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Host Trees (host + tree)
Terms modified by Host Trees Selected AbstractsHost,parasite relations of an angiospermous root parasite (Thonningia sanguinea Vahl) in logged and unlogged sites of Budongo forest reserve, western UgandaAFRICAN JOURNAL OF ECOLOGY, Issue 3 2009Concy Acen Olanya Abstract Host,parasite relationships of an angiospermous root parasite (Thonningia sanguinea) were investigated in logged and unlogged sites of Budongo Forest Reserve. Host trees were identified and their diameters measured in 20 × 20 m plots established randomly in sites where the parasites were presumed to occur. The distance of the point of attachment of the parasite from the base of the host stem was determined and overstorey density measured at the centre of each plot. There were more parasites in the logged than in the unlogged sites (878 and 425 individual parasites ha,1 respectively). The parasite was not host specific but Alchornea laxiflora (Benth) Pax and K.Hoffm, Celtis mildbraedii Engl and Lasiodiscus mildbraedii Engl had relatively more parasites than other species. The parasite could be found within a radius of 2 m from the base of the host stem. The diameter of hosts ranged from 1 to 95 cm. There was a positive correlation between overstorey density and occurrence of T. sanguinea. Conservation of T. sanguinea, therefore, requires maintenance of intact forests with closed canopies rather than logged sites with many gaps and hence low overstorey density. Résumé On a étudié les relations hôte-parasite d'un angiosperme parasite des racines (Thonningia sanguinea) sur des sites exploités ou non de la Réserve forestière de Budongo. On a identifié les arbres hôtes et on a mesuré leur diamètre dans des parcelles de 20 × 20 m établies au hasard dans des sites où le parasite était supposé se trouver. La distance entre le point d'ancrage du parasite et la base du tronc de l'hôte fut déterminée, et la densité de la végétation aérienne fut mesurée au centre de chaque parcelle. Il y avait plus de parasites dans les parcelles exploitées que dans les parcelles nonexploitées (878 et 425 parasites par ha, respectivement). Le parasite n'était pas spécifique de l'hôte, mais Alchornea laxiflora (Benth) Pax et K.Hoffm, Celtis mildbraedii Engl et Lasiodiscus mildbraedii Engl avaient relativement plus de parasites que d'autres espèces. Le parasite peut se trouver dans un rayon de deux mètres de la base du tronc de l'hôte. Le diamètre du tronc de l'hôte variait de 1 à 95 cm. Il y avait une corrélation positive entre la densité de la végétation aérienne et l'occurrence de T. sanguinea. Donc, la conservation de T. sanguinea requiert la préservation de forêts intactes avec des canopées fermées plutôt que des sites exploités avec des nombreuses clairières et donc, une faible densité de couverture végétale. [source] Species richness patterns and metapopulation processes , evidence from epiphyte communities in boreo-nemoral forestsECOGRAPHY, Issue 2 2006Swantje Löbel For several epiphyte species, dispersal limitation and metapopulation dynamics have been suggested. We studied the relative importance of local environmental conditions and spatial aggregation of species richness of facultative and obligate epiphytic bryophytes and lichens within two old-growth forests in eastern Sweden. The effect of the local environment was analyzed using generalized linear models (GLM). We tested whether species richness was spatially structured by fitting variogram models to the residuals of the GLM. In addition, we analyzed the species-area relationship (area=tree diameter). Different environmental variables explained the richness of different species groups (bryophytes vs lichens, specialists vs generalists, sexual vs asexual dispersal). In most groups, the total variation explained by environmental variables was higher than the variation explained by the spatial model. Spatial aggregation was more pronounced in asexually than in sexually dispersed species. Bryophyte species richness was only poorly predicted by area, and lichen species richness was not explained by area at all. Spatial aggregation may indicate effects of dispersal limitation and metapopulation dynamics on community species richness. Our results suggest that species groups differ in habitat requirements and dispersal abilities; there were indications that presence of species with different dispersal strategies is linked to the age of the host tree. Separate analyses of the species richness of species groups that differ in the degree of habitat specialization and dispersal ability give insights into the processes determining community species richness. The poor species-area relationship, especially in lichens, may indicate species turnover rather than accumulation during the lifetime of the host tree. Epiphyte species extinctions may be mainly caused by deterministic processes, e.g. changes in habitat conditions as the host tree grows, ages and dies, rather than by stochastic population processes. [source] Importance of species interactions to community heritability: a genetic basis to trophic-level interactionsECOLOGY LETTERS, Issue 1 2006Joseph K. Bailey Abstract Recent community genetics studies have shown that specific genotypes of a host plant support distinct arthropod communities. Building upon these findings, we examined the hypothesis that a trophic community consisting of cottonwood trees, a galling herbivore and avian predators could also be related to the genetics of the host tree. We found genetic correlations among phytochemistry of individual tree genotypes, the density of a galling herbivore, and the intensity of avian predation on these herbivores. We detected significant broad-sense heritability of these interactions that range from H = 0.70 to 0.83. The genetic basis of these interactions tended to increase across trophic levels suggesting that small genetic changes in the cottonwood phenotype could have major consequences at higher trophic levels affecting species interactions and energy flow. These findings show a heritable basis to trophic-level interactions indicating that there is a significant genetic basis to community composition and energy flow that is predictable by plant genotype. Our data clearly link plant genetics to patterns of avian foraging and show that species interactions are important components of community heritability and ecosystem processes. Overall, these data support the hypothesis that evolution of plant traits can alter trophic-level interactions and community composition. [source] Trophic Egg Production in a Subsocial Shield Bug, Parastrachia japonensis Scott (Heteroptera: Parastrachiidae), and its Functional ValueETHOLOGY, Issue 12 2005Mantaro Hironaka Females of the gregarious shield bug, Parastrachia japonensis Scott (Heteroptera: Parastrachiidae) engage in extensive parental care behaviors that include egg and nymph guarding and progressive provisioning of drupes of the solitary host tree, Schoepfia jasminodora (Olacaceae: Rosidae: Santales). We noted that some eggs in every egg mass failed to turn pink and develop eye-spots indicative of developing embryos, suggesting that they are infertile, and therefore non-viable. We also observed newly hatched nymphs probing, and presumably feeding, on