Cocoon Shell Weight Research Articles

A composite method for mapping quantitative trait loci without interference of female achiasmatic and gender effects in silkworm, Bombyx mori.

The silkworm, Bombyx mori, is an economically important insect that was domesticated more than 5000 years ago. Its major economic traits focused on by breeders are quantitative traits, and an accurate and efficient QTL mapping method is necessary to explore their genetic architecture. However, current widely used QTL mapping models are not well suited for silkworm because they ignore female achiasmate and gender effects. In this study, we propose a composite method combining rational population selection and special mapping methods to map QTL in silkworm. By determining QTL for cocoon shell weight (CSW), we demonstrated the effectiveness of this method. In the CSW mapping process, only 56 markers were used and five loci or chromosomes were detected, more than in previous studies. Additionally, loci on chromosomes 1 and 11 dominated and accounted for 35.10% and 15.03% of the phenotypic variance respectively. Unlike previous studies, epistasis was detected between loci on chromosomes 11 and 22. These mapping results demonstrate the power and convenience of this method for QTL mapping in silkworm, and this method may inspire the development of similar approaches for other species with special genetic characteristics.

Improvement of Eri Silkworm (Samia ricini D.) Tolerant to High Temperature and Low Humidity Conditions by Continuously Regime

Improvement of eri silkworm tolerant to high temperature condition was carried out by selection and continuous rearing (1 – 12 generation) under high temperature (42±1 °C) and low relative humidity (50±5%R.H.). The eri silkworm rearing at a normal temperature (25±2 °C; 80±5%R.H.) served as control treatment. The result revealed that eri silkworm was continuously tolerant to high temperature of 42±1˚C with low relative humidity (50±5%R.H.) up to 12 generations. Among treated generations with high temperature, the silkworm survived from larva stage (1st – 5th instar) to adult in all generations ranking 16.67 – 54.17%. Between F12 and F1, survival rate of larva – adult stage of F12 was 43.33% less than F1 (54.17%), but not significantly different (P<0.05). For cocoon yields, fresh cocoon weight, pupa weight and cocoon shell weight of F12 were lower than F1. Shell ratio of F12 (11.84%), total cocoon shell weight (5.72g) and fresh cocoon/10,000 larvae (9.39 kg) were not significantly different to F1(11.61 %, 5.72 g and 10.55 kg, respectively). It was clearly, if the egg yields were considered, egg laying/moth, hatchability, total egg laying and total hatchability increased from F1 to F12. The result indicates that the thermotolerant property of eri silkworm SaKKU1 is heritable by high temperature up to F12. This study is a first report on continuously heat tolerant improvement of eri silkworm in Thailand and elsewhere.

Effect of Temperatures on Growth, Yields and Heat Shock Protein Expression of Eri Silkworm (Samia ricini D.)

The effect of high temperatures on the growth, yields and heat shock protein (HSP) production of eri silkworm (Samia ricini D.) was carried out by exposure the 5th instar day 3 larvae to different temperatures, 36±1, 40±1, 42±1, 45±1 and 48±1°C for 3 hours, compared to control treatment by rearing eri silkworm continuously at normal temperature (25±2°C, 80±5%R.H.). After treated with high temperature condition, the eri silkworm larvae were reared at 25±2°C, 80±5%R.H.until cocooning, pupation, adult stage, coupling and laying eggs. The result exhibited that survival rates, cocooning rate and almost yields varied inversely to temperatures especially between 42±1 – 48±1°C. At the highest temperature, survivals and yields were the lowest, while those values were the maximum nearly all control treatments. At 48±1°C treatment, the means of all parameters were the lowest; larva survival (50.00%), survival of larva – adult (38.33%) and cocooning rate (41.67%), which were significantly different to other treatments(P<0.05). Other yields affected by 48±1°C were also the lowest; fresh cocoon weight(2.5078 g), pupa weight (2.1508 g), shell weight (0.3429 g), total cocoon shell weight(2.88 g), fresh cocoon weight/10,000 larvae (10.47 kg), egg laying/moth (287.56 eggs), hatchability (72.67%), total egg laying (1,121.33 eggs) and total hatchability (800.11 eggs). Detection of HSP of 5th instar larvae day 3 of eri silkworm treated with 5 different temperatures (36±1, 40±1, 42±1, 45±1 and 48±1 °C) was performed using sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS–PAGE), compared to control treatment (25±2°C; 80±5%R.H.). The result was clearly that the eri silkworm treated with all high temperatures expressed HSP bands of approximate 50 kDa. Whereas HSP band was not detectable in control treatment. The HSP is applicable in the thermotolerant variety improvement program of eri silkworm.

