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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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ThesisItem Open Access Evaluation of certain botanicals against cowpea aphid, Aphis craccivora Koch(2018) Mohapatra, Swapnalisha; Gogoi, IneeField and laboratory experiments were conducted in the experimental farm, Department of Horticulture, Assam Agricultural University, Jorhat and Department of Entomology, Assam Agricultural University, Jorhat during 2017-18 to evaluate the efficacy of few botanicals in reducing aphid population and to study the natural enemy complex associated with the cowpea aphid. A preliminary laboratory bioassay was carried out to determine the LC50 and relative toxicity of some botanicals (leaf extracts) viz., Pongamia pinnata, Polygonum hydropiper, Ocimum sanctum, Ageratum conyzoides, Lantana camara and Murraya koenigii along with check imidacloprid 17.8 SL and control. From the present work on bioassay, the order of toxicity to Aphis craccivora with respect to LC50 values was as imidacloprid (0.045%) > O. sanctum (0.828%) > P. hydropiper (1.158%) > M. koenigii (2.100%) > A. conyzoides (4.664%) > L. camara (5.779%) > P. pinnata (6.011%) after 24 hours, imidacloprid (0.036%) > O. sanctum (0.480%) > P. hydropiper (0.576%) > M. koenigii (1.209%) > A. conyzoides (3.188%) > L. camara (4.201%) > P. pinnata (4.328%) after 48 hours exposure period and imidacloprid (0.031%) > O. sanctum (0.316%) > P. hydropiper (0.341%) > M. koenigii (0.707%) > A. conyzoides (2.381%) > L. camara (3.200%) > P. pinnata (3.357%) after 72 hours. The order of relative toxicity was imidacloprid > O. sanctum > P. hydropiper > M. koenigii > A. conyzoides > L. camara > P. pinnata for the exposure period of 24, 48 and 72 hours, respectively. On the basis of LC50 values the most effective ones i.e., O. sanctum, P. hydropiper and M. koenigii each @ 5% were taken for further study on bio-efficacy along with neem oil @ 1%, river sand + neem leaf powder @ 10kg/ha (3: 1 ratio), ash @ 10kg/ha, ash + river sand @ 10kg/ha (5: 1 ratio), check imidacloprid 20gm a.i/ha and control. In the bio-efficacy study of the botanicals P. hydropiper leaf extract @ 5% was found to be most effective in reducing the aphid population up to 77.48% followed by neem oil @ 1% (74.11%), O. sanctum leaf extract @ 5% (74.00%), M. koenigii extract @ 5% (70.96%), ash @ 10kg/ha (68.04%), river sand + neem leaf powder @ 10kg/ha (3:1 ratio) (44.48%) and ash + river sand @ 10kg/ha (5:1 ratio) (42.53%) after seven days of spraying. All together five coccinellid predators viz., Coccinella transversalis, Cheilomenes sexmaculata, Harmonia dimidiata, Micraspis discolor and Brumoides suturalis were recorded as natural enemies feeding on aphids. From the correlation studies with weather parameters, aphids showed a significant negative correlation with average relative humidity (r = -0.515) and rainfall (r = -0.514). Among the coccinellid predators, Coccinella transversalis (r = -0.517) and Harmonia dimidiata (r = -0.505) showed significant negative correlation with average relative humidity. All the predators found viz., Coccinella transversalis (r = 0.883), Cheilomenes sexmaculata (r = 0.611), Harmonia dimidiata (r = 0.584), Micraspis discolor (r = 0.770) and Brumoides suturalis (r = 0.605) showed significant positive correlation with their prey i.e aphid, Aphis craccivora.ThesisItem Open Access LIFE CYCLE OF LAC INSECT ON DIFFERENT HOST PLANTS IN ASSAM CONDITION(AAU, Jorhat, 2018) Saikia, Priyanka; Das, PurnimaField and laboratory experiments were conducted at Lac park and Lac laboratory, Department of Entomology, Assam Agricultural University, Jorhat-13 to study the life cycle of lac insect, Kerria chinensis (Mahd.)and its associated fauna on four different host plants viz., Flemingia semialata (Roxb.), Flemingia macrophylla (Willd.), Flemingia strobilifera (Roxb.) and Cajanas cajan (Linn.). The study was conducted for two consecutive seasons of lac crop i.e., from 14th May to 27th October, 2017 (Season I) and 28th October, 2017 to 20th April, 2018 (Season II). Among the four investigated hosts, F. semialata (Roxb.) was recorded as superior to the other hosts in terms of broodlac production, phukilac production and scrappedlac yield (205.9 g, 98.96 g and 41.51 g) respectively, along with other parameters i.e. highest initial density of settlement (nos./sq.cm), final density of settlements (nos./sq.cm), density at crop maturity (nos./sq.cm), cell size (mm), cell weight (mg), resin weight (mg), fecundity (nos. of crawlers /female cell), broodlac yield (kg) and broodlac ratio (broodalc yield at harvesting/inoculated broodlac), and having lowest per cent of male cells, mortality % and broodlac-scrappedlac ratio. Life cycle in season I was completed in 165.21 days in F. semialata (Roxb.) whereas in season II life cycle took 172.21 days to complete. Likewise, all the parameters showed better results in season II compared to season I. The present investigation has strongly proved that the Kerria species prevailed in the North Eastern part of India is Kerria chinensis (Mahd.) (gene bank accession no. MH562709). Study on natural enemy complex of lac encrustation at lac laboratory, revealed the occurrence of three species of predators viz., Eublema amabilis Moore, Psedohypatopa pulverea Meyr. and Oryzaephilus surinamensis Linn., two species of parasitoids viz., Tachardiaephagus tachardiae (Howard) and Eupelmus tachardiae (Howard) and three species of hyperparasitoids viz., Eurytoma pallidiscapus, Cam., Apanteles tachardiae, pp. nov. and Bracon greeni Ashmead. Maximum population of pests were recorded during November, 2017 as compared to May, 2018. Eublema amabilis Moore were recorded more than other pests in lac encrustation F. semialata (Roxb.). The period of investigation in both the seasons (May, 2017 to April, 2018) showed the occurrence of 12 species of phytophagous pests on F. semialata (Roxb.), 11 species on F. macrophylla (Willd.), 3 species on F. strobilifera (Roxb.) and 3 species on C. cajan (Linn.). Four different species of coccinellid beetle viz., Coccinella transversalis Linn., Cheilomenes sexmaculata Fab., Micraspis discolor Fab. and Harmonia dimiata were recorded as natural enemies on crop pests of Flemingia ecosystem. Studies on population density of Archips sp., Somena scintillans Walker, Euproctis sp., Aphis craccivora Koch and Myzus persicae Sulzer were recorded in field condition. Correlation studies revealed that the population density of Archips sp. exhibited significant positive correlation with maximum temperature, minimum temperature, rainfall , wind speed and bright sunshine hours. The population density of S. scintillans Walker showed significant positive correlation with maximum temperature, minimum temperature and rainfall; whereas it showed significant negative correlation with bright sunshine hours. Similarly population density of Euproctis sp. showed significant negative correlation with maximum temperature and minimum temperature. The population density of A. craccivora Koch showed significant negative correlation with minimum temperature, rainfall and wind speed; whereas it showed significant positive correlation with bright sunshine hours. The population density of Myzus persicae Sulzer showed significant negative correlation with wind speed and significant positive correlation with bright sunshine hours. Multiple regression equations were developed for each of Archips sp., Somena scintillans Walker, Euproctis sp., A. craccivora Koch and Myzus persicae Sulzer to predict their seasonal incidences under the agro climatic conditions of Jorhat. The crop calendar revealed that the important pests of host plants viz., Archips sp. were occurred from July to October; Euproctis sp. from April to August; Somena scintillan Walker from August to November; Aphis craccivora Koch from July to February and Myzus persicae Sulzer from September to February in both seasons.ThesisItem Open Access Efficacy of some biopesticides and synthetic insecticides against banana leaf and fruit scarring beetle, Nodostoma subcostatum Jacoby (Coleoptera: Chrysomelidae)(2018) Kalita, Biraj; Gogoi, IneeField and laboratory experiments were conducted in the experimental farm, Department of Horticulture, Assam Agricultural University, Jorhat and Department of Entomology, Assam Agricultural University, Jorhat during 2017-18to evaluate in vitro and in vivo efficacy of biopesticides and synthetic insecticides against banana leaf and fruit scarring beetle A preliminary laboratory bioassay was carried out to determine the LC50 and relative toxicity of the treatmentsviz., azadirachtin 0.03 EC, Beauveria bassiana WP, Metarhizium anisopliae WP, imidacloprid 17.8 SL, profenofos 50 EC along with check chlorpyriphos 20 EC and control. From the present work on bioassay, the order of toxicity with respect to LC50 values was profenofos 50 EC>imidacloprid 17.8 SL>azadirachtin 0.03EC>Metarhizium anisopliae WP>Beauveria bassiana WPfor the exposure period of 1,3 and 5 days, respectively.For field bio efficacy, the treatments were tested at three critical stages of growth of the banana plant and among the treatments tested, chlorpyriphos @ 0.05% proved to be the best treatment at all the three stages of growth in perusal of its ability in reducing the beetle population at 3, 7 and 15 days after treatment, followed by profenofos @ 1.5 L/ha and imidacloprid @ 20 g a.i./ha. Among the biopesticides, azadirachtin @ 2.5 L/ha arrayed up itself as the best over the other two. Plants that were bud injected with imiacloprid registered highest pulp to peel ratio, fruit weight, bunch weight, yield