四种植物精油对蚊虫的熏杀活性及酯酶活性的影响

为了筛选高效、环保、低抗性的植物源灭蚊剂,揭示植物精油熏杀蚊虫的作用机理,测试了湖南香薷Elsholtziahunanensis、藿香Agastacherugosus、八角Illiciumverum和剑叶金鸡菊Coreopsislanceolata精油对白纹伊蚊Aedesalbopictus和致倦库蚊Culexpipiensquinquefasciatus成蚊的熏杀活性及对2种蚊虫体内乙酰胆碱酯酶（AChE）和非特异性酯酶（NSE）活性的影响。结果表明,4种植物精油对蚊虫的熏杀效果显著,但同种植物精油对2种蚊虫的熏杀活性有差异。藿香精油对白纹伊蚊的熏杀效果最好（LC50值为26．12μg．cm-3）,八角精油对致倦库蚊的熏杀活性最强（Lc50值为29-31μg·cm-3）。4种植物精油对白纹伊蚊和致倦库蚊体内AChE活性起诱导作用;对致倦库蚊体内NSE活性均有抑制作用,其中八角精油的酶活性抑制率最高（19．79％）。湖南香薷和八角精油对白纹伊蚊NSE活性有抑制作用,酶活性抑制率分别为34．90％和25．26％;藿香和剑叶金鸡菊精油对白纹伊蚊NSE活性有促进作用,酶活性增长率分别为25．66％和66．35％。综合分析4种植物精油对蚊虫的熏杀活性及对酯酶活性的影响,湖南香薷和藿香精油更适宜作为植物源灭蚊产品的备选材料。     

Isolation of a Pseudomonas fluorescens metabolite/exotoxin active against both larvae and pupae of vector mosquitoes

A formulation was developed from the metabolite(s) of a novel Pseudomonas fluorescens Migula strain (VCRC B426) and tested against 4th-instar larvae and pupae of three species of vector mosquitoes, Anopheles stephensi Liston, Culex quinquefasciatus Say and Aedes aegypti (L). The larvae and pupae of An. stephensi were the most susceptible to the formulation, followed by those of C. quinquefasciatus and Ae. aegypti, in that order, and the dosage requirement for pupal mortality was less than that required for larval mortality. The LC50 dosage requirements for larvae of these mosquito species were, respectively, 70.4, 511.5 and 757.3 microg protein ml(-1), whereas for pupae they were, respectively, 2.0, 9.4 and 19.2 microg protein ml(-1). The lethal fraction was purified from the culture broth and its molecular mass, as determined by high performance liquid chromatography, was 44kDa. This is the first report of a microbial formulation acting upon mosquito pupae, a non-feeding stage. Its mode of action and efficacy to control mosquitoes under field conditions need to be studied further.     

野胡萝卜果实精油对蚊幼虫的毒杀活性

采用浸液法研究了野胡萝卜Daucus carota果实精油对白纹伊蚊Aedes albopictus和致倦库蚊Culexpipiens quinquefasciatus幼虫的毒杀活性;利用气相色谱-质谱联用（GC-MS）对精油的主要成分进行了定性、定量分析。结果发现,野胡萝卜果实精油毒杀白纹伊蚊和致倦库蚊4龄幼虫的24h LC50值分别为67.87μg.mL-1和34.12μg.mL-1;精油中共含有34种化合物,相对含量最高的是α-蒎烯（54.72%）,其次为β-红没药烯（11.35%）和β-细辛脑（10.14%）;对6种活性化合物进行定量分析,含量最高的是α-蒎烯（577.46mg.mL-1）,其次是月桂烯（80.26mg.mL-1）、柠檬烯（28.95mg.mL-1）、β-石竹烯（24.38mg.mL-1）、β-蒎烯（11.59mg.mL-1）和γ-萜品烯（2.33mg.mL-1）。研究结果表明,野胡萝卜果实精油对蚊幼虫的毒杀效果强于以往文献报道的多种植物精油,是开发高效环保蚊虫杀幼剂的好材料。     

