<p> Chapter 1-4 focuses on investigating whether forced copulations occur in teneral females, and how the female responds. There has only been one paper to report mating in newly eclosed (teneral) female matings in fruit flies (Drosophila melanogaster), and it was suggested to be forced. The focus of this thesis is to determine whether teneral matings are forced and how this may affect the future remating and reproductive success of females. Within the thesis, chapter 1 and 4 results suggest that teneral matings occur in both Canton-S and wild caught females, and occur in females less than 30 minutes post eclosion. Chapter 3 compared the male/female interaction of teneral females vs. immature females that successfully reject male mating attempts. Males were more aggressive with teneral females, and females displayed more rejection behaviours during courtship and mating. Chapter 4, was aimed at investigating what the reproductive consequences are, and results suggest that a teneral mating yields less progeny than a mature mating, and 68% of tenerally mated females remate at maturity.</p> <p> Chapter 5 and 6 focuses on investigating whether situational caffeine tolerance can be developed in fruit flies. Chapter 5 results indicate that caffeine causes a rest disruption, and a general tolerance to the rest disrupting effects can be gained over 6 days of repeated administration. The experiments in chapter 6 used various protocols to investigate whether a situational tolerance will develop, using odours and colours as associative cues. No conclusive results were found.</p> / Thesis / Master of Science (MSc)