The aim of the present study was to compare the ixodicide efficacy of 1% permethrin applied as a shampoo-bath in single treatment and a combined formulation of 2% permethrin + 1% piperonyl butoxide applied as powder i...The aim of the present study was to compare the ixodicide efficacy of 1% permethrin applied as a shampoo-bath in single treatment and a combined formulation of 2% permethrin + 1% piperonyl butoxide applied as powder in a single treatment against Rhipicephalus sanguineus ticks, in naturally infested dogs. Eighteen adult cross-mixed dogs, harboring to at least 20 ticks/animal, were selected on pre-treatment live tick counts. On day 0, the dogs were then divided in 3 groups of 6 animals each, for treatment: Group 1 (G1) received 1% permethrin applied as shampoo-bath (approximately 10 ml/kg bw), according to label instructions. G2 was treated with 2% permethrin + 1% piperonyl butoxide applied as powder, and rubbed as massage on the body, as recommended by the producer. G3 served as a non-treated control. After the treatment, the dogs were checked out for live ticks counting on days 0, 1, 7, and 14. The ixodicide efficacy was assessed based on the percentage reductions of ticks on the days analyzed post-treatment, with respect to the untreated control. Results showed that permethrin alone removed ticks on 81%, 93.1% and 89.6% for days 1, 7 and 14, respectively. The combined formulation of 2% permethrin + 1% piperonyl butoxide exerted a better efficacy of 98.8, 97.7 and 97.0%, respectively. It is concluded that this combined formulation was highly effective at rapidly repelling and killing Riphicephalus sanguineus ticks on naturally infected dogs, showing a significant effect on days 1, 7 and 14 after tick exposure. The sustained high and quick level of efficacy of this combination may well interfere with the transmission of Riphicephalus sanguineus ticks. It is concluded that the sustained high level of efficacy of the permethrin + piperonyl butoxide combination may well exert an additive effect and could interfere with the transmission of Riphicephalus sanguineus ticks.展开更多
Effects of sublethal piperonyl butoxide （PB） on parasitization of Bemisia tabaci （Gennadius） （Hemiptera： Aleyrodidae） by Encarsia bimaculata Heraty et Polaszek （Hymenoptera： Aphelinidae） were evaluated both ...Effects of sublethal piperonyl butoxide （PB） on parasitization of Bemisia tabaci （Gennadius） （Hemiptera： Aleyrodidae） by Encarsia bimaculata Heraty et Polaszek （Hymenoptera： Aphelinidae） were evaluated both in cage and greenhouse experiments. When first, second and third instar B. tabaci nymphs were treated with PB, all but the first instar were significantly prolonged. Data indicated that sublethal PB could improve E. bimaculata parasitism rates without influencing parasitoid eclosion rates. Prolonged development increased rates of parasitism by E. bimaculata, from 17.6% to 24.7% in cages, presumably by increasing the duration of host exposure. Sublethal PB combined with E. bimaculata as an integrated approach to control B. tabaci was evaluated using life table parameters under greenhouse conditions. Indices of population trend （I） calculated from life tables were estimated at 4.6 for B. tabaci exposed to PB and parasitoids compared to 14.1 with parasitoids alone and 23.5 in un- treated controls. The results showed that after PB was sprayed and parasitoids introduced, development ofB. tabaci was delayed and the peak of each stage was postponed. The older nymphal stage had highest mortality, primarily due to mortality caused by parasitism by E. bimaculata.展开更多
Background:Long-lasting insecticide nets(LLINs)are a core malaria intervention.LLINs should retain efficacy against mosquito vectors for a minimum of three years.Efficacy and durability of Olyset®Plus,a permethri...Background:Long-lasting insecticide nets(LLINs)are a core malaria intervention.LLINs should retain efficacy against mosquito vectors for a minimum of three years.Efficacy and durability of Olyset®Plus,a permethrin and piperonyl butoxide(PBO)treated LLIN,was evaluated versus permethrin treated Olyset®Net.In the absence of WHO guidelines of how to evaluate PBO nets,and considering the manufacturer’s product claim,Olyset®Plus was evaluated as a pyrethroid LLIN.Methods:This was a household randomized controlled trial