Browsing by Author "RAMA RAO, C.V."
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ThesisItem Open Access IMPACT OF CULTIVATION METHODS OF RICE ON PEST AND DEFENDER POPULATION AND MANAGEMENT OF LEAF FOLDER, Cnaphalocrosis medinalis GUENEE WITH NEWER INSECTICIDES(Acharya N.G. Ranga Agricultural University, 2018) PALAGANI, CHENNA RAO; RAMA RAO, C.V.A field experiment entitled “Impact of cultivation methods of rice on pest and defender population and management of leaf folder, Cnaphalocrosis medinalis Guenee with newer insecticides.” was conducted at Agricultural College Farm, Bapatla, during kharif 2017. In the investigations, population dynamics of insect pests and defenders in different planting methods (normal transplantation, system of rice intensification, dry direct sowing, wet direct sowing and drum seeding) of paddy and the efficacy of certain new insecticides against rice leaf folder in dry direct sowing method were studied. Among the different cultivation methods of rice on pest incidence revealed that the lowest mean per cent leaf damage by leaf folder was observed in dry direct sowing (5.30%) and drum seeding (5.33%), whereas the highest mean per cent leaf damage by leaf folder was recorded in normal transplantation (7.76%). In case of BPH and WBPH the lowest mean population per hill was observed in system of rice intensification (3.95 and 2.28), whereas the highest mean population of BPH and WBPH per hill was recorded in normal transplantation (8.89 and 4.66), respectively. Similarly, green leafhopper mean population per hill was lowest in system of rice intensification (1.21) and dry direct sowing (1.29) and the highest mean population per hill was recorded in normal transplantation (1.78). In case of natural enemy population, the mean population of mirid bugs per hill was highest in normal transplantation (4.71) method which was on par with drum seeding (4.56) and wet direct sowing (4.35), whereas in system of rice intensification the lowest mean population of 2.83 per hill was recorded. Similarly, the highest mean population of coccinellids per hill was observed in normal transplantation (1.06) and wet direct sowing (0.90) method, whereas the lowest mean population per hill was recorded in system of rice intensification (0.71). In case of spiders highest mean population per m2 was recorded in normal transplantation (3.53) and dry direct sowing (3.28) whereas in system of rice intensification the lowest mean population of 2.44 per m2 was noticed. The impact of cultivation methods of rice on grain yield indicated that system of rice intensification to be superior over other cultivation methods by recording grain yield of 6432.50 kg ha-1 which was on par with dry direct sowing and drum seeding with a grain yield of 6072.00 kg ha-1 and 5773.50 kg ha-1 respectively. Management of rice leaf folder with certain newer insecticides revealed that all the insecticide treatments were found superior over untreated control. Amongst them, flubendiamide 39.35% SC @ 0.3 ml l-1, chlorantraniliprole 9.3% + lambda cyhalothrin 4.6% ZC @ 0.8 ml l-1 and chlorantraniliprole 18.5% SC @ 0.3 ml l-1 were the most effective insecticides in reducing leaf folder infestation with 63.71, 56.72 and 54.80 per cent reduction over untreated control, respectively. The plots treated with flubendiamide 39.35% SC @ 0.3 ml l-1, chlorantraniliprole 9.3% + lambda cyhalothrin 4.6% ZC @ 0.8 ml l-1, chlorantraniliprole 18.5% SC @ 0.3 ml l-1 and flubendiamide 19.92% + thiachloprid 19.92% SC @ 0.5 ml l-1 recorded higher grain yield with 64.33, 63.46, 61.55 and 50.08 per cent increase over untreated control respectively.ThesisItem Open Access INSECTICIDE INDUCED RESURGENCE OF RICE BROWN PLANTHOPPER, Nilaparvata lugens (Stal) (Hemiptera:Delphacidae) AND MANAGEMENT WITH CERTAIN INSECTICIDES(Acharya N G Ranga Agricultural University, Guntur, 2019) ANAND KUMAR, A. D. V. S. L. P.; RAMA RAO, C.V.Indiscriminate use of insecticides is leading to resurgence of insect pests in various crops. Rice brown planthopper management has become very difficult due to its ability to develop resurgence to different insecticides regularly used by the farmers. Keeping this in view studies were initiated to find out the insecticides causing resurgence and their effect on biology of brown planthopper and also reasons for resurgence. Studies were also conducted to find out the effective insecticide rotations for management of BPH during kharif and rabi 2017-18. Information generated on insecticide usage pattern adopted by the rice growers revealed that calendar based sprays irrespective of pest and disease incidence, use of non-recommended synthetic pyrethroids for controlling insect pests, application of insecticides at higher doses than the recommended level, mixing more than one pesticide (cock tails) to control insect pests and diseases simultaneously and defective spraying etc. are some of the practices followed by the