Term of Award

1982

Degree Name

Master of Science in Biology

Document Type and Release Option

Thesis (restricted to Georgia Southern)

Department

Department of Biology

Committee Chair

James H. Oliver, Jr.

Committee Member 1

Daniel V. Hagan

Committee Member 2

W. Keith Hartberg

Abstract

Male and female Dermanyssus gallinae develop from haploid and diploid embryos, respectively. The question of whether this condition is due to a form of gynogenetic arrhenotoky (mating triggering haplodiploid egg development) or due to parahaploidy (all eggs fertilized, but male -destined embryos extrude a complete genome) is investigated by attempts to rear progeny in vitrofrom eggs dissected from virgins, by chromosome analysis of embryos, by mating experiments involving gamma irradiated sterilized males, and by studying sex ratios. Efforts to rear progeny from eggs dissected from virgins failed due to immaturity of eggs. Some diploid cells containing three heterochromatic and three euchromatic chromosomes were observed in putative male embryos (i.e. mostly haploid cells present), although no chromatin extrusion was seen. Reduction of numbers of male progeny produced by gamma irradiated males suggest that radiation damaged sperm penetrate eggs destined to become males. Crosses between males treated with 3, 5, 10, 20, 30, 50 and 70 krads and untreated virgin females produced significantly fewer males than untreated controls. There was a positive correlation between increasin dosage levels of radiation and egg and larval mortality, and decreases in numbers of adult male progeny. Sex ratios of untreated mites changed from a predominance of male progeny in the first two gonotrophic cycles to a predominance of females in the remainingoviposition cycles; opportunity for multiple matings did not affect sex ratio or egg production. The overall cumulative sex ratio from all gonotrophic cycles was approximately one to one. Current evidence favors the probability that male D. gallinae achieves haploidy by elimination of three chromosomes.

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