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One Host Species (one + host_species)
Selected AbstractsPredators, parasitoids and pathogens: species richness, trophic generality and body sizes in a natural food webJOURNAL OF ANIMAL ECOLOGY, Issue 1 2000J. Memmott Summary 1.,A food web is presented which describes trophic interactions among the herbivores, parasitoids, predators and pathogens associated with broom, Cytisus scoparius (L.) Link. The data come from published work on the community at a single site. The web comprises a total of 154 taxa: one plant, 19 herbivores, 66 parasitoids, 60 predators, five omnivores and three pathogens. There are 370 trophic links between these taxa in the web. The taxa form 82 functionally distinct groups, called trophic species. 2.,Predators consumed significantly more species than did parasitoids: a median of two prey species per species of predator (range = 1,9), compared to a median of one host species per species of parasitoid (range = 1,4). Significant differences in the number of species consumed were also found among the five predator groups: birds (median = 4), spiders (median = 5), Coleoptera (median = 1), Diptera (median = 2) and Hemiptera (median = 7). 3.,Vulnerability, measured by numbers of consumer species, was significantly affected by the herbivores' feeding styles: externally feeding herbivores were most vulnerable and the concealed herbivores were least vulnerable. Miners were vulnerable to the most parasitoid species and externally feeding herbivores were the most vulnerable to predators. 4.,Resource species had a median vulnerability of 13 consumer species, a figure far higher than that in most published food webs. No significant relationship was found between species' vulnerability to predators and vulnerability to parasitoids. However, there was a strong negative relationship between the percentage mortality due to predation and percentage mortality due to parasitism. 5.,The broom food web contains nine orders of insects, a figure higher than previously recorded. The web also contains vertebrates, arachnids, bacteria and fungi. Most of the interactions between the orders were weak. Connectance was calculated for the complete web, the parasitoid sub-web and the predator sub-web. The connectance of the predator sub-web, a value of 0·0364, was more than an order of magnitude larger than the connectance of the entire web (0·0156) or the parasitoid sub-web (0·018). 6.,The body lengths of 52 species in the food web were estimated from field guides or museum specimens. Larger predators consumed smaller prey in 93% of predator,prey interactions. Smaller parasitoids consumed larger hosts in 79% of parasitoid,host interactions. Parasitoids were significantly smaller than predators. 7.,The 52 species were arranged in order of increasing body length along the columns and down the rows of a food web matrix. The predator sub-web was predominantly upper triangular with 8% of non-zero elements falling below the leading diagonal. The parasitoid sub-web was predominantly lower triangular with 21% non-zero elements falling above the leading diagonal. The entire web contains entries both above and below the main diagonal and thus violates a central assumption of the cascade model. [source] A quantitative genetic analysis of leaf beetle larval performance on two natural hosts: including a mixed dietJOURNAL OF EVOLUTIONARY BIOLOGY, Issue 1 2000Ballabeni Published quantitative genetic studies of larval performance on different host plants have always compared performance on one host species or genotype vs. performance on another species or genotype. The fact that some insects may feed on more than one plant species during their development has been neglected. We executed a quantitative genetic analysis of performance with larvae of the leaf beetle Oreinaelongata, raised on each of two sympatric host plants or on a mixture of them. Growth rate was higher for larvae feeding on Adenostylesalliariae, intermediate on the mixed diet and lowest on Cirsium spinosissimum. Development time was shortest on A. alliariae, intermediate on mixed diet and longest on C. spinosissimum. Survival was higher on the mixed diet than on both pure hosts. Genetic variation was present for all three performance traits but a genotype by host interaction was found only for growth rate. However, the reaction norms for growth rate are unlikely to evolve towards an optimal shape because of a lack of heritability of growth rate in each single environment. We found no negative genetic correlations for performance traits among hosts. Therefore, our results do not support a hypothesis predicting the existence of between-host trade-offs in performance when both hosts are sympatric with an insect population. We conclude that the evolution of host specialized genotypes is unlikely in the study population. [source] Orientation of specialist and generalist fungivorous ciid beetles to host and non-host odoursPHYSIOLOGICAL ENTOMOLOGY, Issue 3 2000Roger Guevara Abstract Most ciids (Ciidae) are strict fungivores specialized on fruit bodies of wood-rotting fungi. The Ciidae includes both specialist and generalist species. Recent evidence suggests that ciids locate and discriminate their potential hosts based mainly on fungal odours. In this study, we investigated the field distribution of ciids in a local woodland near Bath, U.K. We also evaluated experimentally the behavioural responses of ciids to host and non-host fungi in an olfactometer, and explored potential differences in putative aroma compounds in host fungi. Our field data showed that Octotemnus glabriculus, Cis boleti and Cis nitidus have preference for one host species, whereas C. bilamellatus has no preference. The experimental evidence was in accordance with the field observations. The specialists O. glabriculus, C. boleti and C. nitidus were specifically attracted to odour compounds of their preferred host fungi: Coriolus versicolor for the first two beetles and Ganoderma adspersum for the latter one. By contrast, the generalist C. bilamellatus was attracted to odours from C. versicolor, G. adspersum and Piptoporus betulinus. The evidence from this and other published studies suggest that ciids depend mainly on fruit body odours for location and discrimination of their host fungi. In accordance with this, we observed diffierential behavioural responses of ciids to aroma compounds of host and non-host species. [source] Pirate ants (Polyergus breviceps) and sympatric hosts (Formica occulta and Formica sp. cf. argentea): host specificity and coevolutionary dynamicsBIOLOGICAL JOURNAL OF THE LINNEAN SOCIETY, Issue 4 2007JEREMY M. BONO The pace and trajectory of coevolutionary arms races between parasites and their hosts are strongly influenced by the number of interacting species. In environments where a parasite has access to more than one host species, the parasite population may become divided in preference for a particular host. In the present study, we show that individual colonies of the pirate ant Polyergus breviceps differ in host preference during raiding, with each colony specializing on only one of two available Formica host species. Moreover, through genetic analyses, we show that the two hosts differ in their colony genetic structure. Formica occulta colonies were monogynous, whereas Formica sp. cf. argentea colonies were polygynous and polydomous (colonies occupy multiple nest sites). This difference has important implications for coevolutionary dynamics in this system because raids against individual nests of polydomous colonies have less impact on overall host colony fitness than do attacks on intact colonies. We also used primers that we designed for four microsatellite loci isolated from P. breviceps to verify that colonies of this species, like other pirate ants, are comprised of simple families headed by one singly mated queen. © 2007 The Linnean Society of London, Biological Journal of the Linnean Society, 2007, 91, 565,572. [source] | ||||||||||