An olfactometer for measuring the repellent effect of chemicals on the stable fly Stomoxys calcitrans (L.)

An olfactometer is described that permits the evaluation of chemicals acting in the vapour phase against the stable fly Stomoxys calcitrans (L.). Hungry flies, held in a metal frame cage covered with soft gauze, are attracted to a target held adjacent to one side of the cage, and emitting an attractive airflow. Flies landing on the target are counted at intervals of 15s. Flies starved for 24h were tested in the olfactometer when 2, 3 and 4 days old. With the exception of the first exposure of the 4-day-old flies, all the flies of the three ages showed greater than 80% attraction to the olfactometer target after exposure for 2 min, for each of four successive exposures at 10-min intervals. For all ages there was a significant increase in attraction at the second exposure but no further increase with subsequent exposures. It is likely that the sensillae, stimulated by the first exposure, subsequently responded faster. Eight chemicals were incorporated into the airflow behind the target to test their effect on flies. Permethrin (a low vapour pressure pyrethroid) and crotoxyphos (a low vapour pressure organophosphate) did not act in the vapour phase. Empenthrin (a high vapour pressure pyrethroid) and dichlorvos (a high vapour pressure organophosphate) both exhibited the toxic effect of knock-down on the flies without repellency. Oil of citronella and citronellol, two known fly repellents, gave a general reduction of attraction that was dose dependent; fewer flies found the target and those that did stayed a shorter length of time. Natural pyrethrum gave a similar effect to these two at lower concentrations, but at higher concentrations, it also showed a repellent effect. N,N-Diethyl-m-toluamide gave a low reduction in attraction. The olfactometer shows potential for use with other flying insects, both to observe the effects of an insecticide and also to study the behavioural responses in the absence of insecticides.     

实蝇引诱物的研究概况

一类可以吸引实蝇成虫前去产卵繁殖,或是作某种生存活动的物质,都可以成为实蝇成虫的引诱物。本文就国内外目前研发的实蝇引诱物概况作简要的概述,所述研究内容主要包括植物性实蝇引诱物,人工混合配制的实蝇引诱物,应用光波技术对实蝇进行诱杀,性激素人工合成材料对实蝇诱杀等三大类型,有些研究成果已得到应用。     

实蝇高引诱性酵母菌的分离和筛选

实蝇是一类重要的检疫性园艺害虫,易造成果实未熟先黄、脱落和腐烂。利用饵剂进行成虫诱杀是防治实蝇最有效的手段之一,而国内目前普遍缺乏绿色高效的实蝇饵剂。多种微生物被报道对实蝇具有引诱能力,配合诱捕器使用,可以成为一种高效绿色的成虫防治技术。本研究从海南、广东、广西、江西、浙江、湖北等地的柑橘、番石榴、杨桃等虫果及寄主叶片上分离获得了357株酵母菌菌株,通过26S rDNA测序,鉴定出这些菌株分属于8个属、25个种,包含假丝酵母属Candida(6种)、有孢汉逊酵母属Hanseniaspora(5种)、毕赤酵母属Pichia(9种)、酿酒酵母属Saccharomyces(1种)、有孢圆酵母属Torulaspora(1种)、子囊酵母属Galactomyces (1种)、Starmerella属(1种)和威克汉姆酵母属Wickerhamomyces属(1种)。在所有分离培养的酵母菌中,优势种是仙人掌有孢汉逊酵母Hanseniaspora opuntiae,优势度指数为0.22。在模拟田间环境的半封闭网室中测定357株酵母菌株发酵液对南亚果实蝇Zeugodacus tau和橘小实蝇Bactrocera dorsalis雌雄成虫的引诱活性,初步筛选获得发酵液引诱活性较好的菌株12株,其引诱南亚果实蝇和橘小实蝇的数量分别是阳性对照的1.0~3.7倍和3.2~7.8倍。进一步筛选发现克鲁维毕赤酵母Pichia kluyveri ZJGJA31和球形环孢菌Torulaspora globosa HBMTA13发酵液对南亚果实蝇田间引诱能力分别为(10.6±1.7)头/诱捕器和(6.8±1.1)头/诱捕器;对橘小实蝇田间引诱能力分别为(9.1±1.1)头/诱捕器和(23.0±2.9)/诱捕器。结果表明,P.kluyveri ZJGJA31和T.globosa HBMTA13发酵液具有被开发成实蝇引诱剂的潜在价值。     

