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Insect Taxa (insect + taxa)
Selected AbstractsConservation of Insect Diversity: a Habitat ApproachCONSERVATION BIOLOGY, Issue 6 2000Jennifer B. Hughes To explore the feasibility of basing conservation action on community-level biogeography, we sampled a montane insect community. We addressed three issues: (1) the appropriate scale for sampling insect communities; (2) the association of habitat specialization,perhaps a measure of extinction vulnerability,with other ecological or physical traits; and (3) the correlation of diversity across major insect groups. Using malaise traps in Gunnison County, Colorado, we captured 8847 Diptera (identified to family and morphospecies), 1822 Hymenoptera (identified to morphospecies), and 2107 other insects (identified to order). We sampled in three habitat types,meadow, aspen, and conifer,defined on the basis of the dominant vegetation at the scale of hundreds of meters. Dipteran communities were clearly differentiated by habitat type rather than geographic proximity. This result also holds true for hymenopteran communities. Body size and feeding habits were associated with habitat specialization at the family level. In particular, habitat generalists at the family level,taxa perhaps more likely to survive anthropogenic habitat alteration,tended to be trophic generalists. Dipteran species richness was marginally correlated with hymenopteran species richness and was significantly correlated with the total number of insect orders sampled by site. Because these correlations result from differences in richness among habitat types, insect taxa may be reasonable surrogates for one another when sampling is done across habitat types. In sum, community-wide studies appear to offer a practical way to gather information about the diversity and distribution of little-known taxa. Resumen:No existe ni el tiempo ni los recursos para diseñar planes de conservación para cada especie, particularmente para los taxones poco estudiados, no carismáticas, pero ecológicamente importantes que componen la mayoría de la biodiversidad. Para explorar la factibilidad de basar acciones de conservación en biogegrafía a nivel comunitario, muestreamos una comunidad de insectos de montaña. Evaluamos tres aspectos: (1) la escala adecuada para el muestreo de comunidades de insectos; (2) la asociación de especialización de hábitat,quizá una medida de vulnerabilidad de extinción,con otras características ecológicas o físicas; y (3) la correlación de la diversidad a lo largo de los grupos principales de insectos. Mediante el uso de trampas en el condado Gunnison, en Colorado, capturamos 8847 dípteros (identificados a nivel de familia y morfoespecies), 1822 himenópteros (identificadas hasta morfoespecies) y 2107 otros insectos (identificados a nivel de orden). Muestreamos tres tipos de hábitats,vega, álamos temblones y coníferas,definidos en base a la vegetación dominante a escala de cientos de metros. Las comunidades de dípteros estuvieron claramente diferenciadas por tipos de hábitat y no por la proximidad geográfica. Este resultado también se mantiene para las comunidades de himenópteros. El tamaño del cuerpo y los hábitos alimenticios estuvieron asociados con la especialización del hábitat a nivel de familia. En particular, los generalistas de hábitat a nivel de familia,los taxones que posiblemente tengan mayor probabilidad de sobrevivir alteraciones antropogénicas del hábitat,tendieron a ser generalistas tróficos. La riqueza de las especies de dípteros estuvo marginalmente correlacionada con la riqueza de especies de himenópteros y estuvo significativamente correlacionada con el número total de órdenes de insectos muestreadas por sitio. Debido a que estas correlaciones resultaron de diferencias en la riqueza de especies entre tipos de hábitats, los taxones de insectos podrían ser substitutos mutuos razonables cuando se muestrea entre diferentes tipos de hábitats. En resumen, los estudios a lo largo de comunidades parecen ofrecer una forma práctica de recolectar información sobre la diversidad y distribución de los taxones poco estudiados. [source] Can host-range allow niche differentiation of invasive polyphagous fruit flies (Diptera: Tephritidae) in La Réunion?ECOLOGICAL ENTOMOLOGY, Issue 4 2008PIERRE-FRANCOIS DUYCK Abstract 1.,Biological invasions bring together formerly isolated insect taxa and allow the study of ecological interactions between species with no coevolutionary history. Among polyphagous insects, such species may competitively exclude each other unless some form of niche partitioning allows them to coexist. 