Background The cryptic nature of pink bollworm Pectinophora gossypiella(Saunders)larvae enables its reduced vul-nerability to insecticidal control.Further,the development of resistance against Bacillus thuringiensis(B...Background The cryptic nature of pink bollworm Pectinophora gossypiella(Saunders)larvae enables its reduced vul-nerability to insecticidal control.Further,the development of resistance against Bacillus thuringiensis(Bt)toxins posed a serious threat to transgenic cotton cultivation.This necessitated determining the critical timing of spray applications on the control effectiveness.This study assessed the influence of egg age(freshly laid vs.three-day-old)and the loca-tion of larvae(directly exposed to the insecticide residues on the boll rind vs.burrowed inside the bolls)on insecticide control efficacy.Results The results revealed a significant decrease in the ovicidal activity of tested insecticides with an increase in the age of eggs from one day old to three days old(paired t-test,P<0.05).The larvae directly exposed to the insec-ticide residues on the boll rind were more susceptible(>80%mortality)than the larvae exposed after they had bur-rowed inside the bolls(<49%mortality).The inhibitory effects of tested insecticides on developmental biology were more pronounced in the experiment on pre-larval release insecticide treatment compared with insecticide treatment given post-larval release and entry inside the bolls.Conclusion Egg age influences the insecticide susceptibility,as does the larval location,directly exposed vs bur-rowed inside the bolls.Older eggs and the larvae that had burrowed inside the green bolls of cotton were relatively less susceptible to the insecticide treatments.The toxic effects of insecticides on egg and larval stages were primar-ily ephemeral.These findings are significant for devising a comprehensive strategy for pink bollworm management on a sustainable basis.展开更多
Background & Objectives: Epidemics of arboviruses such as Dengue, Chikungunya and Zika have been recorded in recent years indicating that Aedes aegypti and Aedes albopictus are both important and very active vecto...Background & Objectives: Epidemics of arboviruses such as Dengue, Chikungunya and Zika have been recorded in recent years indicating that Aedes aegypti and Aedes albopictus are both important and very active vectors in Africa. For vector control, insecticides are on the front line, unfortunately, reported resistance jeopardizes the effectiveness of this strategy. The objective of this review was to determine the geographical distribution and insecticide resistance mechanisms of Ae. aegypti and Ae. Albopictus in Africa. Methods: A systematic review of the literature in scientific databases (PubMed, Google Scholar, ScienceDirect, Hinari) allowed us to identify relevant articles on the geographical distribution of Aedes aegypti, Aedes albopictus and arboviral diseases. On the other hand, studies related to insecticides used in vector control against Aedes, associated resistances and their molecular and metabolic mechanisms. Results: A total of 94 studies met the inclusion criteria for this search. Aedes aegypti is reported in most of Africa, and Aedes albopictus in part. There is a re-emergence and outbreak of Arbovirus epidemics in West and Central Africa. The insecticides used were organochlorines, carbamates, organophosphates and pyrethroids. In Aedes, target site insensitivity and metabolic resistance would be the 2 main mechanisms of resistance to these insecticides. Interpretation & Conclusion: Resistance has been recorded in all four major classes of insecticides recommended by WHO for vector control and eradication. New vector control methods such as the use of plant extracts with larvicidal and adulticidal activities, advanced modern biotechnology techniques, and nanobiotechnology need to be developed.展开更多
Background To control the boll weevil Anthonomus grandis grandis(Coleoptera:Curculionidae),a key pest of cotton in the Americas,insecticides have been intensively used to manage their populations,increasing selection ...Background To control the boll weevil Anthonomus grandis grandis(Coleoptera:Curculionidae),a key pest of cotton in the Americas,insecticides have been intensively used to manage their populations,increasing selection pressure for resistant populations.Thus,this study aimed to detect insecticide resistance and assess insecticide control failure likelihood of boll weevil populations exposed to malathion,profenophos+cypermethrin,and fipronil insecticides.Results Twelve populations of the boll weevil were collected from commercial cotton fileds of the state of Bahia,northeastern Brazil.These populations were exposed to malathion,profenophos+cypermethrin mixture,and fipronil,at their respective maximum label dose for field applications.Three replicates of 10 adult beetles were exposed to the insecticides and mortality was recorded after 24 h treatment.The control failure likelihood was determined after 48 h.Highest median lethal times(LT_(50))were observed for malathion and the profenophos+cypermethrin mixture.Resistance to at least one insecticide was detected in 11 populations;three populations were resistant to malathion and profenophos+cypermethrin;seven were resistant to all insecticides tested.The resistance levels were low(<10-fold)for the three insecticides.Among 12 populations tested,58%of them exhibited significant risk of control failure for the insecticides malathion and profenophos+cypermethrin.The insecticide fipronil was efficient for the control of the boll weevil in 83%of the populations.Conclusions The results confirm the significant risk of insecticide control failure in the boll weevil populations to the main compounds used in the region.Thus,proper insecticide resistance management plans are necessary for the boll weevil in the region,particularly for malathion and profenophos+cypermethrin insecticides.展开更多
