House Fly (Musca domestica L.) Attraction to Insect Honeydew

House flies are of major concern as vectors of food-borne pathogens to food crops. House flies are common pests on cattle feedlots and dairies, where they develop in and feed on animal waste. By contacting animal waste, house flies can acquire human pathogenic bacteria such as Escherichia coli and Salmonella spp., in addition to other bacteria, viruses, or parasites that may infect humans and animals. The subsequent dispersal of house flies from animal facilities to nearby agricultural fields containing food crops may lead to pre-harvest food contamination with these pathogens. We hypothesized that odors from honeydew, the sugary excreta produced by sucking insects feeding on crops, or molds and fungi growing on honeydew, may attract house flies, thereby increasing the risk of food crop contamination. House fly attraction to honeydew-contaminated plant material was evaluated using a laboratory bioassay. House flies were attracted to the following plant-pest-honeydew combinations: citrus mealybug on squash fruit, pea aphid on faba bean plants, whitefly on navel orange and grapefruit leaves, and combined citrus mealybug and cottony cushion scale on mandarin orange leaves. House flies were not attracted to field-collected samples of lerp psyllids on eucalyptus plants or aphids on crepe myrtle leaves. Fungi associated with field-collected honeydews were isolated and identified for further study as possible emitters of volatiles attractive to house flies. Two fungal species, Aureobasidium pullulans and Cladosporium cladosporioides, were repeatedly isolated from field-collected honeydew samples. Both fungal species were grown in potato dextrose enrichment broth and house fly attraction to volatiles from these fungal cultures was evaluated. House flies were attracted to odors from A. pullulans cultures but not to those of C. cladosporioides. Identification of specific honeydew odors that are attractive to house flies could be valuable for the development of improved house fly baits for management of this pest species.     

家蝇抗菌物质的诱导

针刺损伤诱导的家蝇三龄幼虫免疫血淋巴对动、植物病原菌有广谱的抗菌活性,同时,未经诱导的家蝇幼虫也具有抗菌活性。ＳＤＳ－ＰＡＧＥ电泳分析表明：外源诱导能增强原有抗菌物质的表达量,并能激活新的蛋白产生。家蝇免疫血淋巴中的抗菌物质具热稳定性和耐冷冻贮藏的特性     

Multiple Origins of kdr-type Resistance in the House Fly,Musca domestica

Insecticide resistance is a model phenotype that can be used to investigate evolutionary processes underlying the spread of alleles across a global landscape, while offering valuable insights into solving the problems that resistant pests present to human health and agriculture. Pyrethroids are one of the most widely used classes of insecticides world-wide and they exert their toxic effects through interactions with the voltage-sensitive sodium channel (Vssc). Specific mutations in Vssc (kdr, kdr-his and super-kdr) are known to cause resistance to pyrethroid insecticides in house flies. In order to determine the number of evolutionary origins of kdr, kdr-his and super-kdr, we sequenced a region of Vssc from house flies collected in the USA, Turkey and China. Our phylogenetic analysis of Vssc unequivocally supports the hypothesis of multiple independent origins of kdr, super-kdr and kdr-his on an unprecedented geographic scale. The implications of these evolutionary processes on pest management are discussed.     

Genetic Distances Among North American, British, and West African House Fly Populations (Musca domestica L.)

Allozyme and mitochondrial gene diversities were estimated in house flies, Musca domestica L. (Diptera: Muscidae), sampled in Iowa, USA; Berkshire, England; and Kudang, The Gambia. Comparison of genomic allele frequencies among the three populations indicated small differences between the English and American samples but very large distances between English or American and the African. The FST statistic was 0.65 +/- 0.09 for allozymes. Pairwise FST was 0.14 between the English and the American samples; FST was 0.65 between the African population and the English and American. Mitochondrial variation in the same flies was assessed by SSCP methods which revealed nine haplotypes, none of which were shared in common. FST was 0.637 for the mitochondrial haplotypes. The research indicates greatly restricted gene flow between Africa and the temperate regions.     

Survey of Mariner-Like Elements in the Housefly, Musca Domestica

The presence of mariner-like elements in four strains of the housefly, Musca domestica, was surveyed by PCR. Using the inverted terminal repeat (ITR) sequences of the Mos 1element as primers, DNAs were successfully amplified from all strains of the housefly. Southern blot analysis indicated that these amplified DNAs were repetitive sequences in the genome of M. domestica. Sequence analyses of cloned PCR products showed that they were 45% identical to the Mos 1element. These fragments appeared to be nonfunctional, because they contained no intact open reading frame (ORF) capable of encoding transposase. We conclude that these DNAs are degraded mariner-like elements (MLEs) in M. domestica. Because these endogenous MLEs in M. domesticado not encode any functional proteins, they probably would not affect the behavior of mariner-based vectors if such were introduced into this species as transformation vectors.     

