The efficacy of insecticide-treated nets (ITNs) is increasingly compromised by the prevalence of malaria vectors resistant to pyrethroids. In response to this issue, a new generation of ITNs has been developed that in...The efficacy of insecticide-treated nets (ITNs) is increasingly compromised by the prevalence of malaria vectors resistant to pyrethroids. In response to this issue, a new generation of ITNs has been developed that incorporate synergistic components, such as piperonyl butoxide (PBO). The purpose of this study is to provide entomological evidence for the efficacy of a PBO-based ITN brand at the village level, serving as a basis for decision-making before large-scale net deployment. During the high malaria transmission period, ITNs were distributed in each group and vector sampling was conducted biweekly in selected households. Bionomic data were collected to assess the resistance of wild An. gambiae populations to various chemical insecticides. There was a significant disparity in total An. gambiae sl. collected between the ITN arms, the intervention arm (ITN arms), and the control arm (P = 0.003). An. coluzzi was identified as the predominant species in the study area, as confirmed by PCR analysis. Analysis of the blood-feeding inhibition rate revealed that 100% permethrin + PBO ITN exhibited significantly greater inhibition than 66.81% permethrin only ITN. According to the log-time probit regression analysis, permethrin exhibited a knockdown time of 256 min without synergists, while it decreased to 139 min (P = 0.001) when pre-exposed to PBO. The evidence from this trial supports the use of PBO ITNs over standard ITNs for pyrethroids to combat pyrethroid resistance and improve protection against malaria for both individuals and communities, particularly in areas with high pyrethroid resistance.展开更多
Currently, insecticides are considered as the primary approach for controlling western flower thrips, Frankliniella occidentalis（Pergande）（Thysanoptera： Thripidae）. However, the heavy use of insecticides resulted...Currently, insecticides are considered as the primary approach for controlling western flower thrips, Frankliniella occidentalis（Pergande）（Thysanoptera： Thripidae）. However, the heavy use of insecticides resulted in high insect resistance and serious environmental pollution. Given its characteristics of ease of operation and environmental friendliness, insect control using high temperature is receiving considerable renewed research interest. However, although the combination of insecticides and high temperature to control F. occidentalis has been studied before, few studies have focused on the short-term effect of such treatment. In a laboratory study, F. occidentalis adults and second-instar nymphs were exposed to 45℃ for 2 h. Then, their susceptibility to acetamiprid, spinosad, methomyl, and beta-cypermethrin was tested after different periods of recovery time（2–36 h）. Additionally, the specific activity of three detoxification enzymes（esterase, glutathione S-transferase, and cytochrome p450（CYP） monooxygenase） of the treated insects was determined. The results indicated that the fluctuation of susceptibility to insecticides and detoxification enzyme activity during F. occidentalis recovery from heat shock are related. Furthermore, several recovery time points（2, 30, and 36 h） of significant susceptibility to four tested insecticides compared with the control were found during the treatment of adults that were heat-shocked. Recovery time points of higher susceptibility compared with the control depended on different insecticides during the second-instar nymph recovery from heat shock. Interestingly, the fluctuation of CYP monooxygenase activity exhibited a trend that was similar to the fluctuation of susceptibility to insecticides（especially spinosad） during the recovery from heat shock of adults. In addition, the glutathione S-transferase and CYP monooxygenase activity trend was similar to the trend of susceptibility to spinosad during the recovery from heat shock of second-instar nymphs. Our results provide a new approach for controlling F. occidentalis using the combined heat shock and insecticide. This effectively enhances the control efficiency of heat shock and significantly reduces the application of insecticides.展开更多
文摘The efficacy of insecticide-treated nets (ITNs) is increasingly compromised by the prevalence of malaria vectors resistant to pyrethroids. In response to this issue, a new generation of ITNs has been developed that incorporate synergistic components, such as piperonyl butoxide (PBO). The purpose of this study is to provide entomological evidence for the efficacy of a PBO-based ITN brand at the village level, serving as a basis for decision-making before large-scale net deployment. During the high malaria transmission period, ITNs were distributed in each group and vector sampling was conducted biweekly in selected households. Bionomic data were collected to assess the resistance of wild An. gambiae populations to various chemical insecticides. There was a significant disparity in total An. gambiae sl. collected between the ITN arms, the intervention arm (ITN arms), and the control arm (P = 0.003). An. coluzzi was identified as the predominant species in the study area, as confirmed by PCR analysis. Analysis of the blood-feeding inhibition rate revealed that 100% permethrin + PBO ITN exhibited significantly greater inhibition than 66.81% permethrin only ITN. According to the log-time probit regression analysis, permethrin exhibited a knockdown time of 256 min without synergists, while it decreased to 139 min (P = 0.001) when pre-exposed to PBO. The evidence from this trial supports the use of PBO ITNs over standard ITNs for pyrethroids to combat pyrethroid resistance and improve protection against malaria for both individuals and communities, particularly in areas with high pyrethroid resistance.
基金funded by the National Natural Science Foundation of China (31372003)the Shandong Modern Agricultural Technology and Industry System, China (SDAIT-02-021-11)+2 种基金the Taishan Scholarship Construction Engineering Special Fund, Chinathe Startup Fund for Distinguished Scholars (631316)supported by the Qingdao Agricultural University,China
文摘Currently, insecticides are considered as the primary approach for controlling western flower thrips, Frankliniella occidentalis（Pergande）（Thysanoptera： Thripidae）. However, the heavy use of insecticides resulted in high insect resistance and serious environmental pollution. Given its characteristics of ease of operation and environmental friendliness, insect control using high temperature is receiving considerable renewed research interest. However, although the combination of insecticides and high temperature to control F. occidentalis has been studied before, few studies have focused on the short-term effect of such treatment. In a laboratory study, F. occidentalis adults and second-instar nymphs were exposed to 45℃ for 2 h. Then, their susceptibility to acetamiprid, spinosad, methomyl, and beta-cypermethrin was tested after different periods of recovery time（2–36 h）. Additionally, the specific activity of three detoxification enzymes（esterase, glutathione S-transferase, and cytochrome p450（CYP） monooxygenase） of the treated insects was determined. The results indicated that the fluctuation of susceptibility to insecticides and detoxification enzyme activity during F. occidentalis recovery from heat shock are related. Furthermore, several recovery time points（2, 30, and 36 h） of significant susceptibility to four tested insecticides compared with the control were found during the treatment of adults that were heat-shocked. Recovery time points of higher susceptibility compared with the control depended on different insecticides during the second-instar nymph recovery from heat shock. Interestingly, the fluctuation of CYP monooxygenase activity exhibited a trend that was similar to the fluctuation of susceptibility to insecticides（especially spinosad） during the recovery from heat shock of adults. In addition, the glutathione S-transferase and CYP monooxygenase activity trend was similar to the trend of susceptibility to spinosad during the recovery from heat shock of second-instar nymphs. Our results provide a new approach for controlling F. occidentalis using the combined heat shock and insecticide. This effectively enhances the control efficiency of heat shock and significantly reduces the application of insecticides.