천잠 누에고치의 일반 성상

국내에서 생산한 천잠 누에고치의 일반 특성을 고찰한 결과 국내산 천잠 누에고치는 연두색 고치를 지으며, 층상구조를 가지고 있었다. 천잠 누에고치는 외피는 연두색이었고 내피는 흰색을 나타내어 천잠 누에고치의 색상을 나타내는 색소 성분은 외피에 존재하였다. 천잠 누에고치는 고치층의 무게는 0.528 g, 견층두께는 0.424 mm로 측정되었다. 천잠 누에고치를 구성하는 주요 아미노산은 알라닌, 글리신, 세린, 아스파르트산, 티로산, 아르기닌 순으로 나타났으며, X-선 회절분석 결과 <TEX>$2{\theta}=16.8^{\circ}$</TEX>, <TEX>$20.4^{\circ}$</TEX> 부근에서 강한 회절 피크와 <TEX>$2{\theta}=15.0^{\circ}$</TEX>, <TEX>$24.3^{\circ}$</TEX>, <TEX>$30.0^{\circ}$</TEX> 부근에서 날카로운 회절 피크를 나타내었다. 천잠 누에고치는 폭이 <TEX>$20{\mu}m$</TEX> 정도인 섬유가 적층된 구조를 가지고 있으며, 고치의 안쪽과 바깥쪽에 흰색 결정을 가지고 있었다. 천잠 누에고치의 최대 열분해 온도는 <TEX>$370^{\circ}C$</TEX> 부근이었다. 이러한 천잠 누에고치에 대한 연구 결과는 향후 천잠 누에고치를 이용한 소재 개발의 기초 자료로 활용될 수 있을 것으로 기대한다. Antheraea yamamai silkworm cocoon is considered as a natural biocompatible materials, but can not be used as medical resources due to its difficult processability. In this study, we examined the general characteristics including cocoon shell weight and structural and thermal properties of Antheraea yamamai silkworm cocoon. The cocoon shell weight and thickness of wild silkworm cocoon was 0.528 g and 0.424 mm, respectively. The cocoon has yellow-green color in outside cocoon but white in inner layer cocoon. Amino acid analysis showed that the main amino acid of Antheraea yamamai cocoon is alanine, glycine, serine, aspartic acid, tyrosine and arginine. X-ray diffractometry showed that strong diffraction peaks at <TEX>$2{\theta}=16.8^{\circ}$</TEX>, <TEX>$20.4^{\circ}$</TEX>, corresponded to <TEX>${\beta}$</TEX>-sheet structure and sharp diffraction peaks at <TEX>$2{\theta}=15.0^{\circ}$</TEX>, <TEX>$24.3^{\circ}$</TEX>, <TEX>$30.0^{\circ}$</TEX> due to the presence of calcium oxalate on cocoon surface. Antheraea yamamai cocoon was degraded at <TEX>$370^{\circ}C$</TEX>. These results might be used as basic information for development of non-textile materials using Anthereae yamamai silkworm cocoon.