家蝇cDNA文库的构建

自Ｂｏｍａｎ小组 (Ｓｔｅｉｎｅｒ ,1981)从惜古比天蚕(Ｈｙａｌｏｐｈｏｒａｃｅｃｒｏｐｉａ)中分离、纯化出第一种抗菌肽天蚕素以来 ,人们已在昆虫和其他无脊椎动物中发现了 170多种抗菌肽 (Ｌｏｗｅｎｂｅｒｇｅｒｅｔａｌ ,1999)。目前 ,人们不仅搞清楚了多数抗菌肽的氨基酸序列、结构和功能特点 ,而且还对一些抗菌肽的基因进行了克隆 (陈留存和王金星 ,1999)。我们以家蝇为材料 ,分离、纯化出了抗菌肽 ,在此基础上 ,构建了经过诱导的家蝇ｃＤＮＡ文库 ,以克隆其基因。1　材料和方法1 1　实验材料家蝇 (Ｍｕｓｃａｄｏｍｅｓｔｉｃａ)…     

Thiamethoxam Resistance in the House Fly,Musca domestica L.: Current Status,Resistance Selection,Cross-Resistance Potential and Possible Biochemical Mechanisms

The house fly, Musca domestica L., is an important ectoparasite with the ability to develop resistance to insecticides used for their control. Thiamethoxam, a neonicotinoid, is a relatively new insecticide and effectively used against house flies with a few reports of resistance around the globe. To understand the status of resistance to thiamethoxam, eight adult house fly strains were evaluated under laboratory conditions. In addition, to assess the risks of resistance development, cross-resistance potential and possible biochemical mechanisms, a field strain of house flies was selected with thiamethoxam in the laboratory. The results revealed that the field strains showed varying level of resistance to thiamethoxam with resistance ratios (RR) at LC₅₀ ranged from 7.66-20.13 folds. Continuous selection of the field strain (Thia-SEL) for five generations increased the RR from initial 7.66 fold to 33.59 fold. However, resistance declined significantly when the Thia-SEL strain reared for the next five generations without exposure to thiamethoxam. Compared to the laboratory susceptible reference strain (Lab-susceptible), the Thia-SEL strain showed cross-resistance to imidacloprid. Synergism tests revealed that S,S,S-tributylphosphorotrithioate (DEF) and piperonyl butoxide (PBO) produced synergism of thiamethoxam effects in the Thia-SEL strain (2.94 and 5.00 fold, respectively). In addition, biochemical analyses revealed that the activities of carboxylesterase (CarE) and mixed function oxidase (MFO) in the Thia-SEL strain were significantly higher than the Lab-susceptible strain. It seems that metabolic detoxification by CarE and MFO was a major mechanism for thiamethoxam resistance in the Thia-SEL strain of house flies. The results could be helpful in the future to develop an improved control strategy against house flies.     

Evaluation of the House Fly Musca domestica as a Mechanical Vector for an Anthrax

Anthrax is a disease of human beings and animals caused by the encapsulated, spore-forming, Bacillus anthracis. The potential role of insects in the spread of B. anthracis to humans and domestic animals during an anthrax outbreak has been confirmed by many studies. Among insect vectors, the house fly Musca domestica is considered a potential agent for disease transmission. In this study, laboratory-bred specimens of Musca domestica were infected by feeding on anthrax-infected rabbit carcass or anthrax contaminated blood, and the presence of anthrax spores in their spots (faeces and vomitus) was microbiologically monitored. It was also evaluated if the anthrax spores were able to germinate and replicate in the gut content of insects. These results confirmed the role of insects in spreading anthrax infection. This role, although not major, given the huge size of fly populations often associated with anthrax epidemics in domestic animals, cannot be neglected from an epidemiological point of view and suggest that fly control should be considered as part of anthrax control programs.     

