This thesis investigates the potential of two novel insecticides for the control of nuisance Diptera emanating from sewage biological filters. The efficacy of the insect growth regulator pyriproxyfen and a biological nematode Steinernema feltiae for the control of sewage flies were assessed. Both insecticides targeted primarily Sylvicola fenestralis, but also the chironomids Metriocnemus hygropetricus and Limnophyes minimus. Initial laboratory studies determined that concentrations of pyriproxyfen greater than 0.2 mg l-1 inhibited insect egg development or hatching and survival to the first larval instar. Four trials, assessing the efficacy of pyriproxyfen as the formulation Sumilarvoo were undertaken. Significant (P < 0.05) reductions in the emergence of S. fenestralis adults were achieved for doses of 0.5mg L-1, 0.22mg L-1 and 0.2mg L-1 but not for 0.4mg L-1. Reductions ranged from 38% to 100%. There is evidence to suggest that pyriproxyfen may affect adult control over two generations but it may have a limited window of use when targeting adult control. The Chironomid L. minimus was also effectively controlled (P < 0.05) with up to 70% suppression of adult emergence detected. High performance liquid chromatography (HPLC) was ascertained to be an effective analyses tool in determining that pyriproxyfen has a high affinity for sewage sludge's and concentrations > 100 mg L-1 inhibited aerobic and anaerobic purification processes. Laboratory based pathogenicity tests determined that the nematode Steinernema feltiae is a viable biocide capable of infecting the larvae of sewage flies. Field trials at three sites using a dose of one million nematodes per m2 produced significant reductions (P<0.05) in the emergence of S. fenestralis and M hygropetricus. Reductions ranged from 25-67% and 25-91% respectively. No adverse effects on the non-dipteran filter fauna, the purification efficiency, or the invertebrates in the river receiving the work's effluent, were detected after use of both insecticides.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:491049 |
| Date | January 2006 |
| Creators | Cleworth, Mark Andrew |
| Publisher | University of Salford |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | http://usir.salford.ac.uk/43036/ |
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