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At least 955 records · Page 53Linked to original sources
PubMed2003

No variation for Wolbachia-induced hybrid breakdown in two populations of a spider mite.

Wolbachia are cytoplasmically transmitted bacteria that infect several species of mites. In the two-spotted spider mite Tetranychus urticae Koch this symbiont can induce reproductive incompatibility. Wolbachia-induced reproductive incompatibility is observed in crosses between Wolbachia-infected (W) males and uninfected (U) females. This incompatibility is expressed in F1 broods as male-biased sex ratios, an effect called cytoplasmic incompatibility (CI). However, in the two-spotted spider mite, Wolbachia-induced reproductive incompatibility may extend to the F2: broods of virgin F1 females from U x W crosses sometimes suffer increased mortality rates. This F2 effect is called hybrid breakdown (HB). Several isofemale lines derived from mites collected from rose and cucumber plants had been previously tested for CI. Here we report on the results obtained for HB.

Animals↗
PubMed2003

Development of genetic differentiation and postzygotic isolation in experimental metapopulations of spider mites.

We studied the development of genetic differentiation and postzygotic isolation in experimental metapopulations of the two-spotted spider mite, Tetranychus urticae Koch. A genetically diverse starter population was made by allowing six inbred sublines to interbreed. Then three migration patterns were tested: no migration, or one or three immigrants per subpopulation per generation. Variations in four traits were investigated: allozymes, acaricide resistance, diapause, and hatchability. In the allozymes, acaricide resistance, and diapause, genetic variation among subpopulations became high in metapopulations with no migration, but not in the others, which showed that one immigrant is enough to prevent genetic differentiation. Hatchability, which was decreased by interbreeding among the six sublines, gradually recovered in succeeding generations. In metapopulations with no migration, hatchability was reduced again after in-migration at the 15th generation. Different karyotypes or coadapted gene complexes can survive in different subpopulations by genetic drift, and both Wolbachia-infected and -noninfected subpopulations may be selected, which would lead to postzygotic isolation between isolated subpopulations. Our results indicate that sampling effects such as genetic drift or stochastic loss of Wolbachia produce postzygotic isolation in laboratory populations of spider mite.

Animals↗
PubMed2004

Effect of different densities of the twospotted spider mite Tetranychus urticae on CO2 assimilation, transpiration, and stomatal behaviour in rose leaves.

The effect of population density of Tetranychus urticae Koch on CO2 assimilation, transpiration and stomatal behaviour in rose leaves and on the diameter and length of stems and flower buds was investigated under greenhouse conditions. The investigation was performed in order to gain more insight into integrated control systems in rose crops grown under greenhouse conditions. Physiological processes, such as photosynthesis and transpiration, as well as stomatal behaviour and chlorophyll content, were studied as they form part of the plant's nutrition mechanism and therefore affect the quantity and quality of the flowers. Information related to the effect of spider mite population density on bloom quality, diameter and length of stems and flower buds was also collected. The data indicate that increased mite density coincides with a decrease in the net photosynthetic rate, transpiration and chlorophyll content. Higher mite densities on leaves cause stomata to remain open for longer periods, which allows a greater loss of water. Spider mite densities of 10 and 50 mites per leaf cause a reduction in flower stem length of 17 and 26%, respectively, as compared to plants with no mites present.

Animals↗
PubMed2003

Olfactory sensitivity for aliphatic esters in spider monkeys (Ateles geoffroyi).

Using a conditioning paradigm, the authors investigated the olfactory sensitivity of 3 spider monkeys (Ateles geoffroyi) for a homologous series of aliphatic esters (ethyl acetate to n-octyl acetate) and isomeric forms of some of these substances. With all odorants, the monkeys significantly discriminated concentrations below 1 ppm from the odorless solvent, and in several cases, individual monkeys even demonstrated thresholds below 1 ppb. The results showed spider monkeys to have a high olfactory sensitivity for aliphatic esters, which for the majority of substances matches or even is better than that of species such as the rat, the mouse, or the dog. These findings support the assumption that between-species comparisons of neuroanatomical features are poor predictors of olfactory performance.

Acetates↗
PubMed2004

A Silurian sea spider.

