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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 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 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%.ThesisItem Open Access PEST COMPLEX OF BHUT JOLOKIA AND THEIR MANAGEMENT(AAU, Jorhat, 2017-07) Thangjam, Rojeet; Borah, R.K.Field and laboratory experiment on pest complex and their natural enemies, identification and detection of insect vectors, integrated management of important pest of Bhut Jolokia and cost benefit ratio of different treatment modules were carried out during rabi (2014-15 and 2015-16) at Horticultural Orchard, Department of Entomology and Department of Plant Pathology, Assam Agricultural University, Jorhat (Assam). Altogether 110 species of arthropods were found to be associated with Bhut Jolokia at Jorhat, out of which 19 species were identified as pest, 64 as natural enemies and 27 species as casual visitors. Among the different insect pests recorded, 6 species were identified as “major” and they were Aphis gossypii (Glover), Myzus persicae (Sulzer), Bemisia tabaci (Gennadius), Bactrocera latifrons (Hendel), Scirtothrips dorsalis (Hood) and Polyphagotarsonemus latus (Banks). Among the natural enemies recorded, 44 species of predators, 13 species of parasitoids and one species of entomopathogenic fungus belongings to different orders have been reporting for the first time adding the number of natural enemies in Bhut Jolokia ecosystem. Moreover, among the dipteran predators, Syrphid fly (Lathyrophthalmus arvorum) has been reporting for the first time from Assam. All the genotypes of Bhut Jolokia collected from Assam, Manipur and Nagaland showed susceptible to viral diseases. However, the lowest incidence was observed in KCM2 (33.33%) and KCN1 (33.33%). Among the insect pests, 3 species viz., B. tabaci, A. gossypii and M. persicae have also been identified as a vector of Chilli Leaf Curl Virus (ChLCV), Cucumber Mosaic Virus (CMV) and Potato Virus Y (PVY), respectively during the investigation and they were confirmed through DAS-ELISA and PCR technique. Among the different treatment modules, module M2 that includes seedling root dip treatment with imidacloprid 17.8 SL @ 40g a.i./ha for 30 minute just before transplanting + growing of border crop (okra) + spraying of imidacloprid 17.8 SL @ 40g a.i./ha at 20 days after transplanting at 15 days interval (4 sprays) was found to the best performer in suppressing the population of aphid and whitefly followed by module M4 that includes seedling root dip treatment with imidacloprid 17.8 SL @ 40g a.i./ha for 30 minute just before transplanting + growing of border crop (maize) + spraying of lambda cyhalothrin 5 EC @ 25g a.i./ha starting from 20 days after transplanting (4 sprays) which were significantly superior over untreated control module M6. All the treatment modules had also significantly reduced the viral disease incidence as compared to untreated control. But the module M2 was the most effective in reducing the viral disease incidence followed by module M4 in both the seasons. However, these two modules greatly affect the population of coccinellids and spiders. The insecticidal treatment modules had significant effect in reducing the insect pest population and also the incidence of viral diseases thereby increasing the yield of Bhut Jolokia during the investigation. The highest yield was obtained in module M2 (3564.44kg/ha) followed by M4, M1, M3 and M5 (2687.94, 2303.98, 2100.15 and 1511.41kg/ha, respectively). The results on cost benefit ratio revealed that the highest was recorded in module M2 (1: 4.85) followed by M4 (1: 3.37) and M1 (1: 2.13).ThesisItem Open Access BIOECOLOGY ON Lepidiota sp. Indet. (COLEOPTERA: SCARABAEIDAE)(AAU, Jorhat, 2017-07) Gogoi, Dhanalakhi; Baruah, A.A.L.H.Field and laboratory experiments were carried out at Ramie Research Station, Sorbhog and nearby areas and at Soil Arthropod Laboratory of the Department of Entomology, Assam Agricultural University, Jorhat during 2013 - 2017 to engender comprehensive information on the bioecology of Lepidiota albistigma Burmeister, (Coleoptera: Scarabaeidae), a major white grub species endemic to Lower Brahmaputra Valley of Assam. Experimental results confirmed the annual life cycle of L. albistigma with a mean duration