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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.
