Semester

Spring

Date of Graduation

2003

Document Type

Dissertation

Degree Type

PhD

College

Davis College of Agriculture, Natural Resources and Design

Department

Horticulture

Committee Chair

Linda Butler.

Abstract

Despite the wealth of research conducted on gypsy moth [(Lymantria dispar L.)(Lymantriidae: Lepidoptera)] populations dynamics, quantitative analysis of the native lepidopteran community in which gypsy moth has become naturalized is extremely limited. This study examined the population dynamics of native Lepidoptera in two gypsy moth management areas in West Virginia and Virginia. Data were collected between 1995 and 2001 on 18 plots distributed on two national forests (Monongahela National Forest, WV and George Washington National Forest, VA). Four lepidopteran sampling techniques (gypsy moth egg mass surveys, canvas bands and foliage clippings for larval sampling, and light trap samples for adults) were compared. Population estimates obtained from moths captured in light traps and egg mass counts were both correlated with abundance of larvae obtained from foliage clippings. Canvas band samples were only weakly to moderately correlated with data collected from foliage and light trap samples. The effects of the biological pesticide, Bacillus thuringiensis var. kurstaki, on several population parameters (annual abundance, population growth rate, coefficient of variation, and correlation of time series among plots) were negligible for 11 selected species. Quantitative analysis of Lepidoptera populations was performed through analysis of spatial synchrony. Synchrony of both intraspecific and intraspecific local populations was compared with climate variables to assess the potential role of weather on population synchrony. Synchrony of conspecific populations was correlated with that of at least one weather variable for all species. Interspecific synchrony was related to within and among families and season of larval phenology, as well as geographic distribution of species relative to canopy vegetation. Interspecific synchrony was highest among species whose larvae were present during the same season compared to species whose larvae were present during different seasons. To test the hypothesis that Lepidoptera species within the same feeding guild may be synchronized by generalist predators, a model was developed that demonstrated synchronization of prey species by a predator functional response. Prey species projecting relatively similar search images to the predator were more highly synchronized than prey species projecting relatively distant search images.

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