and B:C ratio. Seasonal incidence of leaf and fruit scarring beetleon Dwarf Cavendish was recorded at fortnightly intervals from May, 2017 to April, 2018. Highest population and scars were recorded during second fortnight of September, 2017 and lowest during first fortnight of January, 2018. The average population and scars produced by the insect showed positive and significant correlation with various meteorological factors except morning relative humidity. Multiple regression analysis of beetle population and scars produced by Nodostoma subcostatum with different meteorological parameters showed 69.2 % variation in population and 72.6 % variation in scars due to the combined effect of various meteorological parameters. On considering all the above facts and figures and hitherto due to nonexistence of other anticipatory technology, the bud injection method with imidacloprid and azadirachtin proved to be safer and competent preventive technique for reducing the percentage of blemished fruits (<15%) caused due to banana leaf and fruit scarring beetle in comparison to spraying method of application. This technology required very less quantity of pesticides and was able to keep the original superficial fruit peel appearance and significance, which in turn will able to fetch better price on quality fruits in market and provide financial profit to banana growers and traders.ThesisItem Open Access DEVELOPMENT OF INTEGRATED PEST MANAGEMENT MODULES AGAINST INSECT PESTS OF BHUT JOLOKIA (Capsicum chinense Jacq.)(2019-09) Bora, Sasanka Sekhar; Saikia, D. K.Experiments were carried out under field conditions at the Experimental Farm, Department of Horticulture as well as in the Department of Entomology and Department of Plant Pathology, Assam Agricultural University, Jorhat during 2017-18 and 2018-19 to study the major sucking and chewing pests of Bhut Jolokia causing substantial losses in fruit yield. At present, IPM has been attaining immense importance in the agricultural scenario of India and abroad. Therefore, evaluation of sustainable IPM modules was felt very much necessary in Bhut Jolokia. The result revealed that altogether twenty three numbers of insect pests were associated with the crop and among them aphid (Aphis gossypii Glover/Myzus persicae Sulzar), Whitefly (Bemisia tabaci Gennadius), thrips (Scirtothrips dorsalis Hood), yellow mite [Polyphagotarsonemus latus (Banks)], Cutworm (Agrotis ipsilon Hufuagel) and fruit fly [Bactrocera dorsalis (Hendel)] were considered as the key pests of Bhut Jolokia. Highest incidence of major pests was obtained in the 1st fortnight of April during 2018 as against 2nd fortnight of April during 2019, respectively. A new invasive pest, spiraling whitefly (Aleyrodicus dispersus Russel, Aleyrudidae:Hemiptera) was also reported for the first time in Bhut Jolokia from Assam. Five IPM modules were evaluated against insect pests of Bhut Jolokia, of which module I comprised of recommended dose of fertilizer and farm yard manure+ application of microbial consortium + growth promoter viz., Tricontanol + weeding at 30, 60 and 90 Days after transplanting (DAT) + imidacloprid 17.8 SL 0.4 ml per lt @ 40 days interval was found to be the most effective module in respect of B: C ratio (3.02: 1) followed by module III (Vermicompost 1.25t/ha+ neem cake 500 kg/ha + application of microbial consortium + black polythene mulching + garlic extract @ 10% at 20 and 70 DAT +NSKE 5% at 35 and 100 DAT + installation of sticky trap @ 25 traps /ha) where the B:C ratio was 2.96 with maximum yield of 740.74 gm per plant with next higher yield of 712.13 gm per plant in module I. Hence, module III in comparison to module I seems to be quite promising strategy as it did not require any insecticidal interference keeping natural enemies and ecosystem undisturbed. Out of eight cultivars collected cv. Assam 1 (King) contributed maximum yield of 719.85 gm per plant followed by Assam 4 with 626.67 gm per plant with minimum susceptibility towards pests and diseases. Correlation studies between sucking pests and phenotypic characters indicated that only number of leaves and leaf area index had negative significant impact while other parameters viz., plant height and branches showed no effect. Result of different shade level, 75 per cent shade showed highest plant height and leaf area index of 90.01 cm and 1.81 as against open condition where it was only 53.18 cm and 1.46. The number of leaves and branches of Assam 1 cultivar were to be highest 220.51 cm and 8.75 in open condition, while they were 80.75 cm and 5.13 in 75 per cent shade level. Likewise, for flowering, 116.75 days required in case of 75 per cent shade level, whereas it was only 93.25 days in case of open condition. Similarly, fruit numbers also reduced in case of 75 per cent shade level which was only 27.0 while 92.13 was in