二氯苯醚菊酯浸泡蚊帐防制蚊虫的实验小屋试验

棉纱蚊帐浸泡二氯苯醚菊酯５００ｍｇａｉ／ｍ２在实验小屋试验，浸帐后１年内对中华按蚊和三带喙库蚊的平均毒杀死亡率分别为７８．９％和８０．２％，吸血率为０．２７％和０．２３％，在蚊帐穿孔条件下，即蚊帐每个穿孔的面积为１０×１０ｃｍ，所有孔的面积之和占蚊帐面积的５％，浸帐后７个月内对中华接蚊和三带喙库蚊的平均死亡率为８４．５％和９４．５％，且可降低吸血率，中华按蚊为４４．９％，三带喙库蚊为６６．９％。同时发现二氯苯醚菊酯浸帐有明显阻止蚊虫飞入屋内的现象，阻止入屋率，中华按蚊７７．４％，三带喙库蚊７６．７％；而以溴氰菊酯２５ｍｇａｉ／ｍ２浸帐作比较则无此现象。研究结果证明，二氯苯醚菊酯浸泡蚊帐具有毒杀、接触兴奋驱避和降低吸血率及阻止蚊虫入屋的作用。     

二氯苯醚菊酯浸泡蚊帐防制大劣按蚊及疟疾的现场研究

１９８９年４月～１９９２年３月在海南万宁县北大乡进行了二氯苯醚菊酯浸泡蚊帐防疟试验。在现场选择１０个自然村６１２６人为实验区。浸帐前一年进行了流行病学基本数据调查，１９９０年４～５月和１９９１年４月分别用二氯苯醚菊酯５００ｍｇａｉ／ｍ２剂量浸泡蚊帐，浸帐率９８．２％，两次药帐人口覆盖率分别为７３．６％和７３．５％。实验区浸帐前（１９８９年６～１２月）平均月发病率９．９６‰，浸帐后分别降为３．４５‰（１９９０）和２．０７‰（１９９１），比浸帐前同期分别下降６５．４％和７９．２％。其中恶性疟下降尤其迅速而明显。三年试验结果表明，二氯苯醚菊酯浸泡蚊帐对大劣按蚊自然种群密度及疟疾传播均有明显的防制效果。     

家蝇二氯苯醚菊酯抗性品系酯酶分析

本文利用离体酯酶测定和聚丙烯酰胺凝胶电泳技术，分析了家蝇二氯苯醚菊酯抗性品系（下称Ｐｍ－Ｒ）和敏感品系（下称ＳＳ）的非专一性酯酶变化情况。实验结果显示：Ｐｍ－Ｒ非专一性酯酶活性比ＳＳ略有升高，仅１．５２倍，聚丙烯酰胺凝胶电泳发现二者酯酶带型不一样，各组份所占比例也不同。由此可以推断：在用二氯苯醚菊酯选育的家蝇抗性品系中，抗性的增长与非专一性酯酶活性变化关系不大，而可能与其组成结构的改变有关。     

家蝇二氯苯醚菊酯抗性株分化的研究

本研究采用随机扩增多态DNA(RAPD)技术,探索了家蝇二氯苯醚菊酯抗性株(2000倍)在DNA分子水平上的分化。实验数据采用两种分析方法:1)用RAPDPLOT计算出个体间的遗传距离,进一步用PHYLIP软件包的NEIGHBOR程序进行UPGMA(非加权对组算术平均值聚类)聚类分析;2)经bootstrip方法随机取样100次,然后再进行UPGMA分析,在PHYLIP软件包的CONSENSE中形成合意树。两种分析方法结果极为类似,在聚类树中首先是抗性与非抗性个体分成两群,然后雌、雄个体分成两群,说明抗性株在DNA分子水平上已有明显的分化。OPD-02引物在全部抗性株个体中扩增出了非抗性株所没有的特异性同一片段(100bp左右),提示此片段有可能作为家蝇二氯苯醚菊酯抗性株的分子标记,但需进一步研究确定。     

