Laboratory evaluation of cyromazine against insecticide-resistant field strains of Musca domestica

A screening programme was undertaken to examine the possibility of cross resistance occurring between cyromazine and conventional insecticides. The responses of nine strains of Musca domestica to treatment with cyromazine, trichlorphon, methomyl and pyrethrins with piperonyl butoxide were measured. No tolerance to cyromazine was found, neither was there a direct correlation between larval responses to cyromazine and adult responses to other insecticides. Cyromazine is a potent larvicide against M. domestica and the results of these tests show that it has good potential for the control of houseflies with high levels of resistance to other insecticides.     

Mortality and knockdown effects of imidacloprid and methomyl in house fly (Musca domestica L., Diptera: Muscidae) populations

In this study, the knockdown and mortality effects of imidacloprid and methomyl were investigated. The residual surface applications were carried out to determine the knockdown effects (KDt₅₀ and KDt₉₅) and mortality (LD₅₀ and LD₉₅) induced by each insecticide. For mortality comparisons, the susceptible house fly (Musca domestica L., Diptera: Muscidae) of a WHO population and three natural field‐collected M. domestica populations from Turkey were used. In conclusion, it was found that the resistance to imidacloprid and methomyl was significantly higher in the field populations when compared to the susceptible population from WHO. The results showed that applicators and pest management decision‐makers should control and conduct an integrated pest management strategy by including biological agents to prevent the development of high levels of resistance in the field populations.     

家蝇攻击素(Attacin)基因的克隆与表达

通过同源克隆策略并结合cDNA末端快速扩增(RACE)技术,克隆到了编码家蝇攻击素(Attacin)基因的全长cDNA序列(GenBank登陆号：AY460106),并对相应的氨基酸序列进行了序列比对,对系统关系等进行了生物信息学分析。家蝇Attacin的cDNA全长778bp,其中包括627bp的开放式读码框(ORF),44bp的5’末端非编码区(5’UTR)和107bp的3’末端非编码区(3’UTR),相应的蛋白产物含208个氨基酸,与其他双翅目昆虫的Attacin具有很高的相似性,约50％-70％。以邻接法(Neighbor-Joining,NJ)所构建的系统关系表明,家蝇的Attacin与其他双翅目昆虫的Attacin起源于共同的祖先。应用半定量RT-PCR的方法,研究家蝇幼虫在受到外源刺激后Attacin基因的表达,结果表明,在家蝇幼虫体内Attacin基因呈诱导型表达,表达水平随诱导时间和诱导源的不同而变化。     

Characterization of alanyl aminopeptidase from insecticide resistant and susceptible strains of Musca domestica L.

To investigate the high activity of intracellular proteases in insecticide resistant strains of Musca domestica L., purification by anion‐exchange chromatography and gel filtration of one of the enzymes, alanyl aminopeptidase (Ala AP), in three strains of Musca domestica was carried out. The fractions collected by gel filtration of soluble homogenates of the three strains (571ab, 17bb and Cooper) showed a single peak of Ala AP activity. Partially purified Ala AP of the three strains showed high activity at pH 7.5. The presence or absence of Ca²⁺ in the assay medium did not produce any difference in activity of Ala AP in the 571ab and Cooper strains, but there was a significant difference in the 17bb strain. The activity of Ala AP in all three strains was essentially unaltered in the presence of inhibitors of serine (PMSF), cysteine (E‐64) proteases and carboxypeptidases (pepstatin). Ala AP hydrolyzed alanine amino methylcoumarin (Ala‐AMC) maximally, followed by phenyl alanine amino methylcoumarin (Phe‐AMC), leucyl amino methylcoumarin (Leu‐AMC) and ornithine amino methylcoumarin (Orn‐AMC). Ala AP from the three strains showed differential activity towards various substrates. The comparison of alanyl aminopeptidase's activity from different sources is discussed.     

滁州市家蝇对6种杀虫剂的抗药性调查

采用微量滴定法测定了滁州市家蝇对6种常见杀虫剂的抗药性。结果表明,滁州市的家蝇对毒死蜱、敌敌畏、高效氯氰菊酯、敌百虫、辛硫磷、溴氰菊酯6种常用杀虫剂都产生了很高的抗性,其LD50分别为1.1858、1.9505、0.9530、47.1834、1.2120、1.0053μg/只,相对抗性系数分别为49.62、139.32、207.17、263.59、390.97、1675.50。滁州应停止使用这些杀虫剂,加强对家蝇抗性对策的研究,延缓家蝇抗性的发展。     

The role of the housefly, Musca domestica, in the spread of Aujeszky's disease (pseudorabies)