in a malaria endemic rice cultivation zone of Kirinyaga County,Kenya between 2014 and 2017.Cone bioassays and tunnel tests were done against Anopheles gambiae Kisumu.The chemical content,fabric integrity and LLIN survivorship were monitored.Comparisons between nets were tested for signifcance using the Chi-square test.Exact binomial distribution with 95%confdence intervals(95%CI)was used for percentages.The WHO efcacy criteria used were≥95%knockdown and/or≥80%mortality rate in cone bioassays and≥80%mortality and/or≥90%blood-feeding inhibition in tunnel tests.Results:At 36 months,Olyset®Plus lost 52%permethrin and 87%PBO content;Olyset®Net lost 24%permethrin.Over 80%of Olyset®Plus and Olyset®Net passed the WHO efcacy criteria for LLINs up to 18 and 12 months,respec‑tively.At month 36,91.2%Olyset®Plus and 86.4%Olyset®Net survived,while 72%and 63%developed at least one hole.The proportionate Hole Index(pHI)values representing nets in good,serviceable and torn condition were 49.6%,27.1%and 23.2%,respectively for Olyset®Plus,and 44.9%,32.8%and 22.2%,respectively for Olyset®Net but were not signifcantly diferent.Conclusions:Olyset®Plus retained efcacy above or close to the WHO efcacy criteria for about 2 years than Olyset®Net(1–1.5 years).Both nets did not meet the 3-year WHO efcacy criteria,and showed little attrition,comparable physical durability and survivorship,with 50%of Olyset®Plus having good and serviceable condition after 3 years.Better community education on appropriate use and upkeep of LLINs is essential to ensure efectiveness of LLIN based malaria interventions.展开更多
Malaria incidence in urban areas has generally been low compared to rural areas but recent data indicate that urban malaria remains a public health problem. It is therefore important to understand the factors that pro...Malaria incidence in urban areas has generally been low compared to rural areas but recent data indicate that urban malaria remains a public health problem. It is therefore important to understand the factors that promote urban malaria to help formulate future vector control strategies. This study compared Anopheles gambiae s.l. (A. gambiae s.l.) species composition, distribution and insecticide resistance mechanisms between vegetable and non-vegetable growing areas in Accra Metropolis. Four sites were selected within the city of Accra which comprised of two vegetable-growing and two non-vegetable growing areas. WHO susceptibility tests were carried out on adults A. gambiae s.l. reared from larvae collected from the sites. Five insecticides were tested and the A. gambiae complex, resistance genotypes and enzyme activities of each population were characterized. All A. gambiae s.l. populations tested were resistant to all the insecticides, but relatively lower mortalities were observed in the vegetable growing areas. The mortality against 0.05% deltamethrin was 2.6% (Opeibea) and 12.5% (Korle-Bu) for the vegetable growing areas and 36.2% (Achimota) and 38.9% (Mataheko) in the non-vegetable growing areas. Anopheles gambiae s.s. (95% of Opeibea population) and Anopheles coluzzii, (98% of Korle-Bu population) were the dominant species in the vegetable growing areas. The voltage-gated sodium channel (Vgsc-1014F) frequencies of all the populations were similar but the acetylcholinesterase (ace-1) frequencies were significantly lower (p A. gambiae s.l. from Opeibea than from the other areas. The contribution of urban agriculture in the development of insecticide resistance needs to be considered in the formulation of future vector control strategies alongside other domestic usages.展开更多
Fleas that infest pets are considered important parasites of both animals and humans. These insects cause irritation and can also transmit zoonotic diseases. Research has led to a rapid expansion in the development of...Fleas that infest pets are considered important parasites of both animals and humans. These insects cause irritation and can also transmit zoonotic diseases. Research has led to a rapid expansion in the development of flea control products. In the face of a market that offers dozens of commercial ectoparasiticides for dogs and cats, pet owners and veterinarians must be provided with evidence to support their decision to select a product to control fleas. To compare the efficacy of three