bioRxiv preprint doi: https://doi.org/10.1101/2021.03.22.436391; this version posted March 22, 2021. The copyright holder for this preprint (which was not certified by peer review) is the author/funder, who has granted bioRxiv a license to display the preprint in perpetuity. It is made available under aCC-BY-ND 4.0 International license.
1 Comparative performance analysis of mulberry silkworm (Bombyx mori L.) races for 2 integration of superior yield and maximize profit in West Bengal
3 Megha Kaviraj a, *, Upendra Kumar a, SN Chatterjee b, SL Swain c, M Singh d, Kasinath Nandi e, *
4 a ICAR- National Rice Research Institute, Cuttack, Odisha -753006, India
5 b The University of Burdwan, Burdwan, West Bengal-713104, India
6 c Fakir Mohan University, Balashore, Odisha-756020, India
7 d Triveni Devi Bhalotia College, Raniganj, West Bengal-713347, India
8 cAsansol Girl’s College, Burdwan, West Bengal -713304, India
9 Author’s mail: [email protected] (MK), [email protected] (UK), 10 [email protected] (SNC), [email protected] (SLS), 11 [email protected] (MS), [email protected] (KN)
12 *Corresponding Author: [email protected] (MK), [email protected] (KN)
13 Phone: +91 7908816180
14 Orcid ID: https://orcid.org/0000-0002-4542-0522
15 Abstract
16 India has a prosperous and glorious history in silk production and its silk trade dates back to 15th
17 century. Sericulture is practiced in many regions of India, where West Bengal ranks third in
18 mulberry silk production. About 2000 villages are engaged in mulberry cultivation with
19 plantation area of 37,883 acres. But nowadays, farmers have lack their interest in this sector due
20 to low cost benefit ratio, high investment cost in terms of silk worm rearing, land uses and lack
21 of proper knowledge on different races of Bombyx mori. Therefore, the present study has been
22 aiming to find out the comparative performance of bivoltine, multivoltine, and F1 variety of B.
23 mori by analysed the cocoon, post-cocoon characters, and silk related traits for identifying the bioRxiv preprint doi: https://doi.org/10.1101/2021.03.22.436391; this version posted March 22, 2021. The copyright holder for this preprint (which was not certified by peer review) is the author/funder, who has granted bioRxiv a license to display the preprint in perpetuity. It is made available under aCC-BY-ND 4.0 International license.
24 best superior races of B. mori. The results showed that feeding habits of silkworm larvae of three
25 races had significant effect on cocoon parameters. The average weight of ten 5th instar larvae of
26 bivoltine was higher in comparison with multivoltine and F1 variety. Similar trends were
27 obtained in the average length of silk thread from a single cocoon in bivoltine races, higher by
28 30% and 77.14% from F1 and multivoltine, respectively (P<0.05). We also inquired about
29 capital investment and profit-making of three varieties. Net profit for bivoltine was significantly
30 increased by 15.65% and 10.21% than multivoltine and F1 varieties, respectively.The heatmap
31 analysis revealed that the bivoltine races of B. mori were separately clustered based on the
32 positive correlation of measured variables mostly length of silk thread, renditta, dry cocoon
33 weight, the average weight of larvae, present market price, leaves for rearing, net profit and
34 selling price of cocoon per acre farmland; whereas, the multivoltine and F1 variety clustered in a
35 separate group. From our findings, it is clear that the culture of bivoltine is preferable for the
36 farmers who don’t have enough landed property and also profitable in terms of cocoon, post
37 cocoon and silk traits. Therefore, it is recommended that the farming of bivoltine silkworm is
38 more gainfulcompared to F1 and multivoltine variety, and capable of more income generation
39 than other traditional agricultural crops.
40 Key words: Bombyx mori; Bivoltine; Multivoltine; F1 variety; Economic traits; Heatmap. bioRxiv preprint doi: https://doi.org/10.1101/2021.03.22.436391; this version posted March 22, 2021. The copyright holder for this preprint (which was not certified by peer review) is the author/funder, who has granted bioRxiv a license to display the preprint in perpetuity. It is made available under aCC-BY-ND 4.0 International license.
41 42 Fig. Graphical abstract represents the comparative performance of bivoltine, multivoltine and F1
43 races of B. mori on the aspect of biological and economic traits in tropical climate condition.
44 1. Introduction
45 India is the 2nd largest raw silk manufacturer country and produces five commercially significant
46 silk varieties namely, Mulberry, Tropical Tasar, Temperate Tasar, Eri and Muga (CSB, 2018). It
47 is one of the vital sub-sectors of agriculture and plays a crucial role in farm economy through
48 providing employment round the year and fetches higher income mainly to the rural farm bioRxiv preprint doi: https://doi.org/10.1101/2021.03.22.436391; this version posted March 22, 2021. The copyright holder for this preprint (which was not certified by peer review) is the author/funder, who has granted bioRxiv a license to display the preprint in perpetuity. It is made available under aCC-BY-ND 4.0 International license.
49 families (Roopa and Murthy, 2015; Masrat and Tripathi, 2017). Among all silk varieties,
50 mulberry silk occupies 75% of the total silk production. Sericulture is practiced in many states of
51 India, West Bengal ranks third in mulberry silk production and is highly concentrated in three
52 traditional sericulture districts namely, Malda, Murshidabad and Birbhum, which contributing
53 90% of the total state’s silk production. Currently,West Bengal accounts for 14.5% of the total
54 country’s cocoon production (CSB, 2018) and about 2000 villages are directly involved in
55 mulberry cultivation with plantation area of 37,883 acres (Anonymous, 2016).
56 Rearing of silkworm on large scales with great care in both natural and control conditions
57 scientifically for cocoon production is used as the raw material for silk production (Kamili et al.,
58 2000). Silk is popularly known as “Queen of Textiles” in all over the world for the nature of its
59 unparalleled grandeur, sheen, inherent affinity for dyes, high absorbance, light weight, soft touch
60 and high durability. Mulberry silkworm Bombyx mori (Lepidoptera: Bombycidae) spins the
61 precious silk fibre, which making it one of the most beneficial insects to mankind, and is
62 becoming an attractive multifunctional material for both textile and nontextile uses (Tsukada et
63 al., 2005). Approximately all-commercial silk is made from cocoons spun by silkworms of the
64 genus Bombyx (Lee, 1999).
65 Mulberry (Morus L., Family Moraceae), is an essential foliage crop in sericulture as it is
66 the only natural feed of the silkworm Bombyx mori. Previously, it is believed to have originated
67 at the Himalayans foothills (Koidzumi, 1917). Earlier, Linneaus (1753) classified the genus
68 Morus into five species on the basis of morphological characteristics: Morus alba, M. nigra, M.
69 rubra, M. tartarica and M. indica L. The quality of the mulberry leaves has a direct impact on
70 the normal growth and development of the larvae and also the quality of the cocoon (Legay,
71 1958; Adolkar et al., 2007; Gangwar, 2010). Different races of silkworms are characterized by bioRxiv preprint doi: https://doi.org/10.1101/2021.03.22.436391; this version posted March 22, 2021. The copyright holder for this preprint (which was not certified by peer review) is the author/funder, who has granted bioRxiv a license to display the preprint in perpetuity. It is made available under aCC-BY-ND 4.0 International license.
