Laboratory and field evaluation of the insect growth regulator pyriproxyfen (Sumilarv 0.5G) against dengue vectors

The insect growth regulator pyriproxyfen was tested against Aedes aegypti at 0.01 and 0.02 mg of active ingredient (AI) per liter of water in 60-liter earthern jars. Both concentrations provided 100% control for 4 months. In additional experiments where 10 liters of water were replaced fortnightly, 100% control was still obtained over 4 months with 0.02 mg AI/liter and greater than 93-100% control was obtained over 4 months with 0.01 mg AI/liter. In less-controlled field-trial conditions, pyriproxyfen at a dosage of 0.02 mg AI/liter provided 100% control for 10 wk against Aedes albopictus even though water was replaced either daily or weekly. Although the activity of pyriproxyfen declines after 10 wk, those tests in the plastic tubs showed much higher levels of sustained residual activity compared to those in the earthern jars. Pyriproxyfen did not have an impact on nontarget organisms.     

Laboratory and field evaluations of novaluron, a new insect growth regulator (IGR), against Culex mosquitoes

Limited laboratory and field studies have indicated that the insect growth regulator (IGR) novaluron exhibits good activity against larvae of pest species in the orders Coleoptera, Hemiptera (suborder Heteroptera), and Lepidoptera by both ingestion and contact. We completed laboratory and field studies to evaluate activity and efficacy of novaluron against Culex mosquitoes. In laboratory studies, novaluron was highly active against Cx. quinquefasciatus, as indicated by low levels of inhibition of emergency (IE), at the 50% level, IE50 (0.159 ppb for 2nd-stage larvae and 0.118 ppb for 4th-stage larvae) and IE90, at the 90% level, (0.604 ppb for 2nd-stage larvae and 0.595 ppb for 4th-stage larvae). In outdoor microcosm and mesocosm studies against natural populations, novaluron yielded excellent control of immature Culex mosquitoes for up to 14 days at 1.25, 2.5, and 5 ppb in microcosms, and for up to 7 days at the dosages of 1, 5, and 10 mg/m2 in mesocosms. Based on qualitative observations, novaluron seemed to have a favorable margin of safety for nontarget aquatic invertebrates cohabiting with mosquito larvae. Further large-scale field studies are warranted to evaluate initial efficacy and longevity of novaluron against various mosquito species, as well as its safety for nontarget biota.     

Comparative efficacy of IR3535 and deet as repellents against adult Aedes aegypti and Culex quinquefasciatus

Arm-in-cage laboratory evaluations of 2 proprietary formulations of the mosquito repellents IR3535 and N,N-diethyl-3-methylbenzamide (deet; aqueous cream, hydroalcoholic spray) were made with 10 and 20% concentrations of each repellent. Also, 4 commercially available products containing IR3535 (Expedition insect repellent 20.07% active ingredient [AI], Bug Guard Plus with SPF30 sunscreen 7.5% AI, Bug Guard Plus with SPF15 sunscreen 7.5% AI, and Bug Guard Plus 7.5% AI) were tested. All comparisons were made on an equal formulation or concentration basis. Eight volunteers tested all formulations or products 3 times against laboratory-reared, Aedes aegypti and Culex quinquefasciatus mosquitoes (6-10 days old). Products were applied to a forearm at the rate of 0.002 g/cm2. The other forearm was not treated and served as a control. Elapsed time to 1st and 2nd consecutive bite was recorded. Mean protection time (i.e., time to 1st bite) with proprietary formulations of IR3535 were comparable to those of deet, with 20% concentrations providing greater protection against Ae. aegypti (3 h) and Cx. quinquefasciatus (6 h). Mean protection time for commercial products containing IR3535 ranged from nearly 90 to 170 min for Ae. aegypti and 3.5 to 6.5 h for Cx. quinquefasciatus. Mean time to the 2nd bite was similar to time to 1st bite for each mosquito species, product, and formulation.     