rice growers contributing to the resurgence of brown planthopper infesting rice. Brown planthopper had two peaks with first peak during 41st SMW (i. e., second week of October 2016) followed by second peak during 43rd SMW (i. e., fourth week of October 2016) during kharif 2016. During rabi 2016-17, the activity of BPH was found initially low during 7th SMW (February 12-18) and gradually increased during successive standard weeks (8th-14th SMW) and reached the highest number during 14th SMW (i.e., first week of April). The incidence of WBPH attained peak initially during 38th SMW (September 17-23) and later during third week of October (42nd SMW) during kharif 2016, while in rabi 2016-17 first WBPH was noticed during 7th SMW (February 12-18) and population increased gradually during successive weeks and attained peak number during 13th SMW (March 26-April 1). Brown planthopper had significant negative relationship with morning relative humidity of current week and sunshine hours of two weeks earlier but positive correlation with evening relative humidity two weeks earlier in kharif 2016. Maximum and minimum temperatures (current week, one week and two weeks xviii earlier) and evening relative humidity two weeks earlier in rabi had significantly positive impact on population of BPH. White backed planthopper had significant negative relation with morning relative humidity of current week during kharif 2016. None of the abiotic factors has showed significant relationship with activity of WBPH during rabi 2016-17. Field population of both BPH and WBPH had a positive relationship with light trap catches of planthoppers. The field populations of BPH and WBPH are in the proportion of 69.00 per cent and 31.00 per cent, respectively during kharif 2016 and 98.00 per cent and 2.00 per cent, respectively during rabi 2016-17. Among fourteen insecticides screened in field during kharif and rabi 2016-17 for induction of resurgence in BPH, seven insecticides viz., chlorpyriphos, profenophos, deltamethrin, cypermethrin, bifenthrin, lambda cyhalothrin and imidacloprid significantly increased the population of N. lugens over untreated check and consequently resulted in higher resurgence, whereas the remaining i.e., acephate, monocrotophos, cartap hydrochloride, fipronil, chlorantraniliprole, buprofezin and pymetrozine can be used judiciously, with periodic monitoring for development of resistance and induction of resurgence. The resurgence inducing mechanism of seven identified insecticides was studied in detail in green house experiments. The results revealed that out of seven insecticides applied at two doses (half of the recommended field dose and recommended field dose), four insecticides viz., cypermethrin, deltamethrin, bifenthrin and lambda cyhalothrin significantly enhanced the reproductive rate (153.67 to 227.67 nymphs / 2 females) of N. lugens and consequently resulted in higher resurgence ratio (1.17 to 1.74 folds). Increase in feeding index (144.33 mm2 to 496.00 mm2 honey dew area), growth index (6.35 % to 7.11 %) and sex ratio in favour of females (1.39 to 1.84 females per 1 male) were the additional factors contributing to the resurgence in the population of the brown planthopper caused by the application of synthetic pyrethroids. While chlorpyriphos, profenophos and imidacloprid resulted in brown planthopper resurgence through changes in the nutritional quality of the host plant that may favour the phytophagus herbivores as indicated by the increased feeding indices (135.33 mm2 to 326.33 mm2 honey dew area). The results obtained from both field and green house experiments in the present investigation revealed that insecticide induced resurgence in the populations of brown planthopper is due to the direct stimulatory effect on the reproductive potential of the insect, indirect effect through favourable changes in the nutritional quality of rice plant and selective destruction of natural enemies. Field experiments carried out during kharif and rabi 2017-18 revealed that fipronil (1000 ml ha-1) followed by pymetrozine (300 g ha-1), buprofezin (800 ml ha-1) followed by pymetrozine (300 g ha-1) and acephate (750 g ha-1) followed by pymetrozine (300 g ha-1) were the most effective insecticide rotations in the management of brown planthopper and recorded higher grain yields. With regard to cost benefit ratio, insecticide rotations, acephate (750 g ha-1) followed by pymetrozine (300 g ha-1) and fipronil (1000 g ha-1) followed by pymetrozine (300 g ha-1) had the highest cost benefit ratio of 1: 6.01 and 1: 6.03, respectively. Buprofezin (800 ml ha-1) followed by pymetrozine (300 g ha-1) and fipronil (1000 ml ha-1) followed by dinotefuran (250 g ha-1) are the next best rotations with cost benefit ratioof 1: 5.87 and 1: 5.07, respectively.ThesisItem Open Access PODBORER COMPLEX IN PIGEONPEA (Cajanus cajan (L.) Millsp.,) GENOTYPES AND THEIR MANAGEMENT WITH BIORATIONAL INSECTICIDES(ACHARYA