Starved houseflies were held over a suspension of Aujeszky's virus (PRV-1) for 24-48 h. One group was rinsed in 70% ethanol to kill virus attached to the body surface. No virus was isolated from this group. For the other group the titre of virus decreased more rapidly on the body surface of flies than in the environment. Model experiments demonstrated that the Aujeszky's virus cannot survive in the body of the housefly but the body surface may be contaminated for a period of time depending on the initial viral titre. Experiments showed that susceptible pigs fed on flies contaminated with Aujeszky's virus may become infected. The quantity of virus (5 x 10(5) pfu ml-1) shed by a single housefly during biting and vomiting on the cornea or abraded skin proved to be sufficient to cause infection in susceptible pigs, rabbits and a lamb. It is possible that houseflies could play a role in transmission of infection within herds. Transmission between herds is much less likely.     

Degradation of cuticle during larval-pupal and pupal-adult development of the housefly, Musca domestica

Abstract. The patterns of changes in cuticle weight, its chitin content and chitinase activity have been studied during postembryonic development of the housefly, Musca domestica L. During pupariation the larval cuticle loses weight. During the early part of this weight-loss the decline in chitin content parallels the overall change in cuticle weight. A simultaneous elevation in chitinase activity suggests that at this time the larval cuticle is being enzymatically degraded. Later weight loss may be due to sclerotization. No significant changes in cuticle weight or its chitin content occur in pharate cuticle until one day before eclosion. However, a peak of chitinase activity found at mid-late pupal stage suggests the timing of pupal cuticle breakdown.     

家蝇转铁蛋白基因的克隆和生物信息学分析

为了研究家蝇转铁蛋白基因功能,获得全长cDNA序列并对其蛋白序列进行生物信息学分析,利用在线分析程序和相关工具软件分析转铁蛋白基因的开放读码框,分析编码蛋白的理化性质、结构域、并预测其空间结构和功能。结果表明家蝇转铁蛋白基因编码蛋白由622个氨基酸组成,分子量为70.58kDa,理论等电点为5.33,为稳定蛋白,有跨膜区,含有信号肽,该蛋白属于TR-FER保守结构域家族,亚细胞定位于细胞核,二级结构以无规则卷曲为主,功能预测该蛋白具有酶活性。     

Some effects of CGA 72662 on larval development in the housefly,Musca domestica (L.)

Summary

Houseflies reared on artificial diet supplemented with a range of concentrations of CGA 72662 suffered severe developmental disruption at the larval stage. Death was preceded by the appearance of a range of cuticular lesions and abnormalities. These cuticular abnormalities have been observed under the light and electron microscopes.     

Identification and cloning of a key insecticide-metabolizing glutathione S-transferase (MdGST-6A) from a hyper insecticide-resistant strain of the housefly Musca domestica

Strains of the housefly, Musca domestica, highly resistant to organophosphate (OP) and other insecticides are known because they overproduce glutathione S-transferases (GSTs). Previous work has shown that overproduction in these strains involved numerous isozymes with glutathione conjugating activities (Pesticide Biochem. Physiol., 25 (1986) 169; Mol. General Genetics, 227 (1991) 355; J. Biol. Chem., 267 (1992) 1840; Mol. General Genetics, 245 (1994) 236; J. Mol. Evol., 43 (1996) 236). The current work describes the purification and identification of a M. domestica GST isozyme (pI 7.1) broadly specific for substrates from a housefly strain, Cornell-HR, that is highly resistant against OP-insecticides, and the isolation of two new MdGST genes using the antibody made against it. This isozyme, which was identified from amongst more than 20 isoelectric forms of GSTs of the same subunit size, was highly active for conjugating GSH to the model substrate 3,4-dichloronitrobenzne (DCNB). When expressed in Escherichia coli, one of the cloned GSTs, MdGST-6A, produces an enzyme that conjugates glutathione to the insecticides methyl parathion and lindane. On indication that it was the most active isozyme toward several xenobiotics among several MdGSTs tested, we advance the notion that MdGST-6A probably plays an important role in M. domestica Cornell-HR's resistance towards OP-insecticides. MdGST-6A and a second closely related one found in this work, MdGST-6B, are members of the traditional insect class I family (theta-class) and share the greatest homologies with a cluster of Drosophila GSTs on locus 55. In addition to having the unusually broad substrate specificity, the sequence of the new group of enzymes reveals that it has a highly diverged hydrophobic motif in its active site as compared to other class I GSTs from insects.     

