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Host Use (host + use)
Selected AbstractsVariation 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] Inconsistent use of host plants by the Alaskan swallowtail butterfly: adult preference experiments suggest labile oviposition strategyECOLOGICAL ENTOMOLOGY, Issue 2 2007SHANNON M. MURPHY Abstract 1.,The Alaskan swallowtail butterfly (Papilio machaon aliaska) uses three unrelated plant species as hosts: Cnidium cnidiifolium (Apiaceae), Artemisia arctica (Asteraceae), and Petasites frigidus (Asteraceae). The research presented here investigated whether there are any consistent patterns in host choice by P. m. aliaska females. 2.,The first two experiments were designed to test if P. m. aliaska host preference is constant or if it changes from day to day. If host preference is labile, the experiments were designed to also test whether a female's diet breadth narrows or expands over time. 3.,The third experiment tested the host preferences of female offspring from several wild-caught P. m. aliaska females. If P. m. aliaska individuals are specialised in their host use, then all of the offspring from a single female would likely prefer the same host-plant species. This experiment was also designed to test the Hopkins' host selection principle; does the food plant on which a female is reared as a larva influence her future choices when she is searching for host plants for her own offspring? 4.,The results from all of these experiments indicate that P. m. aliaska females vary greatly in their oviposition behaviour and in their preferences for the three host plants. Most populations appear to consist of generalists with labile oviposition behaviour. There is no evidence to support the Hopkins' host selection principle. 5.,It is suggested that the generalised selection of host plants by P. m. aliaska females may be a ,bet-hedging' strategy and that this strategy may maximise reproductive fitness in an unpredictable environment. [source] Fungivore host-use groups from cluster analysis: patterns of utilisation of fungal fruiting bodies by ciid beetlesECOLOGICAL ENTOMOLOGY, Issue 6 2005Glenda M. Orledge Abstract., 1.,Ciid beetles typically live and breed in the fruiting bodies of lignicolous basidiomycete fungi. This study was undertaken to address the lack of an objective examination of patterns of host use by ciids. 2.,Cluster analysis of ciid host-use datasets from Britain, Germany, North America, and Japan, and subsequent cross-dataset comparisons, demonstrated the existence of ciid host-use patterns of wide geographical occurrence. These patterns were formalised as ciid host-use groups. 3.,Six Holarctic ciid host-use groups, and two host-use subgroups, were identified, and are described. Each host-use group comprises an assemblage of fungal genera and the breeding ciids that it supports. Each taxon belongs to only a single host-use group, but may be associated with several members of that group. There is a strong tendency for closely related taxa to belong to the same host-use group. 4.,It is suggested that ciid host-use groups are defined ultimately by host chemistry, with the ciids that belong to a particular group recognising, and responding positively to, emitted volatiles characterising the fungi belonging to that group. 5.,The idea of the host-use group bears comparison with the concepts of niche and guild, but is not equivalent to either. 6.,Ciid host-use groups have a valuable role to play in underpinning future studies of ciid ecology, also the systematics of both ciids and their fungal hosts. [source] Is selection of host plants by Plagiodera versicolora based on plant-related performance?ENTOMOLOGIA EXPERIMENTALIS ET APPLICATA, Issue 2 2008Sawako Egusa Abstract Plant-related performance may be one of the most important factors in the selection of host plants by insect herbivores. We investigated the importance of plant-related performance in host selection by the willow leaf beetle, Plagiodera versicolora (Laicharting) (Coleoptera: Chrysomelidae), on four willow species: Salix chaenomeloides Kimura, Salix eriocarpa Fr. et Sav., Salix integra Thunb., and Salix serissaefolia Kimura (Salicaceae). Bagging experiments in the field revealed that the performance of P. versicolora adults and larvae differed significantly among willow species under enemy-free conditions and at constant densities. Egg clutch and larval abundance were positively related to adult abundance. Plagiodera versicolora adults did not discriminate strongly among willow species for feeding and oviposition. Larval performance did not differ among willow species in the presence of natural enemies, suggesting that interspecific differences in host quality were overridden by mortality from natural enemies. Adult and egg clutch abundance of P. versicolora changed seasonally despite the temporal stability of adult and larval performance under enemy-free field conditions. Thus, plant-related performance of P. versicolora adults and larvae may contribute little to population growth and temporal dynamics of