The efficacy of two novel insecticides to control nuisance diptera breeding in sewage biological filters

Cleworth, MA

Abstract

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.

Citation

Cleworth, M. The efficacy of two novel insecticides to control nuisance diptera breeding in sewage biological filters. (Thesis). University of Salford

• Thesis Type: Thesis
• Deposit Date: Jul 14, 2017
• Publisher URL: http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.491049
• Related Public URLs: http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.491049
• Award Date: Jan 1, 2006