72 undergoing one, two or several uninterrupted generations during the summer. Such races are
73 called uni-, bi- or multivoltine.
74 Though, India is the second largest producer of raw silk in the world next to China with
75 an annual production of 31,931 MT (CSB, 2018) but the raw silk yarn is of low standard due to
76 multivoltine in nature. Besides, other reason behind low standard of silk is the tropical climatic
77 conditions of the country with marginal sub-tropical and temperate sericultural areas. In tropical
78 areas of the country, multi x bi hybrids are reared and produced silk is not superior in quality and
79 as such is not popular at International market. To overcome this drawback, compatible bivoltine
80 breeds/hybrids for rearing under tropical conditions were developed (Lakshmi et al., 2011) and
81 selected for rearing in field conditions. The productivity of sericulture mainly relies on high
82 breeding stock of the silkworm. The hybridization is a technique used to enhance the yield of
83 silkworm and cocoon production (Brahma et al., 2015). By crossing genetically distinct
84 population understanding the genetic mechanism of the silkworm, high yielding and disease
85 tolerant races with distinct quantitative and qualitative traits can be achieved. The success in
86 silkworm hybridization primarily depends on the selection of initial breeding materials followed
87 by their effective utilization in different combinations to create genetic variability for selection
88 (Mano et al., 1992). In India, it is estimated that nearly 80% of the silk is produced by
89 multivoltine × bivoltine hybrids where multivoltine races are used as a female parent for
90 commercial exploitation. The main reason attributed to this is that the contribution of bivoltine
91 by virtue of its maternal inheritance may result in regular crop loss (Doddaswamy et al., 2009).
92 Suitable silkworm hybrids play a vital role in increasing the productivity and quality of silk
93 which are important for sustainable sericulture industry (Kumar et al., 2011). As per available
94 literature, manifestation of heterosis in silkworm has been established by many breeders (Talebi bioRxiv preprint doi: https://doi.org/10.1101/2021.03.22.436391; this version posted March 22, 2021. The copyright holder for this preprint (which was not certified by peer review) is the author/funder, who has granted bioRxiv a license to display the preprint in perpetuity. It is made available under aCC-BY-ND 4.0 International license.
95 and Subramanya, 2009; Kumar et al., 2012). A variety of hypotheses have been advocated as to
96 the inheritance of voltinism.However, information on three races of B. mori in different
97 voltinism pattern is scanty.
98 Hence, in the present study, an attempt has been made to analyze the comparative
99 performance of bivoltine, multivoltine and F1 variety ofB. mori with significant replications and
100 also, analyzedthe cocoon post-cocoon characters and silk related traits for further commercial
101 application of the best superior races of B. mori.The purpose of this study was to provide
102 information about the superiority based on the aspect of biological and economical perspective
103 of three races of mulberry silk worm for researcher as well as for farmer’s community for
104 sustainable income generation.
105 2. Methodology
106 2.1 Experimental site
107 The present study was conducted at Bishnupur sericulture complex, Bankura, West Bengal,
108 which is located between 23°03 25 N and 87°18 15 E. The altitude is 59 m above the sea
109 level. Bishnupur’s climate is classified as tropical (Fig. 1). The average temperature was 26.6°C
110 and about 1157 mm of precipitation falls annually. The lowest (2 mm) and greatest (255 mm)
111 precipitation was occurred in the month of July and December, respectively.
112 2.2 Experimental material and set up
113 Disease-free egg layings (dfls) of the bivoltine (AP8), multivoltine (Nistari) and F1 variety (a
114 hybridized variety by crossing the multivoltine female moth with bivoltine male moth and the
115 eggs laid after mating are termed as F1 variety) of silkworm strains of Bombyx mori L. were used
116 in this investigation. Different races of silkworms are characterized by undergoing one, two or bioRxiv preprint doi: https://doi.org/10.1101/2021.03.22.436391; this version posted March 22, 2021. The copyright holder for this preprint (which was not certified by peer review) is the author/funder, who has granted bioRxiv a license to display the preprint in perpetuity. It is made available under aCC-BY-ND 4.0 International license.
117 several uninterrupted generations during the summer; such races are called uni-, bi- or
118 multivoltine.Rearing of all the silkworms was done by adopted the procedures of Jolly (1987)
119 and Ullal (1987). Silkworms were reared under standard conditions of 26 ± 2°C, 70 ± 5%
120 relative humidity and 12:12 (L:D) photoperiod (Raina, 2000) (Table 1). Rearing was done in
121 trays measuring 90 x 60cm, placed on rearing racks, 150 x 75 x 200cm that could hold 24 trays
122 each. The silkworm larvae were reared in these trays from their first instar to the fourth. At the
123 onset of the fifth instar, 100 worms of each strain were randomly selected and monitored
124 individually (Fig 2b, 2c). Temperature and humidity in the room ranged between 24 - 27°C and
125 84% - 86% respectively for young age rearing and 23 - 24°C and 65% - 70%, respectively for
126 late age rearing. The rearing room was white-washed and fumigated with sulphur dioxide gas.
127 Rearing trays, stands, incubator and all other tools were disinfected with Formaldehyde (2%)
128 solution. Data was recorded replication- wise for all three variety viz., fecundity, hatching
129 percentage, , larval weight, larval survival percentage, cocoon yield per 10,000 larvae (by weight
130 and by number), good cocoon percentage, pupation percentage, single cocoon weight, single
131 shell weight, average filament length adapted from standard protocol.
132 2.3 Food plant and consumption
133 Mulberry silk worm, being monophagus insect, feeds only on mulberry (Morus indica) leaves.
134 At present mulberry is cultivated in about 2.90 lakh hectares in India. Generally, the favorable
135 growth temperature of mulberry plant is ranging from 24°C - 35°C and prefers slightly the acidic
136 soil ranging from pH 6.2 - 8.2. The favorable plantation season is early monsoon. However, if
137 proper irrigation facilities are available, mulberry can be planted at any time. Mulberry grows in
138 a wide range of soil from clayey loam to loamy soil. Mulberry is a deep rooted perennial plant,
139 therefore, the soil having good water retention capacity. The larvae were fed with mulberry bioRxiv preprint doi: https://doi.org/10.1101/2021.03.22.436391; this version posted March 22, 2021. The copyright holder for this preprint (which was not certified by peer review) is the author/funder, who has granted bioRxiv a license to display the preprint in perpetuity. It is made available under aCC-BY-ND 4.0 International license.
140 leaves (Fig. 2b). Proper and adequate food provided to the larvae because it greatly influence the
141 quality of cocoon. Feeding must satisfy both the appetite and nutritional requirements of the
142 larvae. Normally 4 - 6 feedings were provided per day.
143 2.4 Weight of 10 mature larvae
144 Ten mature larvae were picked randomly from each replicate from fourth to sixth day of final
145 instar and weighed on digital balance and represented as a unit of ‘g’. Maximum larval weight
146 was recorded in each hybrid combination (Jolly, 1987).