the egg mass remains. In the present report, through field observations and experiments involving removal of these non-viable eggs in the laboratory, we demonstrate that their presence is correlated with significant increases in nymphal weight, developmental rate and survival in the absence of other food. Thus, we conclude that an additional manifestation of the parental care behaviors that P. japonensis females use to increase their reproductive success is the production of trophic eggs. Some physical traits of the trophic eggs and their functional role in this system are discussed in the context of our current theoretical understanding of extended parental care. [source] Variations in parasitism in sympatric populations of three invasive leaf minersJOURNAL OF APPLIED ENTOMOLOGY, Issue 9-10 2007S. Girardoz Abstract:, Parasitism was investigated in sympatric populations of three invasive gracillariid leaf miners in Europe, Cameraria ohridella, Phyllonorycter robiniella and Phyllonorycter platani to test the hypotheses that C. ohridella is less heavily parasitized by native parasitoids and attacked by fewer species than the two other invasive species. In all regions investigated, C. ohridella showed a lower parasitism rate, and its parasitoid complex was poorer in species than those of either Phyllonorycter spp. Comparisons were made between sympatric populations of C. ohridella on its main host tree, Aesculus hippocastanum, and an occasional host, Acer pseudoplatanus. Parasitism rates were similarly low and composed of the same parasitoid species on both trees. In contrast, a sympatric population of Phyllonorycter geniculella, a native species mining A. pseudoplatanus, was heavily parasitized by a totally different parasitoid complex. These results suggest that the low parasitism in C. ohridella by native polyphagous leaf miner parasitoids is due neither to its host tree, nor to a problem of synchronization between the phenology of the pest and that of its parasitoids. Instead, it probably results from the inability of the native parasitoids to locate, attack, or develop on a new host that does not have any native congener in Europe. [source] Bark beetle-mediated fungal infections of susceptible trees induce resistance to subsequent infections in a dose dependent mannerAGRICULTURAL AND FOREST ENTOMOLOGY, Issue 3 2009Nadir Erbilgin Abstract 1,Experiments were conducted to determine whether propagule loads on the twig beetles Pityophthorus setosus and Pityophthorus carmeli (Coleoptera: Scolytidae) influence the pathogen infection of the host tree in the Monterey pine- Fusarium circinatum system. 2,On an average, F. circinatum was isolated from 2.6% and 3.3% of trapped P. setosus and P. carmeli, respectively, although the isolation percentages varied over the season, being highest in the spring and lowest in late summer and fall for both species. Mean pathogen load was 13.4 and 22.6 propagules per beetle, on P. setosus and P. carmeli, respectively, and decreased from May to November for both species. The pathogen was also isolated from approximately 55% of both beetle species that emerged from infected branches. Mean propagule load on emerged P. setosus and P. carmeli was 39 and 66.5, respectively. 3,On the basis of these data, beetle species were treated with one of three propagule loads (low, medium, high) and caged onto live branches to determine whether they could transmit the pathogen. At all propagule loads, both species transmitted the pathogen, and transmission percentage and lesion length, a measure of tree susceptibility, were positively correlated with propagule load. 4,To investigate further whether the previous transmission by beetles could affect response of the same trees to subsequent infection with F. circinatum, different branches were inoculated on the same trees used in the transmission study, and lesion lengths were measured. Lesion lengths were lower on trees that had been previously exposed to beetles treated with high or medium propagule loads than on trees that had previously been exposed to beetles treated with low propagule loads. This suggests that the initial infection by beetles carrying high or medium propagule loads induced resistance to subsequent infections of the host, whereas infections caused by beetles with low propagule loads did not. [source] Distribution and population genetic structure of the Mediterranean pine shoot beetle Tomicus destruens in the Iberian Peninsula and Southern FranceAGRICULTURAL AND FOREST ENTOMOLOGY, Issue 2 2006Teresa Vasconcelos Abstract 1,The Mediterranean pine shoot beetle Tomicus destruens has long been indistinguishable from its congeneric Tomicus piniperda. Both species attack pines, and can be found in sympatry. The geographical distribution of T. destruens is still unclear in most of the Mediterranean Basin. 2,We aimed to describe the geographical distribution and zones of sympatry of both species in the Iberian Peninsula and France, and to study the molecular phylogeographical pattern of T. destruens. 3,Tomicus spp. adults were sampled in Portugal, Spain and France, and a portion of the mitochondrial genes COI and COII was sequenced for 84 individuals. Sequences were aligned to a data set previously obtained from French localities. 4,Tomicus destruens was found in all populations, except for one locality in Portugal and in the Landes (France). It was in sympatry with T. piniperda in two locations on Pinus pinaster and one location on Pinus radiata. 5,Within-population genetic diversity was high, but we found a significant pattern of spatial distribution of genetic variation, as well as a significant effect of the host tree. 6,The data suggest the existence of two glacial refugia, from which T. destruens recolonized its current range. One refugium was located in Portugal where the beetle probably evolved on P. pinaster. The corresponding haplotypes show a West,East frequency gradient. The other refugium was probably in the eastern range, where the beetles evolved on Pinus halepensis and P. pinea. The corresponding haplotypes show an East,West frequency gradient. [source] Selective manipulation of predators using pheromones: responses to frontalin and ipsdienol pheromone components of bark beetles in the Great Lakes regionAGRICULTURAL AND FOREST ENTOMOLOGY, Issue 3 2005Brian H. Aukema Abstract 1,One proposed approach to improving biological control of bark beetles (Coleoptera: Scolytidae; alt. Curculionidae: Scolytinae) is to manipulate predator movement using semiochemicals. However, selective manipulation is impeded by attraction of both predators and pests to bark beetle pheromones. 2,The primary bark beetle affecting pine plantations in Wisconsin, U.S.A., is the pine engraver, Ips pini (Say). Other herbivores include Ips grandicollis (Eichhoff) and Dryophthorus americanus Bedel (Curculionidae). The predominant predators are the beetles Thanasimus dubius (Cleridae) and Platysoma cylindrica (Histeridae). 3,We conducted field assays using two enantiomeric ratios of ipsdienol, and frontalin plus ,-pinene. Ipsdienol is the principal pheromone component of I. pini, and frontalin is produced by a number of Dendroctonus species. ,-Pinene is a host monoterpene commonly incorporated into commercial frontalin lures. 