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Assam Agricultural University, Jorhat

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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
    Bioecology and development of IPM module against fruit flies in cucurbits
    (2019-09) Mudoi, Abhilisa; Saikia, Dilip Kumar
    Fruit flies are the excellent candidates for studies of biodiversity, adaptability in changing climatic conditions and invasion to new areas because of their polyphagous nature, high reproductive potential, wide range of distribution and great economic importance as pests. Therefore, an extensive elaboration of fruit flies was carried out in five different districts under Upper, Central and Lower Brahmaputra Valley Zones of Assam to know the prevalence and diversity pattern of different fruit fly species of cucurbits. Five species of fruit flies viz., Bactrocera cucurbitae Coquillett, B. tau Walker, B. dorsalis Hendel, along with two new species viz., B. scutellaris Bezzi and Dacus longicornis Wiedemann were recorded from different districts of Assam. Out of the five districts, maximum number of 2492 individuals were observed to be trapped in cue lure in Darrang district. The species diversity index (1.285) and richness indices (0.393) of fruit fly was found to be highest in Michajan village of Sibsagar district, whereas the lowest species diversity index, (0.656) was in Dhepor village of Sibsagar district but the lowest richness indices (0.132) was observed in Khataniapara village of Darrang district. In respect of distribution pattern, the fruit flies had clumped distribution in all the five different districts under the present investigation. The morphometric parameters of fruit flies showed that the mean body length was the highest (11.846 ± 0.027mm) in female D. longicornis and lowest (5.631±0.053mm) in male of B. cucurbitae. In general, adult males were short-lived as compared to females, however, the adult longevity of female fruit fly in different cucurbits varied from 63.91 ± 1.16, 60.37±0.41, 49.82±0.50mm in respect of B. dorsalis, B. tau and B. cucurbitae against bitter gourd, bitter gourd and bottle gourd, respectively. Morphometrics of immatures stages revealed that the egg (1.26±0.02 × 0.43±0.02), larval (9.59±0.07 × 1.85±0.01) and pupal (5.82±0.01 × 2.46±0.02) size was highest in B. tau followed by B. cucurbitae with 0.88±0.01 × 0.18±0.01, 8.07±0.07 × 1.12±0.01, 5.21±0.03 × 2.22±0.02mm, respectively. It is imperative to obtain a baseline data on the seasonal occurrence pattern of fruit flies and the influence of abiotic factors on their activities in a particular ecosystem. Therefore, an experiment was carried out under field conditions at the Horticultural orchard, Department of Horticulture, Assam Agricultural University, Jorhat during 2017-18 and 2018-19 to find out a suitable eco-friendly management module against fruit flies of bitter gourd. Insect pests encountered with the crop revealed altogether seven species under three orders with four families viz., B. cucurbitae, B. dorsalis, B. tau, Aphis gossypii Glover, Epilachna vigintioctopunctata F., Aulacophora foevicollis Lucas and Monolepta signata Olivier which were registered as major pests of bitter gourd. Among the natural enemies, a total of sixteen species belonging to three orders and seven families were recorded. Twelve different pollinator species were also recorded during the study period associated with the crop. The seasonal incidence of fruit flies indicated a maximum of 189.90 and 179.60 number of fruit flies were trapped during April, 2017-18 and 2018-19, respectively. Among the different insect pests, the relative abundance of fruit fly, B. dorsalis was the highest with 73.65 in 2017-18 and 69.41 per cent in 2018-19 and the lowest was in case of A. foevicolis and A. gossypii, respectively with 1.69 and 2.65 per cent during the respective years. The correlation study with population build up of fruit fly showed a significant positive correlation with maximum and minimum temperature. As regards to fruit fly management strategies, module IV comprised of good agricultural practices, installation of cue lure @ 10/ ha, destruction of damage fruits, spray of neem based insecticides and spray of spinosad 45 SC @ 0.3 ml/L was found to be the best with 0.90 damaged fruits / m2, followed by module III (2.28 damaged fruits / m2) and module II (3.23 damaged fruits / m2). Similarly, module IV (1.36/ m2) and module III (2.46/ m2) was also found to be superior in suppressing the population of phytophagous beetle, E. vigintioctopunctata. In case of M. signata and A. foevocolis, module III (2.30,2.25) and module IV (1.00,1.18) was almost at par in reducing the population. The maximum yield of 97.43 q/ha with a benefit cost ratio of 2.26 was recorded in module IV, followed by next effective module III (83.93 q/ha) with a benefit cost ratio of 2.08. However, the cue lure barrix fly trap showed maximum efficacy related to trap index of 28.76 and the lowest was recorded in molasses trap with trap index of 21.79.