host use in P. versicolora. Potential factors that reduce discrimination of P. versicolora among host willow species are discussed. [source] Effects of parasitoids on a mycophagous drosophilid community in northern Japan and an evaluation of the disproportionate parasitism hypothesisENTOMOLOGICAL SCIENCE, Issue 1 2006Hiroshi YOROZUYA Abstract In a host,parasitoid system comprising mycophagous drosophilids and their parasitoids, the drosophilid and parasitoid species assemblages, host use, and the prevalence of parasitism were assessed, and the "disproportionate parasitism hypothesis" was examined with consideration given to yearly variations. The mycophagous drosophilids, their fungal food resources and parasitoids were studied by carrying out an intensive census throughout the activity seasons of 4 years (2000,2003) in Hokkaido, northern Japan. Five hymenopterous parasitoid species, four braconids and one eucoilid, were found. Parasitoids of mycophagous drosophilids are reported for the first time from Asia. Most parasitism (99.2%) was by braconids, in contrast to the dominance of eucoilids in Europe. Parasitism was restricted to the summer, and the rate was high from early July to early August every year. There was considerable yearly variation in the composition of abundant fungus, drosophilid and parasitoid species, especially between 2000 and 2001. The alternation of dominant host species was coupled with the alternation of dominant parasitoid species that differed in host use. Despite the yearly variation in the system, the most dominant host species suffered disproportionately heavy parasitism by the correspondingly dominant parasitoid species every year. The parasitism rate was positively correlated with the relative host abundance. This thus indicates that the disproportionate parasitism mechanism may operate, via which species coexistence is promoted by a higher rate of parasitism of the dominant species. [source] SEQUENTIAL RAPID ADAPTATION OF INDIGENOUS PARASITOID WASPS TO THE INVASIVE BUTTERFLY PIERIS BRASSICAEEVOLUTION, Issue 8 2007Shingo Tanaka The introduction of a new species can change the characteristics of other species within a community. These changes may affect discontiguous trophic levels via adjacent trophic levels. The invasion of an exotic host species may provide the opportunity to observe the dynamics of changing interspecific interactions among parasitoids belonging to different trophic levels. The exotic large white butterfly Pieris brassicae invaded Hokkaido Island, Japan, and quickly spread throughout the island. Prior to the invasion, the small white butterfly P. rapae was the host of the primary parasitoid Cotesia glomerata, on which both the larval hyperparasitoid Baryscapus galactopus and the pupal hyperparasitoid Trichomalopsis apanteroctena depended. At the time of the invasion, C. glomerata generally laid eggs exclusively in P. rapae. During the five years following the invasion, however, the clutch size of C. glomerata in P. rapae gradually decreased, whereas the clutch size in P. brassicae increased. The field results corresponded well with laboratory experiments showing an increase in the rate of parasitism in P. brassicae. The host expansion of C. glomerata provided the two hyperparasitoids with an opportunity to choose between alternative hosts, that is, C. glomerata within P. brassicae and C. glomerata within P. rapae. Indeed, the pupal hyperparasitoid T. apanteroctena shifted its preference gradually to C. glomerata in P. brassicae, whereas the larval hyperparasitoid B. galactopus maintained a preference for C. glomerata in P. rapae. These changes in host preference may result from differential suitability of the two host types. The larval hyperparasitoid preferred C. glomerata within P. rapae to C. glomerata within P. brassicae, presumably because P. brassicae larvae attacked aggressively, thereby hindering the parasitization, whereas the pupal hyperparasitoid could take advantage of the competition-free resource by shifting its host preference. Consequently, the invasion of P. brassicae has changed the host use of the primary parasitoid C. glomerata and the pupal hyperparasitoid T. apanteroctena within a very short time. [source] MUSEUM SPECIMENS AND PHYLOGENIES ELUCIDATE ECOLOGY'S ROLE IN COEVOLUTIONARY ASSOCIATIONS BETWEEN MITES AND THEIR BEE HOSTSEVOLUTION, Issue 6 2007Pavel B. Klimov Coevolutionary associations between hosts and symbionts (or parasites) are often reflected in correlated patterns of divergence as a consequence of limitations on dispersal and establishment on new hosts. Here we show that a phylogenetic correlation is observed between chaetodactylid mites and their hosts, the long-tongued bees; however, this association manifests itself in an atypical fashion. Recently derived mites tend to be associated with basal bee lineages, and vice versa, ruling out a process of cospeciation, and the existence of mites on multiple hosts also suggests ample opportunity for host shifts. An extensive survey of museum collections reveals a pattern of infrequent host shifts