%0 Journal Article
%J PLoS ONE
%D 2012
%T The rph2 Gene Is Responsible for High Level Resistance to Phosphine in Independent Field Strains of Rhyzopertha dominica
%A Mau, Yosep
%A Collins, Patrick
%A Daglish, Gregory
%A Nayak, Manoj
%A Ebert, Paul
%X <p>The lesser grain borer <em>Rhyzopertha dominica</em> (F.) is one of the most destructive insect pests of stored grain. This pest has been controlled successfully by fumigation with phosphine for the last several decades, though strong resistance to phosphine in many countries has raised concern about the long term usefulness of this control method. Previous genetic analysis of strongly resistant (SR)<em> R. dominica</em> from three widely geographically dispersed regions of Australia, Queensland (SRQLD), New South Wales (SRNSW) and South Australia (SRSA), revealed a resistance allele in the <em>rph1</em> gene in all three strains. The present study confirms that the <em>rph1</em> gene contributes to resistance in a fourth strongly resistant strain, SR2QLD, also from Queensland. The previously described <em>rph2</em> gene, which interacts synergistically with <em>rph1</em> gene, confers strong resistance on SRQLD and SRNSW. We now provide strong circumstantial evidence that weak alleles of <em>rph2</em>, together with<em> rph1</em>, contribute to the strong resistance phenotypes of SRSA and SR2QLD. To test the notion that<em> rph1</em> and<em> rph2</em> are solely responsible for the strong resistance phenotype of all resistant <em>R. dominica</em>, we created a strain derived by hybridising the four strongly resistant lines. Following repeated selection for survival at extreme rates of phosphine exposure, we found only slightly enhanced resistance. This suggests that a single sequence of genetic changes was responsible for the development of resistance in these insects.</p>