Date of Award

1-1-1986

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Biology

Abstract

Ceratophyllus idius is an ectoparasite of purple martins (Progne subis) and commonly inhabits the nest material of these birds. In the Upper Midwest, purple martins migrate in late August and return in mid- or late April. Despite the host's absence and harsh northern winters, a portion of the adult flea population survives to reinfest returning birds. This study was designed to: (1) examine the possible roles of sorbitol and trehalose as biological antifreezes; (2) confirm the role of glycerol as an antifreeze; (3) monitor glycogen and glycerol levels and supercooling points from autumn until spring; (4) determine the temperature stimulus triggering glycerol synthesis; (5) determine if glycerol production is reversible; (6) monitor flea survival; and (7) compare sexes in the above mentioned areas.Assays were done for glycogen, glucose, glycerol, sorbitol and trehalose at 22(DEGREES)C and at 13(DEGREES), 10(DEGREES) and 1(DEGREES)C during a controlled cool-down. After cooling, half of the fleas were held at ambient outdoor conditions and the rest at -6(DEGREES)C. Monthly assays were made mid-October through mid-April on surviving fleas from both regimens.Glucose, trehalose and sorbitol levels were low in all assays and are not considered important as antifreezes in C. idius. Induction of glycerol synthesis was triggered at or prior to 10(DEGREES)C, and by early winter, glycerol levels were about 25X the time zero value. Concurrently, glycogen levels decreased to 6% of the original value in both regimens. After five weeks at -6(DEGREES)C, glycerol levels of freezer-held fleas remained relatively stable through mid-April. Ambient-held glycerol levels varied through mid-April apparently in response to general and short-term temperature trends, and in a controlled warming to 15(DEGREES)C, glycerol levels decreased 26% within two days indicating that the mechanism controlling glycerol levels is both temperature dependent and reversible. In all experiments, glycogen levels varied inversely with glycerol levels. This indicates that glycogen was the major source for glycerol production. In addition, supercooling points corresponded with changing glycerol levels. In the above mentioned assays, the differences between sexes were not statistically significant.Survivorship for ambient-held fleas generally showed a gradual decline from early September (100%) through mid-April (32.4%) indicating that a substantial portion of the adult flea population is able to successfully overwinter and reinfest purple martins upon their return in April.

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