Ricinus communis Linn). Castor plant belongs to the family Euphorbiaceae and is a primary food plant of eri silkworm.

The food provided to silkworms during their rearing affects larval growth, survival rate, cocoon parameters and silk quality.

In the biodiversity of Bhergaon Sub-division in Udalguri, Assam four different varieties of castor plants are available and the reares use all the four varieties of castor leaves randomly without considering the growth and economic parameters of eri silk rearing.

These varieties are: a) Red powdery variety b) Green powdery variety c) Red non-powdery variety d) Green non-powdery variety.

RED AND GREEN VARIETIES OF CASTOR

i) To find out the suitable variety of castor plant in the biodiversity of Bhergaon Sub-division for eri silk rearing.

ii) To find out the castor variety as the best in terms of larval duration, larval weight, larval growth and pupal duration as growth parameters of eri silkworm rearing.

iii) To find out the castor variety as the best in terms of cocoon weight, shell weight, shell ratio and yield/400 larvae as economic parameters of eri silkworm.

The objective of this present study has been:

STUDY AREA

The present study has been conducted at Tangla, Ward No 4 of Bhergaon Sub-division, Udalguri district. Tangla is a busy town in Udalguri district situated in 26.65710 N and 91.91250 E coordinates. The average annual temperature of Tangla is 25.40 C and the average annual rainfall is 184 cm. The relative humidity of Tangla in average is 81%.

Bhergaon sub-division in Udalguri district of Assam is situated in North-Eastern India. Its geographical location is 26° 34' 28.53" N 91° 58' 32.42"E. The average attitude is 37 meters. The climate is humid and congenial, while the relative humidity is around 82%. The annual rainfall is 1850 mm (approx).

Bhergaon Sub-Division, Udalguri

Field Work Details

The eggs of eri silkworm were collected from Sericulture Firm (Central), Mangaldoi and the eggs were disinfected with 2% formalin

The eggs were then kept for hatching.

When the larvae hatched, they were fed on tender castor leaves in a controlled method

Experiments were conducted from the second moulting to harvesting of cocoons

A total of 400 silkworms were maintained separately in 4 wooden trays and the tender leaves of castor were fed four times a day until the larvae reached 3rd instar stage. Semi tender leaves were fed in the 4th and 5th instar stages

The rearing performance of Eri silkworm larvae in each tray was assessed by the

following parameters:

HatchingLarval weight (gm)Larval duration (day) Yield/400 larvae (by number)Yield/400 larvae (by weight) Cocoon weight (gm)Shell weight (gm)Shell ratio (%)Pupal period (day) andPupal weight (gm).

i) In the first bamboo tray the larvae were fed strictly on Red powdery variety of castor leaves till cocoon formation.

ii) In the second tray the larvae were fed on Red non-powdery variety of castor leaves.

iii) The larvae of the third tray were supplied the Green powdery variety of castor leaves.

iv) In the fourth bamboo tray the larvae were fed on Green non-powdery variety of castor leaves till cocoon formation.

The larvae were transferred to bamboo trays for proper growth and observation. The experiment was conducted with 100 larvae per bamboo tray in each

replication as follows:

Analysis of the study

The larval weight of different Eri silkworm reared in the different trays ranged from 6.45 gm to 8.50 gm during 2013 monsoon. The highest larval weight of 8.50 gm

was observed in the larvae reared in the tray with Red powdery castor leaves while the lowest larval weight of

6.45 gm was observed in the tray reared with Green non-powdery castor leaves.

Rearing parameters

Red powdery Red Non-powdery

Green powdery

Green Non-powdery

Larval duration (d)

24 24.5 26 27

Larval weight (gm)

8.5 8 7.2 6.45

Yield/400 larvae

97 ± 2 85 ± 2 80 ± 2 78 ± 2

Cocoon weight (g)

3.59 3.52 3.31 3.18

Shell weight (gm)

0.59 0.55 0.55 0.48

Shell ratio (%)

16.5 16.1 15.75 15.15

Pupal duration (d)

10.24 10.5 10.75 11.0

Pupal weight (gm)

1.99 1.90 1.75 1.72

Table: 1. Rearing performance of eri silkworm, Samia ricini (Donovan) fed with different castor leaves in 2013 monsoon rearing at Tangla.

