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PubMed1992

Arthropods in a hospital and their potential significance in the epidemiology of hospital infections.

Synanthropic and other arthropods were collected and examined for microbes in the summer seasons of 1988 and 1990. The collection was performed in a Prague hospital with departments situated in separate buildings, each surrounded by a park. In 1988, the most attention was given to flies (35 species collected) found outside between the buildings. In 1990, all arthropods found inside the buildings (particularly in the departments of dermatology and urology) were studied. A total of 30 taxons were identified. The microbes found on the bodies of arthropods were isolated in both seasons. In 1990, the hospital environment and biological material from patients (urine, pus) were also examined for the presence of microbes. Altogether 108 strains (21 species) and 116 strains (25 species) were isolated from the arthropods' bodies in 1988 and 1990, respectively. The ecological characterization of the arthropods and results of microbiological studies show that synanthropic arthropods play a significant role in the epidemiology of hospital infections.

Animals↗
PubMed1979

[Mycobacteria in arthropodes of different biotopes (author's transl)].

Many arthropodes are found in close contact with soil and other material contaminated by mycobacteria. In order to clear up their importance as potential carriers of germs of the MAIS complex (Mycobacterium avium, intracellulare, scrofulaceum), we investigated 835 samples of arthropodes taken from different biotopes. Following a treatment according to the cultural method developed by us (Beerwerth, 1967), we isolated 606 strains of mycobacteria from 302 (36.0%) out of 835 samples. Incubation at room temperature was more effective than incubation at 37 degrees C. 96 (15.8%) in 606 strains did not grow at 37 degrees C. In arthropodes taken from pasture-ground we mainly found mycobacteria of group II according to Runyon, while in arthropodes from arable land, stables and saw mills mycobacteria of group III predominated. Samples of arthropodes taken from forests, moorland and waters showed a comparatively similar spectrum of species. Strains of the MAIS complex - M. avium, intracellulare, scrofulaceum - were frequent in areas of saw mills (80 = 20.5% in 356 strains), but rarely found amongst the remaining biotopes (11 = 4.4% in 250 species). Mycobacteria were chiefly isolated from larvae and imagines living in permanent contact with soil and less from winged shapes. The epidemiological importance of arthropodes spreading pathogenic mycobacteria should not be overvalued.

Animals↗
PubMed2001

One-step PCR amplification of complete arthropod mitochondrial genomes.

A new PCR primer set which enables one-step amplification of complete arthropod mitochondrial genomes was designed from two conserved 16S rDNA regions for the long PCR technique. For this purpose, partial 16S rDNAs amplified with universal primers 16SA and 16SB were newly sequenced from six representative arthropods: Armadillidium vulgare and Macrobrachium nipponense (Crustacea), Anopheles sinensis (Insecta), Lithobius forficatus and Megaphyllum sp. (Myriapoda), and Limulus polyphemus (Chelicerata). The genomic locations of two new primers, HPK16Saa and HPK16Sbb, correspond to positions 13314-13345 and 12951-12984, respectively, in the Drosophila yakuba mitochondrial genome. The usefulness of the primer set was experimentally examined and confirmed with five of the representative arthropods, except for A. vulgare, which has a linearized mitochondrial genome. With this set, therefore, we could easily and rapidly amplify complete mitochondrial genomes with small amounts of arthropod DNA. Although the primers suggested here were examined only with arthropod groups, a possibility of successful application to other invertebrates is very high, since the high degree of sequence conservation is shown on the primer sites in other invertebrates. Thus, this primer set can serve various research fields, such as molecular evolution, population genetics, and molecular phylogenetics based on DNA sequences, RFLP, and gene rearrangement of mitochondrial genomes in arthropods and other invertebrates.

Animals↗
PubMed1997

Magnetic orientation and the magnetic sense in arthropods.