Structure of the Aedes aegypti (L.) and Culex quinquefasciatus Say (Diptera: Culicidae) populations in the houses of Phnom Penh (Kampuchea)

Sex ratio and engorged females ratio were studied in the main mosquito species populations (Aedes aegypti, Culex quinquefasciatus and partially Anopheles vagus) in the houses of Phnom Penh. Collections were carried out in 7 different localities, including area from the centre of the town to the periphery. In Ae. aegypti and C. quinquefasciatus populations females were dominant in 5 localities, while males were dominant in 2 localities. Engorged females were predominant over unfed ones in all cases (collections were always carried out in the morning). Structure of population varied slightly according to the date of collection. The influence of two main factors, character of locality and monthly amount of rainfall, on structure of mosquito population is discussed.     

Fumigant toxicity of volatile natural products from Korean spices and medicinal plants towards the rice weevil,Sitophilus oryzae (L)

The fumigant toxicity of various volatile constituents of essential oils extracted from sixteen Korean spices and medicinal plants towards the rice weevil, Sitophilus oryzae L (Coleoptera: Curculionidae), was determined. The most potent toxicity was found in the essential oil from Mentha arvensis L var piperascens (LC₅₀ = 45.5 µl litre^?1 air). GC–MS analysis of essential oil from M arvensis showed it to be rich in menthol (63.2%), menthone (13.1%) and limonene (1.5%), followed in abundance by β‐pinene (0.7%), α‐pinene (0.6%) and linalool (0.2%). Treatment of S oryzae with each of these terpenes showed menthone to be most active (LC₅₀ = 12.7 µl litre^?1 air) followed by linalool (LC₅₀ = 39.2 µl litre^?1 air) and α‐pinene (LC₅₀ = 54.9 µl litre^?1 air). Studies on inhibition of acetylcholinesterase activity of S oryzae showed menthone to have a nine‐fold lower inhibitory effect than menthol, despite menthone being 8.1‐fold more toxic than menthol to the rice weevil. Different modes of toxicity of these monoterpenes towards S oryzae are discussed. © 2001 Society of Chemical Industry     

福建柏精油对蚊虫的生物活性

为筛选环保型植物源灭蚊剂,从福建柏Fokienia hodginsii叶中提取精油,采用浸液法测试了该精油对白纹伊蚊Aedes albopictus和致倦库蚊Culex pipiens quinquefasciatus IV龄幼虫和蛹的毒杀作用,采用密闭圆筒法研究了该精油对2种蚊虫成蚊的熏蒸活性,并用气相色谱-质谱联用法对其化学成分进行了检测。结果表明:福建柏精油对白纹伊蚊IV龄幼虫和蛹的LC50值分别为53.21和144.34μg/mL,对致倦库蚊分别为55.85和147.68μg/mL;在4.36μg/cm3熏蒸剂量下,该精油对白纹伊蚊和致倦库蚊成蚊的KT50值分别为14.63和14.90 min,24 h校正死亡率均为90.00%。从福建柏精油中共检测出16种主要化学成分:其中相对含量最高的为α-蒎烯(α-pinene),为29.25%;其次是马鞭烯醇(bicyclo[2.2.1]hept-3-en-2-ol)10.88%和氧化石竹烯(caryophyllene oxide)9.64%等。研究结果表明,福建柏精油对2种供试蚊虫具有显著的杀虫活性。     