commercially available products against companion animal fleas, a trial was conducted on naturally-infested dogs in order to validate their pulicidal activity. Thirty-two flea-infested dogs with fleas were divided into 4 groups (n = 8) for each treatment. Group 1 received one pipette of permethrin as a spot-on dose of 650 mg/ml. The second group received 9.7% fipronil as a spot-on formulation. Group 3 was treated with a spot-on formulation of permethrin 7.40% plus piperonyl butoxide at 7.40%. Group 4 remained as the untreated control. Fleas of all experimental dogs were examined and counted on days 0, 3, 7, 14, 21 and 28 to determine the percentage of flea reduction. Results showed a 100% efficacy for all tested products. Identified species were: Ctenocephalides felis (75.7%), Ctenocephalides canis (15.9%) and Pulex irritans (9.5%). Based on these results, it was concluded that the three anti-flea products evaluated under the conditions of this study, produced an excellent efficacy as from the third day after treatment.展开更多
Trichoplusia ni caterpillars are polyphagous foliage-feeders and rarely likely to encounter aflatoxin B1 （AFB1）, a mycotoxin produced by Aspergillus flavus and A. parasiticus, in their host plants. To determine how ...Trichoplusia ni caterpillars are polyphagous foliage-feeders and rarely likely to encounter aflatoxin B1 （AFB1）, a mycotoxin produced by Aspergillus flavus and A. parasiticus, in their host plants. To determine how T. ni copes with AFB 1, we evaluated the toxicity ofAFB 1 to T. ni caterpillars at different developmental stages and found that AFB 1 tolerance significantly increases with larval development. Diet incorporation of AFB 1 at 1μg/g completely inhibited larval growth and pupation of newly hatched larvae, but 3μg/g AFB 1 did not have apparent toxic effects on larval growth and pupation of caterpillars that first consume this compound 10 days after hatching. Piperonyl butoxide, a general inhibitor of cytochrome P450 monooxygenases （P450s）, reduced the toxicity of AFB 1, suggesting that AFB1 is bioactivated in T. ni and this bioactivation is mediated by P450s. Some plant allelochemicals, including flavonoids such as fiavones, furanocoumarins such as xanthotoxin and imperatorin, and furanochromones such as visnagin, that induce P450s in other lepidopteran larvae ameliorated AFBI toxicity, suggesting that P450s are also involved in AFB 1 detoxification in T. ni.展开更多
文摘The aim of the present study was to compare the ixodicide efficacy of 1% permethrin applied as a shampoo-bath in single treatment and a combined formulation of 2% permethrin + 1% piperonyl butoxide applied as powder in a single treatment against Rhipicephalus sanguineus ticks, in naturally infested dogs. Eighteen adult cross-mixed dogs, harboring to at least 20 ticks/animal, were selected on pre-treatment live tick counts. On day 0, the dogs were then divided in 3 groups of 6 animals each, for treatment: Group 1 (G1) received 1% permethrin applied as shampoo-bath (approximately 10 ml/kg bw), according to label instructions. G2 was treated with 2% permethrin + 1% piperonyl butoxide applied as powder, and rubbed as massage on the body, as recommended by the producer. G3 served as a non-treated control. After the treatment, the dogs were checked out for live ticks counting on days 0, 1, 7, and 14. The ixodicide efficacy was assessed based on the percentage reductions of ticks on the days analyzed post-treatment, with respect to the untreated control. Results showed that permethrin alone removed ticks on 81%, 93.1% and 89.6% for days 1, 7 and 14, respectively. The combined formulation of 2% permethrin + 1% piperonyl butoxide exerted a better efficacy of 98.8, 97.7 and 97.0%, respectively. It is concluded that this combined formulation was highly effective at rapidly repelling and killing Riphicephalus sanguineus ticks on naturally infected dogs, showing a significant effect on days 1, 7 and 14 after tick exposure. The sustained high and quick level of efficacy of this combination may well interfere with the transmission of Riphicephalus sanguineus ticks. It is concluded that the sustained high level of efficacy of the permethrin + piperonyl butoxide combination may well exert an additive effect and could interfere with the transmission of Riphicephalus sanguineus ticks.