147 2.5 Quantity of leaves required for larvae rearing
148 Amount of leaves required for the rearing of 100 disease free larvae (DFL) of different three
149 races of B. mori and the weight of the leaves expressed in kg.The larvae to be reared should be
150 free from any sort of disease or in other words the eggs should be disease free laying (DFL).
151 2.6 Cocoon characters
152 Following observations were made for different parameters at cocoon stage viz., effective rate of
153 rearing (ERR) by green and dry cocoon weight and by number (Radjabi, 2011).
154 2.6.1 Chhit / green cocoon weight
155 The weight of freshly produced cocoon within which the larvae or pupae are in living condition
156 called chhit. In sericulture industry the term chhit implies the number of green cocoons weigh in
157 one kilogram weight.
158 2.6.2 Dry coccon weight bioRxiv preprint doi: https://doi.org/10.1101/2021.03.22.436391; this version posted March 22, 2021. The copyright holder for this preprint (which was not certified by peer review) is the author/funder, who has granted bioRxiv a license to display the preprint in perpetuity. It is made available under aCC-BY-ND 4.0 International license.
159 The weight of cocoon which was completely dried either in sun or electric oven.The dry cocoon
160 weight of 40 Kg green cocoon from different varieties of mulberry silk worm was recorded.
161 2.7 Post cocoon characters
162 After harvesting, cocoon samples were stifled in hot air oven at 90-600°C for six hours forreeling
163 purpose. Randomly selected cocoons were reeled for post cocoon parameter and data of different
164 parameters viz., total filament length, non-breakable filament length, denier and renditta was
165 recorded (Ullal, 1987).
166 2.7.1 Total filament length
167 It represents the total length of silk filament reeled from a single cocoon in meters randomly
168 selected. Ten cocoons from each replicate were reeled and average filament length was
169 calculated as:
170 Length of raw silk reeled (m) × No. of cocoons maintained per end 171 Total filament length = 172 No. of reeled cocoons* 173 (*Indicates no. of cocoons taken for testing – No. of new unreelable cocoons – No. of converted
174 carry-over cocoons)
175 2.7.2 Renditta
176 Renditta is the amount of cocoon required to extract one kg. of silk thread. Say for example if 10
177 kg. of cocoon is required to extract 1 kg. of silk thread, its renditta will be 10. Here, we estimated
178 the average amount of silk thread produced from 40 kg. of different varieties of cocoons.
179 2.8 Number of DFL reared and cocoon produced in per acre farm land bioRxiv preprint doi: https://doi.org/10.1101/2021.03.22.436391; this version posted March 22, 2021. The copyright holder for this preprint (which was not certified by peer review) is the author/funder, who has granted bioRxiv a license to display the preprint in perpetuity. It is made available under aCC-BY-ND 4.0 International license.
180 The mating is done in captivity located at Bishnupur sericulture farm for both bivoltine and
181 multivoltine and F1 varieties. After fertilization the female moths lay eggs on a piece of clean
182 cloth or on a specially designed card board divided into several squares enclosed by cylindrical
183 cellular (Fig. 2a). The eggs are then collected and washed in 5% bleaching to remove the
184 gummy substance and thereafter treated with 2% formaline solution for sterilization so that the
185 eggs may free from infectious diseases. But for protozoan infections the female moths are
186 examined microscopically. DFL are handed over to the farmers who grow the host plant in
187 their own farm land and use the leaves for rearing. Then the average number of DFL reared
188 was counted and the quantity of cocoon produced (kg) in one acre farm land was also
189 estimated (Radjabi, 2011).
190 2.9 Economic traits
191 2.9.1 Market and selling price of cocoon
192 Market rate of per kg cocoons of three different varieties of silk worm was estimated. Similarly
193 the selling price was calculated with the amount of cocoon of three different races of B.
194 moriproduced in per acre farm land.
195 Selling price of cocoon = Amount of cocoon produced in one acre farm x Rate of per kg cocoon
196 2.9.2 Net profit of three races of B. mori
197 Net profit was calculated with the selling price of cocoon and deducted the cost invest on per
198 acre of leaf producing farm land including agricultural operations viz. and tilling, rearingpruning,
199 removal of dry stems and weeds and also the cost of chemical fertilizers (urea, phosphate,
200 potash), irrigation cost, cost of seed or eggs for 500 DFL of respective variety, cost of lime
201 needed for sterilization of the rearing room and some miscellaneous expenses. bioRxiv preprint doi: https://doi.org/10.1101/2021.03.22.436391; this version posted March 22, 2021. The copyright holder for this preprint (which was not certified by peer review) is the author/funder, who has granted bioRxiv a license to display the preprint in perpetuity. It is made available under aCC-BY-ND 4.0 International license.
202 2.10 Statistical analysis
203 By using the statistical platform National Agricultural Research System (NARS), Indian
204 Agricultural Statistics Research Institute (IASRI), New Delhi, quantified data was analyzed. The
205 mean difference comparison between the varieties was analyzed by analysis of variance
206 (ANOVA) and subsequently by Tukey’s HSD(Honestly significant difference) at 5%. The
207 heatmap was generated by Bray-Curtis distance-based redundancy analysis (dbRDA) using the
208 Vegan package in R software version 3.5.0.
209 3. Result
210 3.1 Weight of 10 mature larvae
211 The average weight of 10fifth instar mature larvae of three races of B. mori was ranges from 28-
212 36 gm (Fig. 3).Significantly (p<0.05) the highest weight of mature fifth instar larva was observed
213 in bivoltine race (36 gm) and the least was recorded in multivoltine silk worm (28 gm).
214 3.2 Quantity of leaves required for larvae rearing
215 The requirement of mulberry leaves for the rearing of 100 DFL of different varieties of silk
216 worm is shown in Fig. 4. The food consumption of bivoltine silkworm was maximum (1000 kg)
217 and multivoltine worm consumed the least amount (600 kg).
218 3.3 Cocoon characters
219 The chhit values of different mulberry silk worm were in a range of 550-900 (unit relative)
220 (Fig.5). The chhit value of multivoltine cocoon was maximum (900) and least was recorded in
221 bivoltine races B. mori (550). Whereas, of weight of a F1 cocoon was showed moderate
222 compared to the others. bioRxiv preprint doi: https://doi.org/10.1101/2021.03.22.436391; this version posted March 22, 2021. The copyright holder for this preprint (which was not certified by peer review) is the author/funder, who has granted bioRxiv a license to display the preprint in perpetuity. It is made available under aCC-BY-ND 4.0 International license.
223 The dry cocoon weight of 40 kg green cocoon was harvested from different variety was showed
224 in Fig. 5. 40 kg green cocoon of different variety were dried and recorded the highest weight in
225 bivoltine (15 kg) and the least was recorded in multivoltine races of B. mori (13 kg).