2.,In the present study, we investigate whether the ability to exploit different fruits can increase the likelihood of coexistence of four species of polyphagous Tephritidae, one endemic and three successive invaders, in the island of La Réunion. In the laboratory, we studied the performances of all four species on the four most abundant fruit resources in the island, as well as the relative abundances of fly species on these four fruit species in the field. We observe no indication of niche partitioning for any of the four abundant fruits. 3.,Analyses of an extensive field data series suggest that: (i) the four fly species largely overlap in fruit exploitation, once climatic effects are accounted for; (ii) however, one species (Ceratitis capitata) can exploit rare fruit species that are not exploited by others present in the same climatic niche; and (iii) the endemic species C. catoirii, now nearly extinct in La Réunion, has no private niche with respect to either climatic range or fruit use. 4.,On the whole, with the possible exception of C. capitata, the results point to a limited role of fruit diversity in encouraging coexistence among polyphagous tephritids recently brought into contact by accidental introductions. [source] Linking metal bioaccumulation of aquatic insects to their distribution patterns in a mining-impacted riverENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 6 2004Daniel J. Cain Abstract Although the differential responses of stream taxa to metal exposure have been exploited for bioassessment and monitoring, the mechanisms affecting these responses are not well understood. In this study, the subcellular partitioning of metals in operationally defined metal-sensitive and detoxified fractions were analyzed in five insect taxa. Samples were collected in two separate years along an extensive metal contamination gradient in the Clark Fork River (MT, USA) to determine if interspecific differences in the metal concentrations of metal-sensitive fractions and detoxified fractions were linked to the differences in distributions of taxa relative to the gradient. Most of the Cd, Cu, and Zn body burdens were internalized and potentially biologically active in all taxa, although all taxa appeared to detoxify metals (e.g., metal bound to cytosolic metal-binding proteins). Metal concentrations associated with metal-sensitive fractions were highest in the mayflies Epeorus albertae and Serratella tibialis, which were rare or absent from the most contaminated sites but occurred at less contaminated sites. Relatively low concentrations of Cu were common to the tolerant taxa Hydropsyche spp. and Baetis spp., which were widely distributed and dominant in the most contaminated sections of the river. This suggested that distributions of taxa along the contamination gradient were more closely related to the bioaccumulation of Cu than of other metals. Metal bioaccumulation did not appear to explain the spatial distribution of the caddisfly Arctopsyche grandis, considered to be a bioindicator of metal effects in the river. Thus, in this system the presence/absence of most of these taxa from sites where metal exposure was elevated could be differentiated on the basis of differences in metal bioaccumulation. [source] EVOLUTION OF INSECT METAMORPHOSIS: A MICROARRAY-BASED STUDY OF LARVAL AND ADULT GENE EXPRESSION IN THE ANT CAMPONOTUS FESTINATUSEVOLUTION, Issue 4 2005Michael A. D. Goodisman Abstract Holometabolous insects inhabit almost every terrestrial ecosystem. The evolutionary success of holometabolous insects stems partly from their developmental program, which includes discrete larval and adult stages. To gain an understanding of how development differs among holometabolous insect taxa, we used cDNA microarray technology to examine differences in gene expression between larval and adult Camponotus festinatus ants. We then compared expression patterns obtained from our study to those observed in the fruitfly Drosophila melanogaster. We found that many genes showed distinct patterns of expression between the larval and adult ant life stages, a result that was confirmed through quantitative reverse-transcriptase polymerase chain reaction. Genes involved in protein metabolism and possessing structural activity tended to be more highly expressed in larval than adult ants. In contrast, genes relatively upregulated in adults possessed a greater diversity of functions and activities. We also discovered that patterns of expression observed for homologous genes in D. melanogaster differed substantially from those observed in C. festinatus. Our results suggest that the specific molecular mechanisms involved in