基金Acknowledgments This research was supported by the China National Natural Science Foundation （30400292, 31071743）, National Basic Research Program of China （973 project 2006CB 102005, 948 project 2011 4 6 1） and Na- tional Department Public Benefit Research Foundation （201003065）.
文摘Effects of sublethal piperonyl butoxide （PB） on parasitization of Bemisia tabaci （Gennadius） （Hemiptera： Aleyrodidae） by Encarsia bimaculata Heraty et Polaszek （Hymenoptera： Aphelinidae） were evaluated both in cage and greenhouse experiments. When first, second and third instar B. tabaci nymphs were treated with PB, all but the first instar were significantly prolonged. Data indicated that sublethal PB could improve E. bimaculata parasitism rates without influencing parasitoid eclosion rates. Prolonged development increased rates of parasitism by E. bimaculata, from 17.6% to 24.7% in cages, presumably by increasing the duration of host exposure. Sublethal PB combined with E. bimaculata as an integrated approach to control B. tabaci was evaluated using life table parameters under greenhouse conditions. Indices of population trend （I） calculated from life tables were estimated at 4.6 for B. tabaci exposed to PB and parasitoids compared to 14.1 with parasitoids alone and 23.5 in un- treated controls. The results showed that after PB was sprayed and parasitoids introduced, development ofB. tabaci was delayed and the peak of each stage was postponed. The older nymphal stage had highest mortality, primarily due to mortality caused by parasitism by E. bimaculata.
基金The work was funded as a collaborative project by the WHO Pesticide Evalua‑tion Scheme,Geneva,Switzerland.
文摘Background:Long-lasting insecticide nets(LLINs)are a core malaria intervention.LLINs should retain efficacy against mosquito vectors for a minimum of three years.Efficacy and durability of Olyset®Plus,a permethrin and piperonyl butoxide(PBO)treated LLIN,was evaluated versus permethrin treated Olyset®Net.In the absence of WHO guidelines of how to evaluate PBO nets,and considering the manufacturer’s product claim,Olyset®Plus was evaluated as a pyrethroid LLIN.Methods:This was a household randomized controlled trial in a malaria endemic rice cultivation zone of Kirinyaga County,Kenya between 2014 and 2017.Cone bioassays and tunnel tests were done against Anopheles gambiae Kisumu.The chemical content,fabric integrity and LLIN survivorship were monitored.Comparisons between nets were tested for signifcance using the Chi-square test.Exact binomial distribution with 95%confdence intervals(95%CI)was used for percentages.The WHO efcacy criteria used were≥95%knockdown and/or≥80%mortality rate in cone bioassays and≥80%mortality and/or≥90%blood-feeding inhibition in tunnel tests.Results:At 36 months,Olyset®Plus lost 52%permethrin and 87%PBO content;Olyset®Net lost 24%permethrin.Over 80%of Olyset®Plus and Olyset®Net passed the WHO efcacy criteria for LLINs up to 18 and 12 months,respec‑tively.At month 36,91.2%Olyset®Plus and 86.4%Olyset®Net survived,while 72%and 63%developed at least one hole.The proportionate Hole Index(pHI)values representing nets in good,serviceable and torn condition were 49.6%,27.1%and 23.2%,respectively for Olyset®Plus,and 44.9%,32.8%and 22.2%,respectively for Olyset®Net but were not signifcantly diferent.Conclusions:Olyset®Plus retained efcacy above or close to the WHO efcacy criteria for about 2 years than Olyset®Net(1–1.5 years).Both nets did not meet the 3-year WHO efcacy criteria,and showed little attrition,comparable physical durability and survivorship,with 50%of Olyset®Plus having good and serviceable condition after 3 years.Better community education on appropriate use and upkeep of LLINs is essential to ensure efectiveness of LLIN based malaria interventions.