at a higher taxonomic level, and yet, frequent shifts at a lower level, which suggests that ecological constraints structure the coevolutionary history of the mites and bees. Certain bee traits, particularly aspects of their nesting behavior, provide a highly predictive framework for the observed pattern of host use, with 82.1% of taxa correctly classified. Thus, the museum survey and phylogenetic analyses provide a unique window into the central role ecology plays in this coevolutionary association. This role is apparent from two different perspectives,as (a) a constraining force evident in the historical processes underlying the significant correlation between the mite and bee phylogenies, as well as (b) by the highly nonrandom composition of bee taxa that serve as hosts to chaetodactylid mites. [source] Spatial and temporal variability in host use by Helicoverpa zea as measured by analyses of stable carbon isotope ratios and gossypol residuesJOURNAL OF APPLIED ECOLOGY, Issue 3 2010Graham Head Summary 1.,A high dose/refuge strategy has been adopted in the USA to manage the risk of Bacillus thuringiensis (Bt) resistance in target pests such as the cotton bollworm (CBW), Helicoverpa zea (Boddie) in transgenic Bt cotton Gossypium hirsutum L. Structured refuges, consisting of non-Bt cotton, have been a mandated part of this strategy to produce non-selected insects that are temporally and spatially synchronous with insects from the Bt crop, diluting Bt resistance alleles through mating. However, the bollworm is highly polyphagous and exploits a large number of crop and weedy hosts concurrently with Bt cotton. 2.,A study was carried out in five major US cotton-producing states during 2002 and 2003 using the ratios of 13C to 12C in bollworm moths to estimate the proportions of the population originating from C3 or C4 plants. A separate study measured gossypol residues in moths from four states in 2005 and 2006, enabling the identification of moths whose natal hosts were cotton rather than other C3 hosts. 3.,C4 hosts served as the principal source of bollworm moths from mid-to-late June to early September, depending on the state. Beginning in late August/early September and lasting 1,4 weeks, the majority of moths exhibited isotopic compositions characteristic of C3 hosts. During this period, however, the minimum percentage of moths that developed as larvae on C4 hosts was typically >25%. By mid-September and through October and November, the majority of the bollworm population exhibited C4 isotopic compositions. 4.,Between late June and early August, cotton-derived bollworm moths (moths with gossypol residues) comprised <1% of moths in all states, and remained below this level throughout the season in North Carolina. In other states, cotton-derived moths increased between early August and early September to peak at an average of 19·1% of all moths. 5.,Synthesis and applications.,Data on 13C/12C ratios and gossypol residues in CBW moths were used to assess the importance of structured non-Bt cotton refuges for the management of Bt resistance risk in H. zea. Weekly estimates of bollworm breeding on cotton, C3 plants other than cotton and C4 plants showed that, throughout the season, the majority of bollworm moths caught in pheromone traps adjacent to cotton fields did not develop as larvae on cotton. This result implies that management practices in cotton such as the use of structured cotton refuges will play a relatively minor role , particularly compared with maize Zea mays L. , in managing potential resistance to Bt cotton in populations of the CBW in the US Cotton Belt. [source] Host-race formation: promoted by phenology, constrained by heritabilityJOURNAL OF EVOLUTIONARY BIOLOGY, Issue 4 2009A. V. WHIPPLE Abstract Host-race formation is promoted by genetic trade-offs in the ability of herbivores to use alternate hosts, including trade-offs due to differential timing of host-plant availability. We examined the role of phenology in limiting host-plant use in the goldenrod gall fly (Eurosta solidaginis) by determining: (1) whether phenology limits alternate host use, leading to a trade-off that could cause divergent selection on Eurosta emergence time and (2) whether Eurosta has the genetic capacity to respond to such selection in the face of existing environmental variation. Experiments demonstrated that oviposition and gall induction on the alternate host, Solidago canadensis, were the highest on young plants, whereas the highest levels of gall induction on the normal host, Solidago gigantea, occurred on intermediate-age plants. These findings indicate a phenological trade-off for host-plant use that sets up the possibility of divergent selection on emergence time. Heritability, estimated by parent,offspring regression, indicated that host-race formation is impeded by the amount of genetic variation, relative to environmental, for emergence time. [source] Preference,performance relationship and influence of plant relatedness on host use by Pityogenes chalcographus L.AGRICULTURAL AND FOREST ENTOMOLOGY, Issue 4 2009Coralie Bertheau Abstract 1Pityogenes chalcographus L. (Coleoptera: Scolytinae) causes damage in European coniferous forests, primarily on Picea abies L. Karst., but is also recorded on other native and exotic Pinaceae species. Estimating the adequacy between adult preference and larval performance of this beetle among its host-range, as well as the influence of plant taxonomic relatedness on these parameters, would provide useful information on the beetle's ability to shift onto novel hosts. 