骚扰库蚊内蒙古新记录及其感染Wolbachia的检测

本研究对内蒙古满洲里地区采集到的尖音库蚊复合组蚊虫进行自育性实验和雄蚊阳茎鉴定,证实内蒙古满洲里地区发现的尖音库蚊复合组蚊虫是骚扰库蚊新记录,其自育率为72．5％,雄蚊阳茎DV／D的比值在-0．0648与0．0577之间。随后应用Wolbachia的wsp基因特异引物,通过PCR方法对其进行检测。实验结果表明,内蒙古满洲里地区骚扰库蚊的雌蚊和雄蚊体内均检测到Wolbachia感染,感染率为79．71％。     

白纹伊蚊诱蚊诱卵器应用效果的现场研究

目的评价白纹伊蚊诱蚊诱卵器现场应用效果。方法在地下停车场布放诱蚊诱卵器，7d后收回，连续3次。结果每杯诱蚊数在0～8只之间，90．80％的诱蚊诱卵器进蚊数不超过3只；所有布放的诱蚊诱卵器均没有蚊虫产卵；诱捕的蚊虫以白纹伊蚊为主，占有率为80．17％，其中雌性伊蚊47．42％，雄性伊蚊52．58％；3次试验的平均诱蚊指数为63．22％，平均诱蚊密度指数为（1．98±1．24）；布放地点的光照强度和距离下水道的远近对诱蚊结果没有显著影响。结论诱蚊诱卵器对白纹伊蚊具有较好的诱捕效果，适合用于登革热的常规监测，但在不同环境条件下的应用还需进一步研究。     

淡色库蚊三氟氯氰菊酯抗性株的选育及交互抗性的研究

本研究在实验室条件下进行淡色库蚊（Ｃｕｌｅｘｐｉｎｐｉｅｎｓｐａｌｅｎｓ）三氟氯氰菊酯抗性品系的选育，观察抗性的发展趋势，测定交互抗性谱，分析抗性品系的种群生存力、吸血率、孵化率等主要生物学特征，并比较了两个品系的相对适合度。结果发现：淡色库蚊对三氟氯氰菊酯的抗性经６代的选育后达到４１．８倍。前４代稳步上升，第５代（Ｆ４）有所下降，以后又继续攀升，抗性的发展出现波动：通过对抗性品系（Ｒ）和敏感品系（Ｓ）生长、发育、生殖等观察发现：Ｒ品系在孵化率、化蛹率、羽化率和产卵率等方面均明显低于Ｓ品系，对有关参数进行统计分析发现Ｒ品系相对Ｓ品系仅具０．４１的适合度；经６代选育所得的三氟氯氰菊酯抗性品系对三种拟除虫菊酯药物有明显交互抗性，尤其是与二氯苯醚菊酯交互抗性达４０倍以上，与溴氰菊酯、氯氰菊酯的交互抗性也在２０倍以上，与两种有机磷类杀虫剂马拉硫磷、敌百虫无交互抗性，与氨基甲酸酯类的残杀威不仅没有交互抗性，还稍有下降。这些为进一步研究蚊虫对拟除虫菊酯的抗性机理打下了基础，为防治提供了一些依据。     

刘氏中剑水蚤防治蚊幼虫的研究

作者在济宁市各种水域中广泛采集了中剑水蚤，经过培养后一种鉴定为刘氏中剑水蚤（Ｍｅｓｏｃｙｃｌｏｐｓｌｅｕｃｋａｒｔｉ），在实验室及现场中进行了系统评价。在室内，刘氏中剑水蚤对三种蚊幼虫均有较高的捕食力，２０２０比例下，中剑水蚤对白纹伊蚊Ⅰ龄幼虫在２４、４８和７２ｈ捕食率分别为９６％、１００％和１００％，对淡色库蚊幼虫分别为６５％、７５％和８０％，对中华按蚊分别为７５％、９０％和９０％。蚊笼模拟试验表明，中剑水蚤可分别于８、９和１０周内消灭白纹伊蚊、淡色库蚊和中华按蚊的幼虫种群，成蚊于２周后消失。大池培养经济易行，获得成功。现场试验证明，刘氏中剑水蚤在蚊虫孳生地可成功地建立自己的种群，存活时间长于蚊虫季节，因此可长期防治蚊幼虫。中剑水蚤防治白纹伊蚊的效果好于淡色库蚊。应用中剑水蚤的长持效和Ｂ．ｓ．及Ｂ．ｔ．ｉ．的速效，在防治淡色库蚊和白纹伊蚊方面取得了更明显的效果，幼虫密度降低率９０％以上，持效整个蚊虫季节。因此二者合用可作为蚊虫综合防治的一个组成部分。     