metamorphosis will differ substantially between insect taxa. Systematic investigation of gene expression during development of other taxa will provide additional information on how developmental pathways evolve. [source] The mitochondrial genome of the bristletail Petrobius brevistylis (Archaeognatha: Machilidae)INSECT MOLECULAR BIOLOGY, Issue 3 2006L. Podsiadlowski Abstract The complete mitochondrial genome of the bristletail Petrobius brevistylis has been determined. The genome is 15 698 bp long and bears the standard set of genes common to all arthropods as well as a major non-coding A + T-rich region, the putative mitochondrial control region. A unique gene order was revealed as it differs from other hexapod and crustacean mitochondrial genomes in the position of tRNA-Tyr. Genome features like nucleotide composition and codon usage are compared with that of other insect taxa. A + T content is similar in species of Archaeognatha and Zygentoma, but obviously lower than in Collembola and Pterygota. This A + T bias significantly affects also amino acid frequencies and may be a problem for phylogenetic analyses. [source] Metal concentrations of insects associated with the South African Ni hyperaccumulator Berkheya coddii (Asteraceae)INSECT SCIENCE, Issue 2 2006ROBERT S. BOYD Abstract The high levels of some metals in metal hyperaccumulator plants may be transferred to insect associates. We surveyed insects collected from the South African Ni hyperaccumulator Berkheya coddii to document whole-body metal concentrations (Co, Cr, Cu, Mg, Mn, Ni, Pb, Zn). We also documented the concentrations of these metals in leaves, stems and inflorescences, finding extremely elevated levels of Ni (4 700,16 000 ,g/g) and high values (5,34 ,g/g) for Co, Cr, and Pb. Of 26 insect morphotypes collected from B. coddii, seven heteropterans, one coleopteran, and one orthopteran contained relatively high concentrations of Ni (> 500 ,g/g). The large number of high-Ni heteropterans adds to discoveries of others (from California USA and New Caledonia) and suggests that members of this insect order may be particularly Ni tolerant. Nymphs of the orthopteran (Stenoscepa) contained 3 500 ,g Ni/g, the greatest Ni concentration yet reported for an insect. We also found two beetles with elevated levels of Mg (> 2 800 ,g/g), one beetle with elevated Cu (> 70 ,g/g) and one heteropteran with an elevated level of Mn (> 200 ,g/g). Our results show that insects feeding on a Ni hyperaccumulator can mobilize Ni into food webs, although we found no evidence of Ni biomagnification in either herbivore or carnivore insect taxa. We also conclude that some insects associated with hyperaccumulators can contain Ni levels that are high enough to be toxic to vertebrates. [source] Using scissors to quantify hardness of insects: do bats select for size or hardness?JOURNAL OF ZOOLOGY, Issue 4 2007P. W. Freeman Abstract Scissors are used to determine the hardness of fresh insects of different size and taxa. Our results indicate a strong relationship between the size of an insect and its hardness, which can be expressed as log(Fmax)=0.65 × log(V)+,. Fmax is the maximal force needed to cut the insect and is our measure of insect hardness. V is the volume of the insect and , is a constant that can be derived for different insect taxa. The value of 0.65 was found as an average of beetle and moth samples, and this number appears consistent across insect taxa. We found that beetles averaged about 3.2 times harder than moths of the same size. Beetles were also more variable in hardness than moths, with the softest beetles about equal in hardness to an average moth of the same size. Using our data on insect hardness coupled with data on the diets of bats and their bite forces from the literature, we attempt to determine whether the upper size limit of insects taken by a bat is limited by the insect's dimensions or its hardness. Our results indicate that both these factors may be important. [source] Endectocide residues affect insect attraction to dung from treated cattle: implications for toxicity testsMEDICAL AND VETERINARY ENTOMOLOGY, Issue 4 2007K. D. FLOATE Abstract A 3-year study was performed in southern Alberta, Canada to assess the effect of endectocide residues on the attractiveness of cattle dung to colonizing insects. In 2003 and 2004, insect captures were compared between pitfall traps baited with dung of untreated cattle and paired traps baited with dung of cattle that had been treated 7 days previously with topically applied doramectin, eprinomectin, ivermectin or moxidectin. Faecal residues associated with each compound affected insect captures