2Choice and no-choice assays were conducted under laboratory conditions. Adult preference and larval performance parameters among two native (Pinus sylvestris L. and Picea abies) and three exotic north American [Pinus contorta Dougl., Picea sitchensis (Bong.) Carr. and Pseudotsuga menziesii Mirbel (Franco)] conifer species were measured. 3Pityogenes chalcographus exhibited a significant positive relationship between preference and performance. Picea abies was both the preferred and the most suitable host species for larval development. The closest relative, P. sitchensis, was the second best choice in terms of preference and performance. Pseudotsuga menziesii occupied an intermediate position for both beetle preference and performance, and Pinus spp. were the least suitable hosts for beetle development. 4Adult preference and larval performance ranking among hosts provides little support to the plant taxonomic relatedness hypothesis. Taxonomic relatedness could play a role on the diet breadth, although only at a limited scale, within the genus Picea. At higher taxonomic levels, other factors such as bark thickness might be decisive. [source] Behaviour and ecology of the western corn rootworm (Diabrotica virgifera virgifera LeConte)AGRICULTURAL AND FOREST ENTOMOLOGY, Issue 1 2009Joseph L. Spencer Abstract 1,The western corn rootworm (WCR) is a historic pest with a legacy of resistance and behavioural plasticity. Its behaviour and nutritional ecology are important to rootworm management. The success of the most effective and environmentally benign rootworm management method, annual crop rotation, was based on an understanding of rootworm behaviour and host,plant relationships. Enthusiastic adoption of crop rotation, provided excellent rootworm management, but also selected for behavioural resistance to this cultural control. 2,Though well-studied, significant gaps in WCR biology remain. Understanding the topics reviewed here (mating behaviour, nutritional ecology, larval and adult movement, oviposition, alternate host use, and chemical ecology) is a starting point for adapting integrated pest management and insect resistance management (IRM) to an expanding WCR threat. A presentation of significant questions and areas in need of further study follow each topic. 3,The expansion of WCR populations into Europe exposes this pest to new environmental and regulatory conditions that may influence its behaviour and ecology. Reviewing the state of current knowledge provides a starting point of reference for researchers and pest management decision-makers in North America and Europe. 4,The trend toward increasing adoption of transgenic maize will place an increasing premium on understanding WCR behaviour. IRM plans designed to promote sustainable deployment of transgenic hybrids are grounded on assumptions about WCR movement, mating and ovipositional behaviour. Preserving the utility of new and old management options will continue to depend on a thorough understanding of WCR biology, even as the ecological circumstances and geography of WCR problems become more complex. [source] Cryptic speciation and patterns of phenotypic variation of a highly variable acanthocephalan parasiteMOLECULAR ECOLOGY, Issue 19 2007M. L. STEINAUER Abstract An investigation of a parasite species that is broadly host- and habitat-specific and exhibits alternative transmission strategies was undertaken to examine intraspecific variability and if it can be attributed to cryptic speciation or environmentally induced plasticity. Specimens of an acanthocephalan parasite, Leptorhynchoides thecatus, collected throughout North America were analysed phylogenetically using sequences of the cytochrome oxidase I gene and the internal transcribed spacer region. Variation in host use, habitat use, and transmission were examined in a phylogenetic context to determine if they were more likely phylogenetically based or due to environmental influences. Results indicated that most of the variation detected can be explained by the presence of cryptic species. The majority of these species have narrow host and microhabitat specificities although one species, which also may comprise a complex of species, exhibits broad host and habitat specificity. Alternate transmission pathways only occurred in two of the cryptic species and correlate with host use patterns. Taxa that mature in piscivorous piscine hosts use a paratenic fish host to bridge the trophic gap between their amphipod intermediate host and piscivorous definitive host. One potential example of environmentally induced variation was identified