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Abstract The objective of this thesis is to study the biological effects of larvae of Aedes albopictus induced by ultrasound exposure. Ultrasound is widely used in medical and biological techniques, most of them are cell killing or tumor eliminating by high-intensity ultrasound. In order to analyse the influences of ultrasound biological effects in vivo, the larvae of mosquito, in this research, were exposed to continuous-wave ultrasound. Some preliminary observations were made with 0-day larvae. The oscillation of the trachea in larvae in response to the ultrasound radiation is simulated using Miller¡¦s cylindrical-bubble activation theory. Dimensions of tubes in the respiratory system of larvae were measured by microscope. The resonant frequency of the tracheae were calculated, and its range is about 0.6¡ã1.5 MHz. It was observed that the tracheae in 0-day larvae were ruptured by ultrasound exposure, and the larvae were dead in the duration of growth, some fourth instar larvae failed to mature into pupae. The maximum mosquito larvae mortality was with 1 MHz irradiation, and it¡¦s in good agreement with the resonant frequency calculated in this paper.

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No description available.

Giralang Pond was a water body, with little emergent or submerged vegetation, designed to trap fine sediment and buffer input of rising water to Ginninderra Wetland downstream. Ginninderra Wetland was designed to retain and use sediment nutrients and other potential hazardous materials in urban run-off. Water in the Wetland was more turbid and had lower magnesium concentration, redox potentials and dissolved oxygen concentration than did Giralang Pond. Water temperature was a minimum of 4 °C in the winter and reached a summer maximum of 30 °C Giralang Pond had more organisms but fewer taxa than Ginninderra Wetland. The greatest abundance in the pond resulted principally from high numbers of two numerically dominant species Calamoecia sp. and Micronecta sp.. More organisms were found in vegetated habitats of Ginninderra Wetland than open water habitats. The number of invertebrates and the number of taxa found in Typha domingensis did not differ significantly from similar estimates for Schoenplectus validus, Gambusia qffinis was the dominant predator in both water bodies. On one occasion, G. qffinis reached population densities of 35 individuals per m-2 . G. qffinis was five times more abundant in Gininnderra Wetland than in Giralang Pond and also showed a preference for vegetated areas. G. qffinis over-grazed it's prey on several occasions. G. qffinis, invertebrate predators and prey followed a pattern of a community in a stable predator-prey cycle. Prey in early spring increased population numbers and then decreased when G. qffinis and other predators increased their numbers. The pattern was further strengthened by occurring in both areas of open water and vegetated habitat types.