누에 장려품종간 교잡누에의 실용형질 비교

This study was conducted to consider practical use of F2 hybrid and intervariety crossing for the improvement of silkworm eggs export and silkworm eggs manufacture. Now Kumokjam and Baegokjam come into wide use to sericulture farmers but comparison test of F1, F2 hybrid and intervariety have not been done. We weighed against the productivity among economical character. While larval period of F2 among them is most long time, pupation percentage and cocoon yield per 10,000 3rd molted larvae are lower than intervariety. With comparing F2 and intervariety, single cocoon weight of F2 is lower 9 ~ 21% than intervariety, and cocoon shell weight of F2 was lower 10 ~ 18% than intervariety. By number of cocoons per liter, F2 hybrid was lower and more irregular size than intervariety. In coparison with number of egg laid, F2 hybrid Baegokjam was 655 ea (14%) and Kumokjam 625 ea (40%) more than F1 hybrid. Also, F2 hybrid for filament grade went down than F1 hybrid. The advantage of egg production in F2 hybrid can reduce costs because there is no necessity for sex discrimination and germination control. But besides increase of number of egg laid, the productivity including economical characters was greatly lowered. Except for being a lot of laying eggs, cocoon productivity of the F2 was greatly reduced by degeneration of practical traits. Therefore the further studies are needed in order to increase utilization value of the F2 hybrid silkworm.

Nanoparticulate anatase TiO2 (TiO2 NPs) upregulates the expression of silkworm (Bombyx mori) neuropeptide receptor and promotes silkworm feeding, growth, and silking

Bombyx mori orphan G protein-coupled receptor, BNGR-A4, is the specific receptor of B. mori neuropeptide F (BmNPFR, neuropeptide F designated NPF). BmNPFR binds specifically and efficiently to B. mori neuropeptides BmNPF1a and BmNPF1b, which activates the ERK1/2 signaling pathway to regulate B. mori food intake and growth. Titanium dioxide nanoparticles (TiO2 NPs) can promote B. mori growth. However, whether the mechanisms of TiO2 NPs’ effects are correlated with BmNPFR remains unknown. In this study, the effects of TiO2 NPs (5mg/L) feeding and BmNPFR-dsRNA injection on B. mori food intake and growth were investigated; after TiO2 NPs treatments, B. mori food intake, body weight, and cocoon shell weight were 5.82%, 4.64%, and 9.30% higher, respectively, than those of controls. The food intake, body weight, and cocoon shell weight of the BmNPFR-dsRNA injection group were reduced by 8.05%, 6.28%, and 6.98%, respectively, compared to the control. After TiO2 NPs treatment for 72h, the transcriptional levels of BmNPFR, BmNPF1a, and BmNPF1b in the midgut were 1.58, 1.43, and 1.34-folds, respectively, of those of the control, but 1.99, 2.26, and 2.19-folds, respectively, of the BmNPFR-dsRNA injection group; the phosphorylation level of MAPK was 24.03% higher than the control, while the phosphorylation level of BmNPFR-dsRNA injection group was 71.00% of control. The results indicated that TiO2 NPs affect B. mori feeding and growth through increasing the expression of BmNPFR. This study helps clarify the roles of BmNPF/BmNPFR system in TiO2 NPs’ effects on B. mori feeding, growth, and development.

Rearing technique for a wild silk worm Actias selene hubner (Lepidoptera: Saturniidae)

Actias selene Hubner (Lepidoptera: Saturniidae) is wild silk worm of India. It has durable silk. Therefore, its conservation and exploitation in silk industry is integral part of sericulture. However, silk production technology of A. selene is not developed so far. Hence, in the present paper preliminary rearing technique of A. selene is given. Cocoons were formed within 45 days. Cocoon weight, shell weight, shell length, shell width and shell thickness were 7.42 g, 0.93 g, 4.2 cm, 2.2 cm and 0.18 mm respectively, while shell ratio calculated was 12.53%. The rearing success of A. selene was 25% on Terminalia tomentosa W. & A. The mated females laid 105 eggs and produced 22 offspring’s with an average sex ratio (m: f) 1: 0.75.

