Polyplax spinulosa infestation and antibody response in various strains of laboratory rats.

The degree and duration of Polyplax spinulosa Burm. infestation depend on the sex, age and genetic factors of the host. Various rat strains differ in the severity of lousiness. Host grooming is an important factor in the rat-louse relationship. After longlasting infestations rats become partially resistant. Serum antibody level depends mainly on the severity and the duration of the infestation, and follows the dynamics of louse population. Serum antibodies have no direct negative effect on lice.     

Polyplax guatemalensis sp. n. (Phthiraptera: Anoplura), a new sucking louse from Peromyscus grandis, a montane cloud forest rodent from Guatemala

The adult male and female of Polyplax guatemalensis sp. n. are described from the sigmodontine murid rodent Peromyscus grandis Goodwin collected in the Reserva de Biosfera, Sierra de las Minas, Guatemala, at an elevation of 2,200 m. The new species extends the number of known native species of Polyplax in the New World to four with none of them recorded south of Panama. Polyplax guatemalensis is morphologically most closely related to Polyplax auricularis which parasitises a cluster of closely related New World sigmodontine rodents from Canada to Panama. These two species can be distinguished from all other known species of Polyplax by the presence of partially overlapping, subtriangular, anterior abdominal plates in both sexes. Polyplax guatemalensis can be separated from P. auricularis by the abundant tergal abdominal setae and longer pseudopenis in males, and by the presence of one fewer anterior abdominal, subtriangular tergite and sternite in females.     

以控制木虱为重点的柑橘黄龙病综合防治技术研究

柑橘黄龙病是全株系统性发生的毁灭性病害，目前尚无有效的治疗药剂和有效的给药方法，感病后只有挖掉，以免传染，所以俗称柑橘上的癌症。根据桂林市2004年底的调查，全市危害最轻的县病株率达5%，危害最重的县病株率已达到40％～50%。目前该病和其传媒昆虫一柑橘木虱在全广西都有分布，已成为广西的优势产业-柑橘业发展的最大障碍。植物检疫、种植无病苗木、清除病树、防治柑橘木虱等4条综合防治柑橘黄龙病的措施在20世纪60年代就已提出，在70年代末80年代初又加了“隔离种植、加强栽培管理”。     

甲基对硫磷人工抗原的合成与鉴定

根据甲基对硫磷的结构特征,分别从甲基对硫磷的硝基一端或磷酸酯基甲氧基一端引入一定长度的间隔臂和活性基团,设计并合成了4种结构的半抗原;针对各种半抗原所带活性基团的性质,通过多种方法制备了与不同的载体蛋白偶联的人工抗原。进行动物免疫后,得到了针对甲基对硫磷的高效价抗体。     

Towards selective breeding of Atlantic salmon for sea louse resistance: approaches to identify trait markers

Several species of sea lice, in particular Lepeophtheirus salmonis (Kr?yer), affect the welfare and condition of farmed salmon, with an estimated annual cost to the Scottish industry of 15-30 Pounds million. In Atlantic salmon, some stocks show resistance to L salmonis. Such natural resistance could be utilized for stock improvement using molecular genetic technologies. The development of molecular markers linked to resistance genes, allowing the identification of resistant fish, could increase the efficacy of selective breeding programmes. Various approaches to achieve this goal are described. One way to identify genes conferring resistance is to develop screens for salmon genes that are activated upon louse infection. One such screen--differential display--requires no previous knowledge of gene sequences, involves no preconceptions about which gene families are involved and can therefore identify novel genes. Preliminary results of comparative gene expression in sea-louse-challenged and control fish illustrate the application of differential display.     

Determination of knockdown resistance allele frequencies in global human head louse populations using the serial invasive signal amplification reaction

