Browsing by Author "Sridevi, G."
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ThesisItem Open Access Clinicopathological Evaluation of Urinary Tract Infections in Dogs(TANUVAS, 2004) Sridevi, G.; TANUVAS; Thirunavukkarasu, P.S.; Dhanapalan, P.; Paul, W. ManoharThesisItem Open Access RESISTANCE TO LEAFHOPPER, Amrasca biguttula biguttula (Ishida) IN SUNFLOWER: SCREENING AND IDENTIFICATION OF RESISTANCE MECHANISM(PROFFESSOR JAYASHANKAR TELANGANA STATE AGRICULTURAL UNIVERSITY, 2021-07-01) Fatima, T.; Sridevi, G.The present studies were conducted at ICAR-Indian Institute of Oilseeds Research, Rajendranagar and College of Agriculture, Rajendranagar, Hyderabad to screen sunflower germplasm accessions, identify the various biophysical and biochemical factors of resistance and to understand the mechanism of resistance in some of the identified germplasm sources. Fifty seven accessions along with commercial hybrid, Syngenta-SB-275 and a susceptible check, Morden were screened against A. biguttula biguttula in field under natural infestation.The population of leafhopper and leafhopper injury were recorded from all the germplasm accessions during Rabi, 2016-17 and 2017-18 and categorized based on MSI (0: highly resistant; 0.1-1.0: resistant; 1.1-2.5: moderately resistant; 2.6- 3.5: susceptible and 3.6-5.0: highly susceptible). During Rabi 2016-17, out of 57 germplasm accessions screened, twenty two accessions were found resistant with a MSI ranging from 0.6 to 1.0, while twenty five were found moderately resistant with a MSI ranging from1.1 to 2.2, ten accessions were found susceptible with a MSI ranging from 2.6 to 2.7. Syngenta-SB-275 and Morden were found susceptible to leafhoppers with a MSI of 2.6 and 3.2, respectively. During Rabi-2017-18, fifteen germplasm accessions were found as resistant with a MSI of 0.8 to 1.0; thirty accessions were found as moderately resistant with a MSI ranging from 1.2 to 2.4 and twelve accessions as susceptible with a MSI ranging from 2.6 to 3.5. Syngenta-SB-275 andMorden were found susceptible to leafhoppers with a MSI of 3.0 and 3.4, respectively. Thus, fifteen accessions were found resistant to leafhopper consistently for two years, i.e., 2016-17 and 2017-18. Twenty three accessions were recorded moderately resistant while ten accessions were found susceptible for two consecutive years.However, the remaining eight accessions were inconsistent in their reaction. Among the various biophysical and biochemical parameters studied, significant differences were observed in mean values of trichome density (midrib, lateral vein and leaf lamina), trichome length (midrib, lateral vein and leaf lamina), MDA, H2O2, SOD, CAT, POX, APX, total phenols, total free amino acid and total sugars between resistant and susceptible accessions. Correlation of leafhopper nymphal population with biophysical parameters revealed a significant negative correlation with trichome density on midrib (-0.813*), lateral veins (-0.727*), leaf lamina (-0.837*), trichome length on midrib (-0.706*), lateral veins (-0.755*) and leaf lamina (-0.692*)total phenols (-0.886*).Other biophysical factors like plant height, leaf area, petiole length, leaf thickness and midribthickness didn‟t show any significant effect on leafhopper nymphal population. Correlation of leafhopper nymphal population with biochemical factors showed significant positive correlation with malondialdehyde, hydrogen peroxide, total free amino acids and total sugars (r = 0.842*, 0.807*, 0.886* and 0.863*, respectively). Whereas, significant negative correlation with total phenol content (r = -0.886*) was observed. The mechanismof resistance evaluated in terms of settling preference study also revealed less number of nymphs settling on resistant accessions (8.3 to 17.3 nymphs per plant) compared to susceptible check, Morden (47.1 nymphs per plant). The ovipositional preference by A. biguttula biguttula under choice and no-choice tests recorded significantly lowest number of nymphs (4.67 to 7.33 nymphs per plant under choice test and 4.0 to 6.2 nymphs per plant under no-choice test) on resistant accessions, compared to susceptible check, Morden (34.0 nymphs per plant under choice test and 12.8 nymphs per plant under no-choice test). Resistant accessions received less number of feeding punctures(24.33 to 37.50 numbers of punctures per leaf) and lower number of honeydew spots (11.83 to 15.83 number of honeydew spots/8 h/10 nymphs) compared to susceptible check, Morden (195.17 numbers of punctures per leaf and 62.83 number of honeydew spots/8 h/10 nymphs). Developmental studies revealed extended larval period (10.90 to 11.68 days), reduced nymphal survival (15.8% to 32.6%) and shortened adult longevity on resistant accessions (5.40 to 6.16 days) compared to susceptible check, Morden (9.3 days, 64.9% and 10.23 days, respectively). The resistant accessions took more number of days for the development of symptoms compared to susceptible check, Morden. GMU-339, GMU-696 and TSG-401 showed antixenosis and antibiosis mechanism of resistance and in future it can be used in the resistance breeding programme against A.biguttula biguttula.ThesisItem Open Access STUDIES ON LIFE-FERTILITY AND INSECTICIDAL MANAGEMENT OF FALL ARMYWORM(PROFFESSOR JAYASHANKAR TELANGANA STATE AGRICULTURAL UNIVERSITY, 2022-11-04) Supriya, G. B.; Sridevi, G.Studies on life-fertility and insecticidal management of fall armyworm (FAW), Spodoptera