三种商业化二氯苯醚菊酯杀虫剂剂型对致倦库蚊的灭效评估

为评价二氯苯醚菊酯3种不同的商业剂型对致倦库蚊的杀灭效果,本文采用室内药膜法、野外现场挂笼实验评价了3种杀虫剂剂型超低容量喷雾的杀灭效果.结果表明,这3种剂型均对野外现场致倦库蚊有杀灭毒性,其中Aqua-Kontrol和AqualuerTM 在1 h内致死率均大于80%.室内药效测定表明,3种药剂均对致倦库蚊有良好灭效,其中水性列喜镇的80%致倦库蚊致死时间要显著大于另2种药剂.     

两种蚊虫在人工膜喂血装置上吸血与繁殖的观察

本文报导了淡色库蚊（Ｃｕｌｅｘｐｉｎｉｅｎｓｐａｌｅｎｓ）和白纹伊蚊（Ａｅｄｅｓａｌｂｏｐｉｃｔｕｓ）在我们研制的一种新的人工膜喂血装置上的吸血与繁殖结果。新装置采用Ｐａｒａｆｉｌｍ膜和４℃下贮存的猪血，数字控温系统控制血温。通过两种蚊虫经人工膜装置与小白鼠喂血的吸血与繁殖的比较表明：１．蚊虫密度在每笼２５０只雌蚊以下时，两种蚊虫经膜与小白鼠喂血的吸血率无显著性差别。淡色库蚊密度在３００～４００雌蚊／笼时，经膜的吸血率明显高于小白鼠喂血。２．两种蚊虫经膜的吸血量均低于用小白鼠喂血，经膜第一次喂血后的产卵量及卵的孵化率与用小白鼠喂血无明显差别。     

Resistance of malaria vectors to pyrethrins used for impregnating mosquito nets in Benin, West Africa]

Impregnated bednets can be considered a major tool for reducing Anopheles bites, malaria morbidity and overall mortality. The resistance of Anopheles gambiae to pyrethroids used to impregnate bednets and curtains has already been noted in the urban area of Cotonou in Benin (18, 21). In this study, we wished to find out if the resistance observed in Cotonou is localized only in this town or is already extensive throughout Benin. In this case, such resistance would be a handicap to the promotion of impregnated bednets in Benin. The study was carried out in 15 localities throughout the different ecological zones of Benin. The study has also taken into account environmental factors favouring the emergence of resistance. We did susceptibility tests with WHO test kits for adult mosquitoes using impregnated papers. The papers were impregnated with permethrin 0.25%, deltamethrin 0.025% and lambdacyhalothrin 0.1%. We also tested DDT 4% to find out if there was a cross resistance between DDT and the pyrethroids. Two mosquito species were tested: An. gambiae and An melas. In northern Benin, where farmers use insecticides against cotton pests, vectors are susceptible to deltamethrin and lambdacyhalothrin and resistant to permethrin. In the south, An. gambiae is resistant to deltamethrin and permethrin. This resistance is high in the urban zone of Cotonou, in the coastal and lagoon areas and at Kraké, a frontier viliage with Nigeria. The resistance observed in southern Benin is confirmed by the lengthening of the knock-down time of mosquitoes which were exposed for 1 hour to insecticide in impregnated WHO test tubes, and by a reduction of permethrin and deltamethrin remanence effect.     

