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PubMed2006

Additive and interactive effects of plant genotypic diversity on arthropod communities and plant fitness.

Recent research suggests that genetic diversity in plant populations can shape the diversity and abundance of consumer communities. We tested this hypothesis in a field experiment by manipulating patches of Evening Primrose (Oenothera biennis) to contain one, four or eight plant genotypes. We then surveyed 92 species of naturally colonizing arthropods. Genetically diverse plant patches had 18% more arthropod species, and a greater abundance of omnivorous and predacious arthropods, but not herbivores, compared with monocultures. The effects of genotypic diversity on arthropod communities were due to a combination of interactive and additive effects among genotypes within genetically diverse patches. Greater genetic diversity also led to a selective feedback, as mean genotype fitness was 27% higher in diverse patches than in monocultures. A comparison between our results and the literature reveals that genetic diversity and species diversity can have similar qualitative and quantitative effects on arthropod communities. Our findings also illustrate the benefit of preserving genetic variation to conserve species diversity and interactions within multitrophic communities.

Animals↗
PubMed1995

The development of crustacean limbs and the evolution of arthropods.

Arthropods exhibit great diversity in the position, number, morphology, and function of their limbs. The evolutionary relations among limb types and among the arthropod groups that bear them (insects, crustaceans, myriapods, and chelicerates) are controversial. Here, the use of molecular probes, including an antibody to proteins encoded by arthropod and vertebrate Distal-less (Dll and Dlx) genes, provided evidence that common genetic mechanisms underlie the development of all arthropod limbs and their branches and that all arthropods derive from a common ancestor. However, differences between crustacean and insect body plans were found to correlate with differences in the deployment of particular homeotic genes and in the ways that these genes regulate limb development.

Amino Acid Sequence↗
PubMed2006

Phylogenetic relationships of the Wolbachia of nematodes and arthropods.

Wolbachia are well known as bacterial symbionts of arthropods, where they are reproductive parasites, but have also been described from nematode hosts, where the symbiotic interaction has features of mutualism. The majority of arthropod Wolbachia belong to clades A and B, while nematode Wolbachia mostly belong to clades C and D, but these relationships have been based on analysis of a small number of genes. To investigate the evolution and relationships of Wolbachia symbionts we have sequenced over 70 kb of the genome of wOvo, a Wolbachia from the human-parasitic nematode Onchocerca volvulus, and compared the genes identified to orthologues in other sequenced Wolbachia genomes. In comparisons of conserved local synteny, we find that wBm, from the nematode Brugia malayi, and wMel, from Drosophila melanogaster, are more similar to each other than either is to wOvo. Phylogenetic analysis of the protein-coding and ribosomal RNA genes on the sequenced fragments supports reciprocal monophyly of nematode and arthropod Wolbachia. The nematode Wolbachia did not arise from within the A clade of arthropod Wolbachia, and the root of the Wolbachia clade lies between the nematode and arthropod symbionts. Using the wOvo sequence, we identified a lateral transfer event whereby segments of the Wolbachia genome were inserted into the Onchocerca nuclear genome. This event predated the separation of the human parasite O. volvulus from its cattle-parasitic sister species, O. ochengi. The long association between filarial nematodes and Wolbachia symbionts may permit more frequent genetic exchange between their genomes.

Animals↗
PubMed1982

Antigenic relationships of flaviviruses with undetermined arthropod-borne status.