4,Thanasimus dubius was attracted to frontalin plus ,-pinene, and also to racemic ipsdienol. By contrast, I. pini was attracted to racemic ipsdienol, but showed no attraction to frontalin plus ,-pinene. Platysoma cylindrica was attracted to 97%-(,)-ipsdienol and, to a lesser extent, racemic ipsdienol, but not to frontalin plus ,-pinene. Ips grandicollis was attracted to frontalin plus ,-pinene but not to ipsdienol. Dryophthorus americanus was attracted to both ipsdienol and frontalin plus ,-pinene. 5,This ability to selectively attract the predator T. dubius without attracting the principal bark beetle in the system, I. pini, provides new opportunities for research into augmentative biological control and basic population dynamics. Moreover, the attraction of T. dubius, but not P. cylindrica, to frontalin plus ,-pinene creates opportunities for selective manipulation of just one predator. 6,Patterns of attraction by predators and bark beetles to these compounds appear to reflect various degrees of geographical and host tree overlap with several pheromone-producing species. [source] Vertical distribution of Hymenophyllaceae species among host tree microhabitats in a temperate rain forest in Southern ChileJOURNAL OF VEGETATION SCIENCE, Issue 4 2009Maria J. Parra Abstract Question: Are differences in microhabitat preferences of co-occurring epiphytic Hymenophyllaceae species (filmy ferns) correlated with differences in ecophysiological responses to light availability and humidity in the host tree? Location: The Andean foothills in south-central Chile. Methods: We evaluated the distribution pattern of nine filmy fern species in microhabitats that differ in light availability and humidity in four host tree species. A DCA was developed to assess Hymenophyllaceae species microhabitat preference in terms of canopy openness (CO) and relative humidity. We assessed whether differences in chlorophyll content, maximum photochemical efficiency (Fv/Fm), photosynthetic capacity (Amax), evapotranspiration (E) and instantaneous water use efficiency (WUE) are consistent with any pattern. Results: CO and relative humidity differed significantly with height in the host trees. While CO increased with height in a host tree, relative humidity decreased. DCA analysis showed that filmy fern species distribution within and among trees was mainly explained by the relative humidity of the microhabitat. Chlorophyll content, chlorophyll a/b ratio, Amax and E differed significantly among filmy fern species. Amax and E were correlated with axis 1 scores from the DCA analysis. Conclusions: The vertical distribution and abundance of filmy fern species in Chilean temperate rain forest seems to be closely related to the different microhabitats offered by host trees. This pattern may reflect interspecific differences in ecophysiological traits related both to light availability and humidity. Our results suggest that humidity is the main environmental factor driving functional responses and habitat preferences of these filmy fern species. [source] Cophylogeny of the Ficus microcosmBIOLOGICAL REVIEWS, Issue 4 2004Andrew P. Jackson ABSTRACT The various mutualistic and antagonistic symbioses between fig trees (Ficus: Moraceae) and chalcid wasps comprise a community in microcosm. Phylogenetic estimates of figs and fig wasps show general topological correspondence, making the microcosm a model system for cophylogeny. Incongruence between phylogenies from associated organisms can be reconciled through a combination of evolutionary events. Cophylogeny mapping reconciles phylogenies by embedding an associate tree into a host tree, finding the optimal combinations of events capable of explaining incongruence and evaluating the level of codivergence. This review addresses the results of cophylogeny analysis concerning Ficus and discusses the plausibility of different evolutionary events. Five different associations encompassing fig-pollinator, fig-parasite and pollinator-parasitoid interactions are reconciled. The method improves on previous comparisons by employing,jungles'to provide an exhaustive and quantitative analysis of cophylogeny. A jungle is a mechanism for inferring host switches and obtaining all potentially optimal solutions to the reconciliation problem. The results support the consensus that figs codiverge significantly with pollinators but not non-pollinators. However, pollinators still appear to have switched between hosts in contradiction to the traditional model of faithful codivergence. This emphasises the growing realisation that evolutionary transitions in the microcosm are more flexible than previously thought and host specificity is necessary but not sufficient for codivergence. The importance of sampling strategy is emphasised by the influence of taxon set on the fig-pollinator and fig-parasite jungles. Spurious significant results for fig-parasite and fig-parasitoid jungles indicate that the choice of congruence measure influences significance; the total number of events required to reconcile two trees ('total cost') is not a good measure of congruence when switches cannot be realistically weighted. [source] Spatial Distribution of Vascular Epiphytes (including Hemiepiphytes) in a Lowland Amazonian Rain Forest (Surumoni Crane Plot) of Southern Venezuela,BIOTROPICA, Issue 3 2000Jürgen Nieder ABSTRACT The mobile crane of the Surumoni project allowed for the first time ever a complete inventory and spatial description of the epiphytic vegetation of a tropical lowland rain forest plot (1.5 ha), at La Esmeralda on the upper Orinoco River, Venezuela. A total of 778 individual vascular epiphytes of 53 species was found, dominated by 19 orchid species and 14 species of Araceae. Fifty percent of all individual plants were obligate ant-garden epiphytes. The distribution of epiphytes was highly clumped and not random. The clumped occurrence of holoepiphytes (complete life cycle on host tree) was the consequence of the rarity of suitable phorophytes (host trees; e.g., size and age) in the plot and the preference of ants for gaps where most of the ant-garden epiphytes were found. In comparison, hemiepiphytes were distributed more evenly because of greater independence from tree suitability. The dispersal modes of epiphytes did not explain their distribution patterns. There was no consistent difference in distribution between anemochorous and zoochorous epiphytes, presumably because availability of suitable substrate is the more important factor for epiphyte establishment and growth. Whereas the vertical distribution of epiphytes could be attributed largely to deterministic factors such as physiological adaptation and requirements, horizontal distribution appeared to be governed by suitable substrate, which in turn seemed to be governed by stochastic gap formation. RESUMEN En el context0 del proyecto Surumoni se hizo un inventario y un analisis espacial de la vegetación epifitica de un plot de 1.5 ha en el alto rio Orinoco cerca de La Esmeralda (Venezuela) en 1997. Consiste de 778 plantas individuales de 53 especies, entre las cuales destacan las orquideas (19 especies) y las aráceas (14 especies). El 50 porciento de todas las epifitas se encuentran en los jardines epifiticas de hormigas. Las plantas epifiticas muestran una distribución aglomerada y no casual. En el caso de las holoepifitas