Human-landing patterns of Anopheles dirus sensu lato (Diptera: Culicidae) in experimental huts treated with DDT or deltamethrin

Anopheles dirus females landing on humans inside experimental huts treated with residual applications of DDT or deltamethrin were observed during the wet season in Pu Teuy Village, Kanchanaburi Province, western Thailand. Two identical experimental huts were constructed in the fashion of typical local rural Thai homes. Pretreatment (baseline) human-landing collections (HLC) in both huts showed an early evening peak of activity between 1900 and 2000 h with no significant difference in numbers of mosquitoes captured between huts over a period of 30 collection nights. During posttreatment HLC, female mosquitoes continued to show greater landing activity inside huts fitted with insecticide-treated panels during the first half of the evening compared with the second half. A greater number (proportion) of An. dirus females landed on humans in the hut treated with deltamethrin compared with DDT. Comparing pre- and posttreatment HLC, the DDT-treated hut showed a 79.4% decline in attempted blood feeding, whereas exposure to deltamethrin resulted in a 56.3% human-landing reduction. An odds ratio was performed to demonstrate the relative probability (risk) of mosquitoes entering and attempting to blood feed in the two treated huts compared with untreated control huts. Mosquitoes were approximately 0.47 times less likely to land on humans inside a DDT-treated hut compared with the deltamethrin-treated hut. Although both chemicals exerted strong excitatory responses, DDT appears to have a more pronounced and significant (P = 0.002) effect on behavior than deltamethrin, resulting in greater movement away from the insecticide source and thus potential reduction of blood-feeding activity.     

Preliminary field testing of a long-lasting insecticide-treated hammock against Anopheles gambiae and Mansonia spp. (Diptera: Culicidae) in West Africa

The efficacy of an experimental long-lasting insecticide-treated hammock (LLIH) with a long-lasting treated net used as a blanket and made of the same fabric (polyethylene) was tested in a concrete block experimental hut, against the malaria vector Anopheles gambiae s.l. and the arbovirus vectors and nuisance mosquitoes Mansonia africana (Theobald) and Mansonia uniformis (Theobald). The LLIH was treated with the pyrethroid insecticide permethrin. It was evaluated concurrently with ignited mosquito coils over 20 successive weeks. In total, 2,227 mosquitoes (130 An. gambiae and 2,097 Mansonia spp.) corresponding to 27.8 mosquitoes per trap-night were collected in the untreated hut (control). The repellent effect of both coils and LLIH significantly reduced the number of mosquitoes entering the huts (35- 60%). There was no significant difference between LLIH and mosquito coils in blood-feeding inhibition (93-97%) or in mortality (88-98%). The LLIH is more cost-effective and user-friendly than mosquito coils, which need to be replaced nightly to protect people sleeping indoors from mosquito bites. The effects of LLIH on exophagic vectors also need to be investigated because most people that sleep in hammocks are outdoors.     

Efficacy of permethrin-treated uniforms in combination with DEET topical repellent for protection of French military troops in Côte d'Ivoire

In 2000, 22,000 French military personnel were deployed overseas. The French military health service implemented a vector control strategy including personal protection by the use of permethrin preimpregnated battlefield uniforms (BFUs) and the application on the skin of a topical repellent (50% DEET). In 2000, French forces used an industrial process to impregnate cloth with permethrin by soaking it before cut-out of the BFU. A study was implemented in four experimental huts in C?te d'Ivoire to assess the field efficacy of the impregnated BFUs and their resistance to washing. Taking into account the systematic variations in each variable in the field and using a modeling based on logistic regression and discriminant analysis, this study showed that after 6 h without reapplication, the protective effects of the use of DEET as skin repellent was not significant, perhaps due to the high density of Anopheles mosquitoes during the night catching sessions and an average time of effective repellency of < 2 or 3 h in the field. The analysis also showed that the French process of industrial impregnation of permethrin of the BFU offered in 2000 some protection from mosquito bites but not enough to reduce significantly the incidence of malaria among nonimmune troops. No positive or negative interaction was noted when DEET and the impregnated BFUs were used together.     

