Thesis (M.S.)--Kent State University, 2009. / Title from PDF t.p. (viewed Mar. 16, 2010). Advisor: Patrick Lorch. Keywords: Orthoptera; Tettigoniidae; Mormon crickets; Allometry; Geometric mean; Shape ratios; Morphological integration. Includes bibliographical references (p. 100-106).

Many insects are important agricultural pests, and active control is necessary to keep them at abeyance. The naturally occurring entomopathogenic fungus Metarhizium is a promising tool to control pest insects, and its use avoids the well-known harmful side effects of chemical pesticides. Thousands of unique isolates of Metarhizium exist throughout the world. These isolates vary widely in their ability to cause infection and to tolerate stressful habitats. The research reported here tests the THESIS: A laboratory-based system can be devised that identifies, from among many Metarhizium isolates, those isolates with the greatest potential for successful biological control of pest insects in the field. The study was built on the testing of four hypotheses: (1) Laboratory bioassays using target pest insects will distinguish highly virulent strains of Metarhizium from less virulent strains, (2) Quantity and quality of mass-produced pathogenic fungi will vary among species and strains of Metarhizium, (3) The tolerance to ultraviolet radiation will vary among species and strains of Metarhizium, (4) The effect of temperature on growth rates and survival of both Metarhizium spores and hyphae will vary among isolates and species. These hypotheses test four field-relevant traits using a panel of ten isolates of Metarhizium isolates. Seven sets of laboratory experiments were devised to define the range of responses within the traits covered by the hypotheses. This series of general laboratory tests was developed to assist in identifying fungal isolates with high potential for field use. These tests included evaluation of each isolate's (a) insect pathogenicity, (b) mass–production capabilities, (c) tolerance to high temperatures, (d) tolerance to UV-B radiation, (e) rate of vegetative growth, (f) rate of spore germination, and (g) an evaluation of presence or absence of a post–stress growth inhibition. The application of this protocol to the isolates used in this study indicates that four isolates have high field potential, i.e., DWR 203, DWR 346, DWR 356 and ARSEF 324, and three of these were tested in a field trial. By following the procedures outlined in this thesis, selection of “good” isolates can be accomplished in the laboratory, and a successful isolate can be identified from the abundance of isolates present in nature.

While there has long been interest in the form of sexual selection in males, studies characterizing this selection in females remain sparse. Sexual selection on females is predicted for sex-role reversed Mormon crickets, where males are choosy of mates and nutrient-deprived females compete for matings to gain nutritious nuptial gifts. I used selection analyses to describe the strength and form of sexual selection on female morphology. There was no positive sexual selection on the female body size traits predicted to be associated with male preferences and female competition. Instead, I detected selection for decreasing head width and mandible length. Additionally, I tested the validity of a commonly-used instantaneous measure of mating success (mated vs. unmated) by comparing selection results with those determined using a more detailed fitness measure (cumulative mating rate). The two fitness measures yielded similar patterns of selection, supporting the common sampling method comparing mated and unmated fractions.

While there has long been interest in the form of sexual selection in males, studies characterizing this selection in females remain sparse. Sexual selection on females is predicted for sex-role reversed Mormon crickets, where males are choosy of mates and nutrient-deprived females compete for matings to gain nutritious nuptial gifts. I used selection analyses to describe the strength and form of sexual selection on female morphology. There was no positive sexual selection on the female body size traits predicted to be associated with male preferences and female competition. Instead, I detected selection for decreasing head width and mandible length. Additionally, I tested the validity of a commonly-used instantaneous measure of mating success (mated vs. unmated) by comparing selection results with those determined using a more detailed fitness measure (cumulative mating rate). The two fitness measures yielded similar patterns of selection, supporting the common sampling method comparing mated and unmated fractions.