Signs of a vector's adaptive choice: on the evasion of infectious hosts and parasite-induced mortality

Laboratory and field experiments have demonstrated in many cases that malaria vectors do not feed randomly, but show important preferences either for infected or non-infected hosts. These preferences are likely in part shaped by the costs imposed by the parasites on both their vertebrate and dipteran hosts. However, the effect of changes in vector behaviour on actual parasite transmission remains a debated issue. We used the natural associations between a malaria-like parasite Polychromophilus murinus, the bat fly Nycteribia kolenatii and a vertebrate host the Daubenton's bat Myotis daubentonii to test the vector's feeding preference based on the host's infection status using two different approaches: 1) controlled behavioural assays in the laboratory where bat flies could choose between a pair of hosts; 2) natural bat fly abundance data from wild-caught bats, serving as an approximation of realised feeding preference of the bat flies. Hosts with the fewest infectious stages of the parasite were most attractive to the bat flies that did switch in the behavioural assay. In line with the hypothesis of costs imposed by parasites on their vectors, bat flies carrying parasites had higher mortality. However, in wild populations, bat flies were found feeding more based on the bat's body condition, rather than its infection level. Though the absolute frequency of host switches performed by the bat flies during the assays was low, in the context of potential parasite transmission they were extremely high. The decreased survival of infected bat flies suggests that the preference for less infected hosts is an adaptive trait. Nonetheless, other ecological processes ultimately determine the vector's biting rate and thus transmission. Inherent vector preferences therefore play only a marginal role in parasite transmission in the field. The ecological processes rather than preferences per se need to be identified for successful epidemiological predictions

Rights-of-way vegetation management

A manual intended for use by those studying for the Oregon rights-of-way vegetation control exam. Includes chapters on basic weed science, vegetation management strategies; herbicides; factors influencing herbicide performance; special precautions when using herbicides; applying herbicides; calibration, mixing, and calculations; and application equipment. Includes a practice test, glossary, and references. Does not make specific herbicide recommendations.Published June 2004. Reviewed August 2007. Please look for up-to-date information in the OSU Extension Catalog: http://extension.oregonstate.edu/catalogKeywords: vegetation control, weeds, herbicide

Measuring your trees

Procedures outlined in this publication show how to estimate standing volume and annual growth of individual timber stands that are relatively uniform in species, age, size, and density. Estimates of volume and growth are helpful in planning when to harvest or how much to remove in a thinning operation. These estimates can also assist with financial analysis and the tax implications involved in a timber harvest.Published April 2013. 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/catalogKeywords: stand growth, tarif access table, tarif system, volume table, forest inventory, stand volum

Field horsetail and related species, Equisetaceae

The Horsetail (Equisetaceae) family comprises 30 species, all in the ancient genus Equisetum. During the Carboniferous age (more than 230 million years ago), the Horsetail family was the dominant plant group in the world, with plants reaching gigantic size. Two basic forms of horsetails survive today. One is the hollow, jointed, and leafless scouring rush. The other is the horsetail with whorls of slender, green, jointed branches around hollow, jointed stems, often occurring in great numbers, giving the appearance of a horse’s tail.Revised July 1994. Facts and recommendations in this publication may no longer be valid. Please check for up-to-date information in the OSU Extension Catalog: http://extension.oregonstate.edu/catalo

Chemical Weed Control for Home Grounds

Outlines four methods of chemical application, by application method and effect on plants. 1) selective herbicides--foliar use: lawn weeds, weed grasses; 2) selective herbicides--preemergent soil use: annual bluegrass, crabgrass, vegetables, flowers, ornamentals, caneberries, treefruit, conifers; 3) nonselective herbicides--foliar use: blackberries, poison oak, poison ivy, broom, morning glory (bindweed), bamboo, weed grasses, brush; 4) nonselective persistent herbicides (residuals or sterilants)--nonplant areas, stumps. 4 pages