of 336.30 ± 14.25 days. The pre-ovippositional, ovipositional and post-ovipositional period were 8.83 ± 0.75, 3.03 ± 0.76 and 9.13 ± 0.73 days, respectively. The mean fecundity was 22.20 ± 1.1 numbers. Eggs were creamywhite, opaque and elongated in shape with mean length and breadth of 5.61 ± 0.40 mm and 4.32 ± 0.36 mm, respectively. Mean incubation period was found to be10.73 ± 2.02 days. There were three larval instars with the duration of third instar (237.11 ±4.86 days) being significantly longer than the first (22.29 ± 1.10 days) and second (39.65 ± 2.90 days) instar. Mean pupal duration was recorded to be 23.36 ± 1.18 days. The mean length and width of first (16.12 ± 0.77 and 4.37 ± 0.54 mm), second (37.60 ± 1.30 and 9.16 ± 0.46) and third (80.28 ± 2.61 and 13.68 ± 0.63 mm) instar grubs were significantly different from each other.The mean length and width of pupae were recorded to be 43.76 ± 1.32 and 16.53 ± 0.60 mm, respectively. Sexual dimorphism based on adult morphometrics revealed that females (61.58 ± 1.64 mm) were significantly longer than males (57.34 ± 0.85 mm). The length of head plus thorax and abdomen were significantly longer in females (27.23 ± 0.55 mm and 24.36 ± 1.30 mm) than in males (23.88 ± 0.41 mm and 23.80 ± 1.30 mm). The mean length of forelegs (31.20 ± 0.79 mm), mid legs (32.77 ± 0.30 mm) and hind legs (42.42 ± 0.97 mm) were significantly longer in females than the males (Foreleg: 28.244 ± 0.61, Mid legs: 30.42 ± 0.18 mm; Hind leg: 41.32 ± 1.41 mm) but the claws in males were strongly bifid. The female alimentary canal (324.94 ± 7.05 mm) was significantly longer than males (315.80 ± 8.74 mm). Both male and female reproductive system exhibited synchronous attainment of sexual maturity. Distinct sexual dimorphism was also observed in the antennal segments and in antenna sensilla types. Scanning electron microscopic studies revealed 14 different types of sensilla in male and 9 types in female. Lamellae were significantly longer in males. Field surveys revealed that mango, guava, mussaenda, ixora, Assam lemon, arecanut, periwinkle, pomelo, betelvine, thuja, croton and black pepper were the primary hosts for adults. Feeding status of adults was further confirmed by presence of food materials in their dissected alimentary canals. Further, sterozoom microscopic images of mandibles and maxillae of both sexes exhibit dentations which indicated that mandibles and maxillae were fitted for phytophagy with probable application in digging of soil for burrowing. Host specificity test revealed that potato, colocassia, green gram and sugarcane to be the most preferred hosts of grubs. Studies on habitat selection by grubs of L. albistigma at five different ecosystems revealed thatgrubs were significantly more abundantat grasslands which were located near water sources. Grubs of L. albistigma were more abundant at soil depths of 0 - 10 cm and 11 - 20 cm in grassland and cultivated lands. In grasslands, grubs showed significant preference for soil depths of 0 - 10 cm (3.79 ± 3.34) and 11 -20 cm (2.31 ± 2.09). In cultivated fields, the highest population was recorded at the depth of 11 - 20 cm (2.78 ± 1.54) which significantly differed with other depths. There is no significant difference in abundance of grubs at 0 - 10 cm (1.40 ± 1.22), 21- 30 cm (1.40 ± 1.22) and 31- 40 cm (0.57 ± 1.22). The mechanism of survival of grubs were examined by means of a simulation model which displayed that the grubs were atleast able to survive upto 3 days under water whereas, under simulated conditions they survived upto 15 days. SEM results indicated presence of one pair of thoracic and eight pair of abdominal fictional spiracles which denoted that the respiratory system of the grub is peripneustic. The spiracles are characterized by external structures consisting of a central bulla which is surrounded by a smooth cresent shaped sieve/spiracular plate with numerous aeropyles. Absence of a conventional spiraclular opening, presence of a convex projecting central bulla in place of the opening, sclerotized and smooth sieve plate with ultramicroscopic (< 3 micron wide) aeropyles might have provided protection against entry of water into the tracheoles, allowing only gaseous exchange Observations on relative abundance of L. albistigma indicated that the highest population of