Attack of the Clone(s): Genomic Analysis of Russian Wheat Aphid in Australia Suggests a Single Extant Clonal Lineage but Multiple Invasions

ABSTRACT The Russian wheat aphid, Diuraphis noxia , was first detected in Australia in 2016. Despite being recognised as a highly adaptable pest, little is known about the genetic variation present within its invasive Australian range, particularly in relation to other invaded areas. We used genomic data from D. noxia collected across Australian cereal‐growing regions to characterise clonal diversity and compare it to international biotypes. Our results support the occurrence of a single extant clonal lineage in Australia, which is most closely related to biotypes from South Africa. Delta D (Δ D ) estimates indicated no significant differentiation between Australian populations, except for a single population collected shortly after the first detection in Australia in 2016. Significant differentiation was also detected between Australian D. noxia and international biotypes. These findings suggest that extant Australian D. noxia represent a single clonal lineage, whereas a separate invasion may have occurred without establishment. The results provide a baseline for monitoring and management of D. noxia in Australia and contribute to our understanding of invasion genetics and the evolutionary dynamics of invasive aphid populations.