The physical properties of the earth's magnetic field are summarized with the aim of emphasizing their significance as cues that can be exploited in orientational tasks. Past work has revealed magnetic orientation in vertebrates as well as invertebrates, including arthropods. The key finding to date has been that, as opposed to many vertebrates, the magnetic compass of arthropods responds to the polarity, rather than to the inclination of the earth's magnetic field. As in the case of vertebrates, the debate over how arthropods detect magnetic fields has yet to be resolved. Currently, evidence has been reported in support of a detection system based on magnetite crystals together with a variety of detection systems based on events occurring at the molecular level. Interactions between the magnetic and other compasses in orientation experiments suggest the existence of an area in the brain where spatial orientation information from magnetic and other stimuli converges. The slow advance of our knowledge on magnetic orientation in arthropods, as opposed to the much better understanding of magnetic orientation in vertebrates, arises from difficulties in identifying the appropriate behavioural contexts in which arthropods respond to magnetic fields in both laboratory and field situations. Arthropods thus present challenges not only in demonstrating magnetic orientation, but also in elucidating the sensory mechanisms involved in the perception of magnetic fields.

Animals↗
PubMed2002

Origin and evolution of arthropod hemocyanins and related proteins.

Arthropod hemocyanins are large, multimeric, (n x 6) copper-containing proteins that deliver oxygen in the haemolymph of many chelicerate, crustacean, myriapod, and also possibly some insect species. The arthropod hemocyanins belong to a large protein superfamily that also includes the arthropod phenoloxidases, certain crustacean and insect storage proteins (pseudo-hemocyanins and hexamerins), and the insect hexamerin receptors. Here I summarise the present knowledge of the origin, functional adaptations, and evolution of these proteins. Arthropod and mollusc hemocyanins are, if at all, only distantly related. As early as in the arthropod stem line, the hemocyanins emerged from a phenoloxidase-like enzyme. The evolution of distinct hemocyanin subunits, as well as the formation of multi-hexamers occurred independently within the arthropod subphyla. Hemocyanin subunit evolution is strikingly different in the Chelicerata, Myriapoda and Crustacea. Hemocyanins individually gave rise to two distinct copper-less storage proteins, the insect hexamerins and the crustacean pseudo-hemocyanins (cryptocyanins). The receptor responsible for the uptake of hexamerin by the larval fat body of the insects emerged from a hexamerin-precursor. Molecular phylogenetic analyses show a close relationship of the crustacean and insect proteins, providing strong support for a pancrustacean taxon, while structural data suggest a myriapod-chelicerate clade.

Animals↗
PubMed2003

Desiccation stress at sub-zero temperatures in polar terrestrial arthropods.

Cold tolerant polar terrestrial arthropods have evolved a range of survival strategies which enable them to survive the most extreme environmental conditions (cold and drought) they are likely to encounter. Some species are classified as being freeze tolerant but the majority of those found in the Antarctic survive sub-zero temperatures by avoiding freezing by supercooling. For many arthropods, not just polar species, survival of desiccating conditions is equally important to survival of low temperatures. At sub-zero temperatures freeze avoiding arthropods are susceptible to desiccation and may lose water due to a vapour diffusion gradient between their supercooled body fluids and ice in their surroundings. This process ceases once the body fluids are frozen and so is not a problem for freeze tolerant species. This paper compares five polar arthropods, which have evolved different low temperature survival strategies, and the effects of exposure to sub-zero temperatures on their supercooling points (SCP) and water contents. The Antarctic oribatid mite (Alaskozetes antarcticus) reduced its supercooling point temperature from -6 to -30 degrees C, when exposed to decreasing sub-zero temperatures (cooled from 5 to -10 degrees C over 42 days) with little loss of body water during that period. However, Cryptopygus antarcticus, a springtail which occupies similar habitats in the Antarctic, showed a decrease in both water content and supercooling ability when exposed to the same experimental protocol. Both these Antarctic arthropods have evolved a freeze avoiding survival strategy. The Arctic springtail (Onychiurus arcticus), which is also freeze avoiding, dehydrated (from 2.4 to 0.7 g water g(-1) dry weight) at sub-zero temperatures and its SCP was lowered from c. -3 to below -15 degrees C in direct response to temperature (5 to -5.5 degrees C). In contrast, the freeze tolerant larvae of an Arctic fly (Heleomyza borealis) froze at c. -7 degrees C with little change in water content or SCP during further cold exposure and survived frozen to -60 degrees C. The partially freeze tolerant sub-Antarctic beetle Hydromedion sparsutum froze at c. -2 degrees C and is known to survive frozen to -8 degrees C. During the sub-zero temperature treatment, its water content reduced until it froze and then remained constant. The survival strategies of such freeze tolerant and freeze avoiding arthropods are discussed in relation to desiccation at sub-zero temperatures and the evolution of strategies of cold tolerance.