  • ThesisItemOpen Access
    BIOECOLOGY AND MANAGEMENT OF Lepidiota mansueta Burmeister (COLEOPTERA: SCARABAEIDAE)
    (AAU, Jorhat, 2014) Pujari, Dwiban; Dr Badal Bhattacharyya
    Field and laboratory experiments were carried out at Majuli river island and White grub laboratory, Assam Agricultural University, Jorhat to study the bioecology and management of Lepidiota mansueta (Coleoptera: Scarabaeidae) during 2011 to 2013. Experimental results confirmed the biennial life cycle of L. mansueta. The incubation period was found to be varied from 13-18 days with a mean of 15.80 ± 1.70 days. There were three larval instars. The duration of first and second instar were relatively shorter and it ranged from 38-42 (mean: 39.45±1.47 days) and 53-65 days (mean: 61.70 ± 3.53 days) respectively. The third instar grub showed prolonged duration which ranged from 532-556 days with a mean of 542.65 ± 7.60 days. The pupal duration was found to be varied from 26-28 days (mean: 28.60 ± 1.90 days). The total duration from egg to adult ranged from 666-702 days with a mean of 688.20 ± 9.84 days. The mean length and width of egg was 4.96 ± 0.03 and 3.93 ± 0.04 mm, respectively. The mean length and width of first, second and third instar grubs were 13.30 ± 0.95 and 2.47 ± 0.51, 24.10 ± 1.32 and 6.93 ± 0.74, 48.30 ± 1.62 and 10.30 ± 1.02 mm, respectively. The mean length and width of the pupae were found to be 32.60 ± 1.04 and 11.50 ± 0.68 mm respectively. Sexual dimorphism based on adult morphometrics revealed that females were significantly longer in body length (48.4 ± 1.03 mm) than males (43.4 ± 0.51 mm). Although the head plus thorax length of both sexes were identical, the abdomen was significantly longer in female (22.7 ± 0.89 mm) than in male (17.8 ± 0.43 mm). The length of the female alimentary canal (115.0 ± 0.12 mm) significantly differed from the male (94.0 ± 0.08 mm). The mean length of fore legs (18.0 ± 0.12 mm) and mid legs (23.0 ± 0.09 mm) were significantly longer in male than female (Foreleg: 17.2 ± 0.13 and mid leg: 22.1 ± 0.12 mm), whereas the hind legs were identical in both the two sexes. In field conditions, none of the plants were damaged by both sexes of the beetles soon after emergence from the ground. Host specificity test comprised of thirty different plant species conducted in laboratory conditions also revealed that adults of both sexes of L. mansueta were non- feeding. The alimentary canals of dissected adults did not show any food materials in their guts which clearly indicated the non-feeding nature of adults. Further, scanning electron microscopy images of mandibles and maxillae of both sexes of the beetles did not exhibit any dentations which indicate that the mandibles and maxillae were not fitted for phytophagy but probably used for digging of soil for burrowing. In field, the first and second instar grubs were observed from April-May and May-July during 2011 and 2012 respectively. The third instar grubs were noticed in soil throughout the sampling periods with a peak population (4.2 and 3.7 per cubic meter) during August, 2011 & 2012. Habitat selection by L. mansueta grubs studied in five selected ecosystems at Majuli revealed that grubs were significantly more abundant in grasslands which