In contrast to most of the arthropod-borne flaviviruses, the flaviviruses with undetermined arthropod-borne status are probably disseminated only by direct contact with excreta (saliva, urine, feces, etc.); however, as yet undescribed arthropod transmission cycles may be found for some of them. Twenty-two of these flaviviruses, including prototype and recently isolated strains, were compared. Biologic properties were defined by infectivity titrations in suckling mice and Vero, LLC-MK2, and primary Pekin duck embryo cells, and antigenic relationships were defined by complement-fixation and plaque reduction neutralization tests. An antigenic classification scheme is proposed. Antigenic and biologic properties delimit two large clusters. The first, comprising a single antigenic complex, includes those which have yet to be isolated from arthropods, but are likely to be so (Israel turkey meningoencephalitis, Koutango, Negishi and Aroa viruses). The second, encompassing five antigenic complexes, is comprised of viruses which have been isolated exclusively from rodents or bats (Saboya, Carey Island, Dakar bat, Sokuluk, Bukalasa bat, Entebbe bat, Phnom Penh bat, Modoc, Sal Vieja, Jutiapa, San Perlita, Cowbone Ridge, Rio Bravo, Apoi, Tamana bat and Montana Myotis leucoencephalitis viruses) but includes three viruses (Saboya, Sokuluk and Entebbe bat viruses) which may be arthropod-borne, as indicated by replication in mosquito cells in vitro.

Aedes↗
PubMed1996

Assessment of arthropod vectors of infectious diseases in areas of U.S. troop deployment in the Persian Gulf.

Beginning in August 1990, approximately 800,000 coalition troops were deployed to the Persian Gulf during Operations Desert Shield and Desert Storm. There was substantial concern about arthropod-borne diseases, particularly sand fly fever and cutaneous leishmaniasis, because of high morbidity rates in the Persian Gulf during World War II (WWII). In sharp contrast to WWII, there was no report of sand fly fever among coalition forces and only 31 cases of leishmaniasis among 697,000 U.S. troops. To further evaluate the risk of arthropod-borne diseases, an entomologic survey was conducted in 12 areas of Kuwait and Saudi Arabia. A total of 1,556 arthropods was collected during four survey periods in 1992. The suspected vectors of cutaneous Leishmania major infection, sand fly fever, West Nile fever, Rift Valley fever, and Crimean-Congo hemorrhagic fever were identified; however, there was no evidence of arboviruses or Leishmania among collected specimens nor from 51 trapped rodents. There are several possible reasons for the low risk of arthropod-borne infectious diseases among Desert Shield/Storm troops in an area where suspected vectors frequently were found: the use of insecticides and repellents, and the deployment of most ground troops to the open desert during the cooler, winter period--conditions least favorable for the transmission of arthropod-borne diseases.

Animals↗
PubMed2002

Different rates of nucleotide substitutions in Wolbachia endosymbionts of arthropods and nematodes: arms race or host shifts?

The genus Wolbachia encompasses intracellular bacteria found in arthropods and in filarial nematodes. In arthropods, Wolbachia is primarily a reproductive parasite and shows relatively frequent horizontal transfer between host species, while in nematodes it appears to be a mutualist and is strictly vertically transmitted. We can expect that different selective pressures are acting on their genomes. Here we present an analysis of three Wolbachia genes, wsp, ftsZ and dnaA. In wsp of arthropod Wolbachia, an excess of non-synonymous substitutions was observed, providing evidence for positive selection. In nematode Wolbachia, no evidence for positive selection was found. Pressure for amino acid variation in wsp of arthropod Wolbachia could derive either from an arms race with the host or from the occurrence of more frequent hosts shifts due to horizontal transmission. In nematode Wolbachia, the lack of positively selected sites could result from the absence of an arms race, or from the homogeneity of the biochemical environment they exist in (ensured by strict vertical transmission). In ftsZ minor differences in substitution patterns were observed between arthropod and nematode Wolbachia, only in the 3'-portion of the gene. dnaA showed comparable patterns of variation in both lineages, with evidence for strong conservation.

Animals↗
PubMed1992

Ki-1 (CD30) expression in differentiation of lymphomatoid papulosis from arthropod bite reactions.