in both spring and autumn of each year. Effects were detected (P < 0.05) for a total of 94 cases representing 27 insect taxa from 13 families in three orders (Coleoptera, Diptera, Hymenoptera). Two-fold differences in captures were common. Up to six-fold differences were observed. Eleven cases of attraction and 11 cases of repellency were associated with residues of doramectin. Eprinomectin tended to repel insects, with decreased captures for 19 of 29 cases of effect. Ivermectin showed a strong attractive effect, with increased captures for 17 of 25 cases. Moxidectin also showed a strong attractive effect, with increased captures for 17 of 18 cases. Comparisons between compounds suggested that results for doramectin best predicted results for eprinomectin and vice versa. In 2005, insect captures were compared between pitfall traps baited with dung of untreated cattle and traps baited with dung from cattle treated 3, 7 or 14 days previously with topically applied doramectin. Effects were detected in 14 cases plus one case of near significance (P= 0.053). Significant differences between control vs. days 3, 7 and/or 14 dung were detected in nine cases. Residues enhanced captures in seven of these cases. Day 14 dung affected captures in six of these cases. This study shows that endectocide residues can affect the number of insects attracted to colonize and oviposit in dung. Hence, the emergence of their offspring from field-colonized dung of untreated vs. endectocide-treated cattle should not be used as a measure of residue toxicity per se, but rather as a measure of ,insect activity'. Insect activity is a composite measure of residue toxicity, the number and species composition of insect colonists, and the mortality factors (e.g. predation, parasitism, competition) associated with the co-occurrence of these species in the dung pat. [source] The structure and function of auditory chordotonal organs in insectsMICROSCOPY RESEARCH AND TECHNIQUE, Issue 6 2004Jayne E. Yack Abstract Insects are capable of detecting a broad range of acoustic signals transmitted through air, water, or solids. Auditory sensory organs are morphologically diverse with respect to their body location, accessory structures, and number of sensilla, but remarkably uniform in that most are innervated by chordotonal organs. Chordotonal organs are structurally complex Type I mechanoreceptors that are distributed throughout the insect body and function to detect a wide range of mechanical stimuli, from gross motor movements to air-borne sounds. At present, little is known about how chordotonal organs in general function to convert mechanical stimuli to nerve impulses, and our limited understanding of this process represents one of the major challenges to the study of insect auditory systems today. This report reviews the literature on chordotonal organs innervating insect ears, with the broad intention of uncovering some common structural specializations of peripheral auditory systems, and identifying new avenues for research. A general overview of chordotonal organ ultrastructure is presented, followed by a summary of the current theories on mechanical coupling and transduction in monodynal, mononematic, Type 1 scolopidia, which characteristically innervate insect ears. Auditory organs of different insect taxa are reviewed, focusing primarily on tympanal organs, and with some consideration to Johnston's and subgenual organs. It is widely accepted that insect hearing organs evolved from pre-existing proprioceptive chordotonal organs. In addition to certain non-neural adaptations for hearing, such as tracheal expansion and cuticular thinning, the chordotonal organs themselves may have intrinsic specializations for sound reception and transduction, and these are discussed. In the future, an integrated approach, using traditional anatomical and physiological techniques in combination with new methodologies in immunohistochemistry, genetics, and biophysics, will assist in refining hypotheses on how chordotonal organs function, and, ultimately, lead to new insights into the peripheral mechanisms underlying hearing in insects. Microsc. Res. Tech. 63:315,337, 2004. © 2004 Wiley-Liss, Inc. [source] The relative importance of spatial aggregation and resource partitioning on the coexistence of mycophagous insectsOIKOS, Issue 1 2005Kazuo H. Takahashi The relative importance of spatial aggregation and resource partitioning on coexistence was investigated for mycophagous insects in central Japan. The effects of spatial aggregation and resource partitioning were separated by a randomization procedure. From 124 patches of macrosporophores belonging