| pigments from uroleucon nigrotuberculatum induce apoptosis in hl60 human leukemia cells, implicating intracellular oxidative stress and activation of caspases. | two pigmented compounds from uroleucon nigrotuberculatum, uroleuconaphin-b(1) [corrected] (h427) and uroleuconaphin-a(1) [corrected] (h373), significantly diminished the cell viability of hl60 cells with ic50 of 10 microm and 30 microm, respectively, in an 18 h-dye uptake assay. both h427 and h373 augmented the levels of intracellular reactive oxygen species (ros) and induced apoptosis as demonstrated by terminal deoxynucleotidyl transferase-mediated dutp nick-end labeling analysis. ros augmenta ... | 2006 | 17142968 |
| differences in spatial distribution, morphology, and communities of herbivorous insects among three cytotypes of solidago altissima (asteraceae). | • premise of the study: polyploidy in plants can result in genetic isolation, ecological differences among cytotypes, and, ultimately, speciation. cytotypes should be sympatric only if they are segregated in an ecological niche or through prezygotic isolation. we tested whether sympatric diploid, tetraploid, and hexaploid ramets of solidago altissima l. (asteraceae) differ in their ecological niche. • methods: we measured how cytotypes were distributed within habitats, their morphology, and the ... | 2011 | 21926306 |
| parameter estimation techniques for interaction and redistribution models: a predator-prey example. | the use of parameter estimation techniques for partial differential equations is illustrated using a predatorprey model. whereas ecologists have often estimated parameters in models, they have not previously been able to do so for models that describe interactions in heterogeneous environments. the techniques we describe for partial differential equations will be generally useful for models of interacting species in spatially complex environments and for models that include the movement of organ ... | 1987 | 28312473 |
| seasonal occurrence of uroleucon nigrotuberculatum (hemiptera: aphididae) in northern kyushu and mechanisms of its summer disappearance. | regulation mechanisms of insect population dynamics are important for conservation biology and insect pest management. the aphid uroleucon nigrotuberculatum (olive), native to north america, was introduced into japan in the late 1980s. a previous study revealed that, in japan, the aphid population densities increased in spring, but they suddenly disappeared from low-elevation areas in midsummer (called “summer disappearance”). however, the aphids were found continuously in a mountainous area thr ... | 2016 | 26634915 |
| colonization of solidago altissima by the specialist aphid uroleucon nigrotuberculatum: effects of genetic identity and leaf chemistry. | in dominant old-field plant species, genotypic variation in traits important for herbivorous insects may explain variation in insect species abundance. while the importance of plant genetic identity on arthropod abundance has been demonstrated, specific factors that drive genotype choice by insects remain largely unknown. sixteen genotypes of the widely distributed plant species solidago altissima were used to investigate the possible role of nutrients and terpene secondary metabolites in shapin ... | 2015 | 25616613 |
| aphid and ladybird beetle abundance depend on the interaction of spatial effects and genotypic diversity. | intraspecific variation and genotypic diversity of host-plants can affect the structure of associated arthropod communities and the dynamics of populations. similarly, neighboring plants can also affect interactions between host-plants and their associated arthropods. however, most studies on the effects of host-plant genotypes have largely ignored the potential effects of neighboring host-plants on arthropod communities. in this study, we used a common garden experiment to ask how spatial effec ... | 2012 | 21805301 |
| plant genotypic diversity increases population size of a herbivorous insect. | it is critical to incorporate the process of population dynamics into community genetics studies to identify the mechanisms of the linkage between host plant genetics and associated communities. we studied the effects of plant genotypic diversity of tall goldenrod solidago altissima on the population dynamics of the aphid uroleucon nigrotuberculatum. we found genotypic variation in plant resistance to the aphid in our experiments. to determine the impact of plant genotypic diversity on aphid pop ... | 2011 | 21378084 |
| spatial patterns of goldenrod aphids and the response of enemies to patch density. | the two aphid species feeding on goldenrod (solidago altissima) in northern florida (u.s.a.) exhibited behavioral differences that resulted in characteristic spatial patterns. uroleucon nigrotuberculatum alates (winged forms) aggregated when colonizing stems and subsequent non-winged generations were relatively sedentary, resulting in a clumped spatial pattern. u. tissoti colonized stems singly and was more mobile; these behaviors resulted in its more random spatial pattern within fields of gold ... | 1988 | 28312415 |
| comparative population dynamics of two goldenrod aphids: spatial patterns and temporal constancy. | two aphid species, uroleucon nigrotuberculatum and u. caligatum, that feed on the goldenrod solidago altissima, are similar in life histories and feeding habits, but differ markedly in their spatial distribution and temporal variability. in this study, u. caligatum typically occurred in small colonies scattered throughout goldenrod fields, and its numbers remained relatively constant through time, whereas u. nigrotuberculatum occurred in dense colonies and exhibited greater fluctuations in popul ... | 1987 | 29357147 |