226 3.4 Post cocoon characters
227 The average length of silk thread extracted from a single cocoon of multivoltine silk worm was
228 recorded the least length i.e. 400 m and significantly (p<0.05) the longest silk thread was
229 obtained from the bivoltine cocoon i.e. 1750 m. whereas, silk thread length from a cocoon of a
230 F1 variety wasmoderate (Fig. 5).
231 The average amount of silk thread produced from 40 Kg. of different varieties of dry cocoonswas
232 ranges from 3.5-5.5 kg. The silk thread extracted from a constant amount of dry cocoon was
233 recorded maximum in bivoltine cocoon (5.5 kg), and minimum was in multivoltine cocoon (3.5
234 kg).
235 3.5 DFL reared and cocoon produced per acre farm land
236 In one acre of farm land the maximum number of DFL was reared belonged to multivoltine races
237 of B. morii.e500 and the minimum number DFL reared belonged to bivoltine variety (200) (Fig.
238 6). Similar trend was observed in cocoon production in one acre farm (Fig. 6). The highest
239 amount of cocoon produced from multivoltine (200 kg) where, the lowest amount was observed
240 in bivoltine variety (120 kg) (Fig. 6).
241 3.6 Economy
242 The average market price of one kg. of silk was extracted from different varieties of silk worm
243 showed in Fig. 7. We found that the market rate of bivoltine cocoon was the highest (500 in bioRxiv preprint doi: https://doi.org/10.1101/2021.03.22.436391; this version posted March 22, 2021. The copyright holder for this preprint (which was not certified by peer review) is the author/funder, who has granted bioRxiv a license to display the preprint in perpetuity. It is made available under aCC-BY-ND 4.0 International license.
244 rupees) and that of the muiltivoltine cocoon was the least (Rs. 270/-). Whereas the selling price
245 was calculated as per the cocoon produced in one acre farm land and the maximum selling price
246 was observed in bivoltine followed by F1 and multivltine variety i.e. Rs. 60,000/-, Rs. 56,000/-
247 and Rs. 54,000/- , respectively. The net profit ranges from Rs. 34,260 - 40,620/-, the highest net
248 profit coming from bivoltine races of B. mori than the multivoltine and F1 varieties.
249 3.7 Heatmap analysis
250 Heatmap is a 2D graphical color image representation of data which makes use of a predefined
251 color scheme, and different colors display different values and variations in a data matrix (Fig.
252 8). The values between 1 and 2 showed the highest values with respect to the presence of color,
253 whereas -0.5 to -1 and its relevant color showed the lower values.Here, heatmap revealed that the
254 maximum taken parameters are positively correlated with the race of bivoltine mulberry silk
255 worm and the most responsible variables were namely length of silk thread (LT), renditta, dry
256 cocoon weight (DCW), average weight of 10 mature larvae (AWM), present market price (MP),
257 leaves required for rearing, net profit and selling price of cocoon per acre farm land (SPC). In
258 Fig. 8 the bivoltine races of B. mori was separately clustered from the multivoltine and F1
259 variety, where this two clustered unite.
260 4. Discussion
261 The present investigation was made on comparative study of bivoltine, multivoltine and F1
262 variety of mulberry silk worm Bombyx mori. Before going to the field study we studied details
263 about the optimal environmental condition for mulberry silk culture particularly during rearing
264 period (Table 1), which is an essential to derive better financial gain. Besides, optimal bioRxiv preprint doi: https://doi.org/10.1101/2021.03.22.436391; this version posted March 22, 2021. The copyright holder for this preprint (which was not certified by peer review) is the author/funder, who has granted bioRxiv a license to display the preprint in perpetuity. It is made available under aCC-BY-ND 4.0 International license.
265 temperature and humidityskilled manpower is also vital in handling the larvae during the entire
266 rearing period.
267 Mulberry (Morus L.) is essential for the sericulture industry as the primary feed for the
268 silkwormB. mori. The foliage of the host plant (Morus indica, primary host plant) should be soft.
269 The larvae specially the newly hatched ones choose the young and tender leaves and thereby
270 their growth is very likely to be optimum.Since the mulberry silk worms are totally
271 domesticated, they have to be reared on indoor basis. So, there is no possibility to be swallowed
272 by the birds for which the farmers have to face huge financial loss. Mating was occurred in
273 captivity located in the farm for bivoltine, multivoltine and F1 varieties. After fertilization the
274 female moths lay eggs on a piece of clean cloth or on a specially designed card board divided
275 into several squares enclosed by cylindrical cellular. The eggs are then collected, washed and
276 sterilized for free from infectious diseases. But for protozoan infections the female moths are
277 examined microscopically. DFL are handed over to the farmers who grow the host plant in their
278 own farm land and use the leaves for rearing.
279 The present study showed that the tenmature larvalweights of bivoltine races of B. mori was
280 higherto that of the multivoltine and F1 variety. Highlighting the importance of food intake,
281 Horie et al. (1978) reported that requirement of ingestion and digestion of food is 4.2 mg and 1.8
282 mg, respectivelyfor the production of 1 g larval dry weight. The intake of food during total larval
283 life gets reflected by the weight of 10 mature larvae (Ito, 1978). Maximum amount of leaves
284 were required for rearing of bivoltine variety followed by F1 and multivoltine race. In the present
285 study, findings were similar as reported by Rao et al. (1998).Silkworm fecundity is also affected
286 by feeding quality and mulberry varieties (Table 2). Number of laid eggs of bivoltine variety
287 much healthier than the multivoltine and F1 varitywhich achieved due to fresh leaves bioRxiv preprint doi: https://doi.org/10.1101/2021.03.22.436391; this version posted March 22, 2021. The copyright holder for this preprint (which was not certified by peer review) is the author/funder, who has granted bioRxiv a license to display the preprint in perpetuity. It is made available under aCC-BY-ND 4.0 International license.
288 consumption.Previously researchers also reported the same on the aspect on the effect of
289 mulberry varieties on fecundity, silk glands and cocoon characteristics (Krishnaswami et al.,
290 1970; Krishnaswami et al., 1971; Legay, 1958)
291 The cocoon characters are important components, which determine the overall performance of
292 the silkworm and also important for subsequent silk fiber quality (Kumar et al., 2012; Malik et
293 al., 2006; Joge et al., 2003). The result revealed that the bivoltine races showed better
294 performance statistically (P<0.05) in terms of cocoon production compared to the multivoltine
295 and F1 variety, which is corroborated with the recent reports of Sharma and Bali, (2019). They
296 showed the bivoltine cocoons were much superior in comparison to multivoltine with higher silk
297 content, longer filament, higher neatness, cleanness, low boil off loss ratio, higher tensile
298 strength and less variation in evenness(Sharma and Bali, 2019; Dandin et al., 2003).Similar
299 trends of result found in average length of silk thread from a single cocoon of bivoltine races,
300 which was higher by 30% and 77.14% from F1 and multivoltine variety, respectively. The
301 probable reason might be dietary changes in the silkworm, which directly or indirectly influence
302 on the cocoon characters and on post cocoon characters such as quantity of the silk filament and
303 denier (Malik and Reddy, 2007).Various factors such as genetic background of silkworm, food
304 quality, environment and etc., influence the economic traits of the silkworm (Lokesh and
305 Anantha, 2011; Raina, 2001).
306 In the present study we found that the market rate of bivoltine cocoon was the highestthat of the
307 multivoltine cocoon. Whereas the selling price was calculated as per the cocoon produced in one
308 acre farm land and the maximum selling price was observed in bivoltine followed by F1 and
309 multivoltine variety respectively. The net profit for bivoltine races of B. mori was significantly
310 increased by 15.65% and 10.21% in multivoltine and F1 varieties, respectively. From these bioRxiv preprint doi: https://doi.org/10.1101/2021.03.22.436391; this version posted March 22, 2021. The copyright holder for this preprint (which was not certified by peer review) is the author/funder, who has granted bioRxiv a license to display the preprint in perpetuity. It is made available under aCC-BY-ND 4.0 International license.