case of open condition. Yield per plant was also around 718.13 gm per plant in open condition, whereas it was only 223.63 gm per plant in 75 per cent shade level. The major sucking pests and coccinellid predator population found to be in higher side in open condition also. In 75 per cent shaded area the pooled infestation of aphid, whitefly, thrips and mite was 0.62, 0.35, 0.26 and 0.54 numbers per three leaves whereas, it was 1.69, 1.58, 1.25 and 2.58 numbers per three leaves in open condition. Predatory spider population found highest with 0.34 numbers per plant while coccinellid population was lowest with 0.15 numbers per plant at 75 per cent shade level. But coccinellid population was highest with 0.40 numbers per plant in open condition while 0.18 numbers per plant spider also found at open condition, respectively. RT PCR method confirmed the presence of Cucumber mosaic virus (CMV) on whole seed and seed coat, which indicates that CMV transmitted through seed.ThesisItem Open Access Impact of elevated temperature and carbon dioxide on foraging behaviour of Apis cerana F. in oilseed ecosystem(2019-12) Gogoi, Jaya; Rahman, AtaurClimate change associated with rise in concentration of atmospheric carbon dioxide and temperature is expected to affect the activity of pollinator and crop production. Oilseeds are an important component of the agricultural produce, next to food grains. The impact of elevated temperature and carbon dioxide on foraging behaviour of Apis cerana F. in oilseed (rapeseed var. TS-38 and sesamum var. ST-1683) ecosystem was studied separately in two experiments using Carbon Dioxide Temperature Gradient Tunnel (CTGT) and Open Top Chamber (OTC) established at Department of Crop Physiology and Department of Entomology, Assam Agricultural University, Jorhat during 2016-2019. In the first experiment four levels of CO2 (2 ambient at 400 ppm each and elevated of 550 ppm and 650 ppm) and 4 levels of temperature (2 ambient, +2°C and +4°C) and in the second experiment 4 levels of CO2 (2 ambient at 400 ppm each and elevated of 550 ppm and 650 ppm) and 4 levels of temperature (2 ambient, +3°C and +3°C) were used to assess the impacts of elevated temperature and CO2 levels on foraging behaviour of Apis cerana F. in rapeseed and sesamum ecosystem. No anesthetic effect was found on Apis cerana when exposed to different concentrations of CO2 viz., 0.04%, 0.05% and 0.065% for 3 minutes, 15 minutes and 30 minutes. The interactive effect of elevated temperature and CO2 on maximum frequency of flower (rapeseed) visit by Apis cerana was recorded in CTGT III (13.92±0.23) at 0800-0900 hours of the day whereas time spent per flower (6.12±0.17 seconds) at 1000-1100 hours of the day, time taken per trip (47.37±0.47 minutes) and pollen load per trip (7.87±0.12 mg) was recorded in field condition (ambient condition) compared to CTGT III (650 ppm CO2, +4°C). The time taken per trip (F=44.1000, P < 0.0001) and pollen load per trip (F=189.5555, P < 0.0001) varied significantly. Similar results were observed in sesamum also with maximum frequency of flower visit by Apis cerana (9.08±0.13) at 0800-0900 hours of the day, time spent per flower (7.20±0.10 seconds) at 0900-1000 hours of the day, time taken per trip (28.91±0.51 minutes) and pollen load per trip (6.11±0.11 mg) was recorded in field condition (ambient condition) compared to OTC III (650 ppm CO2, +3°C). The highest bee mortality rate of 9.46% was recorded in CTGT III followed by 6.57% (CTGT II) and 3% (CTGT I) during the investigation period. The plant height increased with elevated temperature and CO2 whereas the yield attributing parameters like number of siliqua and capsules per plant, number of seeds per siliqua and capsules and 1000 seed weight of rapeseed and sesamum decreased with elevated temperature and CO2 condition. However, with elevated temperature and CO2 level, the stover yield of rapeseed and sesamum were increased whereas harvest index (HI) decreased significantly. The yield was reduced significantly (F= 61.9680, P < 0.0001 and F= 16.2102, P < 0.0001) with elevated temperature and CO2 condition and the highest yield of rapeseed and sesamum was recorded in field condition (10.05±0.23 q/ha and 7.58±0.27 q/ha) compared to CTGT III (6.03±0.23 q/ha and 5.06±0.27 q/ha). Reduction in crop yield at increased temperature and CO2 was mainly attributed to reduction in foraging activity of A. cerana, number of siliqua and capsules per plant, number of seeds per siliqua and capsules, 1000 seed weight and harvest index. The present study revealed that elevated temperature and CO2 level could decrease the foraging activity of pollinator and crop yield.ThesisItem Open Access Diversity and foraging behaviour of syrphid flies on Brassica campestris L. and Mangifera indica L.