ANTIFUNGAL EFFECT OF OCIMUM SANCTUM L. AGAINST WHITE MUSCARDINE DISEASE OF SILKWORM, BOMBYX MORI L.

ABSTRACT The “Queen of Herb”, Tulsi is an important herb with greater medicinal value used in Ayurveda, Siddha, Unani, Greek and Roman medicine for prevention and cure of many illness. Fifth instar larvae inoculated with Beauveria bassiana were fed with mulberry leaves enriched with different concentrations (1 %, 2%, 3% and 4% ) of ethanolic extract of Ocimum sanctum leaves and its effect on cocoon weight, pupal weight, shell weight, shell ratio and silk characteristics were studied. Among the different concentrations, 3%ethanolic extract of O. sanctum has been found to be most effective against B. bassiana infection as compared to others. Inoculated control group recorded very low economic values as compared to normal control and other treated groups.

Advanced silk material spun by a transgenic silkworm promotes cell proliferation for biomedical application

Natural silk fiber spun by the silkworm Bombyx mori is widely used not only for textile materials, but also for biofunctional materials. In the present study, we genetically engineered an advanced silk material, named hSFSV, using a transgenic silkworm, in which the recombinant human acidic fibroblast growth factor (hFGF1) protein was specifically synthesized in the middle silk gland and secreted into the sericin layer to surround the silk fiber using our previously optimized sericin1 expression system. The content of the recombinant hFGF1 in the hSFSV silk was estimated to be approximate 0.07% of the cocoon shell weight. The mechanical properties of hSFSV raw silk fiber were enhanced slightly compared to those of the wild-type raw silk fiber, probably due to the presence of the recombinant of hFGF1 in the sericin layer. Remarkably, the hSFSV raw silk significantly stimulated the cell growth and proliferation of NIH/3T3 mouse embryonic fibroblast cells, suggesting that the mitogenic activity of recombinant hFGF1 was well maintained and functioned in the sericin layer of hSFSV raw silk. These results show that the genetically engineered raw silk hSFSV could be used directly as a fine biomedical material for mass application. In addition, the strategy whereby functional recombinant proteins are expressed in the sericin layer of silk might be used to create more genetically engineered silks with various biofunctions and applications.

Comparison of phenotypic value changes in pure lines of Bombyx mori (Lepidoptera: Bombycidae) during consecutive generations following initial selection on cocoon weight.

The experiments reported here were conducted to investigate the effect of selection on three quantitative traits, namely cocoon weight, cocoon shell weight, and cocoon shell percentage, during four generations by rearing six pure breeds of domesticated silkworm, Bombyx mori L. (Lepidoptera: Bombycidae) of Chinese and Japanese origin compared with random unselected groups as controls. All stages of rearing and data recording were performed over four rearing periods, with generations 1–3 during successive spring seasons and generation 4 during the autumn season in year 3. Each pure line contained two groups of selected and random (control) groups. Comparisons included the effect of selection methods, pure line, and generation on the phenotypic values. We found strong main effects of pure line, generation, sex, and group and support for nearly all interactions between these main effects for all three response traits. The results indicated that cocoon weight and cocoon shell weight in the selected group were higher than in the control or nonselected group. Both selected and nonselected groups had the lowest cocoon weight, cocoon shell weight, and cocoon shell percentage in the fourth generation when environmental conditions during the autumn season were less favorable than spring. The cocoon weight and cocoon shell weight averages were higher for nonselected groups in the second and third generations, and for the selected group in the first generation due to the direct effect of selection.