esto es la consecuencia de la raridad de forófitas aduecadas (p.e., altura y edad) en el plot y la preferencia de claros ("gaps") por parte de las hormigas. En comparación, tienen una distribución más homogénea las hemi-epifitas porque se desarrollan más independientemente de la calidad de sus forofitas. Las estrategias de dispersión de las epifitas sólo en parte explica sus patrones de distribución. No hay diferencias consistentes entre especies anemocorias y zoocorias, probablemente porque la disponibilidad de sustrato adecuado es el factor más importante para el establecimiento y desarrollo de epifitas. La distribución vertical de las epifitas se caracteriza por una zonación marcada, visible en las diferencias significantes entre la rnayoria de las taxas epifiticas. Mientras que se puede atribuir la distribución vertical a factores deterministicos como adaptaciones y exigencias fisiológicos de las plantas epifiticas, su distribución horizontal se arregla según la presencia de sustrato adecuado, que por su parte es resultado de factores estoquáticos en la formación de claros. [source] Scale dependence of effective specialization: its analysis and implications for estimates of global insect species richnessDIVERSITY AND DISTRIBUTIONS, Issue 1 2007Jon C. Gering ABSTRACT Estimates of global insect species richness are sometimes based on effective specialization, a calculation used to estimate the number of insect species that is restricted to a particular tree species. Yet it is not clear how effective specialization is influenced by spatial scale or characteristics of the insect community itself (e.g. species richness). We investigated scale dependence and community predictors of effective specialization using 15,907 beetles (583 species) collected by insecticide fogging from the crowns of 96 trees (including 32 Quercus trees) located in Ohio and Indiana. Trees were distributed across 24 forest stands (,1 ha) nested within six sites (,10,100 km2) and two ecoregions (> 1000 km2). Using paired-sample randomization tests, we found that effective specialization (fk) exhibited negative scale-dependence in early (May,June 2000) and late (August,September 2000) sampling periods. Our average effective specialization (F) values , those that are comparable to Erwin's (1982) estimates , ranged from 19% to 97%, and increased as spatial scale decreased. We also found that beetle species richness and the number of shared beetle species across host trees were significant and consistent negative predictors of F. This shows that increases in spatial scale, species richness, and the number of trees (and/or tree species) all coincide with decreases in effective specialization. Collectively, our results indicate that estimates of global insect species richness based on effective specialization at a single spatial scale are overestimating the magnitude of global insect species richness. We propose that scale dependence should be promoted to a central concept in the research program on global estimates of species richness. [source] Variation in mistletoe seed deposition: effects of intra- and interspecific host characteristicsECOGRAPHY, Issue 2 2002Juliann Eve Aukema We investigated differences in host infection by a desert mistletoe, Phoradendron californicum, and examined one of the processes that contributes to these differences: variation in seed deposition among host individuals and species. In the Sonoran Desert, P. californicum parasitizes the sympatric leguminous trees Olneya tesota, Cercidium microphyllum, Prosopis velutina, Acacia constricta, and Acacia greggii. We hypothesized that seed deposition depends on host height and crown architecture. At a site in Arizona, frequency of infection did not reflect host relative abundance. Olneya tesota was parasitized at a higher frequency than expected from its abundance and maintained the highest mistletoe loads per individual host. In contrast, P. velutina was infected less frequently than expected. Infection frequency increased with host tree height for all hosts. Mistletoe seed deposition by avian dispersers differed among host species and was disproportionately high in O. tesota and P. velutina. Seed deposition was higher in infected than in non-infected host trees, and increased with tree height in O. tesota but not in C. microphyllum. We suspect that increased seed deposition with height in O. tesota may be due to the preference of seed-dispersing birds for higher perches. Some host tree species, such as C. microphyllum and A. constricta, probably received fewer mistletoe seeds because birds avoid hosts with dense and spiny crowns. Mistletoe populations are plant metapopulations in which host trees are patches and the frequency of infection in each host species/patch type is the result of interspecific differences in the balance between mistletoe colonization and extinction. From this perspective, our study of host use and seed dispersal is a metapopulation study of patch occupancy and propagule distribution among available patch types. Our seed-dispersal study demonstrates that the mechanisms that create pattern in patchy plant populations can be investigated in mistletoe systems. [source] Bacteria in oral secretions of an endophytic insect inhibit antagonistic fungiECOLOGICAL ENTOMOLOGY, Issue 6 2006YASMIN J. CARDOZA Abstract 1.,Colonisation of host trees by an endophytic herbivore, the spruce beetle, Dendroctonus rufipennis, is accompanied by invasion of its galleries by a number of fungal species. Four of these associated species were identified as Leptographium abietinum, Aspergillus fumigatus, Aspergillus nomius, and Trichoderma harzianum. 2.,Trichoderma and Aspergillus significantly reduced spruce beetle survival and reproduction in controlled assays. 3.,A previously undescribed behaviour was observed, in which spruce beetle adults exuded oral secretions, especially within fungus-pervaded galleries. 4.,These oral secretions inhibited the growth of fungi except A. nomius, and disrupted the morphology of the latter. Administration of these secretions indicated a dose-dependent inhibitory effect. 5.,Oral secretions cultured on microbiological media yielded substantial bacterial growth. 6.,Filter-sterilised secretions failed to inhibit fungal growth, evidence that the bacteria are responsible for the antifungal activity. 7.,Nine bacterial isolates belonging to the Actinobacteria, Firmicutes, Gammaproteobacteria, and Betaproteobacteria taxa were obtained from the secretions. 8.,Bacterial isolates showed species-specific inhibitory activity against the four fungi antagonistic to spruce beetle. The bacterium with the strongest fungal inhibition activity was the actinomycete Micrococcus luteus. 9.,The production of bark beetle secretions containing bacteria that inhibit fungal growth is a novel finding. This suggests an additional level of complexity to ecological associations among bark beetles, conifers, and microorganisms, and an important adaptation for colonising subcortical tissue. [source] Community structure of arboreal caterpillars within and among four tree species of the eastern deciduous forestECOLOGICAL ENTOMOLOGY, Issue 6 2003Keith S. Summerville Abstract., 1.,A seasonally replicated experimental design was used to address the question of how differences within and among host tree species affect arboreal caterpillar communities. 