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Discovery of a new strain of Heterorhabditis bacteriophora and use of the inbred line approach to optimize its virulence and cold tolerance

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Title: Discovery of a new strain of Heterorhabditis bacteriophora and use of the inbred line approach to optimize its virulence and cold tolerance
Author: Sharifi-Far, Shahram
Department: School of Environmental Sciences
Program: Environmental Sciences
Advisor: Hallett, Rebecca HShapiro-Ilan, David I
Abstract: ABSTRACT Discovery of a new strain of Heterorhabditis bacteriophora and use of the inbred line approach to optimize its virulence and cold tolerance Shahram Sharifi-Far Advisor: University of Guelph, 2016 Rebecca H. Hallett Co-Advisor: David I. Shapiro-Ilan Serial culturing which leads to trait deterioration is a significant concern in the entomopathogenic nematode production industry for both in vivo and in vitro methods. Prior research indicates that generation of homozygous inbred lines can deter trait loss within a nematode population. I hypothesized that the inbred line approach can be combined with discovery (isolation of new genetic material) to create stable nematode strains with superior biocontrol potential. My objective was to test this hypothesis, in relation to developing superior virulence in colder temperatures. A putative cold-tolerant strain of Heterorhabditis bacteriophora was isolated from a local soil sample in southern Ontario. Ten homozygous inbred lines were generated and screened for biocontrol characteristics, including reproductive capacity, storage stability and virulence in a series of different temperatures. Superiority of the inbred lines compared to their wild-type parents, whether sub-cultured or non-cultured, as well as two commercial strains, was observed. Inbred line 415 exhibited very poor virulence, storage stability, reproductive capacity in small-scale and serial culturing trials, whereas inbred line 324 had the best storage stability, high virulence and reproductive capacity among all passages. Hence, this superior line – inbred line 324 – was selected for commercial use. Furthermore, the hypothesis that discovery can be combined with the inbred line approach to develop stable and superior nematodes for biocontrol was supported.
URI: http://hdl.handle.net/10214/9679
Date: 2016-04


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