Publications by authors named "P J van Helsdingen"

We report initial results from an ongoing effort to build a library of DNA barcode sequences for Dutch spiders and investigate the utility of museum collections as a source of specimens for barcoding spiders. Source material for the library comes from a combination of specimens freshly collected in the field specifically for this project and museum specimens collected in the past. For the museum specimens, we focus on 31 species that have been frequently collected over the past several decades.

View Article and Find Full Text PDF

The study of parasitoids and their hosts suffers from a lack of reliable taxonomic data. We use a combination of morphological characters and DNA sequences to produce taxonomic determinations that can be verified with reference to specimens in an accessible collection and DNA barcode sequences posted to the Barcode of Life database (BOLD). We demonstrate that DNA can be successfully extracted from consumed host spiders and the shed pupal case of a wasp using non-destructive methods.

View Article and Find Full Text PDF
Article Synopsis
  • The planet has approximately 1.9 million described species, with around 17,000 new ones identified each year, primarily from tropical regions, despite a crisis in taxonomy due to lack of manpower and funding.
  • Contrary to common belief, well-studied areas like Europe are also key sources of undiscovered species, with over 770 new multicellular species named annually since the 1950s, contributing to the known 125,000 species in the region.
  • Notably, over 60% of these new species are identified by non-professional taxonomists, highlighting the need for better support for amateur contributions to biodiversity research, especially in light of the ongoing Taxonomic Impediment.
View Article and Find Full Text PDF

The schedule in dosing of intravesical chemotherapy has thus far received little attention. Correlation of optimal contact time with bladder toxicity, as well as maximal chemotherapeutic effect for one of the drugs of first choice for intravesical instillation, i.e.

View Article and Find Full Text PDF

The incidence of urological complications after aorto-iliac graft surgery was prospectively studied in 49 patients and retrospectively in 35 other patients operated on more than five years before. Follow-up of all 49 patients was one year. In one patient a mild asymptomatic hydronephrosis was discovered after four months.

View Article and Find Full Text PDF