311 accounts of expenditure, it was found that other than the cost of DFL, remaining expenses were
312 constant for the procurement of a single crop and this variation for DFL was nominal. But in case
313 of multivoltine silk worm it yields five crops in a year and simultaneously the expenditure on
314 food consumption will be increased proportionally. Since there were no diapauses in this variety,
315 the adult worm immerges from the cocoon almost immediately after cocoon formation
316 completed. Thereafter they undergo coupling, after which the female moth starts to lay eggs.
317 Mulberry leaves required for the rearing of those eggs cannot be available from the same farm
318 land which has already been exhausted during the rearing of first crop. So, another farm land of
319 same area is necessary and accordingly the expenditure will be enhanced.Whereas in case of
320 bivoltine silk worm, per annum two crops are procured and there is enough time gap in between
321 two crops. So the mulberry leaves for feeding the larvae can be easily available from the same
322 one acre field, if irrigation, manuring, pruning and other maintenance job can be done properly.
323 Therefore, the overall expenditure will be much less in comparison with the multivoltine silk
324 worm.Moreover, the heatmap analysis revealed that the bivoltine races of B. mori was separately
325 clustered based on the positively correlation of measured variables mostly length of silk thread,
326 renditta, dry cocoon weight, average weight of 10 mature larvae, present market price, leaves
327 required for rearing, net profit and selling price of cocoon per acre farm land; whereas, the
328 multivoltine and F1 variety clustered in a separate group.Therefore, from the above
329 investigations on the aspect of correlationfound that the bivoltine variety is much superior and
330 also better from the angle of economical as well as biological perspective.
331 5. Conclusion
332 In the present study, results showed the comparison of biological and economic traits of
333 bivoltine, multivoltine and F1 races of B. mori and concluded that silk produced from the bioRxiv preprint doi: https://doi.org/10.1101/2021.03.22.436391; this version posted March 22, 2021. The copyright holder for this preprint (which was not certified by peer review) is the author/funder, who has granted bioRxiv a license to display the preprint in perpetuity. It is made available under aCC-BY-ND 4.0 International license.
334 cocoons of bivoltine variety is much more superior in both the quantity and quality wise than
335 other two races. For multivoltine race, generally five crops can be obtained in a year and there is
336 almost no time gap to prepare the food plants for the rearing the next crop. So, if any farmer like
337 to rear all the five generations in a year, he has to provide extra farm land at two acre which
338 enhances the total investment. But in case of bivoltine race, where two life cycles complete in a
339 year, thereby, there is enough time gap in between two consecutive voltines, within which the
340 same land can yield the mulberry leaves required for feeding the larvae, if it is maintained
341 properly, i.e., irrigation, manuring, pruning and other maintenance tasks. Besides, the silk
342 extracted from the cocoons of the bivoltine variety is superior both in quantity and quality to that
343 of the multivoltine type. So, the families who are involved in silk worm rearing should choose
344 the bivoltine silk worm for better monetary gain at the cost of less labor and other maintenance
345 cost. The silk industry in West Bengal as well as in India is in sick and it provides subsidiary
346 income to the families involving in silk worm rearing specially the women folk. So, attention
347 should be given to educate and motivate them specially the poor and tribal people living in arid
348 zone of the country by community awareness.This comparative study suggests that sericulture
349 particularly with bivoltine races of B. mori is capable of more income generation than other
350 traditional agricultural crops.
351 6. Abbreviations:
352 DFL: Disease free larvae; ERR: Effective rate of rearing; LT: Length of silk thread; DCW: Dry
353 cocoon weight; AWM: Average weight of 10 mature larvae; MP: Present market price; SPC:
354 Selling price of cocoon per acre farm land.
355
356 7. Declarations bioRxiv preprint doi: https://doi.org/10.1101/2021.03.22.436391; this version posted March 22, 2021. The copyright holder for this preprint (which was not certified by peer review) is the author/funder, who has granted bioRxiv a license to display the preprint in perpetuity. It is made available under aCC-BY-ND 4.0 International license.
357 7.1 Ethics approval and consent to participate
358 Not applicable.
359 7.2 Consent for publication
360 Not applicable.
361 7.3 Availability of data and materials
362 All the data and materials presented in the manuscript are the original work of the
363 authors.
364 7.4 Competing interests
365 The authors declare that they have no competing interests.
366 7.5 Funding
367 We declare that there are no funding sources.
368 7.6 Authors’ contributions
369 MK and KN performed the experiment. MK has written the manuscript and analyzed
370 the data. MK, UK, SNC, SLS, MS and KN read and approved the final manuscript.
371 7.7 Acknowledgments
372 We thank all the erstwhile researchers associated with this research. The head of the
373 department of Zoology, Asansol Girl’s College, West Bengal, is highly
374 acknowledged for providing necessary facilities to carry out this research. We also
375 acknowledge ICAR- National Rice Research Institute, Cuttack, Odisha, for analytical
376 support.
377
378
379 References bioRxiv preprint doi: https://doi.org/10.1101/2021.03.22.436391; this version posted March 22, 2021. The copyright holder for this preprint (which was not certified by peer review) is the author/funder, who has granted bioRxiv a license to display the preprint in perpetuity. It is made available under aCC-BY-ND 4.0 International license.
380 Adolkar, V.V., Raina, S.K.,Kimbu, D.M.,2007. Evaluation of various mulberry Morus spp. 381 (Moraceae) cultivars for the rearing of the bivoltine hybrid race Shaanshi BV-333 of the 382 silkworm Bombyx mori (Lepidoptera: Bombycidae). International Journal of Tropical Insect 383 Science, 27(1): 6-14.
384 Anonymous, 2016. Seridoc dairy 2016, Govt. of West Bengal.
385 Brahma, D., Swargiary, A., Dutta, B., 2015. A comparative study on morphology and rearing 386 performance of Samia ricini and Samia canningi crossbreed with reference to different food 387 plants. Journal of Entomology and Zoology Studies, 3(5): 12-19.
388 CSB. 2018. Note on the performance of Indian silk industry & functioning of Central Silk Board, 389 28-29.
390 Dandin, S.B., Basavaraja, H.K., Suresh, Kumar, N., 2003. Factors for success of Indian bivoltine 391 sericulture. Indian Silk. 41(9):5-8.
392 Doddaswamy, M.S., Subramanya, G., Talebi, E., 2009. Studies on some economic traits and 393 biological characters of regular and reciprocal cross between a multivoltine and bivoltine race of 394 the silkworm Bombyx mori. Journal of Entomology and Nematology. (4):50-55.