to 37 species, 3275 individuals belonging to 14 families of Diptera and 11 individuals to Lepidoptera emerged. Since the level of identification varied among insect taxa, the analysis was made in three ways; 1) for all taxa to assess the stability of the whole community, 2) for drosophilid species to assess their persistence in the community, and 3) for species of Drosophila and Mycodrosophila to assess their persistence against congeneric and heterogeneric species. Both spatial aggregation and resource partitioning functioned for the stability of whole mycophagous insect community, and spatial aggregation played a more important role than resource partitioning. On the other hand, only spatial aggregation functioned for the persistence of drosophilid species in the community. According to the analysis on species of Drosophila and Mycodrosophila against congeneric and heterogeneric species, the relative importance of resource partitioning was smaller for the coexistence of within-genus species pairs than for that of between-genus species pairs. These results suggest that the relative importance of these two mechanisms depends on the phylogenetic and guild diversity of community. [source] Evolutionary genetics of genital size and lateral asymmetry in the earwig Euborellia plebeja (Dermaptera: Anisolabididae)BIOLOGICAL JOURNAL OF THE LINNEAN SOCIETY, Issue 1 2010YOSHITAKA KAMIMURA Male genitalia show several evolutionary characteristics, including rapid morphological divergence between closely related species and low within-species phenotypic variability. In addition, genital asymmetry is widespread despite the essentially bilaterally symmetric external morphology of insects. Several hypotheses, such as sexual selection and lock-and-key hypotheses, have been proposed to explain these characteristics of genital evolution. Although these hypotheses provide different predictions about the genetic basis of variation in genitalia, detailed quantitative genetic studies have been conducted in only three insect taxa: heteropterans, dung beetles (Scarabaeidae), and drosophilid flies. For an anisolabidid earwig, Euborellia plebeja, characterized by paired elongated intromittent organs, we estimated the heritabilities and genetic correlations of genital laterality, size of genitalia, and body size. No statistically significant additive genetic, dominance, maternal, or common environmental effects were detected for genital laterality (readiness to use either the left or the right intromittent organ). This result lends further support to the general rule that the direction of antisymmetric variations is randomly determined by non-genetic factors. Irrespective of the restricted phenotypic variation in genitalia compared with body size (allometric slope < 1), as observed in previous studies for other insects, these two traits showed a similar level of genetic variation, measured as the narrow sense heritability (h2) and the coefficient of additive genetic variation (CVA). Comparison suggests the causes of interspecific differences in genetic variability/correlation structures were developmental processes (holo- or hemimetabolous) and/or mode of sexual selection. © 2010 The Linnean Society of London, Biological Journal of the Linnean Society, 2010, 101, 103,112. [source] Insect wing shape evolution: independent effects of migratory and mate guarding flight on dragonfly wingsBIOLOGICAL JOURNAL OF THE LINNEAN SOCIETY, Issue 2 2009FRANK JOHANSSON Although, in some insect taxa, wing shape is remarkably invariant, the wings of Anisopteran dragonflies show considerable variation among genera. Because wing shape largely determines the high energetic costs of flight, it may be expected that interspecific differences are partly due to selection. In the present study, we examined the roles of long-distance migration and high-manoeuvrability mate guarding in shaping dragonfly wings, using a phylogeny-based comparative method, and geometric morphometrics to quantify wing shape. The results obtained show that migration affects the shape of both front and hind wings, and suggest that mate guarding behaviour may also have an effect, especially on the front wing. These effects on front wing shape are at least partly independent. Our findings are interesting when compared with the geographically widespread and ecologically diverse dipterans Acalyptratae (including the genus Drosophila). The wings in that group are similar in function and structure, but show strikingly low levels of interspecific variation. © 2009 The Linnean Society of London, Biological Journal of the Linnean Society, 2009, 97, 362,372. [source] | ||||||||||