Surveillance techniques for non‐native insect pest detection*

The risk of introduction of new insect pest species is growing with the increase in passenger travel and the trade in plant products worldwide. Though effective detection methods exist in a number of cases, only some of them are applied in practice through organized networks. This paper reviews the detection tools available for insect pests, based on commonly available attractants and trapping systems. Chemical attractants are divided into powerful attractants (such as pheromones and para‐pheromones), attractants of lower intensity (such as kairomones and food attractants), and their combinations. Physical attractants are also considered, such as visual cues, which are generally used in combination with olfactory attractants, and light traps. Finally, the diversity of trapping systems is also presented in relation to attractants, trap design and target species.     

贵州实蝇种类及多样性构成

为了解贵州果蔬有害实蝇的种类及其多样性,2010—2011年在贵州德江、铜仁、凯里、都匀、贵阳和兴义共6个地区,采用性诱剂和食物引诱剂对有害果蔬实蝇进行系统监测和多样性分析。结果显示,6个地区2年共诱捕到果蔬有害实蝇14种,其中果实蝇属Bactrocera有11种,寡鬃实蝇属Dacus有3种;各监测地诱捕到实蝇种类数分别为德江3种、铜仁4种、凯里7种、都匀7种、贵阳11种、兴义12种;6地区共同优势种为桔小实蝇Bactrocera dorsalis、南亚果实蝇Bactrocera tau和具条实蝇Bactrocera scutellata,2010、2011年各监测点的相似性系数和多样性指数均存在差异,相似性系数、Simpson指数、Shannon指数和均匀性指数分别在0.25~0.80、0.11~0.68、0.28~1.25和0.18~0.62之间。研究表明,贵州实蝇种类丰富,不同地区优势种存在差异,不同种类为害差别大;各监测地区实蝇种群数量、丰富度、相似性系数和多样性指数整体上从东北向西南逐渐递增。     

DDT and pyrethroids: Receptor binding in relation to knockdown resistance (kdr) in the house fly

The nature of target site or knockdown resistance (kdr) to DDT and pyrethroids was studied by investigating specific binding of [14_C] DDT and [14_C] cis-permethrin to the previously established membrane receptors from the heads of susceptible (sbo) and resistant (kdr) strains of the house fly, Musca domestica L. In vivo studies showed the heads from sbo flies bound two to three times more DDT than those from kdr flies at all doses tested. Reduced binding was also observed in kdr flies in in vitro [14_C] DDT binding assays. Scatchard analysis indicated that kdr flies have the same affinity but fewer receptors per milligram protein in the CNS than sbo flies. Assays with [14_C] cis-permethrin also showed binding was much reduced in kdr flies in comparison with sbo flies. Based on these results, the nature of the target site insensitivity of kdr flies may relate to their having a reduced number of receptors for the insecticides.     

3种金龟甲对寄主植物的行为反应研究

选取不同寄主植物叶片对暗黑鳃金龟、铜绿丽金龟、大黑鳃金龟的雌雄虫进行室内嗅觉试验,结果表明不同植物叶片对上述几种金龟甲的引诱作用差异较显著。大黑鳃金龟雌虫对榆树的选择反应率和选择系数最高,分别为81%和0.61; 雄虫对沟叶结缕草趋向较强,选择反应率和选择系数为93%和0.85。榆树对暗黑鳃金龟雌虫的引诱效果显著,其选择反应率和选择系数达到80%和0.59; 雄虫对桑树有强趋性,选择反应率和选择系数分别高达87%和0.74。女贞对铜绿丽金龟雌雄虫均有好的引诱活性,雌虫选择反应率和选择系数达到79%和0.58,雄虫分别为72%和0.44。以上寄主植物对金龟甲诱集作用的研究不仅对现阶段农田防治金龟甲有重要指导意义,而且还可为金龟甲生防植物的选择及食诱剂的研制和开发提供知识储备。     