(2019-07) Bora, Madhumita Sonowal; Deka, Mukul Kr.Investigation on the diversity and foraging behaviour of syrphid flies on Brassica campestris L. and Mangifera indica L. was carried out in the ICR Farm; Horticulture Orchard, Department of Horticulture and Apiculture laboratory, Department of Entomology, Assam Agricultural University, Jorhat during 2017-2018 and 2018-2019. The insects forager complex of rapeseed consisted of 27 species namely Apis cerana, A. dorsata, Nomia sp., Stomorhina discolour, Episyrphus balteatus, Betasyrphus aeneifrons, Syrphus sp., Eristalinus arvorum, E. polychromata, E. quinquestriatus, E. megacephalus, E. paria, Mesembrius quadrivittatus, Eristalis tenax, Phytomia errans, Melonstoma orientale, Asarkina ericetorum, Sphaerophoria sp., Dideopsis aegrota, Delias pasithoe, Micraspis discolor, Coccinella tranversalis, Chrysomya meghacephala, Musa domestica, Coccinella septempunctata, Syntomoides imaon and Pieris rapae. Out of these Stomorhina discolour was recorded to be maximum (9.37%). Whereas, in mango all total 15 species namely Apis cerana, A. dorsata, A. florea, Stomorhina discolour, Eristalinus arvorum, E. polychromata, E. quinquestriatus, E. megacephalus, E. paria, Mesembrius quadrivittatus, Asarkina ericetorum, Chrysomya meghacephala, Musa domestica, Neptis cartica and Oecophylla smargdina were recorded. Out of these Eristalinus arvorum was recorded to be maximum (12.05%). The highest species diversity index of 2.59 was recorded from rapeseed crop as compared to 2.03 from mango crop. The maximum total body length in Eristalinus arvorum (10.00 ± 0.52 mm) which was followed by E. polychromata (8.64 ± 0.51mm) and minimum Mesembrius quadrivittatus (2.19 ± 0.60 mm), respectively. The principal component analysis of 15 morphometric characters obtained from15 species of syrphids which explained 84.84 per cent variation among the species of syrphids. Whereas, in the principal component 1, 15 morphometric characters were influencing parameters with components loading from 0.985 to 0.280 that accounting for 76.32 per cent of the variation observed. The length and width of eggs of E. balteatus, B. aeneifrons and Syrphus sp. were 0.70 ± 0.01 mm and 0.26 ± 0.00 mm; 0.70 ± 0.01mm and 0.26 ± 0.00 mm; 0.71 ± 0.01 mm and 0.27 ± 0.00 mm, respectively. The incubation periods were 3.20 ± 0.45, 2.80 ± 0.45 and 3.40 ± 0.55 days, respectively. The maximum hatching percentage of eggs was 89.30 per cent of E. balteatus. The larvae passed through three instars. The maximum length and width of first instar larvae were 2.14 ± 0.03 mm and 0.70 ± 0.02 mm of E. balteatus followed by second instar larvae were 4.86 ± 0.05 mm and 0.90 ± 0.05 mm of Syrphus sp., respectively. The minimum duration of first instar larvae of B. aeneifrons was recorded (2.40 ± 0.55 days) followed by second instar larvae of B. aeneifrons and Syrphus sp. were recorded (3.40 ± 0.55 days), respectively. The total life period of male and female of E. balteatus were (37.60 ± 1.52 days and 38.60 ± 1.52 days) recorded. The number of Eristalinus and Syrphini per sq. m per minute on rapeseed was recorded to be maximum (7.89 ± 0.09 and 7.90 ± 0.93) at 1100-1200 and minimum (1.26 ± 0.07 and 1.53 ± 0.18) at 0700-0800 hours of the day. Maximum time spent per flower by Eristalinus and Syrphini also recorded to be 29.04 ± 2.03 seconds and 7.18 ± 0.18 seconds at 0700-0800 hours and minimum was 19.24 ± 3.09 and 5.03 ± 0.05 seconds at 1000-1100 hours of the day. The number of flower visit per minute was recorded to be maximum (3.90 ± 0.22 and 7.82 ± 0.32) at 1000-1100 hours and minimum (2.59 ± 0.21 and 2.95 ± 0.24) at 0700-0800 hours of the day. The number of Eristalinus and Syrphini per sq.m per minute on mango was recorded to maximum (8.04 ± 0.14 and 6.84 ± 0.13) at 1100-1200 and minimum (1.45 ± 0.07 and1.38 ± 0.10) at 0700-0800 hours of the day. Maximum time spent per flower by Eristalinus and Syrphini also recorded to be 26.85 ± 0.92 and 7.45 ± 0.14 seconds at 0700-0800 hours and minimum was 20.76 ± 1.49 and 5.52± 0.09 at 1000-1100 and 1200-1300 hours of the day. The number of flower visit per minute was recorded to be maximum (3.68 ± 0.11 and 6.53 ± 0.10) at 1300-1400 and 1100-1200 hours and minimum (2.54± 0.24 and 2.74± 0.05) at 1500-1600 and 1400-1500 hours of the day. Various meteorological parameters affected the different foraging activities of Eristalinus and Syrphini viz., number of Eristalinus/Syrphini per sq.m per minute, number of flower visit per minute and time spent per flower per second. Temperature and bright sunshine hours showed positive correlation whereas rainfall and relative humidity showed negative correlation with the different foraging activities of Eristalinus and Syrphini. The relative abundance of Eristalinus and Syrphini was recorded to be maximum (9.52 ± 0.69 nos. /5min) at 1100-1200 hours and (7.41 ± 0.38 nos. /5min) at 1200-1300 hours and minimum (1.66 ± 0.33 and 1.98 ± 0.11 nos. /5min) at 0700-0800 hours of the day. The number of loose pollen grain adhering to the bodies of Eristalinus and Syrphini was recorded to be 1333.2 ± 50.48 nos. and 1294.6 ± 65.10 nos. per forager. The maximum pollination index of 7.40 was recorded from Eristalinus as compared to 7.21 of Syrphini on rapeseed. The relative abundance of Eristalinus and Syrphini was recorded to be maximum (8.90 ± 0.22 nos. /5min) at 1100-1200 hours and (7.07 ± 0.51 nos. /5min) at 1200-1300 hours and minimum (2.40 ± 0.17 and 2.49 ± 0.09 nos. /5min) at 0700-0800 hours of the day. The number of loose pollen grain adhering to the bodies of Eristalinus and Syrphini was recorded to be 1415.80 ± 110.80 nos. and 1294.80 ± 60.82 nos. per forager. The maximum pollination index of 9.63 was recorded from Eristalinus as compared to 7.14 of Syrphini on mango.ThesisItem Open Access PLANT MEDIATED SYNTHESIS OF SILVER NANOPARTICLES AND THEIR EFFICACY AGAINST CERTAIN SUCKING PESTS(2019-09) THOMAS, DELLA; Rahman, S.Experiments were carried out in the Department of Entomology and Plant Pathology, Assam Agricultural University, Jorhat during 2017-18 and 2018-19 to study the efficacy of plant mediated synthesized silver nanoparticles against certain sucking pests. The silver nanoparticles were successfully synthesized by using plant extracts such as Tulsi (Ocimum sanctum), Bakul (Mimusops elengi), Garlic (Allium sativum) and Posotia (Vitex negundo). The synthesized silver nanoparticles were characterized by UV-Vis spectrophotometer, Zeta sizer, Fourier Transform Infrared Spectroscopy (FTIR) and Transmission Electron Microscopy (TEM). The UV-Vis spectra recorded peak at 425 nm, 427nm, 420 nm and 430 nm for Tulsi, Bakul, Garlic and Posotia AgNPs, respectively. FT-IR analysis for Tulsi, Bakul, Garlic and Posotia AgNPs showed strong peaks at ranges of 400-4000 cm-1 which exhibited different types of functional groups viz., (O-H, C-H, N-H, H-H and C-C). Zeta potential was determined and recorded the charge of green synthesized silver nanoparticles as -24.2, -24.1, -16.7 and -33.0 mV for Tulsi, Bakul, Garlic and Posotia, respectively. TEM study revealed that the synthesized silver nanoparticles from different plant extracts were spherical and circular in morphology and the average size of 8 to 25 nm. The efficacy of plant mediated synthesized silver nanoparticles against mustard aphid (Lipaphis erysimi), papaya mealybug (Paracoccus marginatus), rugose spiralling whitefly (Aleurodicus rugioperculatus) and two spotted spider mite (Tetranychus urticae) was investigated in the dilutions of 100, 200, 300, 400 and 500 ppm. Nanoparticles obtained from Tulsi were found to be effective against L. erysimi and A. rugioperculatus for both the years 2017-18 and 2018-19 with nymphal mortality of L. erysimi (88.89% and 84.44%) and A. rugioperculatus (86.67% and 84.44%) after the fifth day of treatment. Nanoparticles extracted from Garlic were found to be effective against P. marginatus with 84.44% and 82.22% nymphal mortality for the year 2017-18 and 2018-19. Incase of T. urticae, nanoparticles extracted from Garlic showed the highest mortality of 73.33% and 77.78% for the year 2017-18 and 2018-19, respectively. The LC50 was estimated for all the tested sucking pests against all the synthesized AgNPs in 2017-18 and 2018-19. For L. erysimi the lowest value was calculated from Tulsi AgNPs after the fifth day of treatment for both the years 2017-18 and 2018-19, recorded 119.12 ppm and 109.76 ppm, respectively. For P. marginatus, lowest LC50 of 109.21 ppm was recorded from Garlic AgNPs after the fifth day of the treatment during 2017-18. In 2018-19 also the lowest LC50 value 116.33 ppm was obtained from Garlic AgNPs. For A. rugioperculatus, the lowest LC50 from Tulsi AgNPs was found to be 123.12 ppm during 2017-18 and in 2018-19 also Tulsi AgNPs showed the lowest LC50 value of 139.27 ppm. For T. urticae the lowest value was calculated from Garlic AgNPs after the fifth day of treatment for both the years 2017-18 and 2018-19, recorded 142.57 ppm and 130.39 ppm, respectively. Behavioural changes in selected pests have also been noticed after treating with synthesized silver nanoparticles for both the years 2017-18 and 2018-19. For L. erysimi, the movement became slower, decreased feeding activity and colour changed to brown-black, paralysed, body contents became dry and subsequently death. After application of AgNPs on the eggs of P. marginatus, the colour changed to light orange to dark brown and did not hatch. The neonate crawlers die within 2-3 days after spray, survival was zero in some replicated plates, deformed and swelled body, sluggish if touched brown liquid ooze out. The cream colour changed to dark brown which was often died. For A. rugioperculatus the viability of eggs reduced and nymphs changed their colour