were situated near water sources (8.0, 6.5 & 6.0 nos./m3 during 2011, 2012 and 2013). In open grassland, the mean population of grubs was 4.6, 4.7 & 4.2 numbers per cubic meter during 2011, 2012 and 2013 respectively. Studies on abundance of L. mansueta grubs in grassland and cultivated lands showed significant preference for the soil depth of 0-10 and 11-20 cm. In grassland, grubs showed significant preference for the soil depths of 0-10 (3.18 ± 2.49) and 11-20 cm (1.48 ± 1.06). In cultivated field, the mean number of grubs recorded in 0-10 and 11-20 cm depths were 0.84 ± 0.62 and 0.96 ± 0.66 number, respectively. The grub population recorded in 0-10 and 11-20 cm were found to be at par with each other but significantly differ from 21-30 and 31-40 cm soil depths. Correlation studies between L. mansueta grubs and soil physico-chemical parameters revealed that among soil physical parameters, bulk density (r = -0.804) and sand content (r = -0.482) had significant negative correlations. Among the soil chemical parameters, soil organic matter content (r = 0.834), available nitrogen (r = 0.802) and soil microbial biomass carbon (r = 0.781) had significant positive correlations, while, available P2O5 (r = -0.466) had significant negative correlation on grub population. Multiple regression analysis between grub population and soil parameters revealed that 92.7 per cent grub abundance could be attributed due to the combined influence of soil physico-chemical parameters. The tuber damage caused by the grubs of L. mansueta recorded in potato varied from 22.20 to 30.84 per cent with a mean damage of 28.95 ±1.39 and 27.33 ± 3.14 per cent during 2012 and 2013, respectively. Plant damage in sugarcane ranged from 14.81 to 26.46 with mean damage of 19.25 ± 3.76 and 20.27 ± 1.38 per cent during 2012 and 2013, respectively. The plant damage in green gram and corm damage in colocasia found to be varied from 12.94 to 20.47 and 14.51 to 19.12 with mean damage of 16.02 ± 1.74 & 17.55 ± 1.49 and 17.05 ± 1.33 & 15.52 ± 0.82 during 2012 and 2013, respectively. Among the six insecticides tested for their effectiveness against L. mansueta grubs in potato, fipronil 5 SC @ 150 g a.i./ha recorded lowest per cent of tuber damage on weight basis (5.24 and 4.57%) and this treatment was found to be at par with fipronil 5 SC @ 100 g a.i./ha (5.91 and 5.09%), chlorpyriphos 20 EC @ 400 g a.i./ha (5.55 and 6.20%) and quinalphos 25 EC @ 400 g a.i./ha (6.14 and 6.72%) but significantly superior over rest of the insecticides. On number basis, fipronil 5SC @ 150 g a.i./ha registered lowest tuber damage (4.20%), and it was at par with chlorpyriphos 20 EC @ 400 g a.i./ha (5.25 %) and quinalphos 25 EC @ 400 g a.i./ha (5.66%) during 2012 and chlorpyriphos 20 EC @ 400 g a.i./ha (5.18%), fipronil 5SC @ 100 g a.i./ha (5.99%) and quinalphos 25 EC @ 400 g a.i./ha (6.43%) during 2013, but significantly superior over rest of the treatments. As regards to tuber yield, all the insecticidal treatments exhibited statistical parity except amamectin benzoate 5% SG @ 12.5 g a.i./ha. However, highest benefit cost ratio was recorded in chlorpyriphos 20 EC @ 400 g a.i./ha treated plots (2.50 and 2.62) followed by quinalphos 25 EC @ 400 g a.i./ha (2.23 and 1.85).