PRELIMINARY REARING TECHNIQUE FOR ATTACUS ATLAS (LEPIDOPTERA: SATURNIIDAE) A WILD SILK WORM OF INDIA

Sericulture is agro based industry. India is the only country where all four kinds of silks viz. Mulberry, Muga, Tasar and Eri are commercially exploited. Attacus atlas, Linnaeus (Lepidoptera: Saturniidae) is wild silk worm of India. Its conservation and exploitation in silk production is essential component of wild silk technology development in India. Therefore, rearing technique of A. atlas has been given in the paper. Cocoons were formed within 35-43 days. Cocoon weight, shell weight, shell length, shell width and shell thickness were 9.4 g, 1.82 g, 4.4 cm, 1.4 cm and 0.21 mm respectively, while shell ratio calculated was 19.32%. The rearing success of A. atlas was 15% on Angeer Ficus carica. The mated females laid 147 eggs and produced 22 offspring’s with an average sex ratio (m: f) 1: 0.75.

General Performance and Cocoon Yields of Two Hybrids of the Silkworm, Bombyx Mori L. (Lepidoptera: Bombicidae), Fed on Mulberry Leaves from Different Amended Soils

The performance and cocoon yields of two silkworm hybrids – W1D2 and C1J2 – grown on mulberry leaves from NPK fertilizer-, poultry manure– or non-amended soils were investigated in a 2 x 3 factorial experiment fitted into a completely randomized design with four replicates. Mulberry leaves from the three treatment plots were randomly selected for proximate analysis. Cocoon yield was significantly higher in silkworm hybrid 1 W1D2, irrespective of soil amendments, compared to hybrid 2 C1J2. Number of cocoons, single cocoon weight and shell weight were significantly higher from amended soils compared with the control. Larval and pupal weights were not influenced significantly by silkworm hybrid, soil amendments or their interaction. Fecundity was significantly higher in silkworm fed with leaves amended with NPK compared to leaves from soil amended with manure, which was not significantly different from the control. Larval and adult emergence was not affected by the two amendment factors; however, mortality was significantly higher in the control. Nitrogen, phosphorus and calcium contents were positively correlated with number of cocoons, single cocoon weight, and shell weight. Mineral contents were significantly higher in poultry manure-grown leaves than in NPK-grown ones which was higher than the control. On the other hand, cocoon yield was significantly higher in the NPK-grown leaves. However, both soil amendment methods could be adopted for mulberry leaf production for silkworm rearing.

Genetic analysis of quantitative trait loci for cocoon and silk production quantity in Bombyx mori (Lepidoptera: Bombycidae)

Silk production quantity is the most economically important characteristic of the domesticated silkworm moth, Bombyx mori. It is controlled by multiple loci. The cocoon and silk production quantity of silkworm strains Jingsong and Lan10 have significantly diverged. A backcross population (BC1) was bred using Jingsong and Lan10 as parents to identify quantitative trait loci (QTLs) for silk quality. In this research, a genetic linkage map of the silkworm was constructed using the BC1 mapping population. The map contained 85 sequence-tagged site markers, 80 simple sequence repeat markers, and 16 single nucleotide polymorphisms. A linkage map was constructed from the data, which consisted of 181 markers distributed over 28 expected linkage groups and spans 2147.1 cM in total length. Fourteen QTLs were detected for cocoon filament length, whole cocoon weight, pupae weight, filament weight, and cocoon shell weight. The 14 QTLs were distributed in 5 linkage groups (linkage groups 1, 14, 18, 23 and 25) based on the constructed linkage map. In addition, five QTLs, which had the highest logarithm (base 10) of odds (LOD) values, were located on the first chromosome, three of which located at the same region in linkage group 1. These results represent an important foundation for the map-based cloning of QTLs and marker-assisted selection for improving the silk quality of economically important silkworm strains.