N. G. RANGA AGRICULTURAL UNIVERSITY, 2010) SRAVANA BINDU, GORLA; RAMA RAO, C.V.Studies on “Pod borer complex in pigeonpea (Cajanus cajan (L.) Millsp.,) genotypes and their management with bio-rational insecticides” were undertaken during Kharif 2009-2010 at Regional Agricultural Research Station, Lam, Guntur. Twenty five genotypes of pigeonpea were selected for screening and replicated thrice in a Simple Randomized Block Design. The evaluation of different genotypes against the pod borer complex under field conditions revealed that the genotypes LRG-30 (4.85%), WRP 1-2 (5.26%), TAT-96-29 (6.36%), SM-9 (6.48%), GPM-43(6.56%) and BSMR 737 (6.76%) were on par with each other with respect to the inflorescence damage due to Maruca vitrata (Geyer). The least pod damage due to M. vitrata was recorded in SM-54 (7.7%) followed by NSM-166 (9.56%), 8-1 (9.65%), SM-58 (10.02%), CHILAKA-1 (10.16%), PERINAL-1 (11.55%) and WRG-150 (12.58%) among 25 genotypes screened. Among 25 genotypes screened, the lowest pod damage due to Melanagromyza obtusa (Malloch) was recorded in SM-54 (6.15%), followed by MAHANADI-1 (6.23%), SM-114 (9.10%), JSM-8 (9.40%), and WRG-150 (9.92%). Among 25 genotypes screened, significantly lowest pod damage due to Helicoverpa armigera (Hubner) was recorded in PERINAL-1 (11.53%) and WRG-150 (12.85%). Among the entries evaluated, CHILAKA-1 recorded the highest yield of 866.66 g/5m length which was followed by LRG-30 (850.00 g/5m) and WRG-150 (818.33 g/5m). Among seven bio-rational insecticides evaluated for their efficacy against pod borer complex, treatments like Bacillus thuringiensis (Ber.) @ 2 ml/l and NSKE @ 5% and the chemical check chlorpyriphos + dichlorvos @ 2.5 + 1 ml/l were effective in suppressing the inflorescence damage. Next effective treatments were Verticillium sp (Zimmermann) Viegas @ 5g/l, Metarrhizium anisopliae (Metch.) Sorokin @ 5g/l, Heterosternma indica (Mclichar) @ 30 lakh nematodes/l, Beauveria bassiana (Balsamo) Vuillemin @ 5g/l and Nomuraea rileyi (Farlow) Samson @ 5g/l. Bt @ 2ml/lt and NSKE 5% were on par with each other with least pod damage by M. vitrata H. armigera (2.94% and respectively. 2.97%) (7.09% and 7.48%), and M. obtusa (5.43 % and 7.31%), The chemical check chlorpyriphos + dichlorvos @ 2.5 + 1ml/l which recorded 41.26% inflorescence damage and 6.76, 2.09 and 4.25 per cent pod damage due to M. vitrata, H. armigera and M. obtusa, respectively and was significantly superior over other treatments. Among the bio-rational insecticides the highest yield was recorded in Bt @ 2 ml/l (999.87 Kg/ha) followed by NSKE 5% (955.53 Kg/ha) with 102.23 and 93.25 % increase over control. The highest yield was recorded by the chemical check chlorpyriphos + dichlorvos @ 2.5 + 1ml/l (1263.67 Kg/ha) with 155.58 % increase over control and significantly superior over other treatments.ThesisItem Open Access SCREENING OF PADDY ADVANCED CULTURES AGAINST BROWN PLANTHOPPER, Nilaparvata lugens (Stal.) (DELPHACIDAE: HOMOPTERA) AND ITS MANAGEMENT WITH NEW INSECTICIDE MOLECULES(Acharya N.G. Ranga Agricultural University, 2016) DEEKSHITA, KONCHADA; RAMA RAO, C.V.A field experiment entitled “Screening of Paddy Advanced Cultures against Brown Planthopper, Nilaparvata lugens (Stal.) and its Management with New Insecticide Molecules” was conducted at Agricultural College Farm, Bapatla during kharif 2015. Twenty eight paddy advanced cultures were screened against brown planthopper, N. lugens and the efficacy of certain new insecticides were evaluated. Out of 28 cultures screened for resistance against BPH, four cultures viz., BPT 2789, BPT 2703, BPT 2787 and BPT 2688 with 9.11, 9.59, 9.74 and 9.76 mean population per hill respectively were found resistant with a damage score of three. All other 24 genotypes were rated as moderately resistant with a damage score of five. Management of brown planthopper with certain newer insecticides revealed that all the insecticide treatments were found superior over untreated control. Amongst them, pymetrozine 50 WG @ 0.5 g l-1, dinotefuran 20 SG @ 0.4 g l-1, sulfoxaflor 25 SC @ 0.75 ml l-1 were the most effective insecticide with 62.98, 59.60 and 51.99 per cent population reduction over untreated control respectively. Among the insecticides tested for safety on natural enemies, pymetrozine 50 WG @ 0.5 g l-1 proved to be safer to the green mirid bugs with lowest mortality of 16.96 per cent reduction over precount. The impact of new insecticide molecules on spiders were also tested, where in sulfoxaflor 25 SC 0.75 ml l-1 recorded lowest mortality of 20.40 per cent followed by pymetrozine 50 WG @ 0.5 g l-1 with 23.89 per cent reduction over precount. As per PD ratio, pymetrozine 50 WG @ 0.5 g l-1 recorded the highest pest defender ratio. The grain yield recorded was higher in buprofezin 20 SP @ 1.6 ml l-1 treated plots with 67.98 per cent increase of yield over control followed by pymetrozine 50 WG @ 0.5 g l-1 (63.81 per cent).