Control methods against invasive Aedes mosquitoes in Europe: a review

Five species of invasive Aedes mosquitoes have recently become established in Europe: Ae. albopictus, Ae. aegypti, Ae. japonicus japonicus, Ae. koreicus and Ae. atropalpus. These mosquitoes are a serious nuisance for people and are also competent vectors for several exotic pathogens such as dengue and chikungunya viruses. As they are a growing public health concern, methods to control these mosquitoes need to be implemented to reduce their biting and their potential for disease transmission. There is a crucial need to evaluate methods as part of an integrated invasive mosquito species control strategy in different European countries, taking into account local Aedes infestations and European regulations. This review presents the control methods available or in development against invasive Aedes mosquitoes, with a particular focus on those that can be implemented in Europe. These control methods are divided into five categories: environmental (source reduction), mechanical (trapping), biological (e.g. copepods, Bacillus thuringiensis var. israelensis, Wolbachia), chemical (insect growth regulators, pyrethroids) and genetic (sterile insect technique and genetically modified mosquitoes). We discuss the effectiveness, ecological impact, sustainability and stage of development of each control method. © 2015 Society of Chemical Industry     

Enhanced activity of an insecticidal protein, trypsin modulating oostatic factor (TMOF), through conjugation with aliphatic polyethylene glycol

BACKGROUND: Trypsin modulating oostatic factor (TMOF), a decapeptide (Tyr-Asp-Pro-Ala-Pro₆) isolated from the ovaries of the adult yellow fever mosquito, Aedes aegypti, regulates trypsin biosynthesis. TMOF per os is insecticidal to larval mosquitoes and a good model for the development of technologies to enhance protein insecticide activity by reduced catabolism and/or enhanced delivery to the target. RESULTS: TFA-TMOF-K (TFA = trifluoro acetyl) allowed the specific conjugation of monodispersed, aliphatic polyethylene glycol (PEG) to the amino group of lysine-producing TMOF-K-methyl(ethyleneglycol)₇-O-propionyl (TMOF-K-PEG₇P). The addition of lysine to TMOF reduced its per os larval mosquitocidal activity relative to the parent TMOF, but conjugation of TMOF-K with methyl(ethyleneglycol)₇-O-propionyl increased its toxicity 5.8- and 10.1-fold above that of TMOF and TMOF-K for Ae. aegypti. Enhanced insecticidal activity was also found for larval Ae. albopictus and for neonates of Heliothis virescens and Heliocoverpa zea. Only TMOF-K was found by MS/MS in the hemolymph for H. virescens fed on TMOF-K-PEG₇P. No TMOF, TMOF-K or PEGylated TMOF-K was detected in the hemolymph after topical applications. CONCLUSIONS: This research suggests that aliphatic PEG polymers can be used as a new method for increasing the activity of insecticidal proteins. Copyright © 2011 Society of Chemical Industry     

三种植物精油对致倦库蚊成蚊的熏蒸活性及其混配增效作用

研究了香樟叶、香樟果实、天竺桂叶的水蒸气蒸馏精油对致倦库蚊Culex pipiens quinquefasciatus成蚊的熏蒸活性及其混配增效作用。结果表明:用香樟叶、香樟果实和天竺桂叶精油对致倦库蚊熏蒸20 min后,其24 h的LC50值分别为7.47、4.92和5.70μg/cm3;在设定的熏蒸剂量下,3种精油的半数击倒时间(KT50值)分别为16.62、15.91和16.98 min。将香樟叶精油与天竺桂叶精油以体积比1∶9、3∶7和5∶5混配,其共毒系数分别为152.09、158.20和152.86;将香樟果实精油与天竺桂叶精油以体积比1∶9、5∶5和7:3混配,其共毒系数分别为145.73、146.30和139.79。表明3种植物精油均对致倦库蚊成蚊具有显著的熏蒸活性,将其以适当比例混配后具有增效作用。     

A survey on indoor resting mosquito species in Phnom Penh, Kampuchea

Indoor resting mosquitoes were collected in 7 localities (250 houses) of Phnom Penh at various periods. The mosquitoes were collected for 8 min in every house by means of an aspirator and net. A total of 16 species of mosquitoes resting in houses were found, one of them for the first time in Kampuchea. Culex quinquefasciatus was the predominant species in 6 of the localities observed; its predominance in houses was more or less evident; Aedes aegypti prevailed in one locality. The percentage of A. aegypti predominance in houses corresponds with the risk of occurrence of dengue haemorrhagic fever. Anopheles vagus was found resting in higher abundance in houses of one locality. This fact is of little epidemiological significance because of the zoophilic character of An. vagus in Kampuchea. On the other hand even uncommon occurrence of Anopheles subpictus found in houses may signalize a possibility of an endemic occurrence of malaria in Phnom Penh.     