BACKGROUND: Pediculosis is the most prevalent parasitic infestation of humans. Resistance to pyrethrin‐ and pyrethroid‐based pediculicides is due to knockdown (kdr)‐type point mutations in the voltage‐sensitive sodium channel α‐subunit gene. Early detection of resistance is crucial for the selection of effective management strategies. RESULTS: Kdr allele frequencies of lice from 14 countries were determined using the serial invasive signal amplification reaction. Lice collected from Uruguay, the United Kingdom and Australia had kdr allele frequencies of 100%, while lice from Ecuador, Papua New Guinea, South Korea and Thailand had kdr allele frequencies of 0%. The remaining seven countries investigated, including seven US populations, two Argentinian populations and populations from Brazil, Denmark, Czech Republic, Egypt and Israel, displayed variable kdr allele frequencies, ranging from 11 to 97%. CONCLUSION: The newly developed and validated SISAR method is suitable for accurate monitoring of kdr allele frequencies in head lice. Proactive management is needed where kdr‐type resistance is not yet saturated. Based on sodium channel insensitivity and its occurrence in louse populations resistant to pyrethrin‐ and pyrethroid‐based pediculicides, the T917I mutation appears to be a key marker for resistance. Results from the Egyptian population, however, indicate that phenotypic resistance of lice with single or double mutations (M815I and/or L920F) should also be determined. Copyright © 2010 Society of Chemical Industry     

An improved in vitro rearing system for the human head louse allows the determination of resistance to formulated pediculicides

An improved in vitro rearing system, based on a silicone-reinforced Parafilm^® M membrane, human hair tufts and reconstituted human blood, enabled the large-scale rearing of pediculicide-susceptible (EC-HL) and resistant (SF-HL and BR-HL) strains of human head lice. Developmental time differed for early instars but differences became synchronized as lice matured. Mean survivorship amongst the three strains reared in vitro were not significantly different when compared to EC-HL and SF-HL reared in vivo. The efficacies of three pediculicidal products were assessed under semi-clinical conditions using a modified version of the in vitro rearing system. Treatments of 1% permethrin in acetone, Nix^®, Rid^® or Pronto^® Plus to hair tufts following manufacturer’s instructions were highly efficacious (100% mortality) on EC-HL but differentially efficacious (62.2-84.4% mortality) on SF-HL examined eight days post-treatment. SF-HL that survived the first treatment received an identical second treatment eight days following the first treatment. Survivors (13.3-30.0%) developed to adults (10th-11th day following first treatment) and females successfully laid fertile eggs that developed to first instars. These results confirm resistance to permethrin- and pyrethrin-based pediculicide formulations in SF-HL when assessed under semi-clinical conditions and validates resistance previously determined using filter-paper contact bioassays and unformulated insecticides.     

Wild salmonids and sea louse infestations on the west coast of Scotland: sources of infection and implications for the management of marine salmon farms

The sea louse (Lepeophtheirus salmonis Kr?yer) is a major health problem for both farmed and wild salmonids. This paper investigates louse epidemiology and management in the salmon-farming zone of western Scotland. Based on a review of the marine ecology of wild salmon (Salmo salar L) and sea trout (Salmo trutta L), and catch and farm production statistics, best estimates were made for numbers of wild and farm hosts present in coastal waters in March-June 2000. Applying data for ovigerous female louse infections and fecundity, the sources and risks of larval transmission to wild salmon and sea trout were modelled. Farm salmon in the second spring of production were the primary host group (98% of fish), while numbers of wild salmonids (< 1%) and escaped farm salmon (2%) were relatively insignificant. Farm salmon produced 97% of louse eggs at high levels (eight ovigerous lice per fish), and 78% at low levels (one per fish). Wild salmonids produced < 1% of eggs under both scenarios, but escaped farm salmon produced 3% and 21%, respectively. All hosts potentially cross-infect one another, but farm salmon are more likely to infect wild and farm smolts, and also other farm salmon. Monitoring of lice on sea trout in June 1998-2000 by the Association of West Coast Fisheries Trusts corroborated the model's conclusions. Localised epizootics occurred every year and coincided with the presence of ovigerous lice on local farms. In areas of mixed-year class production on farms, epizootics were evident every spring, but occurred every second spring in areas of single-year class production. In 1998-2000 at least 14-40% of sea trout were infected with potentially lethal infestations of lice. Ovigerous louse levels of < 0.005 per fish were required on farm salmon in the spring of 2000 to produce less eggs than those emitted by wild salmonids. With the industry's continued expansion, and thus increased numbers of farm salmon, a target of zero ovigerous lice will be required on farms to minimise impacts on wild salmonids. Due to the limited long-term efficacy and availability of louse medicines, management strategies are discussed which will improve control, including single-year class production over large areas, alternate S1-S1/2 smolt inputs, and 11-month production cycles.     