from light cream to dark brown and die soon. While incase of T. urticae, legs became folded, move only when it disturbed, body contents come out and dry on the 5th day of post spray. In the pot experiments with biosynthesized AgNPs against L. erysimi showed the highest per cent reduction by Tulsi AgNPs (79.40%) and the least per cent reduction was observed with Posotia AgNPs (61.55%). For P. marginatus, Garlic AgNPs was highly toxic as this caused 58.40% reduction at one day after spraying which was increased to 75.17% after 5 days of spraying. Among different biosynthesized AgNPs, Garlic AgNPs was found to be most effective against T. urticae population which resulted in 69.33% reduction in 5 days after application in potted plants.ThesisItem Open Access Biology of Callosobruchus chinensis (L.) on Green gram, Vigna radiata (L.) and Black gram, Vigna mungo (L.) in two different seasons(AAU, Jorhat, 2019-07) Borthakur, Abhilasa Kousik; Gogoi, IneeField and laboratory experiments were conducted in the Instructional cum Research farm, Department of Agronomy, Assam Agricultural University, Jorhat and Department of Entomology, Assam Agricultural University, Jorhat during 2018-19 to examine the biology of Callosobruchus chinensis (L.) in two different seasons viz., summer and winter considering green gram(variety-Pratap) and blackgram(variety-KU301) as host plants. Ovipositional preference of Callosobruchus chinensis (L.) was also evaluated on four different host plants viz., green gram (variety-Pratap), black gram(variety-KU301), chickpea(variety-JG16) and cowpea(variety-Green fall). The data on biology of C. chinensis (L.) revealed that the insect had a comparatively shorter developmental period in the summer season (April-May) than in the winter season (October-November). In green gram, the fecundity of the insect during summer season was 4.96±0.13 number of eggs while in winter it was 3.60±0.19 number of eggs. The incubation period was found to be 4.92±0.14 days and 6.24±0.13 days during summer and winter respectively. The insect took 17.50±0.12 days to complete its larval period during summer and 23.57±0.18 days during winter. The pupal period was recorded to be 7.53±0.09 days during summer and 9.41±0.07 days during winter. Thus the total developmental period was worked out and noted to be 29.95±0.21 days during summer and 39.22±0.22 days during winter. The longevity of the male was upto 7.73±0.23 days during summer while in winter it survived upto 10.36±0.21 days. The longevity of the female was recorded as 6.70±0.21 days and 8.10±0.27 days during summer and winter respectively. In black gram the mean fecundity was recorded as 3.10±0.12 in summer and 1.57±0.11 in winter. The incubation period was recorded as 5.46±0.12 days and 7.37±0.15 days during summer and winter respectively. The larval period was completed in 18.28±0.08 days during summer and 24.50±0.12 days in winter. The pupal period was 8.17±0.07 days and 10.12±0.12 days during summer and winter respectively. The developmental period was completed in 31.91±0.15 days during summer while it took 42.08±0.21 days during winter. The male longevity was 8.90±0.23 days during summer while 9.40±0.29 days during winter. The longevity of the female was 7.40±0.26 days and 6.80±0.20 days during summer and winter respectively. The data on ovipositional preference revealed that green gram was the most preferred host for egg laying with a mean of 17.40 eggs per four pods, followed by chickpea (14.33), cowpea (11.50) and black gram (8.50). Hatchability percentage was maximum in green gram (90.55%) followed by chickpea (86.24%), black gram (82.86%) and cowpea (81.80%). Maximum adult emergence was observed in green gram (79.16%) and minimum adult emergence was observed in black gram (64.82%). Adult emergence in chickpea was 75.53% and in cowpea it was 76.55%. The data on morphological parameters of the pods revealed that cowpea had the maximum pod length (14.13cm), trichome number/mm2 (14.16) and pod wall thickness (0.73mm) . Correlation analysis between ovipositional parameters and morphological parameters of pods revealed that eggs laid, hatchability percentage and adult emergence had a negative correlation with trichome number/mm2 and pod wall thickness, whereas pod length showed a positive correlation with eggs laid, hatchability percentage and adult emergence percentage. Data on growth parameters revealed that the maximum percentage of reproductive success was shown in green gram (65.52%) followed by Cowpea (55.91%), chickpea (54.56%) and black gram (42.32%). Total developmental period was highest in black gram (33.12 days) followed by chickpea (32.12 days), green gram (31.05 days) and least in cowpea (28.13 days). Growth Index was lowest in black gram (1.96) while the highest was found in cowpea (2.73) followed by green gram (2.56) and