Larval Duration

Red powdery variety: 24 daysRed non-powdery variety: 24.5 days

Green powdery variety: 26 days.Green non-powdery variety: 27 days

Larval Weight

Red powdery variety: 8.5 gmRed non-powdery variety: 8.0 gmGreen powdery variety: 7.2 gm

Green non-powdery variety: 6.45 gm

Yield/400 Larvae

Red powdery variety: 97 ± 2 Red non-powdery variety: 85 ± 2Green powdery variety: 80 ± 2

Green non-powdery variety: 78 ± 2

Cocoon Weight

Red powdery variety: 3.59 gmRed non-powdery variety: 3.52 gm

Green powdery variety: 3.31 gmGreen non-powdery variety: 3.18 gm

Shell Weight

Red powdery variety: 0.59 gmRed non-powdery variety: 0.55 gm

Green powdery variety: 0.55gmGreen non-powdery variety: 0.48 gm

Shell Ratio (%)

Red powdery variety: 16.50%Red non-powdery variety: 16.10%

Green powdery variety: 15.75%Green non-powdery variety: 15.15%

Pupal Duration

Red powdery variety: 10.24 daysRed non-powdery variety: 10.50 days

Green powdery variety: 10.75 daysGreen non-powdery variety: 11.0 days

Pupal Weight

Red powdery variety: 1.99 gmRed non-powdery variety: 1.90 gmGreen powdery variety: 1.75 gm

Green non-powdery variety: 1.72 gm

Leaf varieties

Red Powdery

Red Non-

powderyGreen

Powdery

Green Non-

powdery

Cocoon Weight (gm)

3.59 3.52 3.31 3.18

Pupal Weight (gm)

1.99 1.90 1.75 1.70

Shell Weight (gm)

0.59 0.55 0.55 0.48

Table: 2. Cocoon weight, Pupal weight and Shell weight of Eri silkworm in gram.

00.5

11.5

22.5

33.5

4

Red Powdery Red Non-powdery

Greenpowdery

Green Non-powdery

Cocoon Wt (gm) Pupal Wt (gm) Shell Wt (gm)

A comparision of cocoon weight, pupal weight and shell weight of eri silkworm fed with different varieties of castor leaves from the

data of Table:2

Suggestion

The eri silkworm rearers should provide only Red powdery variety of castor leaves as the food plant to the growing larvae instead of depending much on the secondary or tertiary food plants.

Since, the Red powdery variety of castor leaves is the best among all the four varieties, eri silk rearers should cultivate this breed of castor plant in their farms to overcome the scarcity of primary food plants.

Both government and non-government sericulture farms should do the necessary arrangement for the large scale plantation of Red powdery variety of castor plants.

Government should come forward with some specific schemes to help the common eri silkworm rearers by providing them loans and other facilities to cultivate Red powdery variety of castor plants in their own farms

The government sericulture department itself or with the help of some NGOs should organize training and awareness programmes to provide necessary instructions to the common eri silkworm rearers about the importance and effect of food plants on the growth of eri silkworm and its economic parameters of eri silkworm rearing.

The present work has been conducted strictly in the climatic and geographical conditions of Bhergaon Sub-division for the monsoon breed of eri silkworm. In different climatic and geographical conditions, the effect of food plants on the growth and economic parameters may vary. So, government and sericulture departments should take necessary step to invite experts to work in this field and find out if effect of food plants on the growth and economic parameters of eri silkworm rearing is dependent on the varied climatic and geographical conditions of a locality.