Biochemical studies on sheep body louse Bovicola ovis (Schrank) (Phthiraptera: Trichodectidae): comparison of pyrethroid and organophosphate resistant and susceptible strains

Strains of sheep louse Bovicola ovis (Schrank) with various levels of resistance to pyrethroid and one strain with high degree of resistance to organophosphate (OP) insecticides were used to investigate the biochemical mechanisms of insecticide resistance, i.e., enhanced levels of general esterases, specific acetylcholinesterases (AChE), glutathione S-transferase (GST), and mixed function oxidases. Native gel electrophoresis combined with quantitative enzyme assays showed analogous expression profiles of several esterase isozymes in all the strains tested. The determination of the sensitivity of each esterase isozyme to five inhibitors (acetylthiocholine iodide, butyrylthiocholine iodide, paraoxon eserine sulfate, and pCMB) led to the identification of nine esterases in the B. ovis strain. Gel electrophoresis results are supported by enzyme assay studies where, except for the OP resistant strain, no differences in esterase activities were detected in all the pyrethroid resistant and susceptible strains assayed. Statistical analyses demonstrated that some strains have elevated GST activities compared to the susceptible reference strain.     

Further characterization of celery latent virus

Celery latent virus has been isolated from plants of celeriac (Apium graveolens var.rapaceum).Chenopodium amaranticolor andC. quinoa are good assay plants. Celery (A. graveolens var.dulce) and celeriac (13 cultivars tested) did not react with visible symptoms.Fourteen new artificial hosts were found. New systemic symptomless hosts areAnthriscus cerefolium, Nicotiana megalosiphon, Pisum sativum, Spinacia oleracea andTrifolium incarnatum. Systemic symptoms were caused in the pea cultivars Cicero and Dark Skin Perfection.Five aphid species, includingCavariella aegopodii, four of which not tested with the virus before, were unable to transmit the virus.Seed transmission was confirmed in celeriac (up to 34%) and inC. quinoa (up to 67%) and detected for the first time inAmaranthus caudatus. Detection is easier in seedlings and germinated seeds than in dry seeds.Results of purification were erratic but best at high pH (8 or 9). Sedimentation coefficient was 161 S.An antiserum reacted with purified virus in micro-precipitin tests (titer 256) but, especially at high salt concentrations also in agar gel (titer 64), presumably because of easy degradation of virus protein. Reactions in agar gel also occurred with crude extracts from virus-infectedC. quinoa and celeriac.With the electron microscope flexuous virus particles were found in low concentration in crude sap and in high concentration in purified preparations. Particle measurements revealed an average length of 885 nm (in one preparation 940 nm).Light microscopy did not show inclusion bodies in epidermal strips nor did electron microscopy of ultrathin sections reveal pinwheels and other structures typical of the potyvirus group. The virus evidently belongs to a new morphological group, possibly together with some other viruses hitherto insufficiently studied.The virus seems of potential economic importance only, but it is advised to use virus-free mother plants of celery for seed production.participating in the investigations from August 20th to December 19th 1972, supported by a fellowship of the Fundacion Juan March, Madrid, Spain.     

Genetic and phenotypic characterization of Botrytis calthae

Botrytis calthae is a necrotrophic plant pathogen, closely related to the ubiquitous broad host range fungus Botrytis cinerea, but highly host specific. Botrytis isolates from lesions of Caltha palustris grown at different locations were classified with genetic markers as either B. calthae or Botrytis pseudocinerea, or less frequently as B. cinerea. A PCR‐based identification of B. calthae was developed. Seven haplotypes of B. calthae could be distinguished. Compared to B. cinerea, mycelium growth of B. calthae was similar, but conidiation less abundant, and sclerotia formation was only partially repressed by light. Conidia of B. calthae germinated more slowly, and showed a highly acidic optimum (pH 2·5) compared to B. cinerea conidia (pH 5·3). All B. calthae isolates were sensitive to common anti‐Botrytis fungicides, but showed partial resistance to the succinate dehydrogenase inhibitors boscalid, fluopyram and carboxin. Infection experiments revealed a weak capability of B. calthae to induce necrotic lesions on plants that are hosts for B. cinerea. On C. palustris leaves, B. calthae induced similar lesions to B. cinerea. These data provide a basis for comparative molecular investigation of the physiology and host specificity of B. calthae and closely related Botrytis species.     