grubs were recorded during the month of August whereas lowest was recorded during December, 2014 - 15. Correlation studies between L. albistigma grubs and soil physico-chemical parameters revealed that among all physical parameters, sand (r = -0.693) and silt content (r = -0.845) had significant negative correlations whereas, clay (r = 0.839) recorded a significant positive correlation. Among the chemical parameters, soil organic matter content (r = 0.901) and available nitrogen (r = 0.963) had significant positive correlation with grub population. Microbial investigation on the gut content of third instar grubs of L. albistigma revealed 20 different bacterial cultures of which 5 bacterial cultures designated as B2, B5, B11, B14 and B17 had the highest colony forming unit/ml. Bacterial flora considerably varied in size, colour, pigmentation, margins and elevation and as well as in utilization of carbohydrates and their response to various enzymes.ThesisItem Open Access POPULATION MONITORING AND MANAGEMENT OF RED ANT, Dorylus orientalis WESTWOOD (HYMENOPTERA: FORMICIDAE)(AAU, Jorhat, 2018-01) Devi, Elangbam Bidyarani; Bhattacharyya, BadalField and laboratory experiments were carried out in the farmer’s field of Jorhat and Soil Arthropod Pests Laboratory, Department of Entomology, Assam Agricultural University, Jorhat during 2015-16 and 2016-17 to study the population monitoring and ecofriendly management of red ant, D. orientalis in potato and French bean. The population of red ants were recorded under flood free and flood prone conditions in three different villages each during potato growing season and were correlated with various meteorological parameters and soil physico-chemical properties. Highest population of red ants was observed in all the flood free villages during the 1st fortnight of January, 2016 and 2017 as compared to the flood prone villages, where very negligible population of red ants was noticed. Correlation studies between D. orientalis population and various meteorological parameters during 2015-16 revealed that minimum temperature, soil temperature (morning and evening) and evaporation rate showed significantly negative correlationship whereas relative humidity (morning and evening) exhibited significant positive correlationship in case of flood free villages. However, in flood prone villages minimum temperature as well as morning soil temperature showed significant negative correlation with D. orientalis population. During 2016-17, the population of D. orientalis showed significant negative correlation with temperature (minimum and maximum), soil temperature (morning and evening) and evaporation rate but relative humidity (morning and evening) as well as bright sunshine hours had significant positive correlation with D. orientalis population. Whereas in flood prone villages, relative humidity (morning and evening) showed significant positive correlation with D. orientalis population. In case of soil physico-chemical parameters, bulk density, clay content, CEC, available N and soil microbial biomass carbon showed significant negative correlation while sand, silt content, soil organic carbon and available K2O had significant positive correlation in all the flood free villages. In flood prone villages, sand, silt and clay content, available P2O5, available K2O and CEC had showed positive correlation with D. orientalis population on the other hand, soil pH and available N showed significant positive correlation. Six different eco-friendly managment modules were evaluated against D. orientalis in potato crop. All the tested modules viz., Module-I (with only pre sowing treatment with MOC @ 150 kg/ha + wood ash @ 150 kg/ha + panchagavya @ 3%), Module-II (pre sowing treatment plus soil drenching with neem oil @ 5 ml/lit after 1st & 2nd earthing up (25 & 60 DAS), Module-III (pre sowing treatment plus soil drenching with jatropha oil @ 5 ml/lit after 1st & 2nd earthing up (25 & 60 DAS), Module-IV (pre sowing treatment plus soil drenching with pongamia oil @ 5 ml/lit after 1st & 2nd earthing up (25 & 60 DAS), Module-V (pre sowing treatment plus soil drenching with castor oil @ 5 ml/lit after 1st & 2nd earthing up (25 & 60 DAS) and Module-VI (pre sowing treatment plus soil drenching with sesamum oil @ 5 ml/lit after 1st & 2nd earthing up (25 & 60 DAS) were