Theses and Dissertations

Issuing Body

Mississippi State University

Advisor

Schneider, John C.

Committee Member

Davis, Frank

Committee Member

Musser, Fred

Committee Member

Baker, Gerald

Committee Member

Snodgrass, Gordon

Date of Degree

8-11-2012

Document Type

Dissertation - Open Access

Major

Agriculture and Life Sciences

Degree Name

Doctor of Philosophy

College

College of Agriculture and Life Sciences

Department

Department of Biochemistry, Molecular Biology, Entomology and Plant Pathology

Abstract

This research project consisted of three primary objectives: (1) Improve rearing methods for L. lineolaris, (2) Determine if selected behaviors displaying photoperiodicity are under circadian control, and (3) Estimate phase angle shifts of selected circadian rhythms, in an effort to contribute toward the future improvement of current integrated pest management techniques. Improving rearing methods was accomplished in three areas: (1) Estimating the optimal stocking rate to maximize production while maintaining acceptable insect quality as a function of photoperiodic regime, (2) Estimating fecundity at the optimal stocking rate and photoperiodic regime, and (3) Determining the timing of oviposition, mating, feeding and egg hatch, under the optimal stocking rate and photoperiodic regime. The stocking rate maximizing production of females was 8.93 (SE = 2.54) egg packets/rearing container. It was also determined that average female weight significantly declined as stocking rate increased. Therefore, a lower stocking rate of six oviposition packets is recommended as a compromise between productivity and product quality appropriate for many rearing purposes. Fecundity under the optimal stocking rate was also determined. Females produced an average of zero to seven eggs per day over the course of their lifetime, and an average of 83.49 eggs over the course of a single female’s lifespan (SE = 9.4). This is unusually low compared to other studies due to an infection of Nosema spp. in the laboratory colony. Oviposition peaked nine to 12 days after eclosion. Fecundity data can be used by rearers as a measure of fitness, allowing them to gauge the overall vigor of their colony. Oviposition and mating behaviors were determined to be periodic with respect to photoperiod, while feeding and egg hatch were not. Oviposition and mating were also determined to be under circadian control, because they met the four criteria stated by Saunders (2001). No significant phase angle shift occurred between 16:8 and 12:12 LD photoperiods for either behavior. Therefore the calculation of a phase angle shift was not possible. Additionally, the investigation of light intensity effect on peak oviposition showed that L. lineolaris did not respond differently to on/off light signals compared to simulated “dawn/dusk” signals.

URI

https://hdl.handle.net/11668/19887

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