Synergism of organophosphorus insecticides by diethyl maleate and related compounds in house flies

The toxicity of several organophosphorus and one carbamate insecticide for house flies is enhanced by simultaneous administration of diethyl maleate. Synergism factors vary from 2 to 116 and are strongly dependent on the combination of strain and insecticide studied. In general, it seems that thiono compounds are less synergized than their oxon analogs. Comparison of some analogs of maleic acid esters showed that the diethyl ester was not the most active compound. trans-Phenylbutenone was found to be a good alternative for diethyl maleate. Both diethyl maleate and trans-phenylbutenone deplete glutathione in the flies, but this depletion per se is certainly not the most important mode of action. In vitro experiments made clear that sufficient glutathione remained to permit a substantial insecticide degradation rate. Moreover, treatment of the flies with diethyl maleate 2–4 hr before the insecticide application resulted in a partial or complete disappearance of synergism in a period in which the glutathione concentration in the flies was still very low. Apart from this effect on the glutathione levels in the insect tissues it appeared from further experimental work in vitro that both compounds had a direct inhibitory effect on glutathione-dependent transferase(s) as well as on oxidative enzymes involved in insecticide degradation. The contribution of these reactions to the eventual synergism factor is discussed.     

Effect of <Emphasis Type="Italic">Metarhizium guizhouense</Emphasis> infection on mating competition and mate choice of <Emphasis Type="Italic">Bactrocera latifrons</Emphasis> (Diptera: Tephritidae)

Metarhizium guizhouense PSUM02 treated males of Bactrocera latifrons were investigated for the mating competition among males and mating choice by female flies to develop an auto-dissemination for the control of B. latifrons. In the present study, on day 1–4 of experiment, M. guizhouense–treated male flies were equally competitive with the normal male flies as we did not observe any differences in mating by treated and normal male flies of B. latifrons. Further, mating competitiveness were found low in treated adult male B. latifrons than normal male B. latifrons from 5th days of treatment until death. Kaplan-Meier survival analysis of treated male flies gave average survival times (AST) of 4.3?±?0.1 days, while the healthy female and male flies in the same cage showed AST of 9.3?±?0.3 and 8.3?±?0.4 days, respectively. The AST of untreated flies in control experiment ranged from 14.2–14.5 days. In mating preference experiment, M. guizhouense–treated male flies were chosen by virgin female than gravid female flies for mating. The treated male flies caused mortality in both virgin and gravid female flies in the same cage with AST of 4.4?±?0.1, 5.6?±?0.1 and 7.4?±?0.2 days, respectively, while untreated flies showed AST ranged from 13.9–14.3 days in control. The treated male flies could transmit the fungus infection to both untreated female and male flies as well as in virgin and gravid female flies by mating and contact. Our experiments showed the potentiality of M. guizhouense PSUM02 in management of B. latifrons by auto-dissemination with treated male flies, which transmit the fungus to a healthy population to reduce insect pest infestations.     

斑翅果蝇对寄主果实及其挥发物嗅觉趋性的研究

斑翅果蝇是一种主要为害软皮水果的害虫, 诱捕剂诱捕是防治该害虫的重要手段。为明确斑翅果蝇对寄主果实及其挥发性物质的趋性, 进而研发植物源引诱剂, 本研究利用四臂嗅觉仪测定了斑翅果蝇成虫对不同种类（葡萄、树莓、杨梅、蓝莓、樱桃和草莓）和不同成熟程度鲜果的趋性, 并分析了寄主果实挥发物成分。结果表明:1)斑翅果蝇成虫对过熟鲜果的趋性最强, 其次为成熟鲜果和未熟的鲜果; 2)成虫对葡萄的趋性最强, 其次分别为树莓、杨梅、蓝莓、樱桃和草莓; 3)葡萄挥发物中含量最高的成分为反式-2-己烯醛, 樱桃和树莓中为苯甲醇, 蓝莓中为乙醇。研究结果为进一步开发高效的斑翅果蝇植物源引诱剂奠定了基础。     