电热蚊香片现场防治蚊虫的研究

目的评价霹蚊灵（PWL）与ETOC复配及ETOC单剂电热蚊香片在现场条件下防治蚊虫的效果。方法在开门窗、开灯、开空调的条件下，点燃蚊香后不同时间段内用人诱法捕捉成蚊。结果8个实验房间轮转实验显示加热霹蚊灵蚊香A（PWL／ETOC=2．5mg／2．5mg）、B（PWL/ETOC=4mg／4mg）、C（ETOC=14mg）3种蚊香片后，人诱法捕获的蚊虫数量分别比空白对照房下降了74．3％、79．2％和75．4％。结论3种蚊香在现场应用均具有较好的驱蚊效果，适用于评价蚊香的实际使用效果。     

Field efficacy of "Mosbar" mosquito repellent soap against vectors of bancroftian filariasis and Japanese encephalitis in southern India.

Deet-permethrin "Mosbar" soap was field tested for repellency against mosquitoes by volunteers in urban and rural localities in southern India. Eighty-nine to 100% reduction in man-vector contact was recorded for 8 mosquito species, including Culex quinquefasciatus and recognized vectors of Japanese encephalitis. The soap was highly acceptable to the community.     

Laboratory evaluations of methylated soy oil and monoterpenes as mosquito larvicides

The larvicidal toxicities of methylated soy oil (MSO) and surfactant combinations were compared to 2 commercially available oil larvicides (Golden Bear Oil 1111 and Bonide) in standard laboratory bioassays of 4th-stage larvae of Culex pipiens Linn. The dose lethal to 50% of the test organisms (LD50) and the dose lethal to 95% of the test organisms (LD95) values are presented as microliters (microl) per beaker (treatment surface area of 54 cm2). The 2 surfactant-MSO mixtures differed significantly in their toxicity to Cx. pipiens larvae; 2% Pyroter CPI-40 in MSO was more toxic than 2% Pluronic L121 in MSO (LD50 = 3.8 microl per 54 cm2 and 11.3 microl per 54 cm2, respectively). The 2 most active larvicides were Golden Bear Oil (LD50 = 3.6 microl per 54 cm2) and the 2% Pyroter-MSO mixture. These 2 were not significantly different from each other. Bonide (LD50 = 6.2 microl per 54 cm2) and the Pluronic L121-MSO mixture (LD50 = 11.3 microl per 54 cm2) were less toxic than Golden Bear Oil and the MSO-Pryroter mixture and they were significantly different from each other. Bioassays with 4th-stage larvae of Anopheles stephensi Liston showed that toxicity of the Pyroter-MSO formulations increased about 2-fold from 18 degrees C to 24 degrees C (LD50 = 20.5 microl per 54 cm2 and 11.8 microl per 54 cm2, respectively). The laboratory bioassays suggest that MSO mixed with surfactants are potential mosquito larvicides. We also evaluated the influence of the 2 surfactants on the toxicity of 3 monoterpenes. The larvicidal activity of citral and limonene increased with the addition of surfactants, but neither surfactant enhanced the toxicity of cineole. All 3 monoterpenes, with and without surfactants, were considered poor candidates as surface larvicides because of their high volatilities.     

杀蚊幼剂对外环境水体蚊幼杀灭效果研究

目的了解不同杀蚊幼剂对蚊幼的杀灭效果,为今后防治蚊幼提供科学依据。方法选择水体,随机分为试验组和对照组,于试验前后一定间隔分别测定幼虫密度,并计算出密度指数、相关密度指数（PRI）和杀灭率。试验时分别将试验药剂施放于水体中（施药剂量：毒死蜱0．5、1ga．i／m^3;双硫磷1ga．i／m^3;马拉硫磷2ga．i／m^3）。结果2种剂量毒死蜱投药后1d对蚊幼虫杀灭率均为100％,前者持效66d,后者为69d;施药剂量为1ga．i／m^3双硫磷施药后1d仅发现1只蚊蛹,杀灭率达99．76％,2d达100％,投药后65d时仍达80．56％;2ga．i／m^3马拉硫磷施药后7d杀灭率为100％,12d时为85．59％,14d降至55．18％。结论结果表明,对幼虫杀灭效果及持效期优劣依次为：毒死蜱〉双硫磷〉马拉硫磷。建议今后水体灭蚊幼时,在条件允许的情况下,推荐使用前者.     