2.,Seasonal variation influenced caterpillar community composition most significantly, and the similarity among caterpillar assemblages did not necessarily follow the pattern of phylogenetic relatedness among host trees. 3.,Species richness and abundance of caterpillars were higher on oaks and maples than on American beech. Diversity partitioning models revealed that , diversity was only occasionally greater or less than expected by chance alone. 4.,When , diversity was significant, values tended to be greater than expected by chance among replicate trees within each species and lower than expected by chance among the four tree species. 5.,Differences among trees appeared important for determining patterns of species presence/absence for rare species and influencing patterns of species dominance within caterpillar assemblages. Differences among tree species had a significant effect on overall lepidopteran community composition and mean species diversity (i.e. , diversity). 6.,Because , diversity of caterpillars among host trees was lower than expected by chance, host specificity within the Lepidoptera may be less prevalent than thought previously. [source] Novel insect-tree associations resulting from accidental and intentional biological ,invasions': a meta-analysis of effects on insect fitnessECOLOGY LETTERS, Issue 4 2010Coralie Bertheau Ecology Letters (2010) 13: 506,515 Abstract The translocation of species beyond their native range is a major threat to biodiversity. Invasions by tree-feeding insects attacking native trees and the colonization of introduced trees by native insects result in new insect,tree relationships. To date there is uncertainty about the key factors that influence the outcome of these novel interactions. We report the results of a meta-analysis of 346 pairwise comparisons of forest insect fitness on novel and ancient host tree species from 31 publications. Host specificity of insects and phylogenetic relatedness between ancient and novel host trees emerged as key factors influencing insect fitness. Overall, fitness was significantly lower on novel host species than on ancient hosts. However, in some cases, fitness increased on novel hosts, mainly in polyphagous insects or when close relatives of ancient host trees were colonized. Our synthesis enables greatly improved impact prediction and risk assessment of biological invasions. [source] Dispersal and influences on movement for Anoplophora glabripennis calculated from individual mark-recaptureENTOMOLOGIA EXPERIMENTALIS ET APPLICATA, Issue 2 2005J.S. Bancroft Abstract We conducted an individual mark-release-recapture experiment on the beetle, Anoplophora glabripennis Motchulsky (Coleoptera: Cerambycidae). This invasive beetle has been introduced from Asia to Europe and North America and poses a serious threat to several important species of tree. Eradication efforts may benefit from knowledge of dispersal behaviour. Trees were cut and held to determine emergence rate of A. glabripennis. Unique marks were painted onto 912 beetles released into a group of 165 trees in Gansu, China. Data on subsequent sightings of beetles were used in a truncated diffusion model to calculate flight distances. Characteristics of the trees and climatic information were used in statistical tests for influence on movement. A total of 2245 sightings of beetles were observed and 29% of marked beetles were resighted. The scanning technique using binoculars was 90% effective in finding beetles and provided 81% accuracy for determining the sex of the beetles. Experimental manipulation of density quantified how A. glabripennis congregated on unoccupied trees and were repulsed from crowded hosts. The seasonal emergence rate of adults declined exponentially from July 20 to August 5. The results suggested A. glabripennis fly to nearby host trees at a rate of 34% per day. Median flight distance was estimated at 20 m per day. Statistical analysis with a generalized linear model tested the beetle's propensity to leave a tree and distance of flight. Generally, beetle movement showed a significant response to beetle density, weather conditions, beetle size, and tree size, in that order. The techniques developed here improve on previous recapture techniques to quantify dispersal and can be useful for analysing populations of other organisms. [source] Cecidophagy in adults of Demotina fasciculata (Coleoptera: Chrysomelidae) and its effect on the survival of Andricus moriokae (Hymenoptera: Cynipidae) inhabiting leaf galls on Quercus serrata (Fagaceae)ENTOMOLOGICAL SCIENCE, Issue 1 2010Takayoshi KATSUDA Abstract Females of Demotina fasciculata (Coleoptera: Chrysomelidae) were found to prefer to feed on galls induced by Andricus moriokae (Hymenoptera: Cynipidae) rather than on leaves of its host plant, Quercus serrata (Fagaceae). This is the first record of cecidophagy by adult chrysomelid beetles. Demotina fasciculata did not infest healthy galls induced by another unidentified cynipid species on the same host trees, but did feed on galls inhabited by an inquiline species Synergus quercicola (Hymenoptera: Cynipidae), presumably because such galls remained on the host trees longer than healthy galls. Galls of A. moriokae were infested more severely than cynipid galls inhabited by the inquiline. Therefore, higher density and thicker gall wall in A. moriokae galls seem to make them more suitable targets for D. fasciculata to attack. Larval chambers of A. moriokae galls were stripped by the infestation of gall walls and readily dropped to the ground, resulting in 100% death of cynipid larvae due to desiccation, while 62.5% of pupae survived when they had developed to the late stadium before the fall of larval chambers. [source] Lichen extracts as raw materials in perfumery.FLAVOUR AND FRAGRANCE JOURNAL, Issue 3 2009Part 2: treemoss Abstract This is a comprehensive review of extracts from the lichen Pseudevernia furfuracea (treemoss) that are used in the fragrance industry. Qualitative and quantitative analytical aspects are critically reviewed and the results are compared to those of the related oakmoss extracts. It is shown that more than 90 constituents have been identified so far in treemoss extracts, including 42 depsides, depsidones or depside-derived compounds, and 42 triterpenes or steroids. Constituents of certain host trees, mainly Pinus species, generate specific analytical and toxicological issues which need to be considered in addition to those related to the known degradation products of lichen compounds. A new classification of lichen extracts used as raw materials in fragrance compounding is proposed. Copyright © 2009 John Wiley & Sons, Ltd. [source] Climate change and range expansion of an aggressive bark beetle: evidence of higher beetle reproduction in naïve host tree populationsJOURNAL OF APPLIED ECOLOGY, Issue 5 2010Timothy J. Cudmore Summary 1.,Hosts may evolve defences that make them less susceptible and suitable to herbivores impacting their fitness. Due to climate change-driven range expansion, herbivores are encountering naïve host populations with increasing frequency. 