Lymphomatoid papulosis (LP) is an uncommon cutaneous T-cell lymphoproliferative disorder that can mimic arthropod bite reactions clinically and histologically. Erythematous, crusted papules and nodules occur mainly on extremities of young adults and, when biopsied, display a superficial and deep perivascular infiltrate characterized by atypical lymphocytes and scattered eosinophils. Arthropod bite reactions may show an identical histologic pattern. It has been suggested that up to 10% of patients with LP will eventually develop lymphoma. We examined biopsies from 10 cases of LP and six cases of arthropod bite reactions diagnosed by clinical history and prolonged follow-up, with BerH2, an antibody directed against the Ki-1 antigen (CD30) and found it to be useful in helping distinguish between the two entities. All cases of LP examined showed scattered Ki-1-positive large, atypical lymphocytes in the dermis. In the arthropod bite reactions, there was virtually no staining with BerH2 antibody. This suggests that the abnormal activated T-cells, which comprise the cellular infiltrate in LP, are not present in arthropod bite reactions.

Adult↗
PubMed2004

[Effects of imidacloprid on arthropod community structure in tobacco field].

The effects of imidacloprid on the structure of arthropod community and its sub-communities were analyzed. The results showed that after applied imidacloprid, the species number of arthropod community and its pest sub-community was influenced, but that of its natural insect enemy and spider sub-community was not influenced obviously. The individuals of arthropod community and its pest sub-community in both treatment plot (II) and control plot were decreased after the application of imidacloprid on May 23 to June 13, and the decline degree in treatment plot was larger than that in control plot. The individuals of arthropod community and its pest sub-community at treatment plots had a large decrease, and that in control plot had a large increase after imidacloprid application on June 14. Twice applications with imidacloprid did not reduce the number of the individuals of natural insect enemy and spider sub-community obviously. The individuals of tobacco aphids who were dominant in tobacco field decreased obviously within a period of time after application, and hence, the dominant concentration of arthropod community and its pest sub-community declined, and the diversity and stability increased.

Animals↗
PubMed1991

Parasitic and phoretic arthropods of sylvatic and commensal white-footed mice (Peromyscus leucopus) in central Tennessee, with notes on Lyme disease.

Sixteen species of parasitic or phoretic arthropods were collected from 56 white-footed mice, Peromyscus leucopus, live-trapped in central Tennessee from April through November 1987. Arthropod infestation was compared for mice taken from sylvatic (woodland) versus commensal (household) habitats. Three species were recorded from hosts in both habitats: the sucking louse Hoplopleura hesperomydis, the flea Epitedia wenmanni, and the laelapid mite Androlaelaps casalis. Twelve of the 13 remaining arthropod species were taken only from mice trapped in woodland whereas the phoretic glycyphagid mite Glycyphagus hypudaei was collected only from commensal mice. Arthropod faunas on commensal hosts clearly were impoverished. The 12 additional arthropod species recorded from the woodland mice consisted of 1 nidicolous beetle, Leptinus orientamericanus; 1 bot, Cuterebra fontinella; 3 fleas, Ctenophthalmus pseudagyrtes, Orchopeas leucopus and Peromyscopsylla scotti; 1 tick, Dermacentor variabilis; 2 mesostigmatid mites, Androlaelaps fahrenholzi and Ornithonyssus bacoti; 3 chiggers, Comatacarus americanus, Euschoengastia peromysci, and Leptotrombidium peromysci; and 1 undescribed pygmephorid mite of the genus Pygmephorus. Two nymphal and 100 larval D. variabilis were examined for spirochetes and found to be uninfected.

Animals↗
PubMed1997

U.S. Army soldiers' perceptions of arthropod pests and their effects on military missions.

A survey was conducted to determine the effects of biting and stinging arthropods on military personnel, operations, and training. Nearly 70% of respondents reported experiencing problems attributable to arthropods. Arthropods obstructed movement and field position, prevented concealment and cover, disrupted maneuvers, and caused panic. Twenty percent of respondents reported attendance at sick call for treatment of bites or stings, and 4% were hospitalized or assigned to quarters. Median lost time was 2 days. Bee, wasp, and ant stings and spider and chigger bites were the most frequent causes of lost time. Additional training on biting and stinging arthropods, use of repellents and other personal protective measures, first aid for bites and stings, and conditions requiring medical attention is needed in field units to enhance mission performance and reduce time lost because of arthropods. Materials for treatment of bites and stings should be included in first-aid kits issued for field use.

