Date of Award

2003

Degree Type

Thesis

Degree Name

Bachelor of Science Honours

Faculty

Faculty of Computing, Health and Science

First Advisor

Dr Mark Lund

Abstract

Non-biting midges (Diptera: Chironomidae) become a severe nuisance to humans living close to urban wetlands when they emerge at night to form mating swarms. The phototactic nature of adult chironomids means that large quantities of chironomids congregate around artificial lighting prominent in the surrounding suburbs of urban wetlands. This nuisance problem has compelled the investigation of suitable control options which are able to reduce the numbers of midges to below nuisance levels for an extended period. Currently the options available to control chironomid populations rely on the treatment of affected wetlands with pesticide. These treatment regimes are usually only successful for a short time period because of the intrinsic ability of midges to rapidly recover based on a number of biological and physiological mechanisms which chironomids posses. This study identified a number of key biotic and abiotic factors which determine the ability of chironomids to reach nuisance proportions at Lake Joondalup. Western Australia. The biological factors included: the presence of multivoltine chironomid species, rapid development rates, overlapping cohorts, continuous asynchronous emergence and high fecundity. In addition, the key biotic and abiotic factors included: mild winter temperatures, seasonal fluctuations of water levels, large heterogenous habitat, limited predators and competitors, eutrophic conditions and the ability of chironomids to tolerate poor environmental conditions. These factors were combined into a conceptual model which outlined the critical pathways to the occurrence of nuisance problems. Some alternative treatment options were proposed and theoretically tested based on the application of selective pesticide treatment and the implementation of light traps during periods of low water levels to effectively impede the recolonising potential of the chironomid populations when the lake refills following drying conditions. In addition, this study aided in identifying several key life history characteristics which could be used to test the efficacy of alternative pesticide treatment regimes.

Included in

Entomology Commons

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