Larvicidal and oviposition‐altering activity of monoterpenoids,trans‐anithole and rosemary oil to the yellow fever mosquito Aedes aegypti (Diptera: Culicidae)

BACKGROUND: Aedes aegypti L. is the major vector of dengue fever and dengue hemorrhagic fever. In an effort to find effective tools for control programs to reduce mosquito populations, the authors assessed the acute toxicities of 14 monoterpenoids, trans‐anithole and the essential oil of rosemary against different larval stages of Ae. aegypti. The potential for piperonyl butoxide (PBO) to act as a synergist for these compounds to increase larvicidal activity was also examined, and the oviposition response of gravid Ae. aegypti females to substrates containing these compounds was evaluated in behavioral bioassays. RESULTS: Pulegone, thymol, eugenol, trans‐anithole, rosemary oil and citronellal showed high larvicidal activity against all larval stages of Ae. aegypti (LC₅₀ values 10.3–40.8 mg L^?1). The addition of PBO significantly increased the larvicidal activity of all test compounds (3–250‐fold). Eugenol, citronellal, thymol, pulegone, rosemary oil and cymene showed oviposition deterrent and/or repellent activities, while the presence of borneol, camphor and β‐pinene increased the number of eggs laid in test containers. CONCLUSIONS: This study quantified the lethal and sublethal effects of several phytochemical compounds against all larval stages of Aedes aegypti, providing information that ultimately may have potential in mosquito control programs through acute toxicity and/or the ability to alter reproductive behaviors. Copyright © 2008 Society of Chemical Industry     

Susceptibility of adult Aedes aegypti (L.) and Culex quinquefasciatus Say (Diptera; Culicidae) to DDT in Kampuchea.

The susceptibility to 4% DDT was tested in adult Aedes aegypti and Culex quinquefasciatus mosquitoes collected in houses in Phnom Penh (Kampuchea). It was found that in spite of the fact that insecticide treatment had not been performed for many years, the populations of both species as a whole remained resistant. However, there were some differences in the susceptibility between males and females and between engorged and hungry females. Possible causes of these differences are discussed in the present paper.     

Occurrence of Aedes aegypti (L.) and Culex quinquefasciatus Say (Diptera, Culicidae) in houses of different constructions in Phnom Penh, Kampuchea

The relation between the number of mosquito specimens of the most abundant species Aedes aegypti (L.) and Culex quinquefasciatus Say and the construction of houses which they inhabited was studied. The effect of the building materials and of the height at which the floor was situated above the ground were assessed in five and four localities, respectively. It was found that in the localities having the character of a town the mosquitoes were most abundant in houses constructed from corrugated plate and in those the floor of which was situated 2-3.5 m above the ground. In the locality of a village character, the mosquitoes were most numerous in brick houses with the floors at the ground level.     

Insecticide resistance in vector mosquitoes in China

Because of their special behaviour, physiology and close relationship with humans, mosquitoes act as one of the most important vectors of human diseases, such as filariasis, Japanese encephalitis, dengue and malaria. The major vector mosquitoes are members of the Culex, Aedes and Anopheles genera. Insecticides play important roles in agricultural production and public health, especially in a country with a huge human population, like China. Large quantities of four classes of insecticides, organochlorines, organophosphates, carbamates and pyrethroids, are applied annually to fields or indoors in China, directly or indirectly bringing heavy selection pressure on vector populations. The seven major species of vector mosquito in China are the Culex pipiens L. complex, C. tritaeniorhynchus Giles, Anopheles sinensis Wied., A. minimus Theobald, A. anthropophagus Xu & Feng, Aedes albopictus (Skuse) and Ae. aegypti L., and all have evolved resistance to all the above types of insecticide except the carbamates. The degree of resistance varies among mosquito species, insecticide classes and regions. This review summarizes the resistance status of these important vector mosquitoes, according to data reported since the 1990s, in order to improve resistance management and epidemic disease control, and to communicate this information from China to the wider community.     