Animals↗
PubMed1976

Vertebrate Golgi complexes have beads in a similar position to those found in arthropods.

Insects and other arthropods have bead-like structures in Golgi complexes from all cell types. They are arranged in rings at the base of transition vesicles located near the smooth surface of the rough endoplasmic reticulum making the forming face of the Golgi complex and are only seen easily after staining in bismuth salts. Procedures used to demonstrate the beads in arthropod Golgi complexes do not selectively stain any structures where they would be expected to occur in several mouse and tadpole tissues. However, a faint pattern similar to the arthropod GC beads can be made out in the large GCs concerned in the formation of acrosomes during mouse spermatogenesis. Uranyl staining shows particles of about the same size and spacing as the beads of arthropod GCs. We conclude that vertebrate GCs may have beads that differ from arthropods in their staining properties.

Acrosome↗
PubMed1995

Molecular cloning of insect pro-phenol oxidase: a copper-containing protein homologous to arthropod hemocyanin.

Pro-phenol oxidase [pro-PO; zymogen of phenol oxidase (monophenol, L-dopa:oxygen oxidoreductase, EC 1.14.18.1)] is present in the hemolymph plasma of the silkworm Bombyx mori. Pro-PO is a heterodimeric protein synthesized by hemocytes. A specific serine proteinase activates both subunits through a limited proteolysis. The amino acid sequences of both subunits were deduced from their respective cDNAs; amino acid sequence homology between the subunits was 51%. The deduced amino acid sequences revealed domains highly homologous to the copper-binding site sequences (copper-binding sites A and B) of arthropod hemocyanins. The overall sequence homology between silkworm pro-PO and arthropod hemocyanins ranged from 29 to 39%. Phenol oxidases from prokaryotes, fungi, and vertebrates have sequences homologous to only the copper-binding site B of arthropod hemocyanins. Thus, silkworm pro-PO DNA described here appears distinctive and more closely related to arthropod hemocyanins. The pro-PO-activating serine proteinase was shown to hydrolyze peptide bonds at the carboxyl side of arginine in the sequence-Asn-49-Arg-50-Phe-51-Gly-52- of both subunits. Amino groups of N termini of both subunits were indicated to be N-acetylated. The cDNAs of both pro-PO subunits lacked signal peptide sequences. This result supports our contention that mature pro-PO accumulates in the cytoplasm of hemocytes and is released by cell rupture, as for arthropod hemocyanins.

Amino Acid Sequence↗
PubMed2006

The organic preservation of fossil arthropods: an experimental study.

Modern arthropod cuticles consist of chitin fibres in a protein matrix, but those of fossil arthropods with an organic exoskeleton, particularly older than Tertiary, contain a dominant aliphatic component. This apparent contradiction was examined by subjecting modern cockroach, scorpion and shrimp cuticle to artificial maturation (350 degrees C/700 bars/24 h) following various chemical treatments, and analysing the products with pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS). Analysis of artificially matured untreated cuticle yielded moieties related to phenols and alkylated substituents, pyridines, pyrroles and possibly indenes (derived from chitin). n-Alkyl amides, C16 and C18 fatty acids and alkane/alk-1-ene homologues ranging from C9 to C19 were also generated, the last indicating the presence of an n-alkyl component, similar in composition to that encountered in fossil arthropods. Similar pyrolysates were obtained from matured pure C16 and C18 fatty acids. Py-GC/MS of cuticles matured after lipid extraction and hydrolysis did not yield any aliphatic polymer. This provides direct experimental evidence that lipids incorporated from the cuticle were the source of aliphatic polymer. This process of in situ polymerization appears to account for most of the fossil record of terrestrial arthropods as well as marine arthropods that lacked a biomineralized exoskeleton.

Animals↗
PubMed1999

Adaptive strategies of edaphic arthropods.

