An Evaluation of the Cost and Effectiveness of Repellent Applications in Protecting Fruit Orchards

A summer repellent spray program was devised and implemented on a total of 110 acres (9 orchard blocks) of 1- to 3-year-old semi-dwarf apple trees. Cooperating growers were supplied with repellent (Hinder or Clearepel) as required, to allow them to adhere to a flexible 3-to 6-application schedule from May through August. Spraying costs, including labor, equipment, and spray materials, were estimated based on data provided by each cooperating grower for each application completed

Climate, Deer, Rodents, and Acorns as Determinants of Variation in Lyme-Disease Risk

Risk of human exposure to vector-borne zoonotic pathogens is a function of the abundance and infection prevalence of vectors. We assessed the determinants of Lyme-disease risk (density and Borrelia burgdorferi-infection prevalence of nymphal Ixodes scapularis ticks) over 13 y on several field plots within eastern deciduous forests in the epicenter of US Lyme disease (Dutchess County, New York). We used a model comparison approach to simultaneously test the importance of ambient growing-season temperature, precipitation, two indices of deer (Odocoileus virginianus) abundance, and densities of white-footed mice (Peromyscus leucopus), eastern chipmunks (Tamias striatus), and acorns ( Quercus spp.), in both simple and multiple regression models, in predicting entomological risk. Indices of deer abundance had no predictive power, and precipitation in the current year and temperature in the prior year had only weak effects on entomological risk. The strongest predictors of a current year's risk were the prior year's abundance of mice and chipmunks and abundance of acorns 2 y previously. In no case did inclusion of deer or climate variables improve the predictive power of models based on rodents, acorns, or both. We conclude that interannual variation in entomological risk of exposure to Lyme disease is correlated positively with prior abundance of key hosts for the immature stages of the tick vector and with critical food resources for those hosts

MINIMIZING DEER DAMAGE TO FOREST VEGETATION THROUGH AGGRESSIVE DEER POPULATION MANAGEMENT

Controlled hunts were used annually between 1976-90 on the Mary Flagler Cary Arboretum in southeastern New York to control deer (Odocoileus virginianus) population expansion and prevent over-browsing of forested and landscaped areas. The primary objective of the hunts was to remove sufficient numbers of adult female deer each year to stabilize herd growth and minimize browsing pressure. Hunters had to register early, attend a preseason meeting, pass a shooting proficiency test, apply for a deer management permit, and pay a fee. Spring browse-use surveys, using several tree species as an index to browsing pressure, showed low use through 7 winters. Participating hunters strongly supported the controlled hunts citing safety, good access, low hunter numbers, and a quality experience as the features they enjoyed

Diagram of Life Cycle of the Blacklegged Tick <i>(I. scapularis)</i>

<p>Shows the four life stages, egg, larva, nymph, adult, and the times during the life cycle that both abiotic (GDD, PPT), and biotic (acorns and various hosts) factors might exert influence. Year <i>t</i> is the year during which nymphal ticks seek hosts, including humans, and represents the focal year with respect to risk of exposure. </p

Effects of Population Density of Eastern Chipmunks <i>(T. striatus)</i> on DON

<p>Shows relationship between number of chipmunks per 2.25-ha grid in year <i>t</i>−1 and DON (number per 100 m²) in year <i>t.</i> This regression model for DON had the most support. </p

Effects of Acorn and Rodent Densities on DIN

<div><p>(A) Effects of the product of acorn density (acorns per square meter) in year <i>t</i>−2 and mouse <i>(P. leucopus)</i> density (number per 2.25-ha grid) in year <i>t</i>−1 on the density of B. burgdorferi-infected nymphs (number per 100 m²) in year <i>t.</i> This regression model for DIN had the most support. </p> <p>(B) Effects of the product of acorn density (acorns per square meter) in year <i>t</i>−2 and chipmunk <i>(T. striatus)</i> density (number per 2.25-ha grid) in year <i>t</i>−1 on the density of B. burgdorferi-infected nymphs (number per 100 m²) in year <i>t.</i> This regression model for DIN had nearly as much support (AIC_corr) as the mouse model (A) and a higher <i>r</i>² value. </p></div

Effects of Acorn ( Quercus spp.) Density on NIP

<p>Shows effects of acorns per square meter in year <i>t</i>−2 on NIP (percentage of nymphs infected with B. burgdorferi) in year <i>t.</i> This regression model for NIP had the most support. </p

Time Series of Acorn, Tick, and Chipmunk Densities on Study Plots

<p>Shows time series of acorn density (acorns per square meter), chipmunk density (number per 2.25-ha grid), and DON (number per 100 m²) on the two longest-established study plots, Henry Farm (A) and Teahouse (B). Note that, typically, chipmunk density tracks acorn density with a 1-y lag, and DON tracks chipmunk density also with a 1-y lag. </p