395 Gangwar, S.K., 2010. Impact of varietal feeding of eight Mulberry varieties on Bombyx mori L., 396 Agriculture and Biology Journal of North America, 1(3): 350-354.
397 Horie, Y., Inokuchi, T., Watanabe, K., 1978. Quantitative studies of food utilization by the 398 silkworm Bombyx mori L. through the life cycle II. Economy of nitrogen and amino acids. 399 Bulletin of Sericultural Experimental Station. 27(2):531-578.
400 Ito, T., 1978. Silkworm Nutrition; in the Silkworm an Important Labratoary Tool. Tazima,Y. 401 (Ed), 121-157, Kodansha Ltd, Tokyo.
402 Joge, P.G., Pallavi, S.N., Begum, N.A., Mahalingappa, K.C., Mallikarjuna, Mishra, R.K., Gupta 403 VP et al. 2003. Evaluation of double hybrids of silkworm Bombyx mori L. in the field. In: 404 Advances in Tropical Sericulture. Dandin, S.B., Mishra, R.K., Gupta, V.P., Reddy, Y.S., (eds.), 405 102-104, NASSI, Bangalore. bioRxiv preprint doi: https://doi.org/10.1101/2021.03.22.436391; this version posted March 22, 2021. The copyright holder for this preprint (which was not certified by peer review) is the author/funder, who has granted bioRxiv a license to display the preprint in perpetuity. It is made available under aCC-BY-ND 4.0 International license.
406 Jolly, M.S., Ed. 1987.Appropriate sericulture techniques ICTRETS, Mysore, India. 75.
407 Kamili, A.S., Malik, G.N., Trag, A.R., Kukiloo, F.A., Sofi, A.M., 2000. Development of new 408 bivoltine silkworm (Bombyx mori L.) genotypes with higher commercial characters. Journal of 409 Research, SKUAST. 2:66-69.
410 KoidzumiG. 1917.Taxonomy and phytogeography of the genus Morus. Bull. Seric. Exp. Station, 411 Tokyo (Japan) 3: 1–62.
412 Krishnaswami, S., Noamani, K.R., Asan, M., 1970. Studies on the quality of mulberry leaves and 413 silkworm cocoon crop production, Part I, Quality difference due to varieties. Indian Journal of 414 Sericulture, 9(1): 87-93.
415 Krishnaswami, S., Kumarraj,S.,Vijayaragavan, K.,Kasiviswanathan, K., 1971. Silkworm feeding 416 trails for evaluating mulberry leaves as influenced by variety, spacing and nitrogen fertilization. 417 Ibid, 5: 13-17.
418 Kumar, S.N., Murthy, D.P.P., Moorthy, S.M., 2011. Analysis of heterosis over environments in 419 Silkworm (Bombyx mori L.). ARPN Journal of Agricultural and Biological Science. 6(3):39-47.
420 Kumar, S.N., Prakash, Murthy, D.P., Moorthy, S.M.,2012. Analysis of heterosis over 421 environments in silkworm (Bombyx mori L.). ARPN Journal of Agricultural and Biological 422 Science. 6(1):3-10.
423 Lakshmi, H., Chandrashekharaiah, Babu, M.R., Raju, P.J., Saha, A.K., Bajpai, A.K.,2011. HTO5 424 x HTP5: The new bivoltine silkworm Bombyx mori L. hybrid with thermotolerence for tropical 425 areas. International Journal of Plant, Animal and Environmental Sciences. 1(2):88-104.
426 Lee, Y.W., 1999. Silk reeling and testing manual. FAO Agricultural Services Bulletin No. 136. 427 Rome, Italy.
428 Legay, J.M., 1958. Recent advances in silkworm nutrition. Annual Review of Entomology, 3: 429 7586.
430 Linneaus, C., 1753. Species Plantarum, Stockholm, pp. 986. bioRxiv preprint doi: https://doi.org/10.1101/2021.03.22.436391; this version posted March 22, 2021. The copyright holder for this preprint (which was not certified by peer review) is the author/funder, who has granted bioRxiv a license to display the preprint in perpetuity. It is made available under aCC-BY-ND 4.0 International license.
431 Lokesh, G., Anantha, Narayana, S.R., 2011. Changes in the Protein profile of silkworm Bombyx 432 mori. L (Lepidoptera: Bombycidae) in response to the chemical mutagen. International Journal 433 of science nature. 2(3):559-563.
434 Malik, F.A., Reddy, Y.S., 2007. Role of mulberry nutrition on manifestation of post cocoon 435 characters of selected races of the silkworm Bombyx mori L. Serocologia. 47:63-76.
436 Malik, G.N., Massoodi, M.A., Kamili, A.S., Sofi, A.M., 2006. Studies on heterosis in some 437 bivoltine silkworm (Bombyx mori L.) crosses. Journal of Sericulture. 6(1-2):47-49.
438 Mano, Y., Kumar, S.N., Basavaraja, H.K., Reddy, N.M., Datta, R.K.,1992. An index for multiple 439 trait selection for silk yield improvement in Bombyx mori L. National Conference on Mulberry 440 Sericultural Research, Central Sericultural Research and Training Institute, Mysore, India. 116.
441 Masrat, S., Tripathi, A.K., 2017. Sericulture Industry in India A comparative study of Jammu and 442 Kashmir and Madhya Pradesh, International Journal of Business and Administration Research 443 Review. 1(18):81.
444 Radjabi, R., 2011. Nutritive Quality Assessment of Two Mulberry Varieties including Kokosa and 445 Local on Some Biological Parameters and Economical Characters of Silkworm Bombyx mori L. 446 Advances in Environmental Biology, 5(7): 1877-1881.
447 Raina, S.K., 2000. The Economics of sericulture and apiculture modules for income generation in 448 Africa. IBRA, UK. 86.
449 Rao, G.S., 1998. Evaluation and authorization of parent races and their hybrids – Modalities. In: 450 Silkworm breeding, G. Sreerama Reddy (Ed.). Proceedings of the National Workshop March 18- 451 19. Oxford and IBH publishing Co. Pvt. Ltd., New Delhi, India, 227.
452 Roopa, H., Murthy, C., 2015. Trends in arrivals and prices of cocoons in Shirahatti market at 453 Haveri district. International Journal of Commerce and Business Management, 8(1): 131-134.
454 Sharma, K., Bali, K., 2019. Evaluation of indigenous and introduced bivoltine silkworm hybrids. 455 Journal of Pharmacognosy and Phytochemistry, 8(4): 1459-1464. bioRxiv preprint doi: https://doi.org/10.1101/2021.03.22.436391; this version posted March 22, 2021. The copyright holder for this preprint (which was not certified by peer review) is the author/funder, who has granted bioRxiv a license to display the preprint in perpetuity. It is made available under aCC-BY-ND 4.0 International license.
456 Talebi, E., Subramanya, G., 2009. Genetic distance and heterosis through Evaluation Index in 457 silkworm Bombyx mori L. World Applied Sciences. 7(9):1131-1137.