Acclimatization↗
PubMed2005

Use of AFLP markers in surveys of arthropod diversity.

Arthropods comprise the most diverse group of animals on earth and as such have been the subject of considerable evolutionary research. For example, much of our understanding of the genetic basis of evolutionary change is derived from the insect genus Drosophila, one of the most well-studied organisms in biology. Arthropods are also of tremendous economic importance as both providers and chief destroyers of food for human consumption. Thus, the genetic diversity of arthropods is of interest from both a pure research perspective and for practical economic reasons. The amplified fragment length polymorphism (AFLP) method of genetic analysis, developed in the early and mid-1990s (Vos et al., 1995; Zabeau, 1992; Zabeau and Vos, 1993), offers a relatively new method for assessing genetic diversity and has been increasingly applied in studies of arthropods. Originally coined selective restriction fragment amplification (SRFA) (Zabeau and Vos, 1993), the method was renamed (Vos et al., 1995) presumably to reflect its similarity to restriction fragment length polymorphism (RFLP). Since then, AFLPs have become a popular tool in both population genetics to estimate population parameters such as heterozygosity, F-statistics, migration rates, and genetic distances, as well as phylogenetics, to infer relationships among closely related taxa. In arthropods, AFLPs have been used to assess genetic variation both within and between species in various taxa including crustaceans, chelicerates, and insects, often yielding novel insights. In this chapter, we briefly describe the AFLP method and its strengths and limitations. We then discuss the use of AFLPs in surveys of arthropod diversity, highlighting the specific questions addressed using AFLPs. Finally, a section on experimental design and methods, based on research in our laboratory, is provided.

Animals↗
PubMed2001

Hox genes and the phylogeny of the arthropods.

The arthropods are the most speciose, and among the most morphologically diverse, of the animal phyla. Their evolution has been the subject of intense research for well over a century, yet the relationships among the four extant arthropod subphyla - chelicerates, crustaceans, hexapods, and myriapods - are still not fully resolved. Morphological taxonomies have often placed hexapods and myriapods together (the Atelocerata) [1, 2], but recent molecular studies have generally supported a hexapod/crustacean clade [2-9]. A cluster of regulatory genes, the Hox genes, control segment identity in arthropods, and comparisons of the sequences and functions of Hox genes can reveal evolutionary relationships [10]. We used Hox gene sequences from a range of arthropod taxa, including new data from a basal hexapod and a myriapod, to estimate a phylogeny of the arthropods. Our data support the hypothesis that insects and crustaceans form a single clade within the arthropods to the exclusion of myriapods. They also suggest that myriapods are more closely allied to the chelicerates than to this insect/crustacean clade.

Animals↗
PubMed2000

The immunomodulatory factors of bloodfeeding arthropod saliva.

There are potent immunomodulators in saliva of the bloodfeeding arthropods which transmit many of the world's most serious diseases that may benefit the arthropod by preventing the vertebrate host from becoming sensitized to the saliva. In addition, saliva can enhance transmission of parasites/pathogens by arthropods. As a result, vaccines that target the arthropod (e.g. salivary immunomodulators) should be considered as one component of multisubunit vaccines against arthropod-borne parasites/pathogens. Indeed, since vaccines against the pathogens themselves are often not fully protective, vaccines that target several facets of the life cycle of the pathogen may be the most effective at controlling disease transmission. This review covers known immunomodulatory factors in arthropod vector saliva, focusing mainly on sandflies and ixodid ticks.

