Tracking invasion and invasiveness in Queensland fruit flies: From classical genetics to ‘omics’

Three Australian tephritid fruit flies (Bactrocera tryoni - Q-fly, Bactrocera neohumeralis - NEO, and Bactrocera jarvisi - JAR) are promising models for genetic studies of pest status and invasiveness. The long history of ecological and physi- ological studies of the three species has been augmented by the development of a range of genetic and genomic tools, including the capacity for forced multigeneration crosses between the three species followed by selection experiments, a draft genome for Q-fly, and tissue- and stage-specific transcriptomes. The Q-fly and NEO species pair is of particular interest. The distribution of NEO is contained entirely within the wider distribution of Q-fly and the two species are ecologically extremely similar, with no known differences in pheromones, temperature tolerance, or host-fruit utilisation. However there are three clear differences be- tween them: humeral callus colour, complete pre-mating isolation based on mating time-of-day, and invasiveness. NEO is much less invasive, whereas in historical times Q-fly has invaded southeastern Australia and areas of Western Australia and the North- ern Territory. In southeastern fruit-growing regions, microsatellites suggest that some of these outbreaks might derive from ge- netically differentiated populations overwintering in or near the invaded area. Q-fly and NEO show very limited genome diffe- rentiation, so comparative genomic analyses and QTL mapping should be able to identify the regions of the genome controlling mating time and invasiveness, to assess the genetic bases for the invasive strains of Q-fly, and to facilitate a variety of improve- ments to current sterile insect control strategies for that species (Current Zoology 61 (3): 477-487, 2015). Keywords Bactrocera, Genomics, STERILE-insect-technique, Interspecific-hybridisation