Date of Award

8-1977

Document Type

Thesis

Degree Name

Master of Science (MS)

Legacy Department

Entomology

First Advisor

G. R. Carner

Second Advisor

Jewel Jackson

Third Advisor

Raymond Nobul

Abstract

Beauveria and Metarrhizium species were used to evaluate fixation techniques for the scanning electron microscope (SEM). Fixation by Cling Free, glutaraldehyde, critical point drying, and freeze drying were shown to be ineffective in preventing collapse of cells. Vapor fixation with osmium tetroxice (OsO4) prior to freeze drying resulted in a reduction in topographic disruptions. Prolonged vapor fixation with OsO4 was superior in preserving specimens. A taxonomic review of the genus Beauveria was conducted using cultures from the American Type Culture Collection, Rockville, Maryland. Strains of B. bassiana (ATC 26037 and ATC 28701), B. brongniartii (ATC 28336), B. densa (ATC 9452), B. glovulifera (ATC 18980) and B. tenella (ATC 26851) were observed with the SEM. B. globulifera was similar in structure to B. tenella while B. bassiana, B. densa, and B. brongniartii proved to be distinct species. Characteristics observed in type cultures were also used to identify numerous isolates collected from naturally infected hosts. A taxonomic review of the genus Metarrhizium was conducted using culturs from the Boyce-Thompson Institute, Brooklyn, New York. Strains of M. anisopliae (major form), M. anisopliae (minor form) and M. brunneum were observed with the SEM. Colony coloration and conidial size were adequate criteria for taxonomic differentiation of Metarrhizium species.

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