Relative repellency of two formulations of N,N-diethyl-3-methylbenzamide (deet) and permethrin-treated clothing against Culex sitiens and Aedes vigilax in Thailand

Field tests were conducted to compare the effectiveness of 2 repellent formulations of N,N-diethyl-3-methylbenzamide (deet) in combination with permethrin-impregnated military uniforms against Culex sitiens and Aedes vigilax in Thailand. Repellency was determined during a 2 h crepuscular period using volunteers who had been treated with repellents 6, 8, 10, and 12 h prior to the end of each test period. An extended-duration repellent formulation (EDRF) containing 35% deet repelled significantly more Ae. vigilax than 75% deet in ethanol. Although not statistically significant, the EDRF also resulted in fewer biting attempts by Cx. sitiens. Neither formulation provided complete protection against either species 4-12 h post-application, but both provided greater overall protection against Ae. vigilax. Volunteers who wore treated uniforms without repellents were attacked by significantly fewer mosquitoes than controls.     

50%甲基嘧啶磷乳油现场灭蚊幼实验研究

目的观察使用不同剂量甲基嘧啶磷现场灭蚊幼效果,为今后灭蚊幼提供科学依据。方法选择实验场地同时设对照区并测量其水体体积,分别按0.012、0.02、0.1、0.2 g a.i/m3剂量施药,定期用勺捞法分别观察其密度。结果施药剂量在0.012 g a.i/m3时,施药后1~14 d杀灭率为63.03%~92.13%;在0.02g a.i/m3时,施药后1~26 d杀灭率为94.93%~99.45%;0.1 g a.i/m3时,施药后1~30 d杀灭率为75.52%~100%;在0.2 g a.i/m3时,施药后1~16 d杀灭率为74.15%~100%。结论实验证明,甲基嘧啶磷是控制蚊虫孳生的一种良好的有机磷杀虫剂。但在现场使用时,应根据水体污染状态选择合适的剂量,以达到预期效果。     

Laboratory evaluation of cyromazine against insecticide-susceptible and -resistant mosquito larvae

In this study, the activity of cyromazine was evaluated following WHO standard procedures against susceptible and resistant mosquito strains of Anopheles gambiae, Culex quinquefasciatus, and Aedes aegypti. The dose for 50% and 90% inhibition of adult emergence (IE50 and IE90) ranged from 0.028 mg/liter to 0.17 mg/liter and from 0.075 mg/liter to 0.42 mg/liter, respectively. The effects of cyromazine were closer to that of chitin synthesis inhibitors rather than that of juvenile hormone analogues, with only 10-20% pupal mortality. The toxicity of cyromazine was not strongly affected by the presence of common resistance mechanism, i.e., Kdr mutation and Ace.1(R) (resistance ratio from 0.5 to 2.3). The absence of cross resistance with common insecticides (pyrethroids, carbamates, organophosphates) makes cyromazine a potential candidate for disease vector control, especially for the management of insecticide resistance.     