An optimized sericin-1 expression system for mass-producing recombinant proteins in the middle silk glands of transgenic silkworms

The middle silk gland (MSG) of silkworm is thought to be a potential host for mass-producing valuable recombinant proteins. Transgenic MSG expression systems based on the usage of promoter of sericin1 gene (sericin-1 expression system) have been established to produce various recombinant proteins in MSG. However, further modifying the activity of the sericin-1 expression system to yield higher amounts of recombinant proteins is still necessary. In this study, we provide an alternative modification strategy to construct an efficient sericin-1 expression system by using the hr3 enhancer (hr3 CQ) from a Chongqing strain of the Bombyx mori nuclear polyhedrosis virus (BmNPV) and the 3'UTRs of the fibroin heavy chain (Fib-HPA), the fibroin light chain (Fib-LPA), and Sericin1 (Ser1PA) genes. We first analyzed the effects of these DNA elements on expression of luciferase, and found that the combination of hr3 CQ and Ser1PA was most effective to increase the activity of luciferase. Then, hr3 CQ and Ser1PA were used to modify the sericin1 expression system. Transgenic silkworms bearing these modified sericin1 expression vectors were generated by a piggyBac transposon mediated genetic transformation method. Our results showed that mRNA level of DsRed reporter gene in transgenic silkworms containing hr3 CQ and Ser1PA significantly increased by 9 fold to approximately 83% of that of endogenous sericin1. As the results of that, the production of recombinant RFP increased by 16 fold to 9.5% (w/w) of cocoon shell weight. We conclude that this modified sericin-1 expression system is efficient and will contribute to the MSG as host to mass produce valuable recombinant proteins.

Cocoon Characteristics of Antheraea pernyi Silkworm Reared in Korean Oak Field

Antheraea pernyi silkworm is a well known wild silkworm to produce a valuable silk fiber. A. pernyi silkworm was reared in Korean oak field and examined the cocoon characteristics, such as cocoon weight, cocoon shell weight, and percentage of cocoon shell weight. Degumming loss was also measured after alkali degumming process. A. pernyi silkworm spins tawny color cocoon in oval shape. Cocoon shell weight of A. pernyi silkworm, 0.78 g, was heavier than that of B. mori silkworm, 0.51 to 0.63 g. Cocoon shell percentage of A. pernyi silkworm, 32.8%, was higher than that of B. mori silkworm, 23.4 to 25.2%. Degumming loss percentage of A. pernyi silkworm, 17.1%, was lower than that of B. mori silkworm, 25.0%. SEM showed that the surface of the cocoon filament was coarse and oriented with longitudinal direction.

Estimation of Hybrid Vigor of Some Egyptian Single Local Hybrids of Mulberry Silkworm, Bombyx mori L.

Fifteen races resulted from silkworm breeding programat Sericulture Research Department (SRD) were used for hybridization. Fourteen hybrids were obtained and coded as; Giza C, D, R, S, T, U, A, V, W, P, H, L and Qanater 1, 2. The traits of cocoon weight, cocoon shell weight, pupal weight, cocoon shell ratio, silk productivity, fifth instar duration, total larval duration, number of cocoon per liter and pupation ratio were evaluated. Data were analyzed by using three formulae of heterosis over better, mid and checkparent values. Hybrids of Giza V, C, N, Qanater 1 and2 are promising and could be used in commercial cocoon production. Generally, there are some new hybrids can be exploited in commercial scale. Also, the local races can be evolved using the hybridization, inbreeding and selection program.

Developmental and Cocoon Parameters of the Silkworm, Bombyx mori L. (Lepidopter: Bombicidae), Fed on Mulberry Leaves Preserved for Different Durations under Tropical Conditions

The effects on the general performance and cocoon yield of two silkworm hybrids fed with mulberry leaves preserved for 0, 24, 48, 72 and 96 hours were investigated. Leaf samples of each of the treatments were analyzed for nutrient contents. The experiment was a 2 x 5 factorial arrangement fitted into a completely randomized design in 4 replications. One hundred silkworm larvae of each hybrid were allocated to each replicate treatment and fed on the preserved leaves throughout the larval stages. Results showed that duration of preservation and silkworm hybrids significantly influenced the shell ratio, both singly and jointly. Interaction between the two factors was significant for the number of cocoons and cocoon weight. Single cocoon weight and shell weight were significantly higher in larvae fed with leaves preserved at 0 and 24 hours. Fecundity, larval and pupal emergence were not influenced by the two factors. However, higher larval and pupal weights were observed in silkworms fed on leaves preserved for 0 and 24 hours.

