Date of Award:

5-1-1981

Document Type:

Thesis

Degree Name:

Master of Science (MS)

Department:

Biology

Department name when degree awarded

Life Sciences:Biology

Committee Chair(s)

Ting H. Hsiao

Committee

Ting H. Hsiao

Committee

Wilford J. Hanson

Committee

Thomas M. Farley

Abstract

This study was conducted to estimate the arrount of genetic variability present in geographic populations of the Colorado potato beetle, Leptinotarsa decemlineata (Say)(Coleoptera:Chrysomelidae), and to estimate the degree of genetic divergence between these populations. Enzyme products of 11 genetic loci (Acid Phosphatase, Esterase-1, Esterase-2, Fumarase, Glucose-6-phosphate Dehydrogenase, Glutamate Oxalo-acetate Transaminase, α-Glycerophosphate Dehydrogenase, Isocitrate Dehydrogenase, Malic Dehydrogenase, Malic Enzyme, Superoxide Dismutase) were examined by starch gel electrophoresis for 11 geographic populations from the United States, Mexico, and Europe. The average heterozygosity of L. decemlineata was found to be 0. 201+ 0.043 with an average proportion of polymorphic loci of 0.516+0.078. The geographic populations examined (excluding MEX) were found to be genetically similar with average genetic distance of 0.023+0.015, and a fixation index of 0.074. One locus (Superoxide Dismutase} was found to be diagnostic, separating the Mexican population from the others. Hetero-zygosity of the population from Mexico was significantly lower than the other populations. The average genetic distance between the Mexican population and the others was found to be 0.205± 0 .025, indicating that it may be a distinct subspecies. The moderately high levels of genetic variability found in L. decemlineata suggest that the species is highly adaptable and capable of expansion of host range and geographic distribution.

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