Insecticide resistance in Tephritid flies

Tephritid flies attack a large variety of fruits, which constitute highly-priced commodities in many countries. Insecticides have been used extensively for their control.Although resistance development in fruit flies has not kept pace with that in other insects, possibly due to their high mobility and tendency for wide spatial dispersal, recent studies have indicated that selection pressure has now reached the point where resistance is detectable in the field and control may therefore become problematic. The status of resistance to the commonly used insecticides in the most significant Tephritid pests, such as the Mediterranean fruit fly Ceratitis capitata, the oriental fruit fly Bactrocera dorsalis, the olive fly Bactrocera oleae and the melon fly Bactrocera cucurbitae, is reviewed. Emphasis has been placed on the resistance mechanisms that have been elucidated at the biochemical and molecular level. Prospects for using this knowledge alongside genomic information in Tephritidae to develop novel strategies of potential practical importance for resistance management are discussed.     

The A302S mutation in Rdl that confers resistance to cyclodienes and limited cross-resistance to fipronil is undetectable in field populations of house flies from the USA

Fipronil is a relatively new insecticide with great potential for insect control, however widespread use of cyclodiene insecticides has selected for an A302S mutation in the Rdl (GABA gated chloride channel) allele. This mutation gives resistance to cyclodienes and limited cross-resistance to fipronil. Given the concern over the possible reduction in efficacy and/or lifetime that fipronil might be used for pest control (given the extensive use of cyclodienes in the past), it is important to know the frequency of the A302S Rdl mutation in field populations. To ascertain the relative frequency of the A302S Rdl mutation in house fly populations we used three experimental approaches. First, we attempted to select for fipronil resistance by initially treating 33,100 field collected flies and selecting 14 additional generations. We were unable to produce a highly resistant strain. Second, we directly sequenced field collected flies. Third, we tested field collected house flies with a diagnostic dose of dieldrin and then genotyped the survivors. Out of the 4750 flies tested, there were no Rdl resistance alleles detected. We conclude that the resistant Rdl allele is rare in house flies in the US due to decades without cyclodiene use and a fitness disadvantage (in the absence of cyclodienes) of the 302S Rdl allele. The limited cross-resistance provided by the cyclodiene resistant Rdl allele, combined with the very low frequency of this allele in field populations, suggests that fipronil could be a promising insecticide for house fly control.     

Resistance in the highly DDT-resistant 91-R strain of Drosophila melanogaster involves decreased penetration,increased metabolism,and direct excretion

Resistance to 4,4′-dichlorodiphenyltrichloroethane (DDT) in the 91-R strain of Drosophila melanogaster is extremely high compared to the susceptible Canton-S strain (>1500 times). In addition to enhanced oxidative detoxification, the 91-R strain also has a reduced rate of DDT penetration, increased levels of reductive and conjugative metabolism, and substantially more excretion than the Canton-S strain. Contact penetration of DDT was ∼30% less with 91-R flies, which also had significantly more cuticular hydrocarbons and a thicker, more laminated cuticle compared to Canton-S flies, possibly resulting in penetration differences. DDT was metabolized ∼1.6-fold more extensively by 91-R than Canton-S flies, resulting in dichlorodiphenyldichloroethane (DDD), two unidentified metabolites and polar conjugates being formed in significantly greater amounts. 91-R flies also excreted ∼4-fold more DDT and metabolites than Canton-S flies. Verapamil pretreatment reduced the LD₅₀ value for 91-R flies topically dosed with DDT by a factor of 10-fold, indicating that the increased excretion may involve, in part, ATP-binding cassette (ABC) transporters. In summary, DDT resistance in 91-R is polyfactorial and includes reduced penetration, increased detoxification and direct excretion.     

