Thesis (M.S.)--Virginia Polytechnic Institute and State University, 1992. / Vita. Abstract. Includes bibliographical references (leaf 68). Also available via the Internet.

Thesis (M.S.)--Virginia Polytechnic Institute and State University, 1994. / Vita. Abstract. Includes bibliographical references (leaves 99-103). Also available via the Internet.

Thesis (M.S.)--Virginia Polytechnic Institute and State University, 1994. / Vita. Abstract. Includes bibliographical references (leaves 98-107). Also available via the Internet.

Thesis (M.S.)--Virginia Polytechnic Institute and State University, 1994. / Vita. Abstract. Includes bibliographical references (leaves 154-164). Also available via the Internet.

Thesis (Ph. D.)--West Virginia University, 1999. / Title from document title page. Document formatted into pages; contains x, 149 p. : ill. Vita. Includes abstract. Includes bibliographical references (p. 138-142).

Thesis (Ph. D.)--West Virginia University, 2000. / Title from document title page. Document formatted into pages; contains ix, 118 p. : ill. (some col.). Vita. Includes abstract. Includes bibliographical references.

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Field studies were conducted to evaluate the effect of mating disruption on the mating success of the gypsy moth, Lymantria dispar (L), in low-density populations. The gypsy moth is an insect pest of hardwood forests in many regions of the world. The discovery of the sex pheromone disparlure (cis-7,8-epoxy-2-methyloctadecane) produced by females marked the start of a new era in the control and management of gypsy moth populations. Sex pheromones, like disparlure, have been used for detecting new populations, monitoring the spread of populations and for population control based on the disruption of mating communication. Although mating disruption has been used against populations of insect pests in agricultural and forest systems, considerable information about the use of this method for managing gypsy moths is still lacking. Studies, therefore, were designed and carried out specifically to improve current understanding of the mechanism of mating success, to evaluate existing techniques for mating disruption, and to develop methods that would improve the application of pheromone used for mating disruption so as to reduce the costs associated with the use of this management tactic. The first study was conducted to compare the mating success and mortality of gypsy moth females in low-density populations in Virginia and Wisconsin because of differences, which have been observed in the population dynamics and the impact of management strategies between these two states. The results suggested that the higher rate of population spread in Wisconsin might be due to the increased mating success of females compared with Virginia, which may be due in part to increased long-distance dispersal of males and increased longevity of females. The effect of artificial pheromone applied at various doses and formulations on mating success in low-density gypsy moth populations also was studied. Dose-response relationships were obtained for pheromone doses ranging from 0.15 to 75 g a.i./ha. The doses of 37.5 and 15 g a.i./ha of pheromone were shown to effectively disrupt mating and, therefore, have been recommended for operational use. The results also showed that the disruption of mating and attraction of males to pheromone-baited traps as a result of application of pheromone formulated in plastic flakes (Disrupt® II, Hercon Environmental, Emigsville, PA) was stronger and lasted longer than for the pheromone formulated as microcapsule (3M Canada Co., London, Ontario, Canada) and in liquid (Shin-Etsu Chemical Co. Ltd, Tokyo, Japan). Another study was carried out to improve the use and efficacy of the pheromone for mating disruption by reducing the amount of pheromone that was sprayed and the flight distance during aerial application. This study showed that in mountainous landscapes the effect of disparlure along the valley between mountains could be observed at a larger distance (633 ± 63 m) from the treated area than across the valley (104 ± 22m). In a relatively flat area, the effective distance for mating disruption was similar to the effective distance across the valley in a mountainous area (67 ± 17m). These dispersal characteristics of the pheromone provided further evidence that it could be used effectively in mating disruption treatments. Finally, a portable Electroantennogram (EAG) device was evaluated for its ability to detect disparlure sprayed for mating disruption in gypsy moth populations. The study found no relationship between the dose of artificial airborne pheromone and response of gypsy moth antenna as measured by the voltage ratio. The inability to detect differences between airborne pheromone concentrations in the plots treated for mating disruption might have been due to high variability among antennae and also by the inability of the EAG device to detect the low concentration of airborne pheromone used operationally for mating disruption. Further studies are required to improve the sensitivity of the portable EAG device before it can be recommended for use in the field. / Ph. D.

The connection between variable synchrony of insect eclosion with host budburst and variability in insect densities was investigated. Experiments with gypsy moth (Lymantria dispar L.) larvae determined the duration of acceptable foliage after budbreak of nine hardwood species. Four competing conceptual models of environmental influences on the timing of budburst were compared and evaluated. The best budburst model was combined with an eclosion model to estimate the frequency of asynchrony and its correlation with density. Synchrony with budburst has a smaller effect than weather after hatch, on the population size of the gypsy moth, but neither is the driving force behind density changes. However, comparison of traits of 300 species of Macrolepidoptera showed that 50% of outbreak species, but only 24% of nonoutbreak species begin feeding at the time of budburst; this suggests a stronger relation between synchrony and population dynamics than was found with the gypsy moth.