458 Tsukada, M., Islam, S., Arai, T., Bosch, A., Fred, G., 2005. Microwave irradiation technique to 459 enhance protein fiber properties. Autex Research Journal. 5(1): 40-8.
460 Ullal, S.R., Narasimhanna, M.N., 1987. Handbook of practical sericulture. 3rd ed. Central Silk 461 Board, Bangalore, India. 166.
462
463 Legends
464 Fig. 1 Geographical location and coordinates of experimental site in Bishnupur sericulture
465 complex, Government of West Bengal at Bishnupur, West Bengal, India.
466 Fig. 2 a. Photograph of cellule on the card within which the female moths are laying eggs. b.
467 Mature fifth instar larvae of M12W multivoltine variety feeds on fresh mulberry leaves. c.
468 Mature larvae of multivoltine variety just starting cocoon formation on chandraki.
469 Fig. 3 The graph represented the average weight of ten mature larvae and renditta of bivoltine,
470 F1 and multivoltine mulberry silk worm of B mori.
471 Fig. 4 The bar graph represented the amount of leaves required for rearing the bivoltine, F1 and
472 multivoltine mulberry silk worm of B mori.
473 Fig. 5 The line graph represented the length of the silk thread; chhit, number of green cocoons
474 weigh per kg; dry cocoon weight in bivoltine, F1 and multivoltine mulberry silk worm of B mori.
475 Fig. 6 The bar graph represented the number of disease free larvae (DFL) rearing on per acre
476 farm land and amount of cocoon produced per acre farm land in bivoltine, F1 and multivoltine
477 mulberry silk worm of B mori. bioRxiv preprint doi: https://doi.org/10.1101/2021.03.22.436391; this version posted March 22, 2021. The copyright holder for this preprint (which was not certified by peer review) is the author/funder, who has granted bioRxiv a license to display the preprint in perpetuity. It is made available under aCC-BY-ND 4.0 International license.
478 Fig. 7 The graph represented the economic traits of bivoltine, F1 and multivoltine races of B.
479 mori in terms of present selling price of respective cocoons, present market rate of cocoons and
480 net profit per acre farm land.
481 Fig. 8 The heatmap visualized different measured variables with bivoltine, F1 and multivoltine
482 races of B. mori. The color code from Z score 0-1 depicted higher values whereas, color code
483 from Z score 0 to -1 showed lower values. Variables (LT- length of the silk thread, Renditta,
484 DCW- dry cocoon weight, AWM- average weight of ten mature larvae, cocoon- amount of
485 cocoon produced in one acre farm land, DFL- number of disease free larvae per acre farm land,
486 MP- present market price of cocoon, Chhit, mulberry leaves required for larvae rearing, net
487 profit and SPC- present sell price of cocoon per acre farm land) and varieties are grouped
488 according to their similarity cluster in profile.
489 Table 1. Environmental condition required for larval growth of silk worm.
490 Table 2. Estimation of fecundity in multivoltine silk worm at optimal temperature 22-28°C and
491 relative humidity of the atmosphere 60-85%.
492 Fecundity= Number of eggs lay by each female moth immediately after mating.
493 Here fecundity calculated by total number of eggs laid on a specialized card board demarcated
494 with twenty squares for 20 female moths, which surrounded by a cylindrical cellule (Fecundity=
495 Total number of eggs in twenty cellule (9679) / Number of female months laid eggs (20).
496
497
498
499 bioRxiv preprint doi: https://doi.org/10.1101/2021.03.22.436391; this version posted March 22, 2021. The copyright holder for this preprint (which was not certified by peer review) is the author/funder, who has granted bioRxiv a license to display the preprint in perpetuity. It is made available under aCC-BY-ND 4.0 International license.
500
501
502
503
504
505
506 Fig. 1Geographical location and coordinates of experimental site in Bishnupur sericulture complex, 507 Government of West Bengal at Bishnupur, West Bengal, India. bioRxiv preprint doi: https://doi.org/10.1101/2021.03.22.436391; this version posted March 22, 2021. The copyright holder for this preprint (which was not certified by peer review) is the author/funder, who has granted bioRxiv a license to display the preprint in perpetuity. It is made available under aCC-BY-ND 4.0 International license.
508 509 Fig. 2 a. Photograph of cellule on the card within which the female moths are laying eggs. b. Mature fifth 510 instar larvae of M12W multivoltine variety feeds on fresh mulberry leaves. c. Mature larvae of 511 multivoltine variety just starting cocoon formation on chandraki.
40 Average weight of 10 mature larvae Renditta 7
35 6 30 5 25 4 20 Weight (kg)
3 Weight (kg) 15 2 10
5 1
0 0 Bivoltine F1 variety Multivoltine 512 513 Fig. 3 The graph represented the average weight of ten mature larvae and renditta of bivoltine, F1 and 514 multivoltine mulberry silk worm of B mori. bioRxiv preprint doi: https://doi.org/10.1101/2021.03.22.436391; this version posted March 22, 2021. The copyright holder for this preprint (which was not certified by peer review) is the author/funder, who has granted bioRxiv a license to display the preprint in perpetuity. It is made available under aCC-BY-ND 4.0 International license.
1200
1000
800
(kg) 600
400
200 Amount of leaves requiredfor rearing
0 Bivoltine F1 variety Multivoltine 515 516 Fig. 4 The bar graph represented the amount of leaves required for rearing the bivoltine, F1 and 517 multivoltine mulberry silk worm of B mori.
518
2000 Length of silk thread (mts) 15.5 1800 Chhit (number) Dry cocoon weight (kg) 15 1600 1400 14.5
1200 14 1000 800 13.5
600 13 400 12.5 200 0 12 Bivoltine F1 variety Multivoltine 519 520 Fig. 5 The line graph represented the length of the silk thread; chhit, number of green cocoons weigh per 521 kg; dry cocoon weight in bivoltine, F1 and multivoltine mulberry silk worm ofB mori. bioRxiv preprint doi: https://doi.org/10.1101/2021.03.22.436391; this version posted March 22, 2021. The copyright holder for this preprint (which was not certified by peer review) is the author/funder, who has granted bioRxiv a license to display the preprint in perpetuity. It is made available under aCC-BY-ND 4.0 International license.
600 Number of DFL per acre farm land Amount of cocoon produced per acre farm land 500
400
300 Number
200
100
0 Bivoltine F1 variety Multivoltine 522 523 Fig. 6 The bar graph represented the number of disease free larvae (DFL) rearing on per acre farm land 524 and amount of cocoon produced per acre farm land in bivoltine, F1 and multivoltine mulberry silk worm 525 of B mori.
526
Present sell price of cocoon per acre of farm land 70000 Net profit 600
60000 500 50000 400 40000 300 30000 200 20000 10000 100 Unit (as Indian currency rupees) currency Indian (as Unit Unit (as Indian currency rupees) currency Indian (as Unit 0 0 527 Bivoltine F1 variety Multivoltine 528 Fig. 7 The graph represented the economic traits of bivoltine, F1 and multivoltine races of B. mori in 529 terms of present selling price of respective cocoons, present market rate of cocoons and net profit per acre 530 farm land. bioRxiv preprint doi: https://doi.org/10.1101/2021.03.22.436391; this version posted March 22, 2021. The copyright holder for this preprint (which was not certified by peer review) is the author/funder, who has granted bioRxiv a license to display the preprint in perpetuity. It is made available under aCC-BY-ND 4.0 International license.