2.,Aggressive bark beetles are among the most important agents of disturbance in coniferous forest ecosystems. The presence of bark beetle outbreaks in areas with a historically unsuitable climate, in part a consequence of climate change, provided an opportunity to assess the hypothesis that the mountain pine beetle Dendroctonus ponderosae has higher reproductive success in lodgepole pine Pinus contorta trees growing in areas that have not previously experienced frequent outbreaks. 3.,We felled and sampled mountain pine beetle-killed trees from historically climatically suitable and unsuitable areas, i.e. areas with and without a historical probability of frequent outbreaks. Reproductive success was determined from a total of 166 trees from 14 stands. 4.,Brood productivity was significantly affected by climatic suitability class, such that mean brood production per female increased as historical climatic suitability decreased. 5.,Synthesis and applications. The current study demonstrates that the mountain pine beetle has higher reproductive success in areas where its host trees have not experienced frequent beetle epidemics, which includes much of the current outbreak area in north central British Columbia. This increased productivity of mountain pine beetle is likely to have been a key reason for the rapid population buildup that resulted in unprecedented host tree mortality over huge areas in western Canada. The outbreak thus provides an example of how climate change-driven range expansion of native forest insects can have potentially disastrous consequences. Since an increased reproductive success is likely to accelerate the progression of outbreaks, it is particularly critical to manage forests for the maintenance of a mosaic of species and age classes at the landscape level in areas where host tree populations are naïve to eruptive herbivores. [source] Single host trees in a closed forest canopy matrix: a highly fragmented landscape?JOURNAL OF APPLIED ENTOMOLOGY, Issue 9-10 2007J. Müller Abstract:, Whether trees represent habitat islands and therefore are influenced by similar biogeographic processes as ,real' islands is controversial. For trees in highly fragmented landscapes the impacts of spatial isolation on arthropod communities have already been demonstrated. However, we have almost no evidence that in large forests the arthropod communities on single trees in a closed canopy matrix are influenced by similar processes. In the present study the influence of spatial isolation on the specialized oak crown fauna was analysed in a large broadleaved forest area in northern Bavaria, Germany. The dependence of specialists on the proportion of oaks in the surrounding forest was investigated by using flight interception traps (67 on oak, 19 on beech). As target species, saproxylic and herbivorous Coleoptera and Heteroptera were sampled. The following two hypotheses were tested: (1) The proportion of oak specialists differs for oaks in beech forests and oaks in oak forests. (2) The proportion of oak specialists increases with the proportion of oaks in the surrounding forest. For all species groups, the proportion of oak specialists was higher in oak crowns than in beech crowns. Herbivorous beetles and true bugs showed a higher proportion of specialists in oak forests than on single oaks in beech forests. The proportion of herbivorous oak specialists increased significantly with increasing numbers of adjacent oak trees, while saproxylic Coleoptera showed no relationship to oak density. For herbivorous Coleoptera a threshold of higher proportion occurred where >30% oak was present, and for Heteroptera a first threshold was identified at values >70% and a second at >30%. This indicates that larger habitat patches within a closed forest canopy matrix support larger populations of herbivorous oak specialists. Hence, similar effects of spatial isolation might occur in a closed forest as have already been shown for highly fragmented open landscapes. [source] Size of orchard trees as a factor affecting behavioural control of apple maggot flies (Dipt., Tephritidae) by trapsJOURNAL OF APPLIED ENTOMOLOGY, Issue 7 2001R. J. Prokopy Over a 3-year period (1997,1999), we examined the influence of tree size on effectiveness of traps for behaviourally controlling apple maggot flies, Rhagoletis pomonella (Walsh), in small blocks of trees in Massachusetts commercial apple orchards. Traps were red spheres coated with Tangletrap and baited with an attractive synthetic host fruit odour (butyl hexanoate). Traps were placed 6 m apart on perimeter apple trees of each block and were designed to intercept apple maggot flies immigrating into blocks from unmanaged host trees. Based on captures of adults by unbaited red spheres placed near the centre of each block to monitor degree of adult penetration into the interior and on percentages of fruit injured by apple maggot, traps surrounding blocks of small trees (1.5 m canopy diameter) planted at high density were more effective in controlling apple maggot flies (relative to control obtained by insecticide sprays used in comparison blocks) than were traps surrounding blocks of large trees (3.7 m canopy diameter) planted at low density, with traps surrounding blocks of medium-size trees (2.5 m canopy diameter) planted at medium density generally providing an intermediate level of control. [source] Performance of seedlings of the invasive alien tree Schinus molle L. under indigenous and alien host trees in semi-arid savannaAFRICAN JOURNAL OF ECOLOGY, Issue 1 2010Donald M. Iponga Abstract We assessed the importance of host trees in influencing invasion patterns of the alien tree Schinus molle L. (Anacardiaceae) in semi-arid savanna in South Africa. Recruitment of S. molle is dependent on trees in its invaded habitat, particularly Acacia tortilis Hayne. Another leguminous tree, the invasive alien mesquite (Prosopis sp.), has become common in the area recently, but S. molle rarely recruits under canopies of this species. Understanding of the association between these species is needed to predict invasion dynamics in the region. We conducted experiments to test whether: (i) seedling survival of S. molle is better beneath A. tortilis than beneath mesquite canopies; (ii) growth rates of S. molle seedlings are higher beneath A. tortilis than beneath mesquite. Results showed that growth and survival of S. molle did not differ significantly beneath the native A. tortilis and the alien Prosopis species. This suggests that microsites provided by canopies of mesquite are as good for S. molle establishment as those provided by the native acacia. Other factors, such as the failure of propagules to arrive beneath mesquite trees, must be sought to explain the lack of recruitment beneath mesquite. Résumé Nous avons évalué l'importance des arbres hôtes dans les facteurs qui influencent les schémas d'envahissement de l'arbre exotique Scinus molle L. (Anacardiaceae) dans une savane semi aride d'Afrique du Sud. Le recrutement de S. molle dépend des arbres de l'habitat qu'il envahit, et particulièrement de l'Acacia tortilis Hayne. Un autre arbre de la famille des légumineuses, l'envahissant « mesquite » (Prosopis sp.), est devenu commun dernièrement dans la région, mais S. molle recrute rarement sous la canopée de cette espèce. Il est nécessaire de bien comprendre l'association entre ces espèces pour prévoir la dynamique des envahissements