in three populations of these parasites, which differ on their abilities to infect different host species. [source] Divergent host plant adaptation drives the evolution of sexual isolation in the grasshopper Hesperotettix viridis (Orthoptera: Acrididae) in the absence of reinforcementBIOLOGICAL JOURNAL OF THE LINNEAN SOCIETY, Issue 4 2010TONY GRACE Early stages of lineage divergence in insect herbivores are often related to shifts in host plant use and divergence in mating capabilities, which may lead to sexual isolation of populations of herbivorous insects. We examined host preferences, degree of differentiation in mate choice, and divergence in cuticular morphology using near-infrared spectroscopy in the grasshopper Hesperotettix viridis aiming to understand lineage divergence. In Kansas (USA), H. viridis is an oligophagous species feeding on Gutierrezia and Solidago host species. To identify incipient mechanisms of lineage divergence and isolation, we compared host choice, mate choice, and phenotypic divergence among natural grasshopper populations in zones of contact with populations encountering only one of the host species. A significant host-based preference from the two host groups was detected in host-paired feeding preference studies. No-choice mate selection experiments revealed a preference for individuals collected from the same host species independent of geographic location, and little mating was observed between individuals collected from different host species. Female mate choice tests between males from the two host species resulted in 100% fidelity with respect to host use. Significant differentiation in colour and cuticular composition of individuals from different host plants was observed, which correlated positively with host choice and mate choice. No evidence for reinforcement in the zone of contact was detected, suggesting that divergent selection for host plant use promotes sexual isolation in this species. © 2010 The Linnean Society of London, Biological Journal of the Linnean Society, 2010, 100, 866,878. [source] Host plant toxicity affects developmental rates in a polyphagous fruit fly: experimental evidenceBIOLOGICAL JOURNAL OF THE LINNEAN SOCIETY, Issue 4 2009NATHALIE ERBOUT Various, non-exclusive mechanisms have been invoked to explain the observed association between host plant use and speciation in insect species. In the Afrotropical genus Ceratitis (Diptera: Tephritidae), morphological, molecular, and biochemical data suggest that evolutionary radiation of stenophagous clades originates from their ability to exploit toxic hosts. To test whether, and to what extent, the development and fitness of Ceratitis fasciventris, a polyphagous congener known to infest over 43 host species, is adversely affected by host plant toxicity, we compared the rates of development, survival, and reproduction of captive bred individuals in four media that differ in alkaloid concentration. Despite reduced pupal and adult sizes, C. fasciventris larvae developing under low alkaloid concentrations successfully developed to the adult stage, probably as a result of accelerated pupation and ensuing restricted exposure to the toxic environment. High alkaloid concentrations, however, impaired their developmental process and prevented subsequent reproduction. The adverse effects of host plant toxicity on larval development in polyphagous fruit flies indicate that high alkaloid concentrations pose a significant constraint on host use by polyphagous Ceratitis species. © 2009 The Linnean Society of London, Biological Journal of the Linnean Society, 2009, 97, 728,737. [source] Advancing Entertainment Education: Using The Rosie O'Donnell Show to Recognize Implementation Strategies for Saturated MarketsCOMMUNICATION THEORY, Issue 2 2009Deborah L. Larson Entertainment-education (E-E) has been widely and successfully implemented in developing countries around the world, but it is much harder to utilize in media-saturated countries. However, talk shows can be a niche market for E-E campaigns. As evidence, The Rosie O'Donnell Show has made a significant contribution to the television industry and to entertainment-education research by redefining how advocacy, education, and entertainment can work through a variety talk show format. An extemporaneous talk show can implement E-E campaigns through four main strategies to target its viewers: (1) Variability, or using a variety of forms to provide campaign information, (2) using multimediated synergistic avenues and online connections, (3) creating audience proactivity by using a small group elements to promote self and collective efficacy, and host appeal to bridge the local to national gap, and (4) the host's use of instinctive intentionality in aggregating campaign messages. As executive producer and host of her show, Rosie O'Donnell affected awareness, disseminated educational information, and encouraged proactive behavior with social, political, and philanthropic agendas through repetitive, positive, and proactive entertainment-education messages. [source] | |||||||||||||||||||