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Assam Agricultural University, Jorhat

Assam Agricultural University is the first institution of its kind in the whole of North-Eastern Region of India. The main goal of this institution is to produce globally competitive human resources in farm sectorand to carry out research in both conventional and frontier areas for production optimization as well as to disseminate the generated technologies as public good for benefitting the food growers/produces and traders involved in the sector while emphasizing on sustainability, equity and overall food security at household level. Genesis of AAU - The embryo of the agricultural research in the state of Assam was formed as early as 1897 with the establishment of the Upper Shillong Experimental Farm (now in Meghalaya) just after about a decade of creation of the agricultural department in 1882. However, the seeds of agricultural research in today’s Assam were sown in the dawn of the twentieth century with the establishment of two Rice Experimental Stations, one at Karimganj in Barak valley in 1913 and the other at Titabor in Brahmaputra valley in 1923. Subsequent to these research stations, a number of research stations were established to conduct research on important crops, more specifically, jute, pulses, oilseeds etc. The Assam Agricultural University was established on April 1, 1969 under The Assam Agricultural University Act, 1968’ with the mandate of imparting farm education, conduct research in agriculture and allied sciences and to effectively disseminate technologies so generated. Before establishment of the University, there were altogether 17 research schemes/projects in the state under the Department of Agriculture. By July 1973, all the research projects and 10 experimental farms were transferred by the Government of Assam to the AAU which already inherited the College of Agriculture and its farm at Barbheta, Jorhat and College of Veterinary Sciences at Khanapara, Guwahati. Subsequently, College of Community Science at Jorhat (1969), College of Fisheries at Raha (1988), Biswanath College of Agriculture at Biswanath Chariali (1988) and Lakhimpur College of Veterinary Science at Joyhing, North Lakhimpur (1988) were established. Presently, the University has three more colleges under its jurisdiction, viz., Sarat Chandra Singha College of Agriculture, Chapar, College of Horticulture, Nalbari & College of Sericulture, Titabar. Similarly, few more regional research stations at Shillongani, Diphu, Gossaigaon, Lakhimpur; and commodity research stations at Kahikuchi, Buralikson, Tinsukia, Kharua, Burnihat and Mandira were added to generate location and crop specific agricultural production packages.

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  • ThesisItemOpen Access
    DIVERSITY, POPULATION DYNAMICS AND MANAGEMENT OF INSECT PESTS OF TEA
    (2023) Rabha, Himadri; Dutta, B. C.
    Diversity study of insect pest complex of tea was carried out at three agroclimatic zones of Assam viz.,Upper Brahmaputra Valley Zone (Jorhat) North Bank Plain Zone (Udalguri) and Lower Brahmaputra Valley Zone (Kokrajhar) during 2019-20, 2020-21 and 2021-22, respectively. Laboratory experiments were carried out at Biocontrol laboratory, Department of Entomology, Assam Agricultural University and at laboratory of Krishi Vigyan Kendra, Udalguri. The field experiment was conducted in the tea garden of Udalguri district during 2021-22. Survey results revealed that a total of 4 mites and 22 different insect species belonging to 7 orders and 19 families were found to be associated with tea as recorded from different locations of Assam. In addition, 7 species of insects were found to be as visitors of the tea ecosystem in different period of time. Moreover, 11 different types of natural enemies were also observed. Among the sucking insect pests, per cent infestation of tea mosquito bug was recorded maximum (43.22 per cent) in Jorhat district. Among defoliator pests, per cent infestation of looper caterpillar was recorded maximum (34.23 per cent) in Udalguri district. Among all the insect and mite pests, tea mosquito bug showed highest degree of infestation in Jorhat i.e., 46.21 per cent whereas in case of red spider mite and looper caterpillar, highest degree of infestation was recorded 54.80 and 46.32 per cent in Udalguri district, respectively. Among all the insect and mite pests recorded during the study, tea mosquito bug, red spider mite and looper caterpillar showed moderate (34-66 per cent) degree of infestation, so they are considered as major pests. During 2019-20, the species richness in Jorhat showed maximum value of 1.50 in defoliator pests. The variation of species richness indices indicated a highest value of 1.54 and 1.50 in Udalguri during 2020-21 and 2021-22 in defoliator pests, respectively. Whereas, in Kokrajhar, the highest value was 1.55 in sucking pests (2020-21) and 1.59 in defoliator pests (2021-22). Shannon- Wiener index revealed that the highest value of 2.21 in defoliator pests in Jorhat (2019-20). During 2020-21, in Udalguri, it was found to be highest in sucking pests with value 2.10 and 2.21 in Kokrajhar, respectively. During 2021-22, Shannon- Wiener index showed highest value of 2.10 in Udalguri district and 