Background Cotton crop is infested by numerous arthropod pests from sowing to harvesting,causing substantial direct and indirect yield losses.Knowledge of seasonal population trends and the relative occurrence of pest...Background Cotton crop is infested by numerous arthropod pests from sowing to harvesting,causing substantial direct and indirect yield losses.Knowledge of seasonal population trends and the relative occurrence of pests and their natural enemies is required to minimize the pest population and yield losses.In the current study,analysis of the seasonal population trend of pests and natural enemies and their relative occurrence on cultivars of three cotton species in Central India has been carried out.Results A higher number and diversity of sucking pests were observed during the vegetative cotton growth stage(60 days after sowing),declining as the crop matured.With the exception of cotton jassid(Amrasca biguttula biguttula Ishida),which caused significant crop damage mainly from August to September;populations of other sucking insects seldom reached economic threshold levels(ETL)throughout the studied period.The bollworm complex populations were minimal,except for the pink bollworm(Pectinophora gossypiella Saunders),which re-emerged as a menace to cotton crops during the cotton cropping season 2017–2018 due to resistance development against Bt-cotton.A reasonably good number of predatory arthropods,including coccinellids,lacewings,and spiders,were found actively preying on the arthropod pest complex of the cotton crop during the early vegetative growth stage.Linear regression indicates a significant relationship between green boll infestations and pink bollworm moths in pheromone traps.Multiple linear regression analyse showed mean weekly weather at one-or two-week lag periods had a significant impact on sucking pest population(cotton aphid,cotton jassid,cotton whitefly,and onion thrips)fluctuation.Gossypium hirsutum cultivars RCH 2 and DCH 32,and G.barbadense cultivar Suvin were found susceptible to cotton jassid and onion thrips.Phule Dhanvantary,an G.arboreum cotton cultivar,demonstrated the highest tolerance among all evaluated cultivars against all sucking pests.Conclusion These findings have important implications for pest management in cotton crops.Susceptible cultivars warrant more attention for plant protection measures,making them more input-intensive.The choice of appropriate cultivars can help minimize input costs,thereby increasing net returns for cotton farmers.展开更多
Background The pink bollworm(Pectinophora gossypiella,PBW)is a major cotton pest,causing economic losses by damaging seeds and fiber.Cotton growers typically use systemic and broad-spectrum insecticides for its manage...Background The pink bollworm(Pectinophora gossypiella,PBW)is a major cotton pest,causing economic losses by damaging seeds and fiber.Cotton growers typically use systemic and broad-spectrum insecticides for its manage-ment,which pose risks to human health and the environment.Consequently,there is a need for eco-friendly alterna-tives.This study evaluates the bio-efficacy of the entomopathogenic fungus Metarhizium anisopliae strain TMBMA1 against pink bollworm and assesses its compatibility with major insecticides.Additionally,to comprehend the dynam-ics of colonization and the infection processes of entomopathogenic fungi(EPF),scanning electron microscopy(SEM)of infected larvae was carried out.Result We challenged the second instar PBW larvae to eight different concentrations(1×10^(3) to 1×10^(10) conidia mL^(-1))of an M.anisopliae strain TMBMA1.The highest mortality(100%)occurred at the higher concentrations i.e.,1×109 and 1×10^(10) spores mL^(-1),while the lowest mortality rate(46.6%)was observed at 1×10^(3) spores mL^(-1) con-centration compared to control(3.33%).TMBMA1’s biocontrol efficacy was validated by Probit analysis,exhibiting an exceptionally low median lethal concentration(LC50)value of 7.1×10^(5).The comparative evaluation revealed that the M.anisopliae strain TMBMA1 performed excellently with insecticide[Cypermethrin 10%(volume fraction)emulsifiable concentrate(EC)at 1 mL·L^(-1) water]giving 100%mortality,both being superior to a commercial prod-uct of M.anisopliae(60%).According to SEM analysis,the EPF strain was profusely colonized on both the internal and external surfaces of PBW larvae.Compatibility studies with insecticides revealed>98%and>96%reduction in the sporulation of M.anisopliae due to the treatment of Emamectin Benzoate 1.5%(mass fraction)+Profenofos 35%(mass fraction)water dispersible granules(WDG)and Profenofos 50%EC,respectively.In contrast,Cypermethrin 10%EC,Emamectin Benzoate 5%(mass fraction)Soluble Granules and Neem Seed Kernel Extract(NSKE)0.15%(volume fraction)treatments reported lower reduction(11.45%,13.79%and 21.21%respectively)in spore production.Conclusion According to the current investigations,the M.anisopliae strain TMBMA1 exhibits high virulence against PBW and offers a promising eco-friendly solution for managing this pest.It shows significant potential to pro-liferate on both external and internal surfaces of PBW.This strain can be integrated into PBW management programs with chemical insecticides,improving pest control and lessening environmental impact.展开更多