dans la région. Nous avons réalisé des expériences pour tester si : i) la survie des jeunes plants de S. molle est meilleure sous une canopée d'Acacia tortilis que de « mesquite »; ii) le taux de croissance des jeunes plants de S. molle est supérieur sous les A. tortilis que sous les « mesquite ». Les résultats montrent que la croissance et la survie de S. molle ne sont pas significativement différentes sous les espèces natives Acacia tortilis natifs et sous les espèces exotiques de Prosopis. Ceci suggère que les microsites constitués par les canopées de « mesquite » sont aussi bons pour l'établissement de S. molle que ceux qu'offrent les acacias natifs. D'autres facteurs, tels que le fait que les propagules ne parviennent pas à arriver jusque sous les « mesquite », pourraient être invoqués pour expliquer le manque de recrutement sous ces arbres. [source] Invasive alien plants infiltrate bird-mediated shrub nucleation processes in arid savannaJOURNAL OF ECOLOGY, Issue 4 2007S. J. MILTON Summary 1,The cultivation and dissemination of alien ornamental plants increases their potential to invade. More specifically, species with bird-dispersed seeds can potentially infiltrate natural nucleation processes in savannas. 2To test (i) whether invasion depends on facilitation by host trees, (ii) whether propagule pressure determines invasion probability, and (iii) whether alien host plants are better facilitators of alien fleshy-fruited species than indigenous species, we mapped the distribution of alien fleshy-fruited species planted inside a military base, and compared this with the distribution of alien and native fleshy-fruited species established in the surrounding natural vegetation. 3Abundance and diversity of fleshy-fruited plant species was much greater beneath tree canopies than in open grassland and, although some native fleshy-fruited plants were found both beneath host trees and in the open, alien fleshy-fruited plants were found only beneath trees. 4Abundance of fleshy-fruited alien species in the natural savanna was positively correlated with the number of individuals of those species planted in the grounds of the military base, while the species richness of alien fleshy-fruited taxa decreased with distance from the military base, supporting the notion that propagule pressure is a fundamental driver of invasions. 5There were more fleshy-fruited species beneath native Acacia tortilis than beneath alien Prosopis sp. trees of the equivalent size. Although there were significant differences in native plant assemblages beneath these hosts, the proportion of alien to native fleshy-fruited species did not differ with host. 6Synthesis. Birds facilitate invasion of a semi-arid African savanna by alien fleshy-fruited plants, and this process does not require disturbance. Instead, propagule pressure and a few simple biological observations define the probability that a plant will invade, with alien species planted in gardens being a major source of propagules. Some invading species have the potential to transform this savanna by overtopping native trees, leading to ecosystem-level impacts. Likewise, the invasion of the open savanna by alien host trees (such as Prosopis sp.) may change the diversity, abundance and species composition of the fleshy-fruited understorey. These results illustrate the complex interplay between propagule pressure, facilitation, and a range of other factors in biological invasions. [source] Ecology and management of exotic and endemic Asian longhorned beetle Anoplophora glabripennisAGRICULTURAL AND FOREST ENTOMOLOGY, Issue 4 2009Jiafu Hu Abstract 1The Asian longhorned beetle is native to China and Korea, and was found for the first time outside its native habitat in the U.S.A. in 1996, with subsequent detections being made in Canada and several European countries. 2We review the taxonomy, distribution, basic biology, behaviour, ecology and management of endemic and exotic Anoplophora glabripennis, including information that is available in the extensive Chinese literature. 3This species has caused massive mortality of Populus species in China and models have demonstrated that it could become established in many locations worldwide. 4Anoplophora glabripennis is polyphagous but prefers Acer, Salix and Populus, section Aigeiros. 5Although A. glabripennis adults do not disperse far when surrounded by host trees, they have the potential to fly more than 2000 m in a season. 6Volatile organic compounds from preferred host trees are attractive to A. glabripennis and this attraction is heightened by drought stress. Males and females orientate to a volatile released by female A. glabripennis and males attempt to copulate after contacting a sex pheromone on the female cuticle. 7At present, A. glabripennis is being (or has been) eradicated from areas where it has been introduced. After detection, extensive surveys are conducted and, if breeding populations are detected, at the very least, infested trees are removed and destroyed. Close attention is paid to imported solid wood packaging material to prevent new introductions. 8Standard practice to control A. glabripennis in China is to spray insecticides in tree canopies. In North America, largely as a preventative measure, systemic insecticides are injected into trees. Entomopathogenic fungi have been developed for the control of A. glabripennis, and entomopathogenic nematodes, coleopteran and hymenopteran parasitoids and predatory woodpeckers have been investigated as biocontrol agents. 9Ecological control of A. glabripennis in China involves planting mixtures of preferred and nonpreferred tree species, and this practice can successfully prevent outbreaks. [source] Vertical distribution of Hymenophyllaceae species among host tree microhabitats in a temperate rain forest in Southern ChileJOURNAL OF VEGETATION SCIENCE, Issue 4 2009Maria J. Parra Abstract Question: Are differences in microhabitat preferences of co-occurring epiphytic Hymenophyllaceae species (filmy ferns) correlated with differences in ecophysiological responses to light availability and humidity in the host tree? Location: The Andean foothills in south-central Chile. Methods: We evaluated the distribution pattern of nine filmy fern species in microhabitats that differ in light availability and humidity in four host tree species. A DCA was developed to assess Hymenophyllaceae species microhabitat preference in terms of canopy openness (CO) and relative humidity. We assessed whether differences in chlorophyll content, maximum photochemical efficiency (Fv/Fm), photosynthetic capacity (Amax), evapotranspiration (E) and instantaneous water use efficiency (WUE) are consistent with any pattern. Results: CO and relative humidity differed significantly with height in the host trees. While CO increased with height in a host tree, relative humidity decreased. DCA analysis showed that filmy fern species distribution within and among trees was mainly explained by the relative humidity of the microhabitat. Chlorophyll content, chlorophyll a/b ratio, Amax and E differed significantly among filmy fern species. Amax and E were correlated with axis 1 scores from the DCA analysis. Conclusions: The vertical distribution and abundance of filmy fern species in Chilean temperate rain forest seems to be closely related