  • ThesisItemOpen Access
    Molecular Characterization and Physiological Aspects of Lepidiota mansueta Burmeister (Coleoptera: Scarabaeidae
    (2016) Handique, Gautam; Baruah, A. A. L. H
    The present investigations were carried out in the Department of Entomology and Department of Soil Science, DBT-AAU Centre, Assam Agricultural University (AAU), National Bureau of Agricultural Insect Resources, Bangalore and Tezpur University, during the years 2011-2015 to generate a comprehensive information on the molecular phylogeny as well as some physiological aspects of Lepidiota mansueta, a major white grub species endemic to Majuli river island of Assam. Molecular analysis of genetic diversity revealed that the highest per cent polymorphism and Polymorphism Information Content (PIC) was found for BEM 22 marker which was 80 per cent and 0.799 respectively, while lowest percent polymorphism and PIC was recorded for BEM 11 i.e. 8 per cent and 0.083, respectively. Estimation of genetic similarities among the 18 species of scarab beetles suggested that all species were dissimilar to one another. The similarity value ranged from 0.130 to 0.714. The lowest similarity value was found in between Adoretus renardi and Apogonia blanchardi (0.118) followed by A. blanchardi and Holotrichia sp. (0.130) and the highest similarity value was found between Maladera insanabilis and Onitis philemon (0.769) followed by O. philemon and Adoretus bicolor (0.714). The species L. mansueta had a close similarity to Maladera insanabilis (0.643) while the same was observed to be the lowest with Apogonia blanchardi (0.250). Two major clusters were derived from the dendrogram in which, L. mansueta could be comprehended to be genetically close to M. insanabilis, Catharsius molossus, O. philemon, A. renardi, Anomala pellucida and A. bicolor. However, within this group, L. mansueta stands as an outgroup. Laboratory experiments also revealed distinct sexual dimorphism in the antennal segments between the male and female beetles of L. mansueta. The length and breadth (mean+SD) of pedicel (0.574+0.165; 0.326+0.057), flagellum (1.452+0.272; 0.472+0.113), proximal lamellae (1.699+0.378; 0.767+0.103), middle lamella (1.724+0.174; 0.729+0.092) and distal lamella (1.686+0.137; 0.652+0.097) was significantly higher in males than the females which was recorded to be 0.322+0.014 & 0.214+0.011, 0.797+0.058 & 0.293+0.046, 1.503+0.229 & 0.594+0.069, 1.572+0.190 & 0.577+0.080 and 1.460+0.214 & 0.532+0.027 for pedicel, flagellum, proximal lamellae, middle lamella and distal lamella, respectively. Sensilla located in the antennae of both sexes of L. mansueta beetles also exhibited dimorphism. Scanning Electron Microscopic studies revealed 3 types of sensilla in males and 7 types in females. Wind tunnel bioassays showed clear affinity of adult males and females to prothoracic region (PTR) extracts of males while only males were found to be attracted to the abdominal extracts of females. GC-EAG readings also exhibited clear response of both male and female antennae to the PTR extracts of males while significant response was observed only in male antenna to abdominal extracts of females. GC-MS/FID analysis revealed 4 different compounds in the PTR extracts of males viz., cis-9-Hexadecenal, cis-9-Hexadecenoic acid, Octadec-9-enoic acid and 1-Hexacosene. Likewise, female abdominal extracts also registered 4 compounds viz., cis-9-Hexadecenoic acid, 18-Nonadecenoic acid, Octadec-9-enoic acid and 9,19-Cyclolanost-24-en-3-ol, acetate during the course of study. Microbial investigation of the gut content of third instar grubs of L. mansueta revealed 20 different bacterial cultures. Out of these, 5 bacterial cultures designated as B1, B6, B11, B15 and B19 had the population load with highest colony forming unit/ml. Bacterial flora was considerably varied in size, margins, elevation, gram staining and shape and the variations were based on utilisation of carbohydrates as well as their response to different enzymes. Out of the 5 bacterial cultures, B1, B6 and B15 exhibited cellulose degrading activities in laboratory conditions.