Date of Award:

5-1-1971

Document Type:

Dissertation

Degree Name:

Doctor of Philosophy (PhD)

Department:

Biology

Department name when degree awarded

Zoology

Committee Chair(s)

Donald W. Davis

Committee

Donald W. Davis

Committee

D. M. Hammond

Abstract

Males and females of the greater wax moth were irradiated with gamma rays during various ages of eggs, larvae, pupae, and adults. Survivors were mated with untreated moths and spermatophore transfer, oviposition, egg hatch, and adult development were studied. The F1 progeny were also mated to untreated moths and similar observations made. Males from selected irradiated and F1 groups were tested for mating competitiveness with untreated males. Females were more sensitive to irradiation than males, and fewer females than males developed to the adult stage in both the irradiated and the F1 generation. Irradiation of either parent during the egg or larval stages tended to inhibit egg fertilization, while irradiation during the pupal or adult stages tended to cause lethality to the F1 embryos. Irradiated females transmitted more lethal effects to the F1 generation than irradiated males. The F1 males transmitted more lethal effects to the F2 generation than the F1 females regardless of which parent of the F1 generation was irradiated. The F1 males of irradiated males transmitted more lethal effects to the F2 generation than the F1 males of irradiated females. The F1 males were generally less fecund than the irradiated parent. No eggs hatched from untreated females mated to the F1 sons of male parents irradiated as 0-1 day, 3-4 day, or 6-7 day pupae at 4, 4, and 16 kilorads, respectively, or as adults at 16 kilorads. Their eggs usually developed an embryo before death, but some were nonembryonated when the male parents were irradiated as 6-7 day pupae or adults. Females mated to the F1 sons of male parents irradiated as last instar larvae or adults received significantly more spermatophores than those of the control. No such effect was noted when the parent was irradiated during other developmental stages. Males irradiated as eggs or larvae at sterilizing dosages competed poorly with untreated males for mates, and females placed with them mated repeatedly until they mated with a normal male. Males irradiated as 3-4 day, and 6-7 day pupae at sub-sterilizing dosages of 6, 9, and 16 kilorads were not fully competitive with normal males for mates. However, their F1 sons were highly competitive, and accomplished 81-92 percent of the matings in tests in which 50 percent was presumed to indicate full competitiveness. The results of this research suggest two possible methods of controlling the greater wax moth by the use of irradiated insects. One method would be to release sub-sterilized moths that would transmit the deleterious effects of the irradiation to subsequent generations and cause widespread decreased fecundity. The reproductive potential of moths from the natural population might then be lowered to the extent that the population would take a long time to build up to economically damaging numbers. This method might achieve effective control but eradication would probably not be attained because the males would not be sterile. A second method would be to irradiate insects at a sub-sterilizing dosage that was sufficiently large to induce sterility in the F1 progeny. For this latter method, it would be better to irradiate 6-7 day pupae at 16 kilorads, mate them to untreated females in the laboratory, and release large numbers of sterile F1 progeny. Because sterile males would be used in this second method, eradication might be possible.

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