Background The emergence of pink bollworm(PBW),Pectinophora gossypiella(Saunders)(Lepidoptera:Gelechiidae),in cotton due to Bt resistance and concealed feeding habit has created a need for alternative,eco-friendly,and...Background The emergence of pink bollworm(PBW),Pectinophora gossypiella(Saunders)(Lepidoptera:Gelechiidae),in cotton due to Bt resistance and concealed feeding habit has created a need for alternative,eco-friendly,and cost-effective control methods.This study aimed to evaluate the bio-efficacy and reproductive potential of two native strains of entomopathogenic nematodes(EPNs),Heterorhabditis indica,namely CICR-HI-CL and CICR-HI-MN,against PBW larvae and pupae under in-vitro conditions.Results The larval assay revealed that strain CICR-HI-CL exhibited higher potency than strain CICR-HI-MN against 2nd,3rd,and 4thinstar larvae,with median lethal dose(LD50)values of 5.45,4.45,and 4.60 infective juveniles(IJs)per larva,respectively.In case of pupal bioassay,both EPN strains demonstrated greater virulence when applied directly(LD50values:29.65 and 73.88 IJs per pupa for strains CICR-HI-CL and CICR-HI-MN,respectively)compared to soil application(147.84 and 272.38 IJs per pupa).Both EPN strains successfully penetrated and reproduced on 4thinstar larvae,resulting in maximum production of 19.28 and 20.85 lakh IJs per larva in the next generation when inoculated at 30 IJs per larva.Conclusion The present study has generated useful information on the virulence and reproductive potential of two strains of EPN H.indica(CICR-HI-CL and CICR-HI-MN)against PBW,a dreaded pest of cotton.Higher virulence and reproductive potential of EPN strains demonstrated their ability to multiply,sustain and perpetuate on larval and pupal stages of PBW.The knowledge generated will help formulate effective management strategies for PBW with the inclusion of EPN as a potential biological control candidate.The soil-dwelling life stages viz.,last instar hibernating larvae and pupae of PBW can be the ideal weak links to make a successful use of H.indica for sustainable management of PBW in the cotton ecosystem.However,before taking these EPN strains to field for managing PBW,detailed studies investigating their biocontrol potential against PBW under field conditions are needed.展开更多
基金Funding support for the Crop Pest Surveillance and Advisory Project(CROPSAP)。
文摘Background Cotton crop is infested by numerous arthropod pests from sowing to harvesting,causing substantial direct and indirect yield losses.Knowledge of seasonal population trends and the relative occurrence of pests and their natural enemies is required to minimize the pest population and yield losses.In the current study,analysis of the seasonal population trend of pests and natural enemies and their relative occurrence on cultivars of three cotton species in Central India has been carried out.Results A higher number and diversity of sucking pests were observed during the vegetative cotton growth stage(60 days after sowing),declining as the crop matured.With the exception of cotton jassid(Amrasca biguttula biguttula Ishida),which caused significant crop damage mainly from August to September;populations of other sucking insects seldom reached economic threshold levels(ETL)throughout the studied period.The bollworm complex populations were minimal,except for the pink bollworm(Pectinophora gossypiella Saunders),which re-emerged as a menace to cotton crops during the cotton cropping season 2017–2018 due to resistance development against Bt-cotton.A reasonably good number of predatory arthropods,including coccinellids,lacewings,and spiders,were found actively preying on the arthropod pest complex of the cotton crop during the early vegetative growth stage.Linear regression indicates a significant relationship between green boll infestations and pink bollworm moths in pheromone traps.Multiple linear regression analyse showed mean weekly weather at one-or two-week lag periods had a significant impact on sucking pest population(cotton aphid,cotton jassid,cotton whitefly,and onion thrips)fluctuation.Gossypium hirsutum cultivars RCH 2 and DCH 32,and G.barbadense cultivar Suvin were found susceptible to cotton jassid and onion thrips.Phule Dhanvantary,an G.arboreum cotton cultivar,demonstrated the highest tolerance among all evaluated cultivars against all sucking pests.Conclusion These findings have important implications for pest management in cotton crops.Susceptible cultivars warrant more attention for plant protection measures,making them more input-intensive.The choice of appropriate cultivars can help minimize input costs,thereby increasing net returns for cotton farmers.
