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20183
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Subject: Sericulture × End date: 2018 × Start date: 2018 × Type: Thesis ×
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    ThesisItemOpen Access
    IMPACT OF ENVIRONMENTAL FACTORS ON POPULATION DYNAMICS OF GALL INSECTS INFESTING SOM (Persea bombycina King) AND SOALU (Litsea monopetala Roxb.) PLANT
    (AAU, Jorhat, 2018) Sahu, Bhupen Kumar; Dutta, L. C.
    The present study on population dynamics of gall insects infesting Som (Persea bombycina King.) and Soalu (Litsea monopetala Roxb.) plant in relation to the weather factors were carried out in the experimental field of Department of Sericulture, Assam Agricultural University, Jorhat and CMER&TI, Lahdoigarh during 2017-18. Results indicate that the gall insects are host and organ specific and they produce galls on only one species. The gall insect infestation starts with laying of tiny eggs on the upper surface of the leaves in both Som and Soalu plants. On hatching of eggs, the first instar nymphs of Pauropsylla beesoni and maggots of Asphondylia spp. initiate the process of gall formation. The initial gall formation stage is a minute colour change in the infested area which gradually developed into a gall structure. The fully developed gall structures observed on the leaves were light greenish in colour initially and later on changed to purplish red in Som plant and light greenish to dark greenish in Soalu plant. Finally, the adults emerged out from the galls by making tiny holes at the terminal end of the galls. Gall insects appeared throughout the year; however the incidence, population density, extent of damage and intensity of attack of the pest varied during different months of the year and reached a peak in the month of July. Correlation and regression studies were carried out between the incidence, population density, extent of damage and intensity of attack of gall insects with the weather parameters viz., temperature (maximum and minimum), relative humidity (maximum and minimum), total rainfall, number of rainy days and bright sunshine hours. Significant correlation was found with temperature (maximum and minimum), relative humidity (minimum) and total rainfall with gall infestation. Relative humidity (maximum) and bright sunshine hours showed negative relationship with population build-up whereas other environmental parameters showed positive relationship with gall infestation. Thus, it may be concluded that the gall insect, Asphondylia spp. on Som and Pauropsylla beesoni Laing on Soalu plant appeared throughout the year and were largely regulated by meteorological factors viz., temperature, relative humidity and rainfall in different months. Therefore, proper eco-friendly management practices, preferably conservation and inundative release of bio-control agents against the gall insect would be necessary to avoid the probable hazards created by inorganic pesticides. Therefore a detailed study on management of the gall insect population with different bio-control agents is the need of the hour.
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    ThesisItemOpen Access
    Effect of mating duration on reproductive parameters and its impact on larval growth and quality of cocoons of eri silkworm, Samia ricini Donovan
    (AAU, Jorhat, 2018) Teronpi, Leedarin; Saikia, Monimala
    The current investigation on effect of mating duration on reproductive parameters and its impact on larval growth and quality of cocoons of eri silkworm, Samia ricinia Donovan, was carried out in the laboratory of Department of Sericulture, Assam Agricultural University, Jorhat in autumn and spring season during the year 2017-2018. The findings revealed that mating duration had significant effect on fecundity/ female/ day, total fecundity, weight of eggs, total weight of eggs and average hatchability percentage and non-significant effect on total oviposition duration and incubation period of eri silk moth. In almost all mating durations and seasons the egg laying percentage was maximum in the first day which gradually decreased with succeeding number of ovipositing days. Irrespective of season, five hours of mating duration was found to be better in total fecundity, weight of eggs and total weight of eggs which was at par with four hours mating duration. Four hours of mating duration was found to be better in both fecundity/ female/ day and average hatchability percentage regardless of season. Season also had significant effect on total oviposition duration, fecundity/ female/ day, total fecundity, weight of eggs, incubation period and average hatchability percentage. Total oviposition duration and incubation period of eri silk moth was recorded longer in spring season than autumn season. Fecundity/ female/ day, total fecundity and weight of eggs of eri silk moth were recorded better in autumn season. But, average hatchability percentage was better in spring season. Mating duration had no significant effect on larval growth and cocoon parameters. However, season had significant effect on larval duration, weight of full grown larvae, weight of matured larvae, ERR (%), cocoon weight, shell weight and pupal weight. Larval duration of eri silk moth was recorded shorter in autumn than spring season. Weight of full grown larvae, weight of matured larvae, ERR (%), cocoon weight, shell weight and pupal weight of eri silk moth was recorded better in autumn season than spring season. But, shell ratio (%) was better in spring season. Interaction effect between mating duration and season was significant in total oviposition duration, weight of eggs/ female/ day, larval duration, cocoon weight and pupal weight. Thus, from the present investigation it may be inferred that a period of three to five hours coupling duration is optimum for maximum egg laying of eri silk moth. In addition to this, though the fecundity and weight of eggs was registered better in autumn, with shorter incubation period and hatching percentage of eggs of the silk moth performed better in spring season. Larval and cocoon parameters showed better performance in the autumn season than spring season.
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    ThesisItemOpen Access
    TRADITIONAL KNOWLEDGE AND CULTURAL PRACTICES IN MUGA SILK PRODUCTION IN NORTH LAKHIMPUR DISTRICT OF ASSAM
    (AAU, Jorhat, 2018) PEGU, KARPUNPULI; Dutta, L. C.
    Sericulture, or silk farming, is the rearing of silkworms for the production of raw silk. It is an agro based labour intensive industry providing gainful employment mostly for rural people. Sericulture includes cultivation of 4 varieties of silkworm mainly mulberry, eri, muga and tasar. The golden silk muga is the gift of nature to the state and it is the pride of Assam. Muga rearers of Assam have been practicing this culture with traditional indigenous practices. Traditional knowledge is generated by the local people with their own experience and experimentation to meet their needs and these are sustainable in nature. Considering this, the present study was conducted to identify and document various Indigenous Traditional Knowledge in muga silk production, to study the extent of use of Indigenous Traditional Knowledge in relation to the socio-economic profile of the respondents and to find out the problems perceived by the muga rearers in North Lakhimpur district of Assam. A random sampling design was followed to obtain a sample size of 120 respondents. Ten independent and one dependent variable was selected for the study. The statistical techniques used for the analysis of data were frequency, percentage, mean, standard deviation, spearman’s correlation co-efficient and weighted mean score (WMS). The findings revealed that 50 per cent of the muga rearers belonged to age group of 36-50 yrs and 55.80 per cent had their education up to middle school. Moreover, 41.70 per cent of the rearers belonged to Other Backward Class, 52.50 per cent of the respondent had medium family size, 40 per cent of the members had income ranging from Rs.75001-100000 and 40 per cent of the members have small size land holding, whereas 68.40 per cent, 70.83 per cent and 58.40 per cent of the respondents had medium level of extension contact, risk bearing ability and decision making ability and on the other hand 40.80 per cent of the respondents have received training exposure. The study further revealed that 64.17 per cent of the respondent had medium level of extent of use of ITK in the district. It was affirmed from the findings that age, family size and size of operational land holding were found to be positive and significant whereas education, extension contact and training exposure were negative and significantly correlated with the extent of use of ITK. On the other hand caste, annual family income, risk bearing ability and decision making ability were found to be positive and non significant with the extent of use of ITK. Major problems reported by muga rearers included lack of capital, glamour, people are not interested to lease their land for muga rearing, impact of environmental pollution, lack of availability of machinery, inadequate marketing facilities, unaffordable cost of hiring vehicles and lack of need based training.