Chitin synthesis inhibitor effect on Aedes aegypti populations susceptible and resistant to organophosphate temephos

BACKGROUND: In Brazil, dengue vector control is hampered by the resistance of Aedes aegypti L. populations to organophosphates (OPs). Insect growth regulators (IGRs) are a promising alternative, as their mechanisms of action are different from those of conventional insecticides. The authors analysed the effect of the IGR triflumuron, a chitin synthesis inhibitor, on the Ae. aegypti insecticide-susceptible strain Rockefeller, as well as on field populations both susceptible (TemS) and resistant (TemR) to the OP temephos. RESULTS: Triflumuron arrested development and inhibited adult emergence of the Rockefeller strain in a dose-dependent way (EI(50) and EI(90) of 0.8 and 1.8 microg L(-1) respectively). A direct relationship between triflumuron concentration and the precocity of its effects was evident. TemS and TemR temephos resistance ratios (RR(90)) were 4.5 and 13.8, triflumuron RR(90) being 1.0 and 1.3 respectively. CONCLUSION: The IGR triflumuron exhibited a dose-dependent effect against the reference Ae. aegypti Rockefeller strain. It was also effective against two field populations, regardless of their OP resistance status. The present results are discussed in the context of utilization of chitin synthesis inhibitors as potential alternatives in the control of Ae. aegypti in Brazil.     

Biochemical and molecular analyses to determine pyrethroid resistance in Aedes aegypti

Dengue fever is an important mosquito-borne viral disease in Taiwan. Insecticide resistance has been shown to significantly reduce the efficacy of vector control interventions. The detection of insecticide resistance is an important component in mosquito abatement programs. In this study, we used the insecticide-impregnated papers bioassay method to reveal high levels of resistance to permethrin in the LYPR and field strains of Aedes aegypti. We used the standard glass cylinder method to observe the knockdown effect of paralysis within 2 to 4 minutes after exposing mosquitoes to pyrethroid vapors. Biochemical assays showed elevated detoxification enzyme activities. Glutathione S-transferases, monooxygenases and β-esterases were the enzymes predominantly responsible for the permethrin resistance of Ae. aegypti in Taiwan. Molecular screening for common insecticide target-site mutations revealed the presence of V1023G and D1794Y mutations. Pearson’s correlation analysis was used to investigate the correlations between the allelic frequency of kdr mutation associated increase with the LC50 values of permethrin and the KT50 values of pyrethroid vaporizers. These findings will be used to assess resistance levels, estimate resistance potential, and formulate monitoring and resistance management strategies.     

Disinsection of aircraft with pressure packs containing the pyrethroids,resmethrin and bioresmethrin

Pyrethrins and the pyrethroids, bioallethrin ((+) trans-chrysanthemic acid ester of (±) allethrolone), resmethrin* (5-benzyl-3-furylmethyl (±)-cis,trans-chrysanthemate) and bioresmethrin? (5-benzyl-3-furylmethyl (+)-trans-chrysanthemate) were compared for insecticidal activity against free-flying Aedes aegypti L. in a Peet-Grady chamber using kerosene solutions and an aerosol particle size. The relative potency for kill of female mosquitoes was 1; 2.3; 6.8; 8.0 respectively. In further experiments, resmethrin and bioresmethrin were compared as aerosol formulations in a Comet 4C aircraft using caged and fed female A. aegypti. Both compounds at 0.1% (by wt.) in pressure packs and 35 g of formulation per 100 m³ provided 99% kill. It is suggested that pressure packs containing 0.5% (by wt.) of either compound should be adequate for disinsection of passenger aircraft. However, bioresmethrin would appear to be the compound of choice in view of its greater biological efficiency under laboratory conditions, and consequent probable greater margin of kill in practice.     