chickpea (2.35). Correlation between Growth Index and growth parameters showed that Growth Index was negatively correlated to developmental period and positively correlated to adult emergence and number of eggs laid. A significantly high positive correlation between Growth Index and percentage adult emergence was exhibited by cowpea and chickpea.ThesisItem Open Access DIVERSITY OF SPIDERS (ARANEAE) IN TEA(AAU, Jorhat, 2018-01) Hazarika, Somar; Bora, D.K.A survey was conducted to study the diversity of spiders in different tea gardens viz., conventional, organic and small grower tea gardens of Jorhat district from May, 2016 to April, 2017. The results revealed a total number of 2954 specimens of spiders collected under 16 genera, 8 families and 20 species viz., Cyrtophoracicatrosa, Nephila kuhlii, Argiope pulchella, Cyclosa mulmeinensis, Neoscona sp, Cyclosa spirifera, Cyclosa bifida, Araneus mitifica, Oxyopes sitae, Oxyopes shweta, Oxyopes sp, Rhene danieli, Phintella vittata, Telamonia dimidiata, Tetragnatha sp, Leucauge decorata, Heteropoda ventoria, Xysticus sp and Perdosa peaudoannulata. Among all the species, Castianeira furva has been recorded for the first time from this region. Species richness (R = 3.07) and evenness (E = 0.96) was recorded the highest in Deha T.E. (organic garden) and was found lowest for Saikia T.E (small grower garden) i.e., 2.51 and0.89 respectively. However, species diversity was recorded highest in conventional garden, Dhloi T.E. (H’ = 2.88). The correlation studies revealed that the spider population exhibited significant positive correlation with total rainfall (r = 0.776) and non-significant for maximum temperature, minimum temperature and evening relative humidity while, a significant negative correlation was observed with morning relative humidity (r = -0.797) and bright sunshine hour (r = -0.676). Some morphological and biochemical characters of seven selected tea clones (TV 1, TV 2, TV 7, TV 9, TV 12, TV 18, TV 23) in the Experimental Garden of Plantation crops, Assam Agricultural University, Jorhat were examined to determine their effects on common insect pests and spider population. The results showed that all the clones were susceptible to the pests, TV 23 being more susceptible compared to others (H. theivora 6.22 no/bush, O. coffeae 18.35 no/leaf, Hyposidra sp 3.43 no/bush). However, no significant difference for spider populations was found to exist amongst the clones. With respect to morphological characters, the examined clones showed significant difference for total number of branches, leaf area and trichome densities. The differences in leaf moisture contentwere also significant. Moreover, it was found that the phenol content of examined clones gradually decreased due to pest infestation and the reduction was highest in TV 23 (22.43%). The linear correlation among morphological and biochemical attributes of selected tea clones with pests showed that total no of branches and leaf area had a non significant negative correlation with H. theivora (r = - 0.664, - 0.333), O. coffeae (r = -0.277, -0.175) and Hyposidra sp (r = -0.156, -0.179) while trichome density had significant negative correlation with H. theivora (r = -0.643) O. coffeae (r = -0.475) and Hyposidra sp (r = - 0.493). However, the moisture content showed a non-significant positive correlation for H. theivora (r=0.064) but established a negative association with O. coffeae (r = -0.446) and Hyposidra sp (r = -0.370). Regarding insect pests, both the reduction in phenol content and spider population exhibited a significant positive association. A field experiment was conducted in the Experimental Garden of Plantation crops, Assam Agricultural University, Jorhat, during 2016 and 2017 to investigate the effect of pesticides on common insect pests and spider population in tea plantation. On the basis of the pooled data of two year observations recorded at 1st, 5th and 10th days after application and revealed that all the treatments showed significant differences over control. Among the treatments thiomethoxam 25% WG @ 0.01% was found to be most effective against H. theivora followed by deltamethrin 2.8 EC @ 0.02% and azadirachtin @ 0.003%, whereas spiromesifen 240 SC @ 0.2% was found to be least effective against H. theivora population. The pooled data on the efficacy of different pesticides on O. coffeae revealed that spiromesifen 240 SC @ 0.2% was most effective followed by ethion 50EC @ 0.25%, deltamethrin 2.8 EC @ 0.02% and azadirachtin @ 0.003% whereas thiomethoxam 25% WG@ 0.01% @ was found to be least effective against O. coffeae population. Among all the treatments ethion 50EC @ 0.25% was found to be most toxic on spider population followed by deltamethrin 2.8 EC @ 0.02% and B. bassiana @ 2% was found safer to spider population which was followed by azadirachtin 5 EC 0.003%.