found to be significantly superior in suppressing red ant infestation as compared to the untreated control. Out of all modules, Module-II was found to be significantly superior and recorded the lowest tuber damage on weight (8.65%) and number (10.70%) basis which was at par with the Recommended package of practices (RPP) (malathion 5% dust @ 40 kg/ha + mustard oil cake @ 150 kg/ha in the soil after 1st & 2nd earthing up) which registered 8.18 and 10.20 per cent tuber damage respectively. The same module also registered highest tuber yield (119.37 q/ha) which was at par with the RPP (120.12 q/ha). The maximum benefit cost ratio (1.43) was recorded in RPP followed by Module-II (1.35) and Module-VI (1.26). Similar trend was also observed when six different eco-friendly managment modules were tested against, D. orientalis in French bean crop. Module-I comprised of only pre sowing treatments (application of MOC @ 150 kg/ha + wood ash @ 150 kg/ha + panchagavya @ 3%) and was common for rest of the modules (M-II to VI). Experimental findings revealed that all the tested modules viz., Module-I, Module-II (soil drenching with neem oil @ 5 ml/lit after 1st weeding up), Module-III (soil drenching with jatropha oil @ 5 ml/lit after 1st weeding up), Module-IV (soil drenching with pongamia oil @ 5 ml/lit after 1st weeding up), Module-V (soil drenching with castor oil @ 5 ml/lit after 1st weeding up) and Module-VI (soil drenching with sesamum oil @ 5 ml/lit after 1st weeding up) were found to be significantly superior in reducing red ant infestation as compared to the untreated control. Out of all the modules tested, Module-II was found to be the best and significantly superior with lowest plant mortality (9.14% and 14.00%) at 40 and 60 DAS respectively, which was found at par with the RPP (8.47 and 13.32 per cent at 40 and 60 DAS respectively). As regards to green pod yield, the RPP registered highest yield (103.23 q/ha) and found at par with Module-II (102.74 q/ha). The maximum benefit cost ratio (1.53) was recorded in RPP followed by Module-II (1.43) and Module-VI (1.37). Laboratory and field evaluation of four groups of baits materials (sugar, lipid, protein and waste) were assessed. Out of the four sugar based bait materials tested, mixture of honey with boric acid was found to be the most effective in attracting maximum (83.00) number of ants followed by the mixture of molasses with boric acid (55.00). In case of lipid based bait materials, mixture of rice bran oil with boric acid was found to be superior in attracting highest (47.33) numbers of ants followed by mustard oil with boric acid (37.00 nos.). Likewise, in case of protein based bait materials, maximum numbers of ant (35.00) were attracted to the mixture of gram flour with boric acid followed by mixture of dog biscuits with boric acid recording (27.67). Similarly, from the waste based bait materials, mixture of sugarcane trash with boric acid attracted maximum red ants (96.67) followed by mixture of banana peel with boric acid (36.67). Based on the laboratory performance, the above bait materials were evaluated against red ant in both potato and French bean crops under field conditions and compared with an untreated control. Out of eight bait materials, the application of rice bran oil with boric acid was found significantly superior as compared to the rest of the bait materials and could attract highest numbers of red ants in potato (1564.66, 1972.33 and 2636.33 at tuber formation, tuber maturity and harvesting stage) and French bean (1277.00, 1436.66 and 1655.33 at pod formation, pod maturity and harvesting stage) respectively.ThesisItem Open Access ECOLOGY AND MANAGEMENT OF MOUND BUILDING TERMITES(AAU, Jorhat, 2017-07) Himangshu Mishra; Bhattacharyya, BadalStudy on ecology and management of mound building termites were carried out in Jorhat and Golaghat district of Assam. Ecological studies were conducted at four different habitats viz., forest, agriculture, rural and urban habitat of both the districts during 2015 and 2016 while management of termites in tea ecosystem was conducted in experimental plot under department of tea husbandry and technology, AAU. Sampling in different habitats revealed 8 species of termites from both the districts. Among the 8 different species, 5 species were belonged to Macrotermitinae