文摘Malaria incidence in urban areas has generally been low compared to rural areas but recent data indicate that urban malaria remains a public health problem. It is therefore important to understand the factors that promote urban malaria to help formulate future vector control strategies. This study compared Anopheles gambiae s.l. (A. gambiae s.l.) species composition, distribution and insecticide resistance mechanisms between vegetable and non-vegetable growing areas in Accra Metropolis. Four sites were selected within the city of Accra which comprised of two vegetable-growing and two non-vegetable growing areas. WHO susceptibility tests were carried out on adults A. gambiae s.l. reared from larvae collected from the sites. Five insecticides were tested and the A. gambiae complex, resistance genotypes and enzyme activities of each population were characterized. All A. gambiae s.l. populations tested were resistant to all the insecticides, but relatively lower mortalities were observed in the vegetable growing areas. The mortality against 0.05% deltamethrin was 2.6% (Opeibea) and 12.5% (Korle-Bu) for the vegetable growing areas and 36.2% (Achimota) and 38.9% (Mataheko) in the non-vegetable growing areas. Anopheles gambiae s.s. (95% of Opeibea population) and Anopheles coluzzii, (98% of Korle-Bu population) were the dominant species in the vegetable growing areas. The voltage-gated sodium channel (Vgsc-1014F) frequencies of all the populations were similar but the acetylcholinesterase (ace-1) frequencies were significantly lower (p A. gambiae s.l. from Opeibea than from the other areas. The contribution of urban agriculture in the development of insecticide resistance needs to be considered in the formulation of future vector control strategies alongside other domestic usages.
文摘Fleas that infest pets are considered important parasites of both animals and humans. These insects cause irritation and can also transmit zoonotic diseases. Research has led to a rapid expansion in the development of flea control products. In the face of a market that offers dozens of commercial ectoparasiticides for dogs and cats, pet owners and veterinarians must be provided with evidence to support their decision to select a product to control fleas. To compare the efficacy of three commercially available products against companion animal fleas, a trial was conducted on naturally-infested dogs in order to validate their pulicidal activity. Thirty-two flea-infested dogs with fleas were divided into 4 groups (n = 8) for each treatment. Group 1 received one pipette of permethrin as a spot-on dose of 650 mg/ml. The second group received 9.7% fipronil as a spot-on formulation. Group 3 was treated with a spot-on formulation of permethrin 7.40% plus piperonyl butoxide at 7.40%. Group 4 remained as the untreated control. Fleas of all experimental dogs were examined and counted on days 0, 3, 7, 14, 21 and 28 to determine the percentage of flea reduction. Results showed a 100% efficacy for all tested products. Identified species were: Ctenocephalides felis (75.7%), Ctenocephalides canis (15.9%) and Pulex irritans (9.5%). Based on these results, it was concluded that the three anti-flea products evaluated under the conditions of this study, produced an excellent efficacy as from the third day after treatment.
文摘Trichoplusia ni caterpillars are polyphagous foliage-feeders and rarely likely to encounter aflatoxin B1 （AFB1）, a mycotoxin produced by Aspergillus flavus and A. parasiticus, in their host plants. To determine how T. ni copes with AFB 1, we evaluated the toxicity ofAFB 1 to T. ni caterpillars at different developmental stages and found that AFB 1 tolerance significantly increases with larval development. Diet incorporation of AFB 1 at 1μg/g completely inhibited larval growth and pupation of newly hatched larvae, but 3μg/g AFB 1 did not have apparent toxic effects on larval growth and pupation of caterpillars that first consume this compound 10 days after hatching. Piperonyl butoxide, a general inhibitor of cytochrome P450 monooxygenases （P450s）, reduced the toxicity of AFB 1, suggesting that AFB1 is bioactivated in T. ni and this bioactivation is mediated by P450s. Some plant allelochemicals, including flavonoids such as fiavones, furanocoumarins such as xanthotoxin and imperatorin, and furanochromones such as visnagin, that induce P450s in other lepidopteran larvae ameliorated AFBI toxicity, suggesting that P450s are also involved in AFB 1 detoxification in T. ni.