CONCLUSIONIn Bhergaon Sub-division of Udalguri district, ericulture is an age-old traditional cottage industry. Next to agriculture, ericulture is the major agro-based industry generating large number of employment in the rural areas of Assam including the Bhergaon sub-division of Udlguri with minimum investment cost. It plays a very vital role in the socio-economic development of the weaker section of the rural population especially among the the tribal community in this part of BTAD especially during their off-agricultural season.

It is needless to mention that any kind of plantation is always helpful in maintaining the CO2 level of atmosphere and has effective role in reducing global warming. Castor plantation can help the eri silkworm rearers not only to overcome the scarcity of primary host plants, but also can be a source of wealth as it can yield precious castor oil. Therefore, the eri rearers of Bhergaon Sub-division should cultivate and use the Red powdery variety of castor leaves as the food plants for eri silkworms rather than the green powdery or green non-powdery varieties of castor leaves available in the biodiversity of this locality.

REFERENCE•Gomma, A. Ahmed. (1972), Biological study on the eri silkworm, Attacus ricini Boisd. Indian J. Seric (1): 81-87

•Hazarika, U., Borah, A. & Chakravorty, R. 2005 (Physiological and biochemical response of castor (Ricinus communis) to application of NPK and their correlation with economic parameters of eri silkworm, Samia ricini (Donovan) in: Proceeding of 20th Congress of international sericulture commission vol II, sec 3 Non mulberry silkworms, 2005, Bangalore, India 94-98

•Sarkar, D.C. 1988, (Ericulture in India, Central Silk Board, Grafo Printers Bangalore, page 1-4••Dookia, B.R.(1980): Varied silk ratios in Cocoons of Eri silkworm (Philosamia ricini Hutt.) reared on different castor varieties in Rajasthan. Indian J. Seric 19(1); 38-40

•Dookia B.R. (1986): Biological studies of the Eri silkworm, (Philosamia ricini Hutt.) on four castor varieties in semi arid climate of Rajasthan. Seric 2(3); 33-34

•Dutta, L.C. and Kalita D.N. (1997): Food consumption and utilization by the larvae of Eri silkworm (Philosamia ricini Hutt.) on diffent food plants. J. Appl. Zool. Res 8(2); 143-144

Slansky, F. Jr. and scriber, J. M. (1985): Food consumption and utilization in Comprehensive Insect Physiology, Biochemistry and Pharmacology. Eds. Kerkut, G.A. and Gillbert, L.I. Vol. IV, Pergamon Press, Oxford: pp 87-160

Baruah, M (2012): Studies on Larval Weight and Shell Ratio of Eri Silkworm (Philosamia ricini) on Castor, Kesseru and Treated Kesseru by Foliar Spray. IJCAES SPECIAL ISSUE ON BASIC, APPLIED & SOCIAL SCIENCES, VOLUME II, JULY 2012

C. Manjunatha Naik , C. Murthy (2011): Evaluation of New Host plant species for ericulture, International Journal of Plant Protection

Das, M &De Sr, Utpal Kumar (2007): Village-Based Informal Ericulture and EndiTextiles in Assam: An Economic Inquiry. The Icfai Journal of EntrepreneurshipDevelopment, Vol. 4, No. 3, pp. 8-29, September 2007

Website•http://www.krishisewa.com/cms/articles/productiontechnology/251erihostcastor.html

•http://www.scienceandnature.org/IJSN_V1(2)_D2010/IJSN_V1(2)_12.pdf

•http://www.ijlbpr.com/jlbpradmin/upload/ijlbpr_51835fbbec469.pdf

•http://cmerti.res.in/faq.html

•http://www.slideshare.net/prarkl/bioprop

Presented by:

Mr. Pranabjyoti Das

Arunodoi Junior College, Tangla

Ms. Archana DasAsst. Professor, Tangla College

Tangla

Mr. Mintu PathakAsst. Professor, Tangla College

Tangla