Pycnogonids (sea spiders) are marine arthropods numbering some 1,160 extant species. They are globally distributed in depths of up to 6,000 metres, and locally abundant; however, their typically delicate form and non-biomineralized cuticle has resulted in an extremely sparse fossil record that is not accepted universally. There are two opposing views of their phylogenetic position: either within Chelicerata as sister group to the euchelicerates, or as a sister taxon to all other euarthropods. The Silurian Herefordshire Konservat-Lagerstatte in England (approximately 425 million years (Myr) bp) yields exceptionally preserved three-dimensional fossils that provide unrivalled insights into the palaeobiology of a variety of invertebrates. The fossils are preserved as calcitic void in-fills in carbonate concretions within a volcaniclastic horizon, and are reconstructed digitally. Here we describe a new pycnogonid from this deposit, which is the oldest adult sea spider by approximately 35 Myr and the most completely known fossil species. The large chelate first appendage is consistent with a chelicerate affinity for the pycnogonids. Cladistic analyses place the new species near the base of the pycnogonid crown group, implying that the latter had arisen by the Silurian period.

Animals↗
PubMed2025

Chromosome-level genome assembly of hawthorn spider mite, Amphitetranychus viennensis (Acari: Tetranychidae).

The hawthorn spider mite, Amphitetranychus viennensis, is a major pest of orchards and ornamentals in the Palaearctic region, with adaptability and acaricide resistance. The lack of high-quality genomic resources limits understanding of its detoxification mechanisms and the development of RNAi-based pest control strategies. In this study, we utilized Illumina, Pacific Biosciences (PacBio), and Hi-C sequencing technologies to assemble a chromosome-level reference genome of A. viennensis. The assembled genome spans 141.96 Mb, with a contig N50 of 1.35 Mb. BUSCO analysis confirmed a high level of completeness, covering 91.6% of annotated genes. The assembly includes 50.97 Mb of repetitive sequences, representing 35.93% of the genome, and annotates 13,968 protein-coding genes. Using Hi-C sequencing, we anchored 47 contigs to three chromosomes, accounting for 97.27% of the estimated nuclear genome and achieving a contig N50 of 45.83 Mb. This high-quality genome assembly provides a valuable foundation for evolutionary and genomic research on spider mites, while also serving as a genetic resource to inform molecular control strategies and support sustainable pest management.

Animals↗
PubMed1984

Spider sedation induced by defensive chemicals of milliped prey.

Wolf spiders (Lycosa spp.) show delayed induced sedation (total immobilization) of prolonged duration (in the order of days) after attacks upon millipeds (Glomeris marginata). The sedation is specifically attributable to glomerin and homoglomerin, two previously characterized quinazolinones present in the defensive secretion of Glomeris. Median sedative doses for the quinazolinones are in the range of 1-7 mug per spider, a fraction of the total (60-90 mug) present in the secretion of medium to full-grown millipeds. A sedative effect upon an invertebrate predator has not previously been demonstrated for an animal defense. Quinazolinones include the synthetic drug methaqualone (Quaalude), a potent human sedative.

Journal Article↗
PubMed1997

Insecticidal activity of monoterpenoids to western corn rootworm (Coleoptera: Chrysomelidae), twospotted spider mite (Acari: Tetranychidae), and house fly (Diptera: Muscidae).

Acute toxicities of 34 naturally occurring monoterpenoids were evaluated against 3 important arthropod pest species; the larva of the western corn rootworm, Diabrotica virgifera virgifera LeConte; the adult of the twospotted spider mite. Tetranychus urticae Koch; and the adult house fly. Musca domestica L. Potential larvicidal or acaricidal activities of each monoterpenoid were determined by topical application, leaf-dip method, soil bioassay, and greenhouse pot tests. Phytotoxicity was also tested on a corn plant. Citronellic acid and thymol were the most topically toxic against the house fly, and citronellol and thujone were the most effective on the western corn rootworm. Most of the monoterpenoids were lethal to the twospotted spider mite at high concentrations; carvomenthenol and terpinen-4-ol were especially effective. A wide range of monoterpenoids showed some larvicidal activity against the western corn rootworm in the soil bioassay. Perillaldehyde, the most toxic (LC50 = 3 micrograms/g) in soil, was only 1/3 as toxic as carbofuran, a commercial soil insecticide (LC50 = 1 microgram/g). Selected monoterpenoids also effectively protected corn roots from attack by the western corn rootworm larvae under greenhouse conditions. alpha-Terpineol was the best monoterpenoid in the greenhouse pot test. The acute toxicity of monoterpenoids was low relative to conventional insecticides. Some monoterpenoids were phytotoxic to corn roots and leaves. l-Carvone was the most phytotoxic, whereas pulegone was the safest. The results with thymyl ethyl ether, one of the synthetic derivatives of thymol, showed a potential of derivatization to reduce monoterpenoid phytotoxicity.

Animals↗
PubMed1985

Do brown recluse spider bites induce pyoderma gangrenosum?