frugiperda (J. E Smith) were carried out during 2019-20 and 2020-21. The life-fertility studies were conducted in the Department of Entomology, College of Agriculture, Rajendranagar, while the trial on bioefficacy of insecticides was carried out during rabi, 2019-20 and 2020-21 at the College farm. Studies on dissipation of selected insecticides were conducted at Pesticide Residues Laboratory, AINP on Pesticide Residues, PJTSAU, Rajendranagar, Hyderabad. The age specific survivorship of S. frugiperda on vegetative and reproductive parts of different host plants (7 no.) and artificial diet, revealed that the larval period of S. frugiperda on vegetative parts ranged between 11.97±0.015 days (tomato leaves) and 13.99±0.035 (paddy leaves) whereas on reproductive parts it ranged between 13.73±0.046 days (tomato fruits) and 14.92±0.072 (sorghum earheads) while on artificial diet, it was 14.84±0.139 days. The pupal period varied between 7.02±0.043 (paddy leaves) and 7.97±0.028 days (maize leaves) on foliage while it ranged between 7.05±0.052 days (sorghum earheads) and 9.87±0.122 days (maize kernels) on reproductive parts. The pupal period of S. frugiperda was recorded highest on artificial diet 8.86±0.170 days. The adult longevity ranged between 9.89±0.098 days (paddy leaves) to 13.84± 0.170 days (maize leaves) and 10.92±0.101 days (sugarcane setts) to 11.90±0.107 days (sorghum earheads) when S. frugiperda fed on vegetative and reproductive parts, respectively and on artificial diet it was 12.02±0.034 days. The total life cycle of S. frugiperda reared on vegetative (33.20±0.091 to 35.92±0.217 days) and reproductive parts (33.99±0.041 to 36.09±0.025 days) was significantly less than that on artificial diet (37.00±0.012 Name of the author : SUPRIYA G. B Title : “STUDIES ON LIFE-FERTILITY AND INSECTICIDAL MANAGEMENT OF FALL ARMYWORM” Degree to which it is submitted : DOCTOR OF PHILOSOPHY IN AGRICULTURE Faculty : AGRICULTURE Department : ENTOMOLOGY Chairperson : Dr. G. SRIDEVI University : PROFESSOR JAYASHANKAR TELANGANA STATE AGRICULTURAL UNIVERSITY Year of submission : 2022 days). S. frugiperda when reared on maize leaves, sorghum leaves and artificial diet showed type-I survivorship curve, while on paddy and tomato leaves it was stair step, type-I. However, on sugarcane leaves, castor leaves, paddy panicles and sugarcane setts, the survivorship curve was type-II, stair step, type-III and type-II, respectively. The age specific survivorship of female S. frugiperda and its fecundity on different hosts were studied. The potential fecundity was significantly highest in artificial diet (4077.14±567.52 eggs) followed by maize leaves (2859.38±169.40 eggs)>castor leaves (2778.86±69.95 eggs)> maize kernels (1627.91±69.82 eggs)> sorghum leaves (1016.98±14.51 eggs). The various life parameters of S. frugiperda on different hosts revealed the suitability of host. The net reproductive rate (R0) was highest (947.43±0.479) in artificial diet, followed by maize leaves (707.57±0.584), maize kernels (496.88 ±2.127) and castor leaves (324.46±0.150), whereas, the highest mean generation time (Tc) was recorded on maize kernels (32.75±0.015 days) followed by artificial diet (32.03±0.012 days). The highest intrinsic rate of increase (rm) value was recorded highest on maize leaves (0.2193±0.00), followed by artificial diet (0.2140±0.00). The highest finite rate of increase (λ) recorded on maize leaves as (1.64±0.003 female offsprings/ female/day) followed by artificial diet (1.62±0.003 female offsprings/ female/day day), whereas highest weekly multiplication rates (WMR) value was recorded on maize leaves (4.64±0.006) followed by artificial diet (4.48±0.006) and castor leaves (3.84±0.006). Doubling time (DT) was recorded highest on maize leaves (3.17±0.006 days) followed by artificial diet (3.24±0.006 days), castor leaves (3.61±0.006 days) and maize kernels (3.67±0.006 days). The stable age distribution of S. frugiperda on different host plants indicated that the larval stage contributed maximum (92.60 to 97.49 %) compared to other stages to the total population, while the life expectancy on different hosts revealed that early stages recorded higher life expectancies than adult stages on all the hosts. The life table study of S. frugiperda on cotton leaves and bolls revealed that the larval duration on cotton leaves was 12.45±0.327 days and on bolls it was 12.47±0.306 days. The survivorship curve on cotton was type-II on both leaves and bolls. The life parameters like R0, Tc, λ, WMR and F2 females, were lower on cotton leaves compared to bolls. The per cent contribution of larvae to stable age was more than 90 per cent on cotton leaves and bolls, similarly, the larval and adult expectancy were significantly lower. The bio-efficacy studies revealed that spinetoram was the most effective insecticide against S. frugiperda with 97.61 per cent reduction in population followed by indoxacarb (91.09 %), spinosad (71.43%), emamectin benzoate (60.21%) and chlorantraniliprole (55.56 %). Among the selected insecticides, the mean highest yield of 3.34 t ha-1 was recorded from spinetoram treated plots followed by indoxacarb (3.09 t ha-1 ) and spinosad (2.45 t ha-1 ) which were found to be on par. The studies on dissipation pattern of selected insecticides in immature maize cobs revealed that indoxacarb persisted for 1.05 days while spinetoram dissipated below the limit of quantification (10 ppb), 2hrs after spraying.