The design of the fly adhesive pad: distal tenent setae are adapted to the delivery of an adhesive secretion

Flies (Brachycera) have adhesive pads called pulvilli at the terminal tarsomere. The pulvilli are covered by tenent setae, sometimes termed tenent hairs, which serve to increase the actual area of attachment to the surface. By using transmission and scanning electron microscopy it is shown that proximal and distal tenent setae have different ultrastructures. The design of distal adhesive setae is adapted for the release of adhesive substances close to the area of contact. It is concluded that secretion injection is precisely targeted under the distal tip of a single seta

Communities of ground-living spiders in deciduous forests: Does tree species diversity matter?

Schuldt A, Fahrenholz N, Brauns M, Migge-Kleian S, Platner C, Schaefer M. Communities of ground-living spiders in deciduous forests: Does tree species diversity matter? BIODIVERSITY AND CONSERVATION. 2008;17(5):1267-1284.The relationships between species diversity and ecosystem functions are in the focus of recent ecological research. However, until now the influence of species diversity on ecosystem processes such as decomposition or mineral cycling is not well understood. In deciduous forests, spiders are an integral part of the forest floor food web. In the present study, patterns of spider diversity and community structure are related to diversity of deciduous forest stands in the Hainich National Park (Thuringia). In 2005, pitfall trapping and quantitative forest floor sampling were conducted in nine plots of forest stands with one (Diversity Level 1), three (DL 2) and five (DL 3) major deciduous tree species. Species richness, measured with both methods, as well as spider abundance in forest floor samples were highest in stands with medium diversity (DL 2) and lowest in pure beech stands (DL 1). The Shannon-Wiener index and spider numbers in pitfall traps decreased from DL 1 to DL 3, while the Shannon-Wiener index in forest floor samples increased in the opposite direction. Spider community composition differed more strongly between single plots than between diversity levels. Altogether, no general relationship between increasing tree species diversity and patterns of diversity and abundance in spider communities was found. It appears that there is a strong influence of single tree species dominating a forest stand and modifying structural habitat characteristics such as litter depth and herb cover which are important for ground-living spiders