Factors affecting winter survival of Heliothis virescens (Fabricius) and Heliothis zea (Boddie) (Lepidoptera: Noctuidae), and subsequent development on wild spring host plants.
| Main Author: | |
|---|---|
| Other Authors: | , , , , |
| Format: | Thesis Book |
| Language: | English |
| Published: |
1981.
|
| Subjects: | |
| Online Access: | Link to OAKTrust Copy Link to ProQuest Copy |
| Abstract: | Mortality of diapausing pupae of Heliothis virescens (Fabricius) and H. zea (Boddie) at temperatures of 10 to -10(DEGREES)C was assessed in the laboratory. A comparison of the exposure times necessary to induce 50% mortality (LT(,50)) indicated that survival of diapausing pupae was significantly higher than that of non-diapausing pupae. Similar comparisons showed no consistent differences in mortality of pupae from different geographic locations within Texas or in pupae preconditioned in several different ways, with the exception of pupae preconditioned at varying temperatures. Contact moisture significant decreased the LT(,50) values of pupae of both species at sub-zero temperatures. Predictive models for low temperature mortality were developed for dry, diapausing pupae. Pupae of H. virescens and H. zea, in plastic vials and in different soils, were exposed to normal winter temperatures in an insectary in College Station, Texas, during the winters of 1978-79 and 1979-80. Survival of H. zea was higher than that of H. virescens in vials during both winters and in soils during 1978-79. Contact moisture significantly reduced survival of pupae of H. zea in vials during both winters, but reduction in the survival of pupae of H. virescens due to the presence of contact moisture was not significant in either winter. No consistent differences were observed in the survival of either species in 3 different soil types or in sterile and non-sterile soils. Increased soil moisture resulted in significant reductions in the survival of both species during 1978-79 and of H. virescens during 1979-80. Termination of diapause by pupae of H. zea in soils due to a warm fall in 1979-80 resulted in greatly decreased survival compared to expected survival based on low temperatures. ... |
|---|---|
| Item Description: | Typescript (photocopy). Vita. "Major subject: Entomology." |
| Physical Description: | xi, 156 leaves : illustrations ; 29 cm |
| Bibliography: | Includes bibliographical references (leaves 83-89). |