Hermes, a Functional Non-Drosophilid Insect Gene Vector from Musca Domestica

Hermes is a short inverted repeat-type transposable element from the house fly, Musca domestica. Using an extra-chromosomal transpositional recombination assay, we show that Hermes elements can accurately transpose in M. domestica embryos. To test the ability of Hermes to function in species distantly related to M. domestica we used a nonautonomous Hermes element containing the Drosophila melanogaster white (w(+)) gene and created D. melanogaster germline transformants. Transgenic G(1) insects were recovered from 34.6% of the fertile G(0) adults developing from microinjected w(-) embryos. This transformation rate is comparable with that observed using P or hobo vectors in D. melanogaster, however, many instances of multiple-element insertions and large clusters were observed. Genetic mapping, Southern blotting, polytene chromosome in situ hybridization and DNA sequence analyses confirmed that Hermes elements were chromosomally integrated in transgenic insects. Our data demonstrate that Hermes elements transpose at high rates in D. melanogaster and may be an effective gene vector and gene-tagging agent in this species and distantly related species of medical and agricultural importance.     

The Y-Chromosomal and Autosomal Male-Determining M Factors of Musca Domestica Are Equivalent

In Musca domestica, male sex is determined by a dominant factor, M, located either on the Y, the X or on an autosome. M prevents the activity of the female-determining gene F. In the absence of M, F becomes active and dictates female development. The various M factors may represent translocated copies of an ancestral Y-chromosomal M. Double mutants and germ line chimeras show that M(Y), M(I), M(II), M(III) and M(V) perform equivalent functions. When brought into the female germ line, they predetermine male development of the offspring. This maternal effect is overruled by the dominant female-determining factor F(D). M(I) and M(II) are weak M factors, as demonstrated by the presence of yolk proteins in M(I)/+ males and by the occurrence of some intersexes among the offspring that developed from transplanted M(I)/+ and M(II)/+ pole cells. The arrhenogenic mutation Ag has its focus in the female germ line and its temperature-sensitive period during oogenesis. We propose that M(I) and Ag represent allelic M factors that are affected in their expression. Analysis of mosaic gonads showed that in M. domestica the sex of the germ line is determined by inductive signals from the surrounding soma. We present a model to account for the observed phenomena.     

The Mutation Masculinizer (Man) Defines a Sex-Determining Gene with Maternal and Zygotic Functions in Musca Domestica L

In Musca domestica, the primary signal for sex determination is the dominant factor M, which is assumed to regulate a postulated female-determining gene F. Presence of M prevents expression of F so that male development ensues. In the absence of M, F can become active, which dictates the female pathway. The existence of F is inferred from F(D), a dominant factor that is epistatic to M. We describe a new mutation masculinizer, which has all the properties expected for a null or strongly hypomorphic allele of F: (1) it maps to the same chromosomal location as F(D), (2) homozygous man/man animals develop as males, (3) homozygous man/man clones generated in man/+ female larvae differentiate male structures, (4) man has a sex-determining maternal effect. About a third of the morphological males synthesize yolk proteins, which indicates that they are intersexual in internal structures. The maternal effect of man is complete in offspring that derive from homozygous man/man pole cells transplanted into female hosts. In this case, all man/+ progeny become fertile males that do not produce yolk proteins. A sex-determining maternal effect has previously been demonstrated for F(D). Like F, maternal man(+) is needed for zygotic man(+) to become active, providing further evidence that man is a loss-of-function allele of F.     

家蝇小热休克蛋白(sHsp20.6)的生物信息学分析

研究家蝇小热休克蛋白sHsp20.6的生物学功能。方法应用生物信息学的方法和工具对家蝇sHsp20.6的理化性质、疏水性、跨膜区和信号肽、膜体分析、二级结构功能域、蛋白质的功能分类预测、多重序列比对与系统发育树构建、三级结构建模进行分析。结果表明:家蝇sHsp20.6是一个亲水蛋白,分子量为20.64kD,等电点为5.66,不具有跨膜区和信号肽,包含有一个HSP20的结构域,主要构成原件为α螺旋和无规则卷曲,三维结构预测显示该蛋白为棒状结构,C端结构域具有7个片层结构。聚类分析显示,家蝇sHsp20.6蛋白与昆虫中的直系同源小热休克蛋白(orthologoussmallheatshockprotein)聚为一类。     

