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.

Des perturbations de l’horloge circadienne imposées par nos modes de vie désynchronisés «24/7» peuvent être néfastes à long terme. Ces horloges contrôlent des rythmes biologiques avec une périodicité d’environ 24h et se synchronisent aux cycles journaliers de lumière-obscurité. Les perturbations de l’horloge peuvent influencer le vieillissement normal et celui de patients atteints de la maladie de Parkinson (MP). Ces patients présentent souvent des symptômes non moteurs incluant des troubles du sommeil et/ou des rythmes circadiens, qui se manifestent avant les déficits moteurs ou cognitifs. L’objectif de ce travail de thèse a été d’explorer l’impact des perturbations de l’horloge circadienne sur le déclin fonctionnel lié à l’âge au cours du vieillissement normal et dans des modèles de MP chez la drosophile. Les résultats obtenus confirment l’impact négatif de l’arythmie circadienne sur la longévité, et révèlent que l’inactivation du gène d’horloge Clock (Clk) augmente le niveau de stress oxydatif dans le cerveau et accélère le déclin des capacités locomotrices au cours du vieillissement. Ce dernier effet a pu être relié à une fonction de Clk dans les neurones d’horloge qui contrôlent les rythmes d’activité-repos en obscurité constante, et leurs connections à un groupe spécifique de neurones dopaminergiques. Nous avons aussi observé que des décalages horaires chroniques mènent également à une accélération du déclin locomoteur lié à l’âge, qui peut être sauvée en adaptant les rythmes lumière-obscurité à la période endogène des drosophiles. Enfin, notre travail souligne l’impact négatif de l’arythmie circadienne sur le déclin locomoteur lié à l’âge dans un modèle de MP. / Long-term disruption of circadian clocks, as occurs often in our "24/7 societies", can be detrimental. These clocks control self-sustained biological rhythms with ~24h periodicity and synchronize to the daily light-dark cycle. Clock disruption may impact normal brain aging as well as Parkinson disease (PD) pathogenesis: PD patients frequently exhibit non-motor symptoms including sleep and/or circadian rhythm disruptions that occur before motor or cognitive deficits, and decrease quality of life. The objective of this PhD work was thus to explore the impacts of circadian disruptions on age-related functional decline, both during normal aging and in a fly model of PD-like conditions using well established Drosophila models. Our results confirmed the negative impact of circadian arrhythmia on longevity and revealed that inactivation of a specific circadian gene, Clock (Clk), increases brain oxidative stress levels and accelerates locomotor decline during aging. The latter effect could be associated with Clk function in the clock neurons that drive circadian rest-activity rhythms in constant darkness, and their connections with a specific cluster of dopaminergic neurons. We also observed that chronic jet lag led to an accelerated age-related locomotor decline that could be rescued by adapting the light-dark to the flies’ endogenous period. Finally, our work demonstrated the negative impact of environmentally imposed circadian arrhythmia on age-related locomotor decline in a fly model of PD.