Evaluation of commercial and field‐expedient baited traps for house flies,Musca domestica L. (Diptera: Muscidae)

A comparison of nine commercial baited fly traps on Florida dairy farms demonstrated that Terminator traps collected significantly more (13,323/trap) house flies (Musca domestica L.) than the others tested. Final Flight, Fly Magnet, and FliesBeGone traps collected intermediate numbers of flies (834‐2,166), and relatively few were caught with ISCA, Advantage, Fermone Big Boy, Squeeze & Snap, or OakStump traps (<300). Terminator traps collected about twice as many flies (799.8/trap) as FliesBeGone traps (343.8) when each trap was baited with its respective attractant, but when the attractants were switched between the two trap types, collections were significantly lower (77‐108) than was observed with traps baited with their respective attractant. Solutions of molasses were significantly more attractive to house flies than honey, maple syrup, or jaggery (date palm sugar). Field‐expedient traps constructed from discarded PET water bottles were much less effective than commercial traps, but painting the tops of such traps with black spray paint resulted in a six‐fold increase in trap capture.     

Survey of insect growth regulator (IGR) resistance in house flies (Musca domestica L.) from southwestern Turkey

Insect growth regulators (IGRs) are currently the fastest‐growing class of insecticides, and in Turkey these products represent a new approach to pest control. In recent years, several IGRs were also registered for the control of the house fly, Musca domestica L. (Diptera: Muscidae), in Turkey. A field survey was conducted in the summers of 2006 and 2007 to evaluate resistance to some agriculturally and medically used IGRs on house flies from livestock farms and garbage dumps in the greenhouse production areas (Merkez, Kumluca, Manavgat, and Serik) of Antalya province (Southwestern Turkey). The results of larval feeding assay with technical diflubenzuron, methoprene, novaluron, pyripoxyfen, and triflumuron indicate that low levels (RF<10‐fold) of resistance to the IGRs exist in the house fly populations from Antalya province. Exceptions, however, were two populations, Guzoren and Toptas, from the Kumluca area which showed moderate resistance to diflubenzuron with 11.8‐fold in 2006 and 13.2‐fold in 2007, respectively. We found substantial variation in susceptibility of field‐collected house fly populations from year to year and from product to product. We generally observed an increase in resistance at many localities sampled from 2006 to 2007. The implications of these results to the future use of IGRs for house fly control are discussed. It will be critically important to continue monitoring efforts so that appropriate steps can be taken if resistance levels start to increase.     

Characterization and description of a virus causing salivary gland hyperplasia in the housefly,Musca domestica

Abstract. A double-stranded DNA virus was isolated from hyperplasic salivary glands of male and female houseflies, Musca domestica L. (Diptera: Muscidae), collected from a dairy in Alachua County, Florida, U.S.A. Sodium dodecyl sulphate (SDS)–polyacrylamide gel electrophoresis (PAGE) of this housefly salivary gland hyperplasia (SGH) virus revealed the presence of two major and eight minor structural polypeptides. Restriction endonuclease analysis indicated that the c. 137 kilobase pair DNA was double-stranded. Weekly sweep-net sampling of the fly population throughout the season (May-October, 1991) showed that 1.5-18.5% of the dissected flies possessed hyperplasic salivary glands. The virus replicated within the nuclei of the salivary gland cells and was transmitted per os to newly-emerged healthy adult flies.     

Visual responses of Musca domestica to pheromone impregnated targets in poultry units

Field trials investigating the effect of visual cues on catches of Musca domestica (Diptera: Muscidae) at toxic targets impregnated with the female sex pheromone (Z)-9-tricosene, were conducted in a caged-layer deep-pit poultry unit in southern England. Targets treated with azamethiphos and baited with 2.5 g of 40% (Z)-9-tricosene impregnated beads caught significantly greater numbers of M. domestica than control targets. The greater attractiveness of the pheromone impregnated targets persisted for at least 5 weeks. The addition of longitudinal black stripes, or a regularly spaced pattern of black spots, to the white targets had no effect on catch rates. However, a pattern of clustered black spots, designed to imitate groups of feeding M. domestica, significantly increased target catches; this effect was particularly pronounced in the targets impregnated with (Z)-9-tricosene. Trials comparing the attractiveness of white and fluorescent yellow pheromone-treated targets under two different lighting regimes indicated that M. domestica does not have a significant preference for either colour. The implications of these results in relation to the control of M. domestica populations in poultry units are discussed.     