A Molecular Marker-Based Linkage Map of Phaseolus Vulgaris L

A seed and flower color marker (P), nine seed protein, nine isozyme and 224 restriction fragment length polymorphism marker loci were used to construct a linkage map of the common bean, Phaseolus vulgaris L. (n = 11). The mapping population consisted of a backcross progeny between the Mesoamerican breeding line 'XR-235-1-1' and the Andean cultivar 'Calima'; the former was used as the recurrent parent. A bean PstI genomic library enriched for single copy sequences (95%) was the source of DNA probes. Sixty percent of the probes tested detected polymorphisms between the parental genotypes with at least one of the four restriction enzymes used here (DraI, EcoRI, EcoRV and HindIII). The computer software Mapmaker was used to determine the linkage relationships and linear order of segregating markers. These markers assorted into 11 linkage groups covering 960 cM of the bean genome. Partial linkage data were used to estimate the total length of the genome at 1200 cM. This estimate and that for the physical size of the genome yield an average ratio of 530 kb/cM. The relatively small size of the genome makes this crop species a good candidate for the isolation of genes via chromosome walking techniques.     

Developmental Analysis of Two Sex-Determining Genes, M and F, in the Housefly, Musca Domestica

In the housefly, Musca domestica, a single dominant factor, M, determines maleness. Animals hemior heterozygous for M are males, whereas those without M develop as females. In certain strains, however, both sexes are homozygous for M, and an epistatic dominant factor, F(D), dictates female development. The requirement for these factors was analyzed by producing, with mitotic recombination, mosaic animals consisting of genetically male and female cells. Removal of F(D) from an M/M;F(D)/+ cell at any time of larval development, even in the last larval instar, resulted in sex-reversal, i.e., in the development of a male clone in an otherwise female fly. In contrast, when M was removed from M/+ cells, the resulting clones remained male despite their female genotype, even when the removal of M happened at embryonic stages. The occurrence of spontaneous gynandromorphs, however, shows that the loss of M in individual nuclei prior to blastoderm formation causes the affected cells to adopt the female pathway. These results are consistent with the hypothesis that M is the primary sex-determining signal which sets the state of activity of the key gene F at around the blastoderm stage. Parallels and differences to the sex-determining system of Drosophila are discussed.     

Pseudomonas aeruginosa in Musca domestica L.: Temporospatial Examination of Bacteria Population Dynamics and House Fly Antimicrobial Responses

House flies associate with microbes throughout their life history. Bacteria ingested by adult flies enter the alimentary canal and face a hostile environment including antimicrobial defenses. Because the outcome of this interaction impacts bacterial survival and dissemination, our primary objective was to understand the temporospatial dynamics of fly-bacteria associations. We concurrently examined the temporospatial fate of GFP-expressing Pseudomonas aeruginosa (GFP-P. aeruginosa) in the house fly alimentary canal along with antimicrobial peptide (AMP) expression. Motile, viable GFP-P. aeruginosa were found in all regions of the alimentary canal and were culturable throughout the observation period (2–24 h). A significant decrease in recoverable bacteria occurred between 2 and12 h, followed by an increase between 12 and 24 h. qRT-PCR analysis showed expression of the AMPs cecropin, diptericin, and defensin both locally (gut) and systemically. Furthermore, mRNA of all AMPs were expressed throughout gut tissues, with some tissue-specific temporal variation. Interestingly, fluctuation in recoverable P. aeruginosa was associated with AMP protein expression in the gut (immunofluorescent signal detection), but not with mRNA (qRTPCR). In regards to vector competence, flies excreted GFP-P. aeruginosa throughout the 24 h period, serving as both reservoirs and disseminators of this bacterium. Collectively, our data show flies can harbor and disseminate P. aeruginosa, and that the interactions of fly defenses with bacteria can influence vector competence.     

Dietary Conjugated Linoleic acid (CLA) in House Fly,Musca domestica,with no Adverse Effects on Development

Conjugated linoleic acid (CLA) acts as a potent cancer inhibitor and biological modulator in several animal models by incorporation in the lipid fractions. Now we report the possibility of incorporation of dietary CLA into insect body lipids. Chemically-synthesized CLA from safflower seed oil was supplied to house fly (Musca domestica) larvae and adults with diet supplements at various levels. Amount of CLA in the pupa and adult body was proportional to the concentrations of CLA in the diet. CLA amount in pupae and adults was 0.17 mg/g and 0.41 mg/g of body, respectively, by 0.1% CLA diet (the lowest dosage), whereas it dramatically increased to 3.05 mg/g and 1.51 mg/g of body, respectively, by 10% CLA diet (the highest dosage). The dietary CLA did not show any adverse effects on the development of larvae and pupae, survivorship and fertility of adults, and eclosion of deposited eggs.