Field efficacy of four insect repellent products against vector mosquitoes in a tropical environment

Four insect repellent products (RPs) (RP 1, Experimental Repellent Lotion [Bayrepel 12%]; RP 2, Experimental Repellent Cream [Bayrepel 5%]; RP 3, Off! Insect Repellent II Aerosol [deet 15%]; and RP 4, Off! Skintastic II Cream [deet 7.5%]) were evaluated simultaneously for their efficacy against vector and nuisance mosquitoes. The aim of this study was to compare the relative efficacy of RPs based on a new repellent compound, Bayrepel (1-piperidinecarboxylic acid, 2-(2-hydroxyethyl)-1-methylpropylester), with deet (N,N-diethyl-m-toluamide)-based RPs. An 8-h field efficacy of above repellents was evaluated against the day-biting mosquito (Aedes albopictus) and night-biting mosquitoes (Culex quinquefasciatus and Anopheles spp.). Evaluation was carried out by exposing humans with repellent-treated bare limbs to mosquitoes landing and to mosquitoes landing and biting. Repellent product 1 or 2 was applied on the left arm and leg, whereas RP 3 or 4 was applied on the right arm and leg, respectively. Application of these 4 RPs significantly reduced (P < 0.05) the landing and the landing and biting of day-biting and night-biting mosquitoes. All 4 RPs were found to be equally effective (P < 0.05) against Ae. albopictus and Cx. quinquefasciatus. However, for protection against Anopheles spp., RPs 1 and 3 exhibited significantly (P < 0.05) better repellency effect than RPs 2 and 4.     

Efficacy of new insect growth regulators against mosquito larvae in dairy wastewater lagoons

Four new insect growth regulators (IGRs) and a slow-release formulation of a currently-used IGR were evaluated for the control of Culex peus and Cx. quinquefasciatus in dairy wastewater lagoons. The IGR AC-291898 (CME 13406) proved highly efficacious, producing 100% control for one week and about 98% control for two weeks at the rate of 0.05 lb AI/acre (0.056 kg/ha). The IGR XRD-473 produced similar results at this rate. The effective rate of these two compounds seems to be in the range of 0.05 to 0.1 lb AI/acre (0.056-0.11 kg/ha). A granular formulation of S-31183 (0.5 G) applied at 0.05 lb AI/acre (0.056 kg/ha) yielded mediocre reduction whereas fenoxycarb EC 1 at up to 0.25 lb AI/acre (0.28 kg/ha) and methoprene 4% slow release pellets at up to 1.0 lb AI/acre (1.12 kg/ha) produced little or no control of Culex in the dairy wastewater lagoons. These compounds need to be applied at higher rates or suitable formulations will have to be developed to achieve satisfactory control.     

3种杀幼剂对蚊幼的现场控制效果研究

目的探讨3种杀幼剂对蚊幼的现场控制效果,为世博会期间蚊虫孳生地控制提供药物和技术储备。方法选择雨水井、水池、沟渠等为现场测试场所,根据面积或体积布施不同剂量的药物,观察施药后蚊幼密度下降情况并计算其持效期。结果 1.0~1.5 mg/L甲基嘧啶磷对雨水井中白纹伊蚊的控制效果达14 d以上,2.0~2.5 mg/L可维持21 d以上。1.0 mg/L甲基嘧啶磷对沟渠中三带喙库蚊的控制效果达10 d,1.5~2.5 mg/L可维持12 d。1.0~1.4 mg/L毒死蜱能有效控制雨水井中的白纹伊蚊和沟渠中的淡色库蚊,持效期长达35 d或更长,0.6~0.8 mg/L达14~21 d。0.4~0.8 mg/L 1%双硫磷能有效控制雨水井中的白纹伊蚊和沟渠中的淡色库蚊,但持效期较短,仅为10~14 d;1.2 mg/L为21 d。现场实验中,0.8 mg/L双硫磷对三带喙库蚊有14 d的控制效果,1.0~1.5 mg/L的控制持效期则为21 d。结论 3种药物均对白纹伊蚊、淡色库蚊、三带喙库蚊有较好的控制效果,持效期为毒死蜱双硫磷甲基嘧啶磷。相同药物对不同环境下不同蚊虫的控制效果有一定差异,因此须根据水体流动、水质状况等合理使用杀幼剂。     

Field evaluation of deet, Repel Care, and three plant based essential oil repellents against mosquitoes, black flies (Diptera: Simuliidae) and land leeches (Arhynchobdellida: Haemadipsidae) in Thailand

