How plant-feeding insects distribute themselves and utilize their host plant resources is still poorly understood. Several processes may be involved, and their relative roles may vary with the spatial scale considered. Herein, we investigate small-scale patterns, namely how population density of a gall midge is affected by individual growth form, phenology, and microsite characteristics of its ...

How insect herbivores affect plant performance is of central importance to basic and applied ecology. A full understanding of herbivore effects on plant performance requires understanding interactions (if any) of herbivore effects with plant density and size because these interactions will be critical for determining how herbivores influence plant population size. However, few studies have cons...

Since the arrival of the soybean aphid, Aphis glycines, to the U.S. in 2000, year to year abundances have varied substantially. Although, field studies have suggested that several resident generalist predators have the ability to suppress A. glycines populations, factors responsible for its population dynamics remain unclear. For natural enemies to regulate herbivore populations, predation rate...

Plant-animal interactions imply costs and benefits with net balance depending on interacting species and ecological context. Ungulates, in particular, confer costs (e.g., plant leaf consumption, flower bud predation) and benefits (e.g., plant overcompensation, seed dispersal) to plants. Magnitude of costs and benefits may be altered by habitat management or ecological conditions favoring high d...

Long-standing theory has predicted that plant defensive and nutritional traits contribute to the population dynamics of insect herbivores. To examine the role of plant variation in density dependence, I took a comparative approach by conducting density manipulation experiments with the specialist aphid, Aphis nerii, on 18 species of milkweed (Asclepias spp.). The strength of density dependence ...

in order to evaluate the interference effect natural population weeds and plant density, an experiment with randomized complete block design in factorial arrangement with 4 replications was conducted in 2006 in a field experiment at ramin agricultural and natural resources university, khouzestan. treatments included two factor, plant density of corn at three levels (4, 7 and 10 plants m-2) and ...

In this study, the yield and yield components were studied using a conventional variety Zhongshuang 11 (ZS 11) and a hybrid variety Zhongyouza 12 (ZYZ 12) at varying plant densities. The increase in plant density led to an initial increase in seed yield and pod numbers per unit area, followed by a decrease. The optimal plant density was 58.5 × 104 plants ha-1 in both ZS 11 and ZYZ 12. The furth...

Delayed transition from the vegetative stage to the reproductive stage of development and increased plant height have been shown to increase biomass productivity in grasses. The goal of this project was to detect quantitative trait loci using extremes from a large synthetic population, as well as a related recombinant inbred line mapping population for these two traits. Ten thousand individuals...

Micro-organism populations on the leaf surface can be an indicator of environmental health in orchards. A method was developed to detect changes in these populations in apple orchards. Firstly, the variation within orchards was investigated by sampling leaves from seven locations within four trees in spring and autumn. The population density and species richness of micro-organisms when grown on...