subfamily, whereas other 3 species belonged to Nasutitermitinae, Kalotermitinae and Amitermitinae subfamily. The genus Odontotermes were found dominant and consisted of four species viz., Odontotermes obesus (Rambur), O. feae (Wasmann), O. parvidens (Holmg. and Holmg.) and O. kapuri (Roonwal and Chhotani) while the remaining 4 species were belonged to different genera and these were Microtermes mycophagous (Desneux), Trinervitermes biformis (Wasmann), Neotermes buxensis (Roonwal and Sen-sarma) and Speculitermes chadaensis (Chatterjee and Thapa). Four different feeding groups of termites were recorded among which soil, litter and fungus feeder were dominantly found. Moreover, out all eight species two termites (O. obesus and O. feae) were dominantly distributed in different habitats of both the district. Morphometric studies of some termite species under Macrotermitinae subfamily revealed that O. feae were comparatively bigger than O. parvidens, M. mycophagous, O. obesus and O. kapuri. Collection of termites from different habitats revealed that higher population of the termite species were recorded from forest habitats than rural, agriculture and urban habitats of both the district. In addition it was also observed that forest habitats had highest mound density per ha (4.42 & 4.35 and 4.50 & 4.40) than rural (3.85 & 3.55 and 3.40 & 3.20), agricultural (3.25 & 3.05 and 3.30 & 3.15) and urban (3.15 & 3.00 and 3.25 & 3.10) sites of Jorhat and Golaghat district respectively. Ecology of mounds were studied through proper observation on nesting patterns of O. obesus and O. feae mounds in different habitats of both the district. Nesting pattern observed in mounds of forest habitats recorded comparatively higher sizes of basal diameter, height, incubation cavities, nursey cell, diameter and depth of the royal chamber from the ground level, moreover the mounds noticed in forest habitats also had higher sizes of length and width of the fungal comb than rural, agriculture and urban habitat of Jorhat and Golaghat. Caste composition recorded in the mounds of different habitats confirmed that higher numbers of worker, soldiers were collected from the mounds of forest habitats. Termite population of O. obesus and O. feae also recorded in the Assam Agricultural University, Campus and the study found fluctuating trend of termite castes in different months during March, 2015 to February, 2016. Correlation of population with mound dimension and weight of the fungal comb revealed that both O. obesus and O. feae showed positively significant correlation with basal diameter [0.982*(0.001) & 0.956*(0.001)], height [0.975*(0.001) & 0.925*(0.001)] and weight of the fungal comb [0.921*(0.002) & 0.925*(0.001)] respectively. Observation on termitophiles and inquilines associated with the mounds of O. obesus and O. feae, stated that scarabaeids and carabids were highly dominant where as staphylids, elaterids, formicids, arachnids and diplopods were moderately dominant termitophiles. Out of different types of inquilines recorded, annelids were highly dominant whereas molluscs and squamets were found moderately and less dominant inquilines. Study on fungal and bacterial colony in the mounds soils of different habitats revealed that, mound soils of forest habitat exhibited higher numbers of bacterial and fungal population than rural, agricultural and urban habitats of both the district. Physicochemical properties of mound soils of different habitat exhibited higher amount of silt (%), clay (%), soil moisture (%), organic carbon (%), available nitrogen (g/kg) and soil microbial biomass (g/kg) than the surrounding mound soil collected from different habitats of both the district. Management of the termites in tea ecosystem revealed that Metarhizium anisopliae registered least number and portion of infestation (13.86 & 12.04% and 14.11 & 12.04%) and showed statistical parity with Heterorhabditis indica treated plant (14.49 & 13.73 and 15.60 & 14.26%) after 30 and 60 days of treatment. The tea plants treated with Jatropha oil 50 EC and Neem oil 30 EC exhibited number of infestation (15.52 & 16.56%) and portion of infestation of (14.60 and 15.36%) while the untreated control plants recorded 38.44 & 37.35 and 40.32 & 39.48 per cent of infestation after 30 and 60 days of treatment respectively.
