Title page for ETD etd-05232003-131327


Type of Document Dissertation
Author Tcheslavskaia, Ksenia Sergeyevna
URN etd-05232003-131327
Title Mating Success in Low-Density Gypsy Moth Populations
Degree PhD
Department Entomology
Advisory Committee
Advisor Name Title
Brewster, Carlyle C. Committee Chair
Sharov, Alexei A. Committee Co-Chair
Bloomquist, Jeffrey R. Committee Member
Liebhold, Andrew M. Committee Member
Roberts, E. Anderson Committee Member
Salom, Scott M. Committee Member
Keywords
  • pheromone concentration
  • electroantennogram
  • mating disruption
  • gypsy moth
Date of Defense 2003-05-06
Availability unrestricted
Abstract
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.

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