Metabolism of O,S-dimethyl propionyl- and hexanoylphosphoramidothioate in the house fly and white mouse

The metabolism of O,S-dimethyl propionyl- and hexanoylphosphoramidothioate was investigated in the white mouse and house flies. Compared to the hexanoylphosphoramidothioate, the propionyl analog is approximately 35-fold more toxic to house flies and is 10-fold less toxic to mice. On a percentage basis, substantially larger amounts of methamidophos were detected in house flies treated topically with the propionylphosphoramidothioate than in flies treated with the hexanoyl derivative. The reverse was evident in the case of the mouse where much larger amounts of methamidophos were formed after oral treatment with the hexanoylphosphoramidothioate. Minor amounts of other metabolic products also were detected, including an unknown from the hexanoylphosphoramidothioate. Metabolism of the S-methyl moiety to carbon dioxide appeared to be a major pathway for metabolic degradation of both compounds in both the white mouse and house fly. The difference in toxicity of the two acylphosphoramidothioates to the mouse and house fly is attributed to difference in the amounts of methamidophos formed in the animals.     

Frequencies and evolution of organophosphate insensitive acetylcholinesterase alleles in laboratory and field populations of the house fly, Musca domestica L.

Resistance to organophosphate (OP) and/or carbamate insecticides can be due to mutations in the acetylcholinesterase gene (Ace). Genotypes of house fly, Musca domestica L., Ace were determined in twelve laboratory maintained strains (originally from North America, Europe and Asia) and two field collected populations from New York and Florida. There were 15 Ace alleles found and 11 of the alleles coded for a susceptible form of the enzyme (i.e., V260, A316, G342 and F407). Three of the four resistance alleles were previously described, while one is new. Phylogenetic analysis of the alleles suggests multiple origins of the F407Y mutation and multiple origins of the G342A mutation that confer OP resistance. Genotyping of field collected house flies from New York and Florida populations revealed the presence of only one resistance allele, Acev10 (containing the non-synonymous mutations for A342 and Y407). All other alleles detected from the field-collected flies coded for a susceptible AChE. Thus, we were able to categorize individual flies as having homozygous susceptible (Ace^S/Ace^S), homozygous insensitive (Ace^I/Ace^I or Acev10/Acev10) or heterozygous AChE. The frequencies of Ace^S and Ace^I were not different between the NY2002 and FL2002 populations. Both populations were out of Castle-Hardy-Weinberg equilibrium, having an excess of Ace^S/Ace^I individuals and very few Ace^S/Ace^S individuals. Comparison of Ace, Vssc and CYP6D1 genotypes indicates individual house flies commonly have resistance alleles at multiple loci. Comparison of genotype data with bioassays, as well as the use of genotype data in resistance studies is discussed.     

Neurophysiological activity and toxicity of pyrethroids derived by addition of methylene,sulfur or oxygen to the chrysanthemate 2-methyl-1-propenyl substituent

Conversion of chrysanthemates to their cyclopropane, episulfide, and epoxide derivatives by addition of methylene, sulfur, or oxygen, respectively, to the 2-methyl-1-propenyl double bond yields products generally of reduced toxicity but enhanced neurophysiological activity and photostability. The reduced toxicity is established with cis-cyphenothrin derivatives administered intracerebrally to mice and topically to house flies and with cis-phenothrin derivatives applied topically to American cockroaches and house flies, even in the presence of piperonyl butoxide for the house flies. In contrast, cyclopropane, episulfide, and epoxide derivatives of phenothrin are more potent than the parent compound in eliciting repetitive firing following stimulation of a cercal sensory nerve of the American cockroach in vitro. The individual 1′R and 1′S isomers of epoxides derived from (1R,cis,αS)cyphenothrin, (1R,cis)phenothrin, and (1R,trans)tetramethrin differ in potency by up to 20-fold for insecticidal activity, >30-fold for intracerebral toxicity to mice, and ～100,000-fold in the cercal sensory nerve assay. In each case the epoxide isomer of higher R_f is more potent than that of lower R_f when derived from a trans-chrysanthemate and vice versa from a cis-chrysanthemate.     