Diethyl methyl benzamide, or deet, a commercial plant-based repellent (Repel Care), and essential ils from 3 species of plants (finger root rhizomes, guava leaves, and turmeric rhizomes), steam distillated and formulated as insect repellents, were evaluated in the field on human volunteers against hematophagous mosquitoes, black flies, and land leeches in Thailand. Field trials were conducted against wild mosquitoes in Bang Bua Thong District, Nonthaburi Province, and in the Thap Lan National Park Headquarters, Nadee District, Pranchinburi Province; anthroophilic black flies (Diptera: Simuliidae) at the Forestry Fire Control Station in Doi Inthanon National Park, Chomthong district, Chiang Mai Province; and land leeches (Arhynchobdellida: Haemadipsidae) in the Khao Yai National Park, Pak Chong District, Nakhon Ratchasima Province. The 3 experimental plant-based essential oil formulations as well as Repel Care and deet provided complete protection from mosquito landing and biting for up to 9 h (duration of the experiment). Similar results were obtained with the 5 products against black flies, providing 100% protection for 9 h but 96-82% protection after 10 and 11 h posttreatment. The 5 repellent products also provided 100% protection against land leeches for at least 8 h. Thi is the 1st report of repellency of plant-based repellents against black flies and land leeches in Thailand. The identification and availability of inexpensive sources of plant-based oils, i.e., finger root rhizomes, guava leaves, and turmeric rhizomes providing long-lasting repellency against blood-sucking organisms are promising leads into commercial production of relatively safe and effective repellents.     

Laboratory and field evaluation of Hilmilin against mosquitoes

Hilmilin (diflubenzuron), an insect growth regulator, was tested for efficacy against Anopheles stephensi, Anopheles culicifacies, Aedes aegypti, and Culex quinquefasciatus in the laboratory and in field conditions. Fifty percent and 90% lethal concentrations (LC50 and LC90) of Hilmilin formulations were determined by exposing early 4th-stage larvae to serial dilutions of the formulation, and data were subjected to log probit analysis. Two doses (0.004 and 0.008 g/m2) were applied in different breeding habitats of mosquitoes with the help of stirrup pumps. Percent inhibition of adult emergence was compared according to a previously described procedure. Laboratory results revealed that both 25WP (wettable powder) and 22SL (semiliquid) formulations showed more or less the same degree of efficacy against tested mosquito species (P < 0.05). Of 4 species tested, An. stephensi was more susceptible, followed by An. culicifacies, Ae. aegypti, and Cx. quinquefasciatus. One hundred percent inhibition of adult emergence was observed at a dose of 0.0125 ppm (25WP and 22SL) against all mosquitoes tested in the laboratory. Both formulations showed almost similar effect when applied in the field at doses of 0.004 and 0.008 g/m2 in their respective preferential breeding habitats. However, the effect was more pronounced at a higher concentration (0.008 g/m2) against all species of mosquitoes. Hilmilin at a dose of 0.008 g/m2 can be used to contain mosquito breeding in stone quarries, pools, cement tanks, unused wells, unused coolers, and irrigation channels.     

Repellency of two deet formulations and Avon Skin-So-Soft against biting midges (Diptera: Ceratopogonidae) in Honduras

Two U.S. military issue deet repellent formulations (75% deet liquid and 33% deet lotion) and Avon Skin-So-Soft were tested against ceratopogonid midges under field conditions in Honduras. Test subjects were U.S. military personnel deployed to Honduras for training. Culicoides furens accounted for 96.3% of all midges collected. The liquid and lotion formulations of deet and Avon Skin-So-Soft provided 97.9, 95.9 and 71.4% protection, respectively, compared with the untreated control. Both deet formulations provided significantly better protection (P less than 0.05) than Avon Skin-So-Soft. The latter provided protection by trapping the midges in the oily film and not by repelling the insects as did the deet formulations.