Impact of pyrethrin resistance on the efficacity of impregnated mosquito nets in the prevention of malaria: results of tests in experimental cases with deltamethrin SC

The effects of impregnated bednets treated with deltamethrin at a dosage of 25 mg a.i./m2 were evaluated at two testing stations in C?te d'Ivoire. The first one was located in Yaokoffikro, where Anopheles gambiae s.s. are resistant to pyrethroids (including deltamethrin), and the second in M'be, close to a large rice-growing area where An. gambiae s.s. are susceptible pyrethroids. In both situations, treating bednets with deltamethrin was very effective in limiting contact between man and vector. 72% fewer female An. gambiae entered the huts in the susceptible area, whereas a decrease of 43% was recorded in the resistant area, indicating that deltamethrin still has a certain repellent effect on resistant populations of An. gambiae s.s. Overall mortality induced by bednets treated with insecticide was significantly higher in the resistant area (56.4% as versus 44.3%). An explanation for this apparent paradox is that the mosquitoes being less repelled by the insecticide remain on the treated material for longer periods of time and most of them eventually die. The results of this study indicate that bednets treated with deltamethrin are an effective prophylactic measure even in areas where An. gambiae s.s. are resistant to pyrethroids and should still be considered as a practical means of personal protection against malaria even in pyrethroid resistance areas with high frequency of kdr resistance genes.     

An experimental tool essential for the evaluation of insecticides: the testing huts

The following study analyses the potentialities of the experimental huts built in M'be Valley (C?te d'Ivoire) where the evaluations of the insecticide products have been carried out for many years in line with the WHOPES protocol on the methodology of stage 2 assays. Starting a testing station first requires a good knowledge of the sensitivity of Anopheles gambiae to the main insecticide families. Then thanks to the experimental huts the efficacy of the various means of treatment can be compared with the one in untreated huts; this study focuses on house spraying using 100 mg a.i./m2 and bednets impregnated with lambda-cyhalothrin at a dose of 15 mg a.i./m2. The fipronil used in house spraying doesn't show any repellent effect, however it does have an irritating effect that increases the natural exophily of An. gambiae females entering the testing huts. The blood-feeding rate recorded in the treated huts was reduced to 24% and to 38% mortality rate consisting mainly of a 24 hours delayed mortality. The bednets treated with lambda-cyhalothrin have greatly reduced the contact between man and vector since the entry rate of An. gambiae females was cut down by 68% compared to the control. The exophily of this anopheles was twofold greater with the impregnated bednets and the blood-feeding rate reduced to 47%. Finally the global mortality rate, two thirds of immediate mortality, one third of delayed mortality, reached 35%. The experimental huts in the M'be Valley therefore provide essential information regarding the selection of the most efficacious insecticides against An. gambiae. This experimental method must be extended to other sites in order to finalize ever more selective and appropriate means of control against nuisance and disease-vector mosquitoes.     

Repellent and adulticide efficacy of a combination containing 10% imidacloprid and 50% permethrin against <Emphasis Type="Italic">Aedes aegypti</Emphasis> mosquitoes on dogs

This study was conducted to assess the repellent and adulticide efficacy of the combination containing 10% imidacloprid and 50% permethrin against Aedes aegypti mosquitoes on dogs. Blood-feeding success rates of the mosquitoes that were exposed to the treated dogs were 4.9 and 4.4% on days 3 and 7 post the combination application (PCA), respectively, and blood-feeding success rates increased to 6.3, 12.8, and 24.5% on days 14, 21, and 28 PCA, respectively. Blood-feeding success rates between the mosquitoes that were exposed to the treated and untreated control dogs on days 3, 7, 14, and 21 PCA were significantly different. All mosquitoes that were exposed to the treated dogs on day 3 PCA died, and mortality rates decreased to 97.1, 77.8, 40.4, and 2.1% on days 7, 14, 21, and 28 PCA, respectively. Mortality rates between the mosquitoes that were exposed to the treated and untreated control dogs on days 3, 7, 14, and 21 PCA were significantly different. This study suggested that this combination can be used to repel and kill mosquitoes on dogs; however, the application of this insecticide combination on dogs needs to be repeated every 3–4 weeks.     