Assessment of synthetic chemicals for disruption of Rhynchophorus ferrugineus response to attractant-baited traps in an urban environment

The red palm weevil (RPW), Rhynchophorus ferrugineus Olivier (Coleoptera, Curculionidae), is one of the most severe pests of ornamental palm species in urban areas of Mediterranean countries. Aiming to discover inhibitory semiochemicals for RPW population management in urban environments, we conducted electroantennographic (EAG) screenings of 17 commercially available synthetic compounds, representing three groups of plant volatiles (isoprenoids, phenyl propanoid derivatives and fatty acid derivatives) known for their repellent effects toward insects. These tests were followed by trap-based screenings of EAG-active menthone, α-pinene and methyl salicylate, singly and in combination, under urban conditions. In EAG bioassays, RPW antennae of both sexes showed positive dose-dependent responses to 13 of the 17 synthetic chemicals with significant differences among them. In field trapping experiments, conducted in the city of Palermo, Italy, from weeks 31 to 38 in 2010 and 2011, α-pinene, tested singly or in combination with methyl salicylate (2010) or menthone (2011), reduced trap catches by about 30% to 40%. Methyl salicylate and menthone alone were inactive. In conclusion, RPW is significantly affected by α-pinene. This isoprenoid is a promising disruptant for semiochemical-based management of this pest. In addition, identification of a large number of EAG-active chemicals could serve as a database for future design of active repellents or attractants of RPW adults.     

Ecdysone metabolism by soluble enzymes from three species of diptera and its inhibition by the insect growth regulator TH-6040

Homogenates of larvae, pupae, and adults of house flies (Musca domestica L.), flesh flies (Sarcophaga bullata Parker), and blow flies (Phormia regina (Meigen)) have been examined for enzymes which convert α- and β-ecdysone to apolar products. Most of the activity was found in the soluble fraction from house flies and flesh flies but none of the blow fly fractions was active. Two enzymes seem to be involved in the ecdysone metabolism, one requiring NADPH and the other functioning without this cofactor. The product of the latter enzyme is thought to be the 3-dehydro-ecdysone. This product is further converted to the 3α-hydroxy isomer of ecdysone by the NADPH-requiring enzyme. On feeding the insect growth regulator TH-6040 (1-(4-chlorophenyl)-3-(2,6-difluorobenzoyl)-urea) to larvae at dietary levels ranging from 0.3 to 10 ppm, the activity of the enzyme producing the 3-dehydro product is reduced by 20 to 82%. It is suggested that the growth regulator exerts its effect on pupal-adult ecdysis through its inhibition of ecdysone metabolism.     

Diversity and frequencies of genetic mutations involved in insecticide resistance in field populations of the house fly (Musca domestica L.) from China

Insecticides have been extensively used for house fly control in China, with dichlorvos and deltamethrin being widely used. Knowledge about the current status of insecticide resistance and the underlying genetic changes is crucial for developing effective fly control strategies. The susceptibility to dichlorvos and deltamethrin, and the frequencies of genetic mutations involved in insecticide resistance were studied in five field populations of the house fly collected across China. Bioassay results show that flies exhibit 14- to 28-fold resistance to dichlorvos and 41- to 94-fold resistance to deltamethrin, indicating that dichlorvos and deltamethrin resistance are common in house fly populations in China. Molecular analysis reveals that flies from the five various locations carry resistance alleles at multiple loci and have diverse allelic types, different relative frequencies and combinations of each allele. Four non-synonymous single nucleotide polymorphisms (SNPs) (i.e. V260L, G342A/V, F407Y) in acetylcholinesterase (Ace) and two mutations (W251L/S) in a carboxylesterase (MdαE7) were commonly present in the field house flies. The L1014H rather than L1014F mutation in the voltage sensitive sodium channel gene (Vssc) was widely distributed in Chinese house flies. CYP6D1v1, which confers pyrethroid resistance, was found in all the five tested populations in China, although its frequency in house fly from Shandong province was very low. Our results suggest that resistance monitoring and management of house flies should be customized for a given location.