531
532 Fig. 8 The heatmap visualized different measured variables with bivoltine, F1 and multivoltine races of 533 B. mori. The color code from Z score 0-1 depicted higher values whereas, color code from Z score 0 to -1 534 showed lower values. Variables (LT- length of the silk thread, Renditta, DCW- dry cocoon weight, 535 AWM- average weight of ten mature larvae, cocoon- amount of cocoon produced in one acre farm land, 536 DFL- number of disease free larvae per acre farm land, MP- present market price of cocoon, Chhit, 537 mulberry leaves required for larvae rearing, net profit and SPC- present sell price of cocoon per acre farm 538 land) and varieties are grouped according to their similarity cluster.
539 bioRxiv preprint doi: https://doi.org/10.1101/2021.03.22.436391; this version posted March 22, 2021. The copyright holder for this preprint (which was not certified by peer review) is the author/funder, who has granted bioRxiv a license to display the preprint in perpetuity. It is made available under aCC-BY-ND 4.0 International license.
Fig. 1 Geographical location and coordinates of experimental site in Bishnupur sericulture complex, Government of West Bengal at Bishnupur, West Bengal, India.
Fig. 2 a. Photograph of cellule on the card within which the female moths are laying eggs. b. Mature fifth instar larvae of M12W multivoltine variety feeds on fresh mulberry leaves. c. Mature larvae of multivoltine variety just starting cocoon formation on chandraki. bioRxiv preprint doi: https://doi.org/10.1101/2021.03.22.436391; this version posted March 22, 2021. The copyright holder for this preprint (which was not certified by peer review) is the author/funder, who has granted bioRxiv a license to display the preprint in perpetuity. It is made available under aCC-BY-ND 4.0 International license.
40 Average weight of 10 mature larvae Renditta 7
35 6 30 5 25 4 20 Weight (kg)
3 Weight (kg) 15 2 10
5 1
0 0 Bivoltine F1 variety Multivoltine
Fig. 3 The graph represented the average weight of ten mature larvae and renditta of bivoltine, F1 and multivoltine mulberry silk worm of B mori.
1200
1000
800
(kg) 600
400
200 Amount of leaves requiredfor rearing
0 Bivoltine F1 variety Multivoltine
Fig. 4 The bar graph represented the amount of leaves required for rearing the bivoltine, F1 and multivoltine mulberry silk worm of B mori.
bioRxiv preprint doi: https://doi.org/10.1101/2021.03.22.436391; this version posted March 22, 2021. The copyright holder for this preprint (which was not certified by peer review) is the author/funder, who has granted bioRxiv a license to display the preprint in perpetuity. It is made available under aCC-BY-ND 4.0 International license.
2000 Length of silk thread (mts) 15.5 1800 Chhit (number) Dry cocoon weight (kg) 15 1600 1400 14.5
1200 14 1000 800 13.5
600 13 400 12.5 200 0 12 Bivoltine F1 variety Multivoltine
Fig. 5 The line graph represented the length of the silk thread; chhit, number of green cocoons weigh per kg; dry cocoon weight in bivoltine, F1 and multivoltine mulberry silk worm of B mori.
600 Number of DFL per acre farm land Amount of cocoon produced per acre farm land 500
400
300 Number
200
100
0 Bivoltine F1 variety Multivoltine
Fig. 6 The bar graph represented the number of disease free larvae (DFL) rearing on per acre farm land and amount of cocoon produced per acre farm land in bivoltine, F1 and multivoltine mulberry silk worm of B mori.
bioRxiv preprint doi: https://doi.org/10.1101/2021.03.22.436391; this version posted March 22, 2021. The copyright holder for this preprint (which was not certified by peer review) is the author/funder, who has granted bioRxiv a license to display the preprint in perpetuity. It is made available under aCC-BY-ND 4.0 International license.
Present sell price of cocoon per acre of farm land 70000 Net profit 600
60000 500 50000 400 40000 300 30000 200 20000 10000 100 Unit (as Indian currency rupees) currency Indian (as Unit Unit (as Indian currency rupees) currency Indian (as Unit 0 0 Bivoltine F1 variety Multivoltine Fig. 7 The graph represented the economic traits of bivoltine, F1 and multivoltine races of B. mori in terms of present selling price of respective cocoons, present market rate of cocoons and net profit per acre farm land.
Fig. 8 The heatmap visualized different measured variables with bivoltine, F1 and multivoltine races of B. mori. The color code from Z score 0-1 depicted higher values whereas, color code from Z score 0 to -1 showed lower values. Variables (LT- length of the silk thread, Renditta, DCW- dry cocoon weight, AWM- average weight of ten mature larvae, cocoon- amount of cocoon produced in one acre farm land, DFL- number of disease free larvae per acre farm land, MP- present market price of cocoon, Chhit, mulberry leaves required for larvae rearing, net profit and SPC- present sell price of cocoon per acre farm land) and varieties are grouped according to their similarity cluster in profile. bioRxiv preprint doi: https://doi.org/10.1101/2021.03.22.436391; this version posted March 22, 2021. The copyright holder for this preprint (which was not certified by peer review) is the author/funder, who has granted bioRxiv a license to display the preprint in perpetuity. It is made available under aCC-BY-ND 4.0 International license.
Table 1. Environmental condition required for larval growth of silk worm.
Larval stage Temperature Humidity 1st inster larva 26-28°C 85% 2nd inster larva 26-28°C 85% 3rd inster larva 24-26°C 80%
4th inster larva 24-25°C 75% th 5 inster larva 23-24°C 70%
Table 2. Estimation of fecundity in multivoltine silk worm at optimal temperature 22-28°C and relative humidity of the atmosphere 60-85%.
Number 1st cellule 2nd cellule 3rd cellule 4th cellule 5th cellule Total Avg. of eggs fecundity Row 1 490±10 380±8 450±10 310±5 650±10 2280 484 Row 2 710±5 240±10 315±8 414±10 680±10 2359 Row 3 430±10 730±10 460±10 490±10 210±8 2320 Row 4 340±10 730±10 355±8 720±10 475±10 2620 Fecundity= Number of eggs lay by each female moth immediately after mating. Here fecundity calculated by total number of eggs laid on a specialized card board demarcated with twenty squares for 20 female moths, which surrounded by a cylindrical cellule (Fecundity= Total number of eggs in twenty cellule (9679) / Number of female months laid eggs (20). bioRxiv preprint doi: https://doi.org/10.1101/2021.03.22.436391; this version posted March 22, 2021. The copyright holder for this preprint (which was not certified by peer review) is the author/funder, who has granted bioRxiv a license to display the preprint in perpetuity. It is made available under aCC-BY-ND 4.0 International license.
Fig. Graphical abstract represents the comparative performance of bivoltine, multivoltine and F1 races of B. mori on the aspect of biological and economic traits in tropical climate condition.