Repellency of aerosol and cream products containing fennel oil to mosquitoes under laboratory and field conditions

The repellency of fennel (Foeniculum vulgare Miller)-containing products (5% aerosol and 8% cream) against mosquitoes was compared with those of citronella oil, geranium oil and deet, as well as three commercial repellents, Baby Keeper cream containing IR3535, MeiMei cream containing citronella and geranium oils, and Repellan S aerosol containing 19% N,N-diethyl-m-toluamide (deet) under laboratory and field conditions. In a laboratory study with female Aedes aegypti (L), fennel oil exhibited good repellency in a release-in-cage test and repellency in skin and patch tests of the oil was comparable with those of citronella and geranium oils. In paddy field tests with five human volunteers, 5% and 8% fennel oil-containing aerosol and cream produced 84% and 70% repellency, respectively, at 90 min after exposure, whereas Baby Keeper cream and MeiMei cream gave 71% and 57% repellency at 90 min after exposure, respectively, and Repellan S aerosol gave 89% repellency at 210 min. The species and ratio of mosquitoes collected were the genera Culex (44.1%), Anopheles (42.2%), Aedes (7.8%) and Armigeres (5.9%). Fennel oil-containing products could be useful for protection from humans and domestic animals from vector-borne diseases and nuisance caused by mosquitoes.     

Antimicrobial activity of essential oils and their components against the three major pathogens of the cultivated button mushroom, Agaricus bisporus

Essential oils of Matricaria chamommilla, Mentha piperita, M. spicata, Lavandula angusti folia, Ocimum basilicum, Thymus vulgaris, Origanum vulgare, Salvia officinalis, Citrus limon and C. aurantium and their components; linalyl acetate, linalool, limonene, α-pinene, β-pinene, 1,8-cineole, camphor, carvacrol, thymol and menthol were assayed for inhibitory activity against the three major pathogens of the button mushroom, Agaricus bisporus, i.e. the fungi Verticillium fungicola and Trichoderma harzianum and the bacterium Pseudomonas tolaasii. The highest and broadest activity was shown by the Origanum vulgare oil. Carvacrol possessed the highest antifungal activity among the components tested.     

Structure–activity relationships of eugenol derivatives against Aedes aegypti (Diptera: Culicidae) larvae

BACKGROUND: Dengue fever is a severe public health problem for several countries. In order to find effective larvicides to aid control programs, the structure‐activity relationships of eugenol derivatives against Aedes aegypti (Diptera: Culicidae) larvae were evaluated. Additionally, the composition and larvicidal activity of Syzygium aromaticum essential oil was assessed. RESULTS: Four compounds representing 99.05% of S. aromaticum essential oil have been identified. The essential oil was active against Ae. aegypti larvae (LC₅₀ = 62.3 and 77.0 ppm, field‐collected and Rockefeller larvae respectively). The larvicidal activity of eugenol, the major compound of the essential oil, was further evaluated (LC₅₀ = 93.3 and 71.9 ppm, field‐collected and Rockefeller larvae respectively). The larvicidal activity and structure‐activity relationships of synthetic derivatives of eugenol were also assessed. The larvicidal activity of the derivatives varied between 62.3 and 1614.9 ppm. Oxidation of eugenol allylic bond to a primary alcohol and removal of the phenolic proton resulted in decreased potency. However, oxidation of the same double bond in 1‐benzoate‐2‐methoxy‐4‐(2‐propen‐1‐yl)‐phenol resulted in increased potency. CONCLUSION: Structural characteristics were identified that may contribute to the understanding of the larvicidal activity of phenylpropanoids. The present approach may help future work in the search for larvicidal compounds. Copyright © 2012 Society of Chemical Industry