Adjuvants, Immunologic↗
PubMed2005

Convergent evolution of chemical defense in poison frogs and arthropod prey between Madagascar and the Neotropics.

With few exceptions, aposematically colored poison frogs sequester defensive alkaloids, unchanged, from dietary arthropods. In the Neotropics, myrmicine and formicine ants and the siphonotid millipede Rhinotus purpureus are dietary sources for alkaloids in dendrobatid poison frogs, yet the arthropod sources for Mantella poison frogs in Madagascar remained unknown. We report GC-MS analyses of extracts of arthropods and microsympatric Malagasy poison frogs (Mantella) collected from Ranomafana, Madagascar. Arthropod sources for 11 "poison frog" alkaloids were discovered, 7 of which were also detected in microsympatric Mantella. These arthropod sources include three endemic Malagasy ants, Tetramorium electrum, Anochetus grandidieri, and Paratrechina amblyops (subfamilies Myrmicinae, Ponerinae, and Formicinae, respectively), and the pantropical tramp millipede R. purpureus. Two of these ant species, A. grandidieri and T. electrum, were also found in Mantella stomachs, and ants represented the dominant prey type (67.3% of 609 identified stomach arthropods). To our knowledge, detection of 5,8-disubstituted (ds) indolizidine iso-217B in T. electrum represents the first izidine having a branch point in its carbon skeleton to be identified from ants, and detection of 3,5-ds pyrrolizidine 251O in A. grandidieri represents the first ponerine ant proposed as a dietary source of poison frog alkaloids. Endemic Malagasy ants with defensive alkaloids (with the exception of Paratrechina) are not closely related to any Neotropical species sharing similar chemical defenses. Our results suggest convergent evolution for the acquisition of defensive alkaloids in these dietary ants, which may have been the critical prerequisite for subsequent convergence in poison frogs between Madagascar and the Neotropics.

Alkaloids↗
PubMed1990

Ecology and management of arthropod pests of poultry.

The worldwide spread of modern, high-density confined poultry production systems under the direction of integrators has intensified the importance of a select number of arthropod ectoparasites and habitat pests. This concentrated production of poultry provides artificial ecosystems that are sometimes ideal for the development of large populations of arthropod pests. At the same time the systems are amenable to integrated pest management involving a multipest and multimethod approach to reducing or eliminating arthropod pests. Since rodents are major pests, they should be included in an integrated pest management program to make the program most cost-effective and attractive to the integrators and producers (5). Quantitative data are scarce on economic effects, and the concept of economic thresholds is difficult to apply either to ectoparasites or to habitat pests. The risk of transporting ectoparasites among flocks is difficult to evaluate and necessitates treatment after early detection of the arthropods. Flies and litter beetles present a threat of disease transmission and the potential for lawsuits from neighbors or public health agencies that are factors not subject to easy cost estimates. The monetary losses of a flock devastated by disease or a farm forced to close are so great that the risks are unacceptable. Production losses from lowered feed conversion ratios and insulation damage are likely to be detected by the sophisticated record-keeping of the integrators. Minimal use of pesticides and other chemicals on poultry and in poultry housing is an objective of the integrators and, consequently, an integrated pest management (IPM) approach that reduces the need for pesticides is attractive. The key to further development of effective arthropod management programs for poultry is the implementation of pest and disease monitoring programs for the complete system. Improvements in arthropod sampling methods and more attention to monitoring the biosecurity systems to minimize ectoparasite dispersal are needed. The integrators have servicemen who regularly visit the production facilities and can be trained to perform monitoring functions and to instigate and supervise integrated pest management measures. With the increasing use of computers by the integrators, the prospects for utilizing the monitoring data in predictive computer simulation models for pest management decision-making justify more efforts to develop such tools (64, 102, 168). Future poultry pest management programs must be based on sound data, which presently is too limited, and must be flexible enough to adjust rapidly to evolving pest problems in rapidly changing production systems.