文摘Background The cryptic nature of pink bollworm Pectinophora gossypiella(Saunders)larvae enables its reduced vul-nerability to insecticidal control.Further,the development of resistance against Bacillus thuringiensis(Bt)toxins posed a serious threat to transgenic cotton cultivation.This necessitated determining the critical timing of spray applications on the control effectiveness.This study assessed the influence of egg age(freshly laid vs.three-day-old)and the loca-tion of larvae(directly exposed to the insecticide residues on the boll rind vs.burrowed inside the bolls)on insecticide control efficacy.Results The results revealed a significant decrease in the ovicidal activity of tested insecticides with an increase in the age of eggs from one day old to three days old(paired t-test,P<0.05).The larvae directly exposed to the insec-ticide residues on the boll rind were more susceptible(>80%mortality)than the larvae exposed after they had bur-rowed inside the bolls(<49%mortality).The inhibitory effects of tested insecticides on developmental biology were more pronounced in the experiment on pre-larval release insecticide treatment compared with insecticide treatment given post-larval release and entry inside the bolls.Conclusion Egg age influences the insecticide susceptibility,as does the larval location,directly exposed vs bur-rowed inside the bolls.Older eggs and the larvae that had burrowed inside the green bolls of cotton were relatively less susceptible to the insecticide treatments.The toxic effects of insecticides on egg and larval stages were primar-ily ephemeral.These findings are significant for devising a comprehensive strategy for pink bollworm management on a sustainable basis.
文摘Background & Objectives: Epidemics of arboviruses such as Dengue, Chikungunya and Zika have been recorded in recent years indicating that Aedes aegypti and Aedes albopictus are both important and very active vectors in Africa. For vector control, insecticides are on the front line, unfortunately, reported resistance jeopardizes the effectiveness of this strategy. The objective of this review was to determine the geographical distribution and insecticide resistance mechanisms of Ae. aegypti and Ae. Albopictus in Africa. Methods: A systematic review of the literature in scientific databases (PubMed, Google Scholar, ScienceDirect, Hinari) allowed us to identify relevant articles on the geographical distribution of Aedes aegypti, Aedes albopictus and arboviral diseases. On the other hand, studies related to insecticides used in vector control against Aedes, associated resistances and their molecular and metabolic mechanisms. Results: A total of 94 studies met the inclusion criteria for this search. Aedes aegypti is reported in most of Africa, and Aedes albopictus in part. There is a re-emergence and outbreak of Arbovirus epidemics in West and Central Africa. The insecticides used were organochlorines, carbamates, organophosphates and pyrethroids. In Aedes, target site insensitivity and metabolic resistance would be the 2 main mechanisms of resistance to these insecticides. Interpretation & Conclusion: Resistance has been recorded in all four major classes of insecticides recommended by WHO for vector control and eradication. New vector control methods such as the use of plant extracts with larvicidal and adulticidal activities, advanced modern biotechnology techniques, and nanobiotechnology need to be developed.
基金supported by Foundation for Research Support of the State of Bahia(FAPESB)the CAPES Foundation(Brazilian Ministry of Education+1 种基金Finance Code 001)for financial supportBahia Association of Cotton Producers。
文摘Background To control the boll weevil Anthonomus grandis grandis(Coleoptera:Curculionidae),a key pest of cotton in the Americas,insecticides have been intensively used to manage their populations,increasing selection pressure for resistant populations.Thus,this study aimed to detect insecticide resistance and assess insecticide control failure likelihood of boll weevil populations exposed to malathion,profenophos+cypermethrin,and fipronil insecticides.Results Twelve populations of the boll weevil were collected from commercial cotton fileds of the state of Bahia,northeastern Brazil.These populations were exposed to malathion,profenophos+cypermethrin mixture,and fipronil,at their respective maximum label dose for field applications.Three replicates of 10 adult beetles were exposed to the insecticides and mortality was recorded after 24 h treatment.The control failure likelihood was determined after 48 h.Highest median lethal times(LT_(50))were observed for malathion and the profenophos+cypermethrin mixture.Resistance to at least one insecticide was detected in 11 populations;three populations were resistant to malathion and profenophos+cypermethrin;seven were resistant to all insecticides tested.The resistance levels were low(<10-fold)for the three insecticides.Among 12 populations tested,58%of them exhibited significant risk of control failure for the insecticides malathion and profenophos+cypermethrin.The insecticide fipronil was efficient for the control of the boll weevil in 83%of the populations.Conclusions The results confirm the significant risk of insecticide control failure in the boll weevil populations to the main compounds used in the region.Thus,proper insecticide resistance management plans are necessary for the boll weevil in the region,particularly for malathion and profenophos+cypermethrin insecticides.