Polyphasic characterization of xanthomonas strains from onion

ABSTRACT Xanthomonas leaf blight has become an increasingly important disease of onion, but the diversity among Xanthomonas strains isolated from onion is unknown, as is their relationship to other species and pathovars of Xanthomonas. Forty-nine Xanthomonas strains isolated from onion over 27 years from 10 diverse geographic regions were characterized by pathogenicity to onion and dry bean, fatty acid profiles, substrate utilization patterns (Biolog), bactericide resistance, repetitive sequence-based polymerase chain reaction fingerprinting, rDNA internally transcribed spacer (ITS) region, and hrp b6 gene sequencing. Multiplication of onion Xanthomonas strain R-O177 was not different from X. axonopodis pv. phaseoli in dry bean, but typical common bacterial blight disease symptoms were absent in dry bean. Populations from each geographical region were uniformly sensitive to 100 mug of CuSO(4), 100 mug of ZnSO(4), and 100 mug of streptomycin sulfate per ml. Biolog substrate utilization and fatty acid profiles revealed close phenoltypic relatedness between onion strains of Xanthomonas and X. axonopodis pv. dieffenbachiae (57% of strains) and X. arboricola pv. poinsettiicola (37% of strains), respectively. A logistic regression model based on fatty acid composition and substrate utilization classified 69% of strains into their geographical region of origin. Sequencing of a portion of the hrp B6 gene from 24 strains and ITS region from 25 strains revealed greater than 97% sequence similarity among strains. DNA fingerprinting revealed five genotype groups within onion strains of Xanthomonas and a high degree of genetic diversity among geographical regions of origin. Based on pathogenicity to onion, carbon substrate utilization, fatty acid profiles, rDNA genetic diversity, and genomic fingerprints, we conclude that the strains examined in this study are pathovar X. axonopodis pv. allii. Implications of genetic and phenotypic diversity within X. axonopodis pv. allii are discussed in relation to an integrated pest management program.     

生防枯草芽孢杆菌L1特性的初步研究

通过对峙培养,测定出枯草芽孢杆菌L1的抑菌谱较宽,特别是对水稻纹枯病菌、大豆菌核病菌、禾谷镰孢菌、辣椒灰霉病菌、玉米小斑病菌抑菌效果明显;枯草芽孢杆菌L1不同发酵时间经湿热灭菌处理后,5 d发酵液中抑菌活性物质含量最高,对水稻纹枯病菌菌丝生长抑制率达83.23%,发酵液随时间延长抑菌效果不再增加;枯草芽孢杆菌L1抑菌活性物质对温度不敏感;枯草芽孢杆菌L1发酵液用硫酸铵梯度沉淀法提取粗蛋白在硫酸铵饱和度达60%～70%(不含60%)沉淀的活性物质抑菌效果最好,对水稻纹枯病菌平均抑菌半径达1.15;枯草芽孢杆菌L1对玉米、大豆、小麦、番茄、菜豆、黄瓜、水稻无致病性,而且还有保鲜和促生作用。     

Agroecological characterization of Xiphinema index in Spain1

The agroecological characteristics of Xiphinema index were determined by studying its spatial and temporal distribution in different environmental conditions in Spain. The host range, life cycle in the Mediterranean continental climate and its relationships with grapevine fanleaf nepovirus are also reported. X. index is widespread in grape-growing areas in a wide range of soil textures and pH, even at high percentage of carbonates. However, it seems to prefer sandy-loam and sandy-clay loam soils, and populations decrease when soil carbonates increase. Its spatial distribution is random but it has a tendency to be found in the deepest clay horizons, where soil moisture is retained. Availability of moisture seems to be the limiting factor for nematode development. Grapevine and fig are the main host plants but X. index is also associated with fruit trees, ornamental crops, vegetable crops, woodlands and other uncultivated soils. Its life cycle in central Spain, where temperature ranges from <0°C until March to above 40°C from May—June until September, takes 6–8 weeks to complete. X. index was found in 14% of all vineyards sampled and in 50% of the fanleaf virus-infected vineyards. Transmission tests using bait plants were successful and the detection of the virus by means of ELISA test in a mimimun of five nematodes was achieved. Fanleaf-like symptoms often occurred in the absence of the virus, as demonstrated by ELISA.     