Animals↗
PubMed2005

Effects of barrier application of granular deltamethrin on subadult Ixodes scapularis (Acari: Ixodidae) and nontarget forest floor arthropods.

We evaluated the effects of a single application of granular deltamethrin made against nymphal Ixodes scapularis Say on the diversity and abundance of forest arthropods taken in pitfall traps in oak forest sites for 16 wk after treatment in central New Jersey. Control of I. scapularis subadults on treated plots ranged between 97 and 100% and continued at least 12 wk postapplication. Significant short-term changes in arthropod assemblages were detected at one of three study sites within 4 wk posttreatment. Effects were not distributed equally across taxa. Seasonal changes in numbers and diversity of forest arthropods in the study areas may have affected the impact of the acaricide in the treatment area. Comparison with control areas indicated that reductions in abundance of some arthropod taxa in the treatment area were detectable 12 wk after treatment. Total arthropod species diversity was not significantly affected by the application, and no treatment effects were detected 16 wk postapplication, suggesting that the arthropod community had recovered from the effects of the application. The merits of barrier applications in integrated tick control programs are discussed.

Animals↗
PubMed2004

[Diversity and stability of arthropod assemblage in tea orchard].

Two tea orchards, simplex tea orchard with weeds removed manually or by herbicides (STO) and complex tea orchard with the weed Hedyotis uncinella (CTO), each with an area of 0. 4 hm2, were established in 1995 in Yingde Hongxing Tea Plantation, Guangdong Province. The primary eigenvalues, species richness index (R), assemblage diversity index (H'), evenness index (J) and species concentration index (C) of arthropod assemblage were employed and compared to assess the efficacy of STO and CTO on the diversity and stabilityof arthropod assemblage. Stability indexes Ss/Si and Sn/Sp and variation coefficient of diversity index ds/dm were utilized as well. The results demonstrated that the R of arthropod assemblage in CTO ranged from 4 to 8, with the highest of 7.7403, while that in STO varied mainly between 4 to 6. The average R of arthropod assemblage in CTO was 5.4672 +/- 0.3483, higher than that in STO (4.8809 +/- 0.3175). The H' of arthropod in CTO (3.8535 +/- 0.1232) was higher, in contrast to the value in STO (3.4654 +/- 0.1856). The J in CTO was higher, while the species concentration index (C) was lower, in comparison to STO. The stability indexes Ss/Si and Sn/Sp of CTO were greater than those of STO, while the ds/dm in CTO (0.1107) was lower than that in STO (0.1855). All these indicated that the diversity of arthropod assemblage was better preserved in CTO, and the assemblage in CTO was more stable.

Animals↗
PubMed1996

Cytoskeletal F-actin polymerization from cytosolic G-actin occurs in the phagocytosing immunocytes of arthropods (Limulus polyphemus and Gromphadorhina portentosa): does [cAMP]i play any role?