2.12 in Kokrajhar district in defoliator insect pests. In terms of Simpson’s diversity index, highest value of 0.87 was recorded in defoliator insect pests in Jorhat district (2019-20). Likewise, during 2020-21, in Udalguri and Kokrajhar district, the highest diversity value of 0.82 and 0.87 were recorded in sucking pests, respectively. During 2021-22, the highest diversity values of 0.86 and 0.87 were recorded in defoliator pests in Udalguri and Kokrajhar, respectively. In Jorhat (2019-20), the maximum number of tea mosquito bug was observed to be 5.9 per bush during the first week of September. The highest population indices record of 20.27 mites per leaf was recorded during third week of November. The maximum number of looper caterpillar was observed to be 4.26 per bush during fourth week of February. Correlation studies between weather parameters and population indices of tea mosquito bug showed significant positive correlation with maximum temperature, minimum temperature, evening relative humidity and rainfall whereas, red spider mite showed significant positive correlation with maximum temperature and negative correlation with morning relative humidity, evening relative humidity and total rainfall. The population indices of looper showed significant positive correlation with morning relative humidity. In Udalguri (2020-21), the maximum population indices of tea mosquito bug, red spider mite and looper caterpillar were recorded as 5.12 per bush during the last week of August, 14.78 per leaf during March to April and 5.02 per bush during second week of March, respectively. Correlation studies between weather parameters and population indices of tea mosquito bug showed significant positive correlation with maximum temperature, minimum temperature and evening relative humidity. The population indices of red spider mite showed significant positive correlation with maximum temperature, whereas, it showed negative correlation with morning relative humidity, evening relative humidity and total rainfall. The looper caterpillar population showed negative correlation with maximum temperature, minimum temperature, evening relative humidity and total rainfall. During 2021-22, the maximum population indices of tea mosquito bug, red spider mite and looper caterpillar were recorded to be 5.79 per bush, 28.12 per leaf, 5.23 per bush, respectively. Correlation studies between weather parameters and population indices of tea mosquito bug showed significant positive correlation with maximum temperature, minimum temperature, evening relative humidity and total rainfall. Red spider mite showed significant positive correlation with maximum temperature and negative correlation with total rainfall whereas, looper caterpillar showed significant negative correlation with maximum temperature, minimum temperature and total rainfall. In Kokrajhar (2020-2021), the maximum population indices of tea mosquito bug, red spider mite and looper caterpillar were recorded to be 4.12 per bush, 27.23 per leaf, 4.12 per bush respectively. Correlation studies between weather parameters and population indices of tea mosquito bug showed significant positive correlation with maximum temperature, minimum temperature, evening relative humidity and rainfall, whereas red spider mite showed non-significant positive correlation with maximum temperature and looper showed significant negative correlation with minimum temperature and total rainfall. During 2021-22, the maximum population indices of tea mosquito bug, red spider mite and looper caterpillar were recorded to be 5.30 per bush, 14.52 per leaf and 10.22 per bush, respectively. Correlation studies between weather parameters and population indices of tea mosquito bug showed a negative correlation with morning relative humidity, evening relative humidity and total rainfall. Red spider mite showed significant positive correlation with maximum temperature and negative correlation with morning relative humidity, evening relative humidity and total rainfall whereas looper caterpillar showed significant negative correlation with maximum temperature, minimum temperature, morning relative humidity, evening relative humidity and total rainfall. Laboratory study on efficacy of different plant extracts against tea mosquito bug showed the highest mortality of 80.00 per cent in case of Pongamia pinata in 120 hours after treatment. The results on efficacy of different plant extracts against adult red spider mite showed that the highest mortality was recorded 93.33 per cent in case of both the treatments of Vitex negundo and Azadirachta indica at 120 HAT. Similarly, bio efficacy of different plant extracts against looper caterpillar showed that the larval mortality was highest with value 86.67 per cent at 120 HAT in case of A. indica. The results on efficacy of plant extracts at field condition reveals that at seven days after spraying, P. pinata recorded the least number of populations of tea mosquito bug with 0.67 number per bush. Again, at seven days after spraying, least number of mites was recorded in case of V. negundo with 7.19 mites per leaf. Moreover, the results showed that the maximum reduction of larval population was found in A. indica with 1.72 looper caterpillar population per bush at seven days after spraying.