No description available.

No description available.

No description available.

No description available.

No description available.

Numerical models of insect flapping flight have previously been developed and used to simulate the performance of insect flight. These models were commonly developed via Blade Element Theory, offering efficient computation, thus allowing them to be coupled with optimisation procedures for predicting optimal flight. However, the models have only been used for simulating hover flight, and often neglect the presence of the induced flow effect. Although some models account for the induced flow effect, the rapid changes of this effect on each local wing element have not been modelled. Crucially, this effect appears in both axial and radial directions, which influences the direction and magnitude of the incoming air, and hence the resulting aerodynamic forces. This thesis describes the development of flapping wing models aimed at advancing theoretical tools for simulating the optimum performance of insect flight. Two models are presented: single and tandem wing configurations for hawk moth and dragonfly, respectively. These models are designed by integrating a numerical design procedure to account for the induced flow effects. This approach facilitates the determination of the instantaneous relative velocity at any given spanwise location on the wing, following the changes of the axial and radial induced flow effects on the wing. For the dragonfly, both wings are coupled to account for the interaction of the flow, particularly the fact that the hindwing operates in the slipstream of the forewing. A heuristic optimisation procedure (particle swarming) is used to optimise the stroke or the wing kinematics at all flight conditions (hover, level, and accelerating flight). The cost function is the propulsive efficiency coupled with constraints for flight stability. The vector of the kinematic variables consists of up to 28 independent parameters (14 per wing for a dragonfly), each with a constrained range derived from the maximum available power, the flight muscle ratio, and the kinematics of real insects; this will prevent physically-unrealistic solutions of the wing motion. The model developed in this thesis accounts for the induced flow, and eliminates the dependency on the empirical translation lift coefficient. Validations are shown with numerical simulations for the hover case, and with experimental results for the forward flight case. From the results obtained, the effect of the induced velocity is found to be greatest in the middle of the stroke. The use of an optimisation process is shown to greatly improve the flapping kinematics, resulting in low power consumption in all flight conditions. In addition, a study on dragonfly flight has shown that the maximum acceleration is dependent on the size of the flight muscle.

Locomotion is central to the survival of many animal species; however large variation in performance, for example in speed or endurance, exists between individuals within a species. Using the bumblebee species, Bombus impatiens, I studied the extent of the variation in several flight performance traits and how they are associated. I first addressed how bumblebee workers vary in foraging effort and observed that only around half of the monitored individuals underwent foraging activity. Additionally, significant variation in metabolic rate between foragers and non-foragers was uncovered. I further investigated if such variation could be associated with flight performance capacity, such as an individual’s ability to carry a load, their flight speed and distance traveled, their wing morphology and kinematics, and their flight metabolic rate. These traits are commonly measured to characterize flight capacity in insects, however the links between them have yet to be investigated. Links between morphology, wing kinematics and peak metabolic rate previously uncovered in the literature were observed in my analysis, although variation in their scaling with body mass was detected. Vertical force scaled isometrically with body mass but was not related to it when expressed in on a mass specific basis (VF m-1g-1, where m is gravitation acceleration). In regard to forward flight speed, body mass does have an affect, however it alone does not have a great degree of explanatory power and other factors such as morphology and wing kinematics are likely to play a greater part in its determination. Finally, maximum flight speed had a significant relationship with total flight time. Together, these results demonstrate that some links do exist between flight performance traits, however links are not present between all traits and certain flight performance traits should be treated as independent of each other.

Flying insects face challenging conditions such as rainfall, fog, and dew. In this theoretical and experimental thesis, we investigate the survival mechanisms of the mosquito, Anopheles, through particles of various size. Large particles such as falling raindrops can weigh up to fifty times a mosquito. Mosquitoes survive such impacts by virtue of their low mass and strong exoskeleton. Smaller particle sizes, as present in fog and insecticide, pose the greatest danger. Mosquitoes cannot fly through seemingly innocuous household humidifier fog or other gases with twice the density of air. Upon landing, fog accumulates on the mosquito body and wings, which in small quantities can be shaken off in the manner of a wet dog. Large amounts of dew on the wings create a coalescence cascade ultimately folding the wings into taco shapes, which are difficult to dry. The insights gained in this study will inform the nascent field of flapping micro-aerial vehicles.

No description available.

Recent studies suggest a possible correlated evolution of wing morphology, wing beat frequency, muscle biochemistry and flight metabolic rate in bees. In order to investigate the degree to which natural selection can act on these traits, an estimation of heritability was required. Commercial and laboratory reared colonies from wild caught queens were used to estimate narrow-sense (h2) and broad-sense (H2) heritability of flight metabolic rate and its associated traits in the bumblebee Bombus impatiens. h2 estimates obtained from parent-offspring regressions were not statistically significant. H2 estimates were significant for morphological traits (body mass and wing morphology) as well as whole-animal traits (flight and resting metabolic rate, wing beat frequency) in both populations. We suggest that queens have a decrease in flight performance as a result of a trade-off between flight and fecundity, explaining the lack of significance in parent-offspring regressions.