Phagocytosis is a major defense reaction in arthropods and is accomplished by two blood cells (hemocytes), the granulocyte (GRs) and plasmatocytes (PLs), collectively called immunocytes. Immunocytes (principally the GRs) from two arthropods, Limulus polyphemus (horseshoe crab) and Gromphadorhina portentosa (Madagascar hissing cockroach) effectively phagocytose fluorescein isothiocyanate (FITC)-conjugated fluoresbrite microspheres (FITC-FM) and chicken (Gallus domesticus) erythrocytes within 1 hr of incubation. Although actin polymerization and changes in intracellular cAMP ([cAMP]i) levels occur during the early stages of phagocytosis in vertebrates, these two phenomena have not been studied in arthropod immunocytes. Using the DNase I inhibition assay, we found a decrease in cytosolic G-actin and an increase in the cytoskeletal F-actin in the phagocytosing immunocytes; the total actin in both resting and phagocytosing immunocytes remained constant. These results showed an 86% increase in F-actin in G. portentosa immunocytes and a 29% increase in those of L. polyphemus after 1 hr of initial incubation with FITC-FM. As in some vertebrates, the role of [cAMP]i in the early stages of phagocytosis in these two animals- and perhaps in arthropods in general-is variable; although we detected some negligible amounts of [cAMP]i (0.10-0.80 pmol/cell at different time intervals) in L. polyphemus immunocytes, it was inconclusive whether those in G. portentosa also contained [cAMP]i. Even in L. polyphemus, the difference in the amounts of [cAMP]i in resting and phagocytosing cells was insignificant (P > 0.05). It was also inconclusive whether [Ca2+]i and/or [Mg2+]i play any roles in the early stages of phagocytosis in the two arthropods in this study. These results suggest that the two phenomena (F-actin polymerization and levels of [cAMP]i in arthropods) are basically similar to those in vertebrate neutrophils and macrophages, which suggests that certain immunological mechanisms are conserved in nature.

Actins↗
PubMed2004

Arthropod FMRFamide-related peptides modulate muscle activity in helminths.

FMRFamide-related peptides are common to a wide variety of invertebrate species, including helminths and arthropods. In arthropods, five distinct FMRFamide-related peptide subfamilies are recognised: the myosuppressins, extended-FLRFamides, -FMRFamides, -RFamides, and sulfakinins, members of which induce potent and diverse myotropic effects. Whilst >80 FMRFamide-related peptides have been identified in nematodes, only four FMRFamide-related peptides have been characterised from flatworms. The Ascaris suum ovijector/body wall bioassay and the Procerodes littoralis muscle fibre bioassay have proved both reliable and sensitive systems for assessing the functional activities of FMRFamide-related peptides in vitro, and data describing the effects of native FMRFamide-related peptides in these systems are rapidly accumulating. This is the first study to determine the cross-phyla activities of non-native FMRFamide-related peptides in both nematode and flatworm species. In the present study, the effects of 10 arthropod FMRFamide-related peptides (leucomyosuppressin [pQDVDHVFLRFamide], schistoFLRFamide [PDVDHVFLRFamide] and truncated analogues [HVFLRFamide and VFLRFamide], lobster peptide I [TNRNFLRFamide], lobster peptide II [SDRNFLRFamide], manducaFLRFamide II [GNSFLRFamide], manducaFLRFamide III [DPSFLRFamide], calliFMRFamide 4 [KPNQDFMRFamide] and perisulfakinin [EQFDDY(SO(3)H)GHMRFamide]), representing the five subfamilies, were examined on the body wall and ovijector of the parasitic porcine nematode, A. suum and dispersed muscle fibres from the free-living turbellarian, P. littoralis. The muscle activity of the ovijector was found to be modulated significantly by each of the arthropod FMRFamide-related peptides tested; the effects were concentration-dependent, reversible and repeatable. All but one (perisulfakinin) of the 10 arthropod FMRFamide-related peptides examined modulated significantly the activity of A. suum body wall muscle. In addition, all of the arthropod FMRFamide-related peptides examined induced potent concentration-dependent contractions of P. littoralis muscle fibres. These results reveal similarities in the ligand requirement(s) between FMRFamide-related peptide receptors within the Phyla Arthropoda, Nematoda and Platyhelminthes, and indicate significant receptor promiscuity, which highlights the potential of FMRFamide-related peptide receptors as legitimate targets for novel endectocidal agents.

Animals↗
PubMed1999

Ectopic gene expression and homeotic transformations in arthropods using recombinant Sindbis viruses.

