Dr Joshua Thia1, Dr Paul Umina2, Prof Ary Hoffmann1

1University of Melbourne, Australia, 2Cesar Australia, Brunswick, Australia

Biography:

Joshua is a postdoctoral fellow at the University of Melbourne. He uses genomic approaches to study the evolution and demography of pests and natural enemies in agro-ecosystems.

Abstract:

The invasive redlegged earth mite, Halotydeus destructor (Tucker, 1952: Trombidiformes; Penthaleidae), is a major pest of Australia grain and pasture crops. Over the last two decades, resistance to organophosphate pesticides has been steadily increasing across this mite’s Australian range. Preliminary work has suggested that this resistance is polygenic, which has so far limited scope to monitor resistance using standard single genetic markers. Polygenic models that characterise the genomic architecture of organophosphate resistance therefore provide a much more attractive approach. Using over 100 redlegged earth mite populations sampled across Australia, we demonstrate that polygenic models built from sequence or copy number variants provide a useful way of identifying populations at high risk of organophosphate resistance. Our work highlights how a polygenic perspective can be applied to better describe the geographic distribution of resistance-conferring alleles when the evolved genomic architecture of resistance is complex. Our candidate polygenic markers of resistance also provide a useful tool for mapping the risk of organophosphate resistance across Australia, guiding area-wide resistance management strategies.