油桃茎痘相关病毒中国分离物基因组的分子特征分析

为明确我国油桃茎痘相关病毒(nectarine stem-pitting-associated virus,NSPaV)基因组的分子特征,利用RT-PCR和RACE技术对NSPaV中国分离物NSPaV-T04基因组进行克隆,采用最大似然法对得到的NSPaV基因组序列和GenBank中的5条NSPaV基因组序列构建系统发育树,应用RDP软件对NSPaV基因组序列进行重组分析。结果表明:中国分离物NSPaV-T04基因组序列全长为4 991 nt,包括4个开放阅读框(open reading frame,ORF),其中ORF1与ORF2共同编码1个RdRp P1-P2融合蛋白,ORF3编码1个CP,ORF5与ORF3共同编码CP通读蛋白。系统发育树和序列比较分析结果显示,中国分离物NSPaV-T04(MN095353)与美国分离物NSPaV/12P42(KT273410)的亲缘关系最近,核苷酸序列同源性最高,为96.4%;NSPaV-T04的RdRp P1变异较大,与GenBank中5条NSPaV基因组核苷酸序列的同源性为90.5%~96.1%,CP较为保守,核苷酸序列的同源性为96.6%~98.7%。重组分析结果显示,中国分离物NSPaV-T04为鉴定的一个重组体(韩国分离物SK)的亲本序列,表明中国分离物NSPaV-T04可能是一个实际的重组体。     

Recovery and characterization of asexual recombinants ofMagnaporthe grisea

Eleven nitrate non-utilizing (nit) mutants were recovered from six field isolates ofMagnaporthe grisea that had different degrees of sensitivity to the blasticide kitazin P (iprobenfos, IBP). Allnit mutants were resistant to chlorate and there were no significant differences in hyphal growth rate, conidial production, sensitivity to IBP, and pathogenicity betweennit mutants and their parent isolates.nit phenotypes and IBP-resistance were used as two independent genetic markers to study asexual recombination inM. grisea. Asexual recombinants were recovered from the heterokaryotic mycelium of three inter-strain pairings, namely, DY2-3(nitl-LR) + A7-3 (nitM-S); A7-3 (nitM-S) + F4-2 (nitl-MR); and F4-2 (nitl-MR) + DY2-4 (nitA-LR), at a frequency of 7.31%, 14.00% and 8.63%, respectively. The growth rate, conidial production and pathogenicity of asexual recombinants were similar to those of parental strains. We concluded that asexual recombination resulting from hyphal fusion might contribute to variability inM. grisea. http://www.phytoparasitica.org posting Nov. 14, 2005.     

Biological characterization of sulfoxaflor, a novel insecticide

BACKGROUND: The commercialization of new insecticides is important for ensuring that multiple effective product choices are available. In particular, new insecticides that exhibit high potency and lack insecticidal cross‐resistance are particularly useful in insecticide resistance management (IRM) programs. Sulfoxaflor possesses these characteristics and is the first compound under development from the novel sulfoxamine class of insecticides. RESULTS: In the laboratory, sulfoxaflor demonstrated high levels of insecticidal potency against a broad range of sap‐feeding insect species. The potency of sulfoxaflor was comparable with that of commercial products, including neonicotinoids, for the control of a wide range of aphids, whiteflies (Homoptera) and true bugs (Heteroptera). Sulfoxaflor performed equally well in the laboratory against both insecticide‐susceptible and insecticide‐resistant populations of sweetpotato whitefly, Bemisia tabaci Gennadius, and brown planthopper, Nilaparvata lugens (Stål), including populations resistant to the neonicotinoid insecticide imidacloprid. These laboratory efficacy trends were confirmed in field trials from multiple geographies and crops, and in populations of insects with histories of repeated exposure to insecticides. In particular, a sulfoxaflor use rate of 25 g ha^?1 against cotton aphid (Aphis gossypii Glover) outperformed acetamiprid (25 g ha^?1) and dicrotophos (560 g ha^?1). Sulfoxaflor (50 g ha^?1) provided a control of sweetpotato whitefly equivalent to that of acetamiprid (75 g ha^?1) and imidacloprid (50 g ha^?1) and better than that of thiamethoxam (50 g ha^?1). CONCLUSION: The novel chemistry of sulfoxaflor, its unique biological spectrum of activity and its lack of cross‐resistance highlight the potential of sulfoxaflor as an important new tool for the control of sap‐feeding insect pests. Copyright © 2010 Society of Chemical Industry