BACKGROUND: The morphological diversity of arthropods makes them attractive subjects for studying the evolution of developmental mechanisms. Comparative analyses suggest that arthropod diversity has arisen largely as a result of changes in expression patterns of genes that control development. Direct analysis of how a particular gene functions in a given species during development is hindered by the lack of broadly applicable techniques for manipulating gene expression. RESULTS: We report that the Arbovirus Sindbis can be used to deliver high levels of gene expression in vivo in a number of non-host arthropod species without causing cytopathic effects in infected cells or impairing development. Using recombinant Sindbis virus, we investigated the function of the homeotic gene Ultrabithorax in the development of butterfly wings and beetle embryos. Ectopic Ultrabithorax expression in butterfly forewing imaginal discs was sufficient to cause the transformation of characteristic forewing properties in the adult, including scale morphology and pigmentation, to those of the hindwing. Expression of Ultrabithorax in beetle embryos outside of its endogenous expression domain affected normal development of the body wall cuticle and appendages. CONCLUSIONS: The homeotic genes have long been thought to play an important role in the diversification of arthropod appendages. Using recombinant Sindbis virus, we were able to investigate homeotic gene function in non-model arthropod species. We found that Ultrabithorax is sufficient to confer hindwing identity in butterflies and alter normal development of anterior structures in beetles. Recombinant Sindbis virus has broad potential as a tool for analyzing how the function of developmental genes has changed during the diversification of arthropods.

Animals↗
PubMed2004

Arthropod diversity in peas with normal or reduced waxy bloom.

Crop traits can alter economically important interactions between plants, pests, and biological control agents. For example, a reduced waxy bloom on the surface of pea plants alters interactions between pea aphids and their natural enemies. In this study, we assess whether the effect of wax reduction extends beyond the 2 or 3 arthropod species closely associated with the plants and into the structure of the broader arthropod community of over 200 taxa at our site. We sampled arthropods on lines of peas with normal and reduced wax in Latah Co., Idaho using pitfall traps within randomly assigned pairs of 5 x 5 meter plots. During the 1998 and 1999 growing seasons, we collected 12,113 individual arthropods from 221 unambiguously identified morphospecies. The number of individuals collected from each morphospecies responded idiosyncratically to the reduced wax peas. To test whether arthropod community structure differed between the collections from plots having peas with normal or reduced wax, we performed a randomization test. The collection from peas with reduced wax had higher species evenness and thus higher community diversity despite having lower species richness. Our results demonstrate the potential of a single plant trait, epicuticular wax, to affect a community of arthropods. Two pests of peas had opposite responses to peas with reduced wax. The number of pea aphids collected was greater from peas with normal wax peas than those with reduced wax. In contrast, the number of pea leaf weevils collected was greater from peas with reduced wax.

Animals↗
PubMed1995

Comparative aspects of peptidergic signaling pathways in the nervous systems of arthropods.

Comparative aspects of arthropod peptidergic systems--in principle--can be studied on the level of precursor sequences (genes, preprohormones), peptide sequences (peptide families), and peptide expression patterns within the nervous system. The number of known arthropod neuropeptide precursor sequences is as yet far too small to provide a reasonably large basis for extended comparative studies. Comparative studies of peptide sequences have shown that many peptides belong to families with homologous members in both invertebrates and vertebrates. Comparative research on peptide expression has to find out whether phylogenetic necessities lead to "hard wired" neurochemical identities, i.e., a more or less fixed "Bauplan" that not only determines the lineage and morphology of a neuron but also its transmitter(s), or whether these necessities demand greater flexibility (plasticity), and hence cause great variability that would complicate comparative studies. As will be shown here, both possibilities appear to exist. On the one hand, peptidergic neurons may exist in comparable form in different groups of arthropods. On the other hand, the neurochemical identity of cells may vary in segmented organisms when comparing serially homologous sets of nerve cells in different segments. As a further complication, identical or similar peptides may serve different functions, even in closely related species. In view of these functional aspects in particular, it appears that peptidergic signalling pathways represent rapidly evolving systems. This conclusion, although very interesting in itself, reduces the use of such systems for general comparisons. However, arthropod nervous systems represent excellent model systems for the study of homology. At least for morphological and ontogenetic aspects arthropods provide numerous opportunities to study homology on the level of the individually identified peptidergic nerve cell.

Amino Acid Sequence↗