Brown recluse spider bites are usually self-limited skin lesions that infrequently progress to bullae, ulceration, and scarring. We treated a patient with a documented brown recluse bite who had recurring lesions resembling pyoderma gangrenosum (PG) that persisted for months. Three other patients referred to Vanderbilt University because of probable brown recluse bite also had pyoderma for the first time after a suspected arthropod bite. The persistent and recurrent pyodermas in these four patients indicate that (1) brown recluse spider bites may not be self-limited but induce PG or PG-like lesions; (2) arthropod bites in general may induce PG in susceptible people; and (3) treatment of the PG-like lesions in these patients may be difficult.

Adult↗
PubMed1996

Envenomation from the brown recluse spider: review of mechanism and treatment options.

The brown recluse spider in commonly found throughout the midsouth region of the United States. Bites from the brown recluse occur when the spider is trapped in clothing or its nest is otherwise disturbed. The bite may be undetected by the patient until hours or days later when a characteristic lesion develops. Mild reactions to envenomation are usually limited to a lesion only. In some cases, a severe reaction results which can be life-threatening. Although there have been case reports of various pharmacological agents used for the treatment of brown recluse bites, none have been shown to be consistently effective. Therapy for brown recluse bites remains centered around aggressive wound care. Early surgical excision has not been shown to be of benefit and in most cases delays healing. This review focuses on the physiological mechanisms of the brown recluse venom and current treatment options.

Journal Article↗
PubMed2004

Herbivore-induced defense response in a model legume. Two-spotted spider mites induce emission of (E)-beta-ocimene and transcript accumulation of (E)-beta-ocimene synthase in Lotus japonicus.

Indirect defense of plants against herbivores often involves the induced emission of volatile infochemicals including terpenoids that attract natural enemies of the herbivores. We report the isolation and characterization of a terpene synthase cDNA (LjEbetaOS) from a model legume, Lotus japonicus. Recombinant LjEbetaOS enzyme produced (E)-beta-ocimene (98%) and its Z-isomer (2%). Transcripts of LjEbetaOS were induced in L. japonicus plants infested with two-spotted spider mites (Tetranychus urticae), coinciding with increasing emissions of (E)-beta-ocimene as well as other volatiles, (Z)-3-hexenyl acetate and (E)-4,8-dimethyl-1,3,7-nonatriene, by the infested plants. We suggest that LjEbetaOS is involved in the herbivore-induced indirect defense response of spider mite-infested L. japonicus via de novo formation and emission (E)-beta-ocimene. Mechanical wounding of the leaves or application of alamethicin (ALA), a potent fungal elicitor of plant volatile emission, also induced transiently increased levels of LjEbetaOS transcripts in L. japonicus. However, wounding or ALA did not result in elevated release of (E)-beta-ocimene. Differences in volatile emissions after herbivory, mechanical wounding, or treatment with ALA suggest that neither a single mechanical wounding event nor ALA simulate the effect of herbivore activity and indicate that herbivore-induced emission of (E)-beta-ocimene in L. japonicus involves control mechanisms in addition to up-regulation of LjEbetaOS transcripts.

Acyclic Monoterpenes↗
PubMed1999

Spider mite-induced (3S)-(E)-nerolidol synthase activity in cucumber and lima bean. The first dedicated step in acyclic C11-homoterpene biosynthesis.

Many plant species respond to herbivory with de novo production of a mixture of volatiles that attracts carnivorous enemies of the herbivores. One of the major components in the blend of volatiles produced by many different plant species in response to herbivory by insects and spider mites is the homoterpene 4,8-dimethyl-1,3(E), 7-nonatriene. One study (J. Donath, W. Boland [1995] Phytochemistry 39: 785-790) demonstrated that a number of plant species can convert the acyclic sesquiterpene alcohol (3S)-(E)-nerolidol to this homoterpene. Cucumber (Cucumis sativus L.) and lima bean (Phaseolus lunatus L.) both produce 4,8-dimethyl-1,3(E),7-nonatriene in response to herbivory. We report the presence in cucumber and lima bean of a sesquiterpene synthase catalyzing the formation of (3S)-(E)-nerolidol from farnesyl diphosphate. The enzyme is inactive in uninfested cucumber leaves, slightly active in uninfested lima bean leaves, and strongly induced by feeding of the two-spotted spider mite (Tetranychus urticae Koch) on both plant species, but not by mechanical wounding. The activities of the (3S)-(E)-nerolidol synthase correlated well with the levels of release of 4, 8-dimethyl-1,3(E),7-nonatriene from the leaves of the different treatments. Thus, (3S)-(E)-nerolidol synthase is a good candidate for a regulatory role in the release of the important signaling molecule 4,8-dimethyl-1,3(E),7-nonatriene.

