| cytogenetics of two species of euceraphis (homoptera, aphididae). | somatic cell divisions, spermatogenesis, and the prophase stages of primary oocytes, are described for two species of birch aphid, euceraphis betulae (koch) and e. punctipennis (zettersted). females of e. betulae have two autosome pairs, two pairs of x-chromosomes of different lengths, and two b-chromosomes. females of e. punctipennis have the same number of x-chromosomes. the sex determination system is x1x2o. e. punctipennis males sometimes have only one b-chromosome. in the spermatogenesis of ... | 1976 | 949924 |
| microbial impacts on plant-herbivore interactions: the indirect effects of a birch pathogen on a birch aphid. | the role of indirect interactions in structuring communities is becoming increasingly recognised. plant fungi can bring about changes in plant chemistry which may affect insect herbivores that share the same plant, and hence the two may interact indirectly. this study investigated the indirect effects of a fungal pathogen ( marssonina betulae) of silver birch ( betula pendula) on an aphid ( euceraphis betulae), and the processes underpinning the interaction. there was a strong positive associati ... | 2003 | 12647147 |
| life-history strategies affect aphid preference for yellowing leaves. | according to the nutrient-translocation hypothesis, yellowing tree leaves are colonized by aphids at the end of the growing season owing to improved availability of nutrients in the phloem sap after chlorophyll degradation. we measured aphid densities on potted betula pendula seedlings in a field site where a small proportion of foliage rapidly turned yellow before normal autumn coloration as a consequence of root anoxia. the number of adults and nymphs of the birch-feeding specialist aphids euc ... | 2009 | 19535364 |
| birch (betula spp.) leaves adsorb and re-release volatiles specific to neighbouring plants--a mechanism for associational herbivore resistance? | plant-emitted semi-volatile compounds have low vaporization rates at 20-25 degrees c and may therefore persist on surfaces such as plant foliage. the passive adsorption of arthropod-repellent semi-volatiles to neighbouring foliage could convey associational resistance, whereby a plant's neighbours reduce damage caused by herbivores. we found that birch (betula spp.) leaves adsorb and re-release the specific arthropod-repelling c(15) semi-volatiles ledene, ledol and palustrol produced by rhododen ... | 2010 | 20298484 |
| genotypic variation in yellow autumn leaf colours explains aphid load in silver birch. | • it has been suggested that autumn-migrating insects drive the evolution of autumn leaf colours. however, evidence of genetic variation in autumn leaf colours in natural tree populations and the link between the genetic variation and herbivore abundances has been lacking. • here, we measured the size of the whole aphid community and the development of green-yellow leaf colours in six replicate trees of 19 silver birch (betula pendula) genotypes at the beginning, in the middle and at the end of ... | 2012 | 22548444 |
| doppler radar detection of exceptional mass-migration of aphids into finland. | our objective was to detect mass migrations of insects of economic significance by insect traps and a doppler weather radar. migrants were sampled by suction traps, tow nets and light traps in the helsinki region. we used radar to observe the migrating insects, and trajectories to backtrack mass migrations of aphids (homoptera, aphididae) in spring 1988. the aphid migrations were clearly observed in trap catches and by radar. the first migration, mainly involving euceraphis betulae, occurred on ... | 0 | 11131288 |
| coexistence of three species of leaf-feeding aphids (homoptera) onbetula pendula. | three sympatric aphid species of european origin (euceraphis betulae (koch),callipterinella calliptera (hartig) andbetulaphis brevipilosa börner) feed onbetula pendula roth in northern california. the component species of this guild partition resources by plant part, feeding sites within leaves and leaf phenological state. overall niche overlap between species reached a maximum of 49.9% betweenb. brevipilosa andc. calliptera. co-occurence ofe. betulae with both other species on leaves was random ... | 1986 | 28311783 |
| the effect of simulated acid rain on performance of the aphid euceraphis betulae (koch) on silver birch. | the effect of artificial acid rain on the reproduction and survival of the aphid euceraphis betulae on silver birch was studied in turku, southern finland. eight bioassays were done during 1984-1986. in four of the bioassays the aphids produced 40% to over 100% more progeny on birches watered with dilute sulphuric acid (ph 3.5) than on control trees. in four other cases the performance of aphids did not differ between the treatments. an index of aphid reproduction pooled over the whole study was ... | 1987 | 28310417 |