For those arthropod species adapted for living below the soil surface, the soil is a refuge from the biotic and abiotic perturbations existing above ground. Convergent morphological, physiological, and behavioral adaptations of epedaphic, euedaphic, and hemiedaphic arthropods to selective aspects of subterranean existence are examined in light of overlapping ecological niches. The abiotic impact of the soil environment and its relationship to arthropod evolution, radiation, and ecology are discussed as well. Specific areas addressed include the invasion of land by marine arthropods, the impact of morphology on arthropod mobility, osmoregulatory/respiratory systems, and defensive strategies.

Journal Article↗
PubMedDate not supplied

[Round Table: Urticaria caused by arthropod bites and stings (excluding Hymenoptera)].

Adverse reactions to arthropod bites (hymenoptera excluded) can be faced with systemic reactions and local reaction. Among the numerous families of arthropods the species most commonly responsible are mosquitoes,. flea, horsefly and tick. In this article we explain the characteristics of reaction caused by arthropods and the mechanisms proposed. An IgE mechanism is incriminated in severe anaphylactic reactions. Various mechanisms have been proposed for local reactions. In order to know the incidence of sensitization and cross-reactivity with other arthropods, we have done a study where we have found that 31% of patients with reaction to mosquito bite had sensitization to Aedes communis and 53% of this group also had sensitization to other arthropods, probably due to a cross-reactivity.

Adult↗
PubMedDate not supplied

[Effect of organophosphorus inhibitors, lupinine and epilupinine derivatives, on mammalian and arthropod cholinesterases].

Studies have been made on the effect of organophosphorus inhibitors on cholinesterases (CHe) from mammals (human and rabbit erythrocytes, mice brain) and arthropods (fly, spring grain aphid, rice weevil and spider tick). Organophosphorus inhibitors were presented by dialkylthiophosphates which contained normal or branching alkyls in the phosphoryl part of their molecule and lupinine or epilupinine residue in the other part of the latter. Increasing the length of alkyl in lupinine derivatives increased their inhibitory effect with respect to mammalian CHe, but decreased it in relation to all the investigated arthropod CHe. For epilupinine derivatives, the same relationship was found with mammalian CHe, being absent in arthropod enzymes. These data indicate the existence of significant differences in spatial structure of both esterase and anionic centers of the enzyme from mammals and arthropods. In arthropod CHe, hydrophobic regions of the esterase center are less developed that in mammalian CHe. The distance between the anionic and esterase centers of CHe is presumably different in the enzymes from different species.

Alkaloids↗
PubMed2006

Laboratory containment practices for arthropod vectors of human and animal pathogens.

Arthropod-borne pathogens have an impact on the health and well-being of humans and animals throughout the world. Research involving arthropod vectors of disease is often dependent on the ability to maintain the specific arthropod species in laboratory colonies. The author reviews current arthropod containment practices and discusses their importance from public health and ecological perspectives.

Animals↗
PubMed1999

Arthropod sensilla: morphology and phylogenetic considerations.

The structures of different types of arthropod sensilla are compared and theories regarding the evolution of these sensory organs are presented. Arthropod sensilla are built according to a common plan, and are probably homologous to scolopidia. Certain similarities in the structure of sensilla in different arthropod groups can be the result of adaptations to specific environments. The structure of sensilla in insect groups, which are regarded to be ancestral, do not appear to be less sophisticated than in groups considered to be more advanced. The different types of pore systems, as well as the structural differentiations of insect olfactory sensillar types remain unexplained. Olfactory sensilla display a large degree of similarity among terrestrial arthropods, whereas crustacean sensilla diverge in structure. In holometabolous insects larval sensilla appear to be structurally quite advanced, and more complex than in the adult. During the ontogeny of both sensilla and scolopidia, these are differentiated in an epithelial layer, resulting in the formation of both sensory and enveloping cells. The developmental patterns of sensilla in the studied insect groups are similar. During the development of sensilla apoptotic process are usually active.

Animals↗