Studies on the Manifestation of Hybrid vigour and Combining Ability in Polyvoltine X Bivoltine (cross breed) Hybrids of Mulberry Silkworm Bombyx mori L.

To meet the local requirement i.e. the tropical stress of Andhra Pradesh and marginal farmers, twenty four new hybrid combinations were tested in Line x Tester method involving eight newly developed polyvoltine oval lines viz., MSO1, MSO2, MSO3, MSO4, MSO5, MSO6, MSO7 and MSO8 and three bivoltine silkworm breeds viz., APS12, APS45 and APS8 as testers. These hybrids were reared to evaluate their performance. Data for eight economically important metric traits viz., fecundity, cocoon yield per 10,000 larvae by number, cocoon yield per 10,000 larvae by weight, survival rate, cocoon weight, cocoon shell weight, cocoon shell ratio and filament length was recorded. General combining ability (gca), specific combining ability (sca) and heterosis were analyzed. Further, the relative merit of the hybrids for all the traits under study was also assessed adopting Evaluation Index method. Based on combining ability effects, heterosis and evaluation index, five hybrid combinations viz., MSO3 x APS45, MSO1 x APS12, MSO7 x APS8, MSO2 x APS45 and MSO1 x APS45 were selected for further evaluation in different seasons.

Management of Climatic Factors for Successful Silkworm (Bombyx moriL.) Crop and Higher Silk Production: A Review

The seasonal differences in the environmental components considerably affect the genotypic expression in the form of phenotypic output of silkworm crop such as cocoon weight, shell weight, and cocoon shell ratio. The variations in the environmental conditions day to day and season to season emphasize the need of management of temperature and relative humidity for sustainable cocoon production. The present review paper discuss in details about the role of temperature and humidity on growth and development of silkworm including recent studies on heat shock protein. Study also discusses the influence of air and light on silkworm development. In addition to this study emphasis on the role of various environmental factors on embryonic development of silkworm egg, nutritional indices of silkworm larva and reproductive potential of silkworm moth. The study also highlights about the care to be required during silkworm spinning and influence of temperature and humidity on post cocoon parameters of silkworm. The study included future strategies to be taken for the management climatic condition for successful cocoon crop. The paper covers 140 references connected with the topic.

Effects of Pyriproxyfen Treatment on the Insect Growth Rates

Larvae of Bombyx mori fed on the mulberry leaves treated with pyriproxyfen extended the larval duration. The silkworm on the third day of the fourth instar fed pyriproxyfen 10‐6 concentration extended the fifth instar duration over 20 days and was not able to spinning silk. Pyriproxyfen was treated at the third day of the fourth instar, the first day of the fifth instar and the fifth day of the fifth instar larvae, the larval body weights were higher by 49%, 38%, 44% than those of the control, respectively. Pyriproxyfen was treated at the third day of the fourth instar, the first day of the fifth instar and the fifth day of the fifth instar larvae, pupal ratio was 91.3%, 80.0%, 12.0% of the control, respectively. Pyriproxyfen was treated at the third day of the fourth instar, the first day of the fifth instar and the fifth day of the fifth instar larvae, the single cocoon weights were 2.11g, 2.99g, 3.83g and cocoon shell weight was 43.2cg 40.9g 20.1g, respectively. When pyriproxyfen was treated at the third day of the fourth instar, the first day of the fifth instar and the fifth day of the fifth instar larvae, the maximum fifth larval silk gland weight of the fifth instar treatment was lower by 59%, 54% than those of the control.