土荆芥生物总碱对家蝇的毒杀作用及药剂敏感性的影响

通过室内毒力测定和生化分析方法,测定了土荆芥生物总碱对敌百虫抗性种群,溴氰菊酯抗性种群,敏感种群等3个家蝇(Musca domestica)种群成虫的毒杀效果,土荆芥生物总碱处理前后家蝇种群成虫对溴氰菊酯和敌百虫的药剂敏感性变化,以及对家蝇成虫羧酸酯酶和谷胱甘肽-S-转移酶的活力的影响。结果表明,土荆芥生物总碱不仅对家蝇有毒杀效果,处理后能提高家蝇对杀虫剂的敏感性,而且能抑制家蝇体内解毒酶系活性。土荆芥生物总碱对不同种群家蝇成虫的LD_(50)没有显著差异;土荆芥生物总碱处理前后,敌百虫对抗性种群和敏感种群的LD_(50)比值分别为1.6277和1.2914,溴氰菊酯对抗性种群和敏感种群的LD_(50)比值分别为2.0768和1.3871;土荆芥生物总碱处理前后,家蝇敌百虫抗性种群、溴氰菊酯抗性种群和敏感种群成虫的羧酸酯酶活性比值分别为1.1692、1.2947和1.2259,谷胱甘肽-S-转移酶活性比值分别为1.2476、1.6519和1.0570。     

Role of prestomal teeth in feeding of the house fly, Musca domestica (Diptera; Muscidae)

Ultrastructural studies of the mouthparts of Musca domestica L. show that the fly's prestomal teeth are more damaging to host tissues than considered previously. When fed on tissue culture or pig cornea, SEM revealed that M. domestica were able to tear and suck up cells. This process occurs so rapidly, and so few cells are involved, that the damage is not perceptible to the naked eye. Except for the prestomal teeth, the mouthparts have few other structures which can inflict the damage observed.     

Reproductive performance of Nesolynx thymus (Hymenoptera: Eulophidae), in relation to age of Musca domestica (Diptera: Muscidae)

An investigation was undertaken to record the influence of host age on the reproductive performance of Nesolynx thymus (Hymenoptera:Eulophidae). This is an indigenous, gregarious, ecto-pupal parasitoid of certain dipteran insects, including the tachinid fly, Exorista bombycis (Louis) which is a well-known endo-larval parasitoid of the silkworm, Bombyx mori. Each gravid N. thymus female was allowed to parasitise 1–4-day-old puparia of Musca domestica L. for 2 days at a parasitoid–host ratio of 1:20. The parasitised host puparia were observed for progeny recovery, sex ratio, female longevity and fitness (adult size). In addition, reproductive performance of the parasitoid progeny was assessed by allowing its females to parasitise for 2 days, 3-day-old puparia of E. bombycis at a parasitoid–host ratio of 1:4. There was a significant negative correlation between host age and parasitisation rate, parasitoid developmental duration, sex ratio and female longevity while the correlation was positive between host age and parasitoid recovery per host puparium. Similarly, negative correlation was observed between host age and morphometric parameters (body length, head width and wing span of male and female and length and width of female abdomen) of the progeny adults. Host age did not have any impact on the reproductive performance of progeny adults when allowed to parasitise puparia of E. bombycis.     

家蝇C-型凝集素的克隆与功能分析

【目的】从家蝇Musca domestica中克隆一种C-型凝集素(C-type lectin)基因,并分析其在家蝇免疫过程中的功能。【方法】根据家蝇转录组信息,克隆了一条C型凝集素基因,将其命名为Mdlectin-C1。构建Mdlectin-C1的原核表达载体,在大肠杆菌Escherichia coli中表达并纯化r Mdlectin-C1蛋白,制备多克隆抗体。利用实时定量PCR(quantitative real-time PCR,qRT-PCR)及Western blot技术对家蝇不同发育阶段和细菌感染前后Mdlectin-C1的表达水平进行检测。运用RNAi技术敲低家蝇1龄幼虫Mdlectin-C1基因表达,然后进行细菌刺激并观察幼虫存活率变化。【结果】Mdlectin-C1 c DNA包含一个546 bp完整开放阅读框,编码181个氨基酸残基,所推导多肽N端包含由21个氨基酸残基组成的信号肽,成熟肽中含有一个保守的碳水化合物识别结构域(carbohydrate-recognition domain,CRD)。qRT-PCR及Western blot结果显示,家蝇从1龄幼虫到蛹的发育过程中,Mdlectin-C1表达量逐步上升,蛹期达到最大值。在革兰氏阴性菌大肠杆菌E.coli和革兰氏阳性菌金黄色葡萄球菌Staphylococcus aureus刺激后,家蝇2龄幼虫Mdlectin-C1均上调表达,并分别在36和3 h时达到最高值。利用RNAi技术成功敲低Mdlectin-C1表达。对Mdlectin-C1基因敲低的1龄幼虫进行细菌刺激,敲低实验组幼虫存活率显著低于正常对照组。【结论】Mdlectin-C1可能参与家蝇抗菌免疫应答,并在此过程中具有重要作用。