to the different microhabitats offered by host trees. This pattern may reflect interspecific differences in ecophysiological traits related both to light availability and humidity. Our results suggest that humidity is the main environmental factor driving functional responses and habitat preferences of these filmy fern species. [source] Host plant quality and defence against parasitoids: no relationship between levels of parasitism and a geometrid defoliator immunoassayOIKOS, Issue 6 2008Netta Klemola Host plant quality has a major influence on the performance, and ultimately on the fitness of an herbivorous insect, but may also have indirect effects on the third trophic level by affecting an herbivore's defensive ability against natural enemies. In a three-year field study, we examined the effects of natural food quality on the ability of autumnal moths, Epirrita autumnata (Lepidoptera, Geometridae), to defend themselves against parasitoids. In each year, we confirmed the variation in quality of host trees (mountain birch, Betulapubescens ssp. czerepanovii) by determining the mass of pupae reared in mesh bags attached to the trees and the water content of leaves. Individuals grown on high quality trees possessed significantly higher encapsulation rate of a foreign antigen as pupae compared to those on low quality trees during the first and third study years; a parallel trend was also found in the second study year, although this difference was not statistically significant. However, in spite of observed differences in encapsulation rates, individuals reared on high and low quality trees did not differ in their levels of parasitisation when exposed to hymenopteran parasioids in the wild and thus were equally vulnerable. Accordingly, the encapsulation response seems not to play a major role on the population ecology scale in the studied system. Our findings also stress the importance of direct resistance tests, which should be conducted along with tests of insect immune function. [source] Complex habitat requirements and conservation needs of the only extant Baroniinae swallowtail butterflyANIMAL CONSERVATION, Issue 3 2004Jorge L. León-Cortés The unique butterfly species, Baronia brevicornis, perhaps the oldest taxon in the Papilionidae, is known to have a very restricted distribution in Mexico. Populations are restricted to southern Mexico in deciduous scrub forest where its host-plants, Acacia trees (Leguminosae), are common and widespread. Little is known of the conservation implications of its relationship with its host trees. We recorded fine scale population data for larval and adult B. brevicornis in 22 km2 of fragmented landscape in southern Mexico. Habitat associations determined from over 1319 transect walks reveal that B. brevicornis exhibited an extremely localised distribution, occupying < 1% of the study area and being mostly associated with Acacia woodlots. Detailed analyses of habitat requirements for larva and/or adult B. brevicornis suggest that it lays its eggs on Acacia pennatula and A. macracantha (two newly recorded larval host-plants), that eggs were laid disproportionately on Acacia trees with long branches (,2= 17.7, P < 0.001) and that the probability of finding adult B. brevicornis between occupied and un-occupied Acacia woodlots increased with host-plant density (,2= 18.4, P < 0.001). The results of this study suggest that conservation recommendations for B. brevicornis must consider the condition of the Acacia habitat network, given that Acacia is mostly associated with human-managed grazing systems. Effective conservation will require the establishment of connected networks of patches where natural dynamics can produce new habitats, as well as the creation of new habitats within colonisation distance. This research provides a rare case study of conservation biology of a Neotropical insect, emphasising the importance of using ecological information to provide management recommendations. [source] Host infestation patterns of the massive liana Hydrangea serratifolia (Hydrangeaceae) in a Chilean temperate rainforestAUSTRAL ECOLOGY, Issue 7 2009MYLTHON JIMÉNEZ-CASTILLO Abstract As competition from lianas reduces fitness of host trees, lianas could influence community composition and structure if potential host species differ in susceptibility to infestation. We quantified infestation frequencies of Chilean temperate rainforest tree species by the massive liana Hydrangea serratifolia (H. et A.) F. Phil (Hydrangeaceae), which climbs using adhesive adventitious roots, and examined relationships with host light requirements and stem diameter. We recorded presence or absence of H. serratifolia in a random sample of 515 trees ,10 cm diameter. Fifty-four per cent of trees were infested by at least one individual of H. serratifolia. Although there was significant interspecific variation in infestation frequency, this variation was not systematically related to light requirements of host tree species. Probability of infestation increased with diameter for most host tree species, and old trees were found to be infested by a wide range of liana size classes, including some stems <2 cm diameter. This evidence supports the proposal that lianas which attach by adhesive roots can colonize host stems of any size. [source] Is the pollen-limited mistletoe Peraxilla tetrapetala (Loranthaceae) also seed limited?AUSTRAL ECOLOGY, Issue 8 2007DAVE KELLY Abstract Seed production in the endemic New Zealand mistletoe Peraxilla tetrapetala (Loranthaceae) has been shown to be consistently pollen limited, but to date there has been no test of whether the species is also seed limited. If it is not seed limited, then pollen limitation may have no effect on population size. We tested for seed limitation by sowing seeds onto host trees at high and low densities at two sites, and following survival for up to 69 months. Our rationale was that unless there is strong density-dependent seedling mortality sufficient to negate increases in seed supply, the species would be seed limited. We simultaneously measured pollen limitation at both sites using pollen augmentation. Peraxilla tetrapetala was strongly pollen limited at both sites over 7 years at Ohau (mean Pollen Limitation Index 0.62), and 12 years at Craigieburn (mean PLI 0.44), before and during the seed-limitation study. There was no significant overall negative effect of density on survival in sown P. tetrapetala seeds over 42,69 months. There was a significant positive effect: seeds were more likely to adhere to branches when sown at high densities. This initial advantage to high-density seeds was gradually eroded by slightly (but non-significantly) lower survival rates of adhered seeds at high density. By the end of the study there was no significant difference in overall survival in high and low density plantings. This means that P. tetrapetala was apparently both pollen limited and seed limited at both our sites. Hence, reduced densities of native bird pollinators caused by introduced mammalian carnivores are likely to reduce the density of adult mistletoes in the next generation. However, the generality of this result may be affected by the fact that mistletoes do not have a dense ,seedling shadow' under the parent mistletoe. [source] | ||||||||||||||||||||||||||||