Air↗
PubMed2004

SPIDER: software for protein identification from sequence tags with de novo sequencing error.

For the identification of novel proteins using MS/MS, de novo sequencing software computes one or several possible amino acid sequences (called sequence tags) for each MS/MS spectrum. Those tags are then used to match, accounting amino acid mutations, the sequences in a protein database. If the de novo sequencing gives correct tags, the homologs of the proteins can be identified by this approach and software such as MS-BLAST is available for the matching. However, de novo sequencing very often gives only partially correct tags. The most common error is that a segment of amino acids is replaced by another segment with approximately the same masses. We developed a new efficient algorithm to match sequence tags with errors to database sequences for the purpose of protein and peptide identification. A software package, SPIDER, was developed and made available on Internet for free public use. This paper describes the algorithms and features of the SPIDER software.

Algorithms↗
PubMed1994

RFLP analysis of ribosomal DNA in sibling species of spider mite, genus Panonychus (Acari: Tetranychidae).

Ribosomal DNA (rDNA) restriction fragment length of spider mites was analysed in three sibling species of genus Panonychus (P. mori, P. citri and P. ulmi) and Tetranychus urticae. Seventy-one fragments were detected by enhanced chemiluminescence (ECL) after Southern hybridization with two genomic rDNA probes of mouse. Percentages of shared fragments within species were larger than those among species, indicating that the variation of rDNAs was useful in phylogenetic studies of spider mite species. In a phenogram based on differences of the rDNA fragment length, the relationship among Panonychus species was compatible with the results of analysis based on the morphological characters.

Animals↗
PubMed2004

Treatment of linear and spider telangiectasia with an intense pulsed light source.

BACKGROUND: The flashlamp-pumped pulsed dye laser (585 and 577 nm) has proved to be an effective and safe treatment option in the therapy of linear and spider facial telangiectasia. Nevertheless, the postoperative purpura, which most patients see as cosmetically disfiguring, has always been a matter of concern. AIMS: To test the effectiveness and safety of an intense pulsed light source (IPLS), which emits non-coherent light adjustable within the 515-1200 nm range, in the treatment of linear and spider facial telangiectasia. PATIENTS & METHODS: One hundred and forty patients with linear and stellate facial telangiectasia were treated with an IPLS. RESULTS: In 94 (67.1%) the results were considered excellent (clearance of 80-100%), 43 (30.7%) showed good results (clearance of 40-80%) and in 3 patients (2.1%) the results were poor (clearance < 40%). Post-treatment side effects were minimal and well tolerated. There were no instances of scarring or other permanent side effects. Owing to the large spot size, a large area could be treated within one session. No anaesthesia was required. CONCLUSION: IPLS is a highly effective and comparably safe therapeutic alternative to the pulsed dye laser in the treatment of facial telangiectasia. The rate of cosmetically relevant side effects is considerably smaller, patient compliance is excellent and the method can easily be applied in an outpatient setting.

Journal Article↗
PubMed2005

SPIDER: software for protein identification from sequence tags with de novo sequencing error.

For the identification of novel proteins using MS/MS, de novo sequencing software computes one or several possible amino acid sequences (called sequence tags) for each MS/MS spectrum. Those tags are then used to match, accounting amino acid mutations, the sequences in a protein database. If the de novo sequencing gives correct tags, the homologs of the proteins can be identified by this approach and software such as MS-BLAST is available for the matching. However, de novo sequencing very often gives only partially correct tags. The most common error is that a segment of amino acids is replaced by another segment with approximately the same masses. We developed a new efficient algorithm to match sequence tags with errors to database sequences for the purpose of protein and peptide identification. A software package, SPIDER, was developed and made available on Internet for free public use. This paper describes the algorithms and features of the SPIDER software.

Algorithms↗
PubMed1996

Predatory behavior of jumping spiders.

Salticids, the largest family of spiders, have unique eyes, acute vision, and elaborate vision-mediated predatory behavior, which is more pronounced than in any other spider group. Diverse predatory strategies have evolved, including araneophagy, aggressive mimicry, myrmicophagy, and prey-specific prey-catching behavior. Salticids are also distinctive for development of behavioral flexibility, including conditional predatory strategies, the use of trial-and-error to solve predatory problems, and the undertaking of detours to reach prey. Predatory behavior of araneophagic salticids has undergone local adaptation to local prey, and there is evidence of predator-prey coevolution. Trade-offs between mating and predatory strategies appear to be important in ant-mimicking and araneophagic species.

Journal Article↗