文摘Background The pink bollworm(Pectinophora gossypiella,PBW)is a major cotton pest,causing economic losses by damaging seeds and fiber.Cotton growers typically use systemic and broad-spectrum insecticides for its manage-ment,which pose risks to human health and the environment.Consequently,there is a need for eco-friendly alterna-tives.This study evaluates the bio-efficacy of the entomopathogenic fungus Metarhizium anisopliae strain TMBMA1 against pink bollworm and assesses its compatibility with major insecticides.Additionally,to comprehend the dynam-ics of colonization and the infection processes of entomopathogenic fungi(EPF),scanning electron microscopy(SEM)of infected larvae was carried out.Result We challenged the second instar PBW larvae to eight different concentrations(1×10^(3) to 1×10^(10) conidia mL^(-1))of an M.anisopliae strain TMBMA1.The highest mortality(100%)occurred at the higher concentrations i.e.,1×109 and 1×10^(10) spores mL^(-1),while the lowest mortality rate(46.6%)was observed at 1×10^(3) spores mL^(-1) con-centration compared to control(3.33%).TMBMA1’s biocontrol efficacy was validated by Probit analysis,exhibiting an exceptionally low median lethal concentration(LC50)value of 7.1×10^(5).The comparative evaluation revealed that the M.anisopliae strain TMBMA1 performed excellently with insecticide[Cypermethrin 10%(volume fraction)emulsifiable concentrate(EC)at 1 mL·L^(-1) water]giving 100%mortality,both being superior to a commercial prod-uct of M.anisopliae(60%).According to SEM analysis,the EPF strain was profusely colonized on both the internal and external surfaces of PBW larvae.Compatibility studies with insecticides revealed>98%and>96%reduction in the sporulation of M.anisopliae due to the treatment of Emamectin Benzoate 1.5%(mass fraction)+Profenofos 35%(mass fraction)water dispersible granules(WDG)and Profenofos 50%EC,respectively.In contrast,Cypermethrin 10%EC,Emamectin Benzoate 5%(mass fraction)Soluble Granules and Neem Seed Kernel Extract(NSKE)0.15%(volume fraction)treatments reported lower reduction(11.45%,13.79%and 21.21%respectively)in spore production.Conclusion According to the current investigations,the M.anisopliae strain TMBMA1 exhibits high virulence against PBW and offers a promising eco-friendly solution for managing this pest.It shows significant potential to pro-liferate on both external and internal surfaces of PBW.This strain can be integrated into PBW management programs with chemical insecticides,improving pest control and lessening environmental impact.
基金the Indian Council of Agricultural Research,New Delhi for the grant in aid through ICAR-Central Institute for Cotton Research,Nagpur Institutional Project。
文摘Background The emergence of pink bollworm(PBW),Pectinophora gossypiella(Saunders)(Lepidoptera:Gelechiidae),in cotton due to Bt resistance and concealed feeding habit has created a need for alternative,eco-friendly,and cost-effective control methods.This study aimed to evaluate the bio-efficacy and reproductive potential of two native strains of entomopathogenic nematodes(EPNs),Heterorhabditis indica,namely CICR-HI-CL and CICR-HI-MN,against PBW larvae and pupae under in-vitro conditions.Results The larval assay revealed that strain CICR-HI-CL exhibited higher potency than strain CICR-HI-MN against 2nd,3rd,and 4thinstar larvae,with median lethal dose(LD50)values of 5.45,4.45,and 4.60 infective juveniles(IJs)per larva,respectively.In case of pupal bioassay,both EPN strains demonstrated greater virulence when applied directly(LD50values:29.65 and 73.88 IJs per pupa for strains CICR-HI-CL and CICR-HI-MN,respectively)compared to soil application(147.84 and 272.38 IJs per pupa).Both EPN strains successfully penetrated and reproduced on 4thinstar larvae,resulting in maximum production of 19.28 and 20.85 lakh IJs per larva in the next generation when inoculated at 30 IJs per larva.Conclusion The present study has generated useful information on the virulence and reproductive potential of two strains of EPN H.indica(CICR-HI-CL and CICR-HI-MN)against PBW,a dreaded pest of cotton.Higher virulence and reproductive potential of EPN strains demonstrated their ability to multiply,sustain and perpetuate on larval and pupal stages of PBW.The knowledge generated will help formulate effective management strategies for PBW with the inclusion of EPN as a potential biological control candidate.The soil-dwelling life stages viz.,last instar hibernating larvae and pupae of PBW can be the ideal weak links to make a successful use of H.indica for sustainable management of PBW in the cotton ecosystem.However,before taking these EPN strains to field for managing PBW,detailed studies investigating their biocontrol potential against PBW under field conditions are needed.
