the pea aphid, acyrthosiphon pisum (harris) is one of the most important pests of pea throughout the world.host stage preference under choice and no-choice tests and age-specific functional response of praon volucre (haliday) parasitizing a. pisum were investigated. the experiments were carried out under laboratory conditions at 25 ± 1 °c, 60 ± 5% rh and a photoperiod of 14: 10 h (l: d). functi...

A well-resolved rhizobial species phylogeny with 51 haplotypes was inferred from a combined atpD + recA data set using Bayesian inference with best-fit, gene-specific substitution models. Relatively dense taxon sampling for the genera Rhizobium and Mesorhizobium was achieved by generating atpD and recA sequences for six type and 24 reference strains not previously available in GenBank. This phy...

Twelve rhizobial isolates were recovered from nodules of common bean (Phaseolus vulgaris) grown in two different locations of Egyptian soils. The most effective strains for nodule formation and nitrogen fixation were selected. Strain specificity with the bean cultivars Saxa, Canoca and Giza 6 from Germany, Colombia and Egypt were studied. The strains were characterized by amplified rDNA restric...

We have used an approximately 8.7-Mb BAC contig of Arabidopsis thaliana Chromosome 4 to trace homeologous chromosome regions in 21 species of the family Brassicaceae. Homeologs of this segment could be identified in all tested species. Painting of pachytene chromosomes of Calepina, Conringia, and Sisymbrium species (2n = 14, 16), traditionally placed in tribe Brassiceae, showed one homeologous ...

The increase in human population and the spread of agriculture over the past 150 years have transformed the landscape in west-central Minnesota into a mosaic of agricultural fields and urban land, leaving only remnants of the once dominant prairie ecosystem. Limited natural habitat in this fragmented landscape threatens the diversity and abundance of native legumes and could impact the size and...

Habitat fragmentation affects the biodiversity and function of aboveground organisms in natural ecosystems but has not been studied for effects on belowground species. In this paper, we consider the diversity of the rhizobia associated with the indigenous legume Dalea purpurea in 3 residual prairie areas in Minnesota and Iowa. Using Dalea purpurea as a trap host, 218 rhizobia were recovered fro...