Relative efficacy of insecticide treated mosquito nets (Diptera: Culicidae) under field conditions

The relative efficacy of insecticide treated mosquito nets was evaluated under field conditions in Dehra village of Dhaulana PHC, District Ghaziabad, U.P., India, during 1996. Nylon nets were impregnated with deltamethrin, cyfluthrin, lambdacyhalothrin, and etofenprox at 25 mg/m2 by standard methods. Repellent, excito-repellency, killing, and airborne actions were monitored from dusk to dawn by hourly collection of mosquitoes that entered and rested in rooms and also females that landed on treated and untreated mosquito nets. Results revealed 15.3-22.9% repellent action, 98.3-99.3% excito-repellency action, and 100% mortality of females that landed on treated fabrics. No significant differences were observed in the efficacy of different synthetic pyrethroids against anophelines. However, against Culex quinquefasciatus Say there was a significant difference between deltamethrin and etofenprox. Control of anophelines was more pronounced than Cx. quinquefasciatus. There was no pronounced airborne action with any insecticide tested. Synthetic pyrethroids with strong airborne action may be more appropriate for impregnation of mosquito nets.     

Combining piperonyl butoxide and dinotefuran restores the efficacy of deltamethrin mosquito nets against resistant Anopheles gambiae (Diptera: Culicidae)

One strategy suggested for the management of mosquito insecticide resistance consists of combining a pyrethroid with an insecticide that has a different mode of action. To restore the efficacy of deltamethrin (pyrethroid) against pyrethroid-resistant strain of Anopheles gambiae Giles (VKPR: homozygous Kdr), deltamethrin was combined with the neonicotinoid insecticide dinotefuran and piperonyl butoxide (PBO). Bednets impregnated with deltamethrin, dinotefuran, and PBO alone and in combination were tested in the laboratory. Knockdown (KD) and mortality were measured using WHO cone tests on susceptible and pyrethroid-resistant adult mosquitoes. The combination of deltamethrin and PBO was synergistic against resistant female An. gambiae (58.2% mortality). Both mortality and knockdown time (KDt(50/95) values) of the tricomponent mixture on the VKPR strain were similar to the insecticidal activity of deltamethrin on the pyrethroid-susceptible KIS strain (98.8 and 100% mortality, respectively). The three-compound mixture of deltamethrin + PBO + dinotefuran showed an insecticidal efficacy greater than the deltamethrin + PBO mixture to the extent of completely restoring the efficacy of deltamethrin on pyrethroid-resistant An. gambiae.     

Premiers tests OMS d’évaluation de la sensibilité aux insecticides chez Anopheles gambiae et Culex quinquefasciatus à Lobito, Angola

Field collections of the most common urban mosquito vectors Anopheles gambiae and Culex quinquefasciatus were carried out in June 2003, March 2004 and November 2005 to gather preliminary data on the insecticide susceptibility in mosquitoes from Lobito (Angola) using the WHO standard bioassays. Bioassays were performed on F0 adults emerging from the field larval collections and on unfed adults from landing catches on volunteers. Batches of mosquitoes from three selected locations (Alto Liro, San Jao and Bela Vista) were exposed for 1 hour to several insecticides such as DDT 4%, carbosulfan 0.4%, permethrin 1%, deltamethrin 0.05% and cyfluthrin 0.15%, in order to estimate the immediate knockdown times (kdT50 and kdT95) and the mortality rate after exposure. The results revealed that mosquito susceptibility to insecticides varied depending on the insecticide, the site and the period of collection. The main local malaria vector A. gambiae (both M and S forms) was basically resistant to DDT and susceptible to all pyrethoids, regardless of the period and the site of collections. The overall mortality rate due to DDT was 73% in Alto Liro, 89% in San Jao and varied depending on the period in Bela Vista between 95% in March 2004 and 100% in November 2005. The mortality due to pyrethoids was 100% at all locations, with the kdT50 and KdT95 times ranging between 9 and 16 minutes and between 18 and 29 minutes, respectively. Concerning the C. quinquefasciatus, populations from Yard and Caponte were resistant to all insecticides tested; the mortality rate was 40% with deltamethrin and 70% with permethrin, while no lethal effect was observed with DDT or carbosulfan. In conclusion, despite its probable high resistance to DDT, the main local malaria vector A. gambiae remained fully susceptible to pyrethroids. This could forecast a good biological efficacy of the scheduled vector control interventions in Angola, based on a large-scale distribution of long-lasting, insecticide-treated nets and on the implementation of indoor residual spraying. The local vector control programme must include well-adapted IEC campaigns and full participation of the community for better management of the insecticide resistance in targeted mosquitoes and for better control of malaria vector populations.