Calow (1983) realized that differences between parasites and their free-living
relatives can be explained by the differences in nutrient richness. I
propose a model that is based on Calow's idea which identifies the relative
position of different trophic strategies (e.g. predation, grazing, parasitism and
others) based on (1) the differences...
Aphids are a widespread family of plant pests, whose abilities to suppress shoot
and root growth are well documented for many terrestrial plants. Only a few studies have
been conducted on conifer aphids of the genus Cinara. Cinara pseudotsugae are known
to attack Douglas-fir seedlings, an important crop in the...
Spotted knapweed, Centaurea maculosa Lam. (Compositae) is an extremely
successful introduced weed species in the northwestern United States. Multiple factors
may be responsible for its success, including chemical defense. Two different types of
putative chemical defense agents are the focus of this thesis. The first is a bitter-tasting
sesquiterpene lactone,...
Aggregation and species association of 9 species of phytophagous and
predaceous mites were studied for 6 yr in an orchard with 100, 2 m tall 'Red
Delicious' apple trees. To quantify aggregation, a method was developed that is
powerful, and easily interpreted. It relates the proportion of habitat occupied to...
Published May 2000. Facts and recommendations in this publication may no longer be valid. Please look for up-to-date information in the OSU Extension Catalog: http://extension.oregonstate.edu/catalog
Monitoring wildlife habitats has become important to forest ecosystem management because it provides valuable information about the response of forests and their species to harvest practices, impacts from recreational use, conservation efforts, and natural and human-caused disturbances. Monitoring is a complex task that requires a variety of abiotic and biotic...
Predator-prey interactions have historically been studied to explain patterns of organization observed in populations and communities. They have also been important in understanding the evolution of antipredator responses in prey and counterstrategies in predators. Despite the breadth of knowledge that exists for heterospecific interactions, relatively few studies have investigated the...