RADseq study of two cryptic Plutella species from Australia. Plutella xylostella and Plutella australiana

The study investigated the biology, ecology and population genetic structure of two cryptic moth species from the genus Plutella, collected from brassicaceous plants throughout southern Australia. The two species included a global pest of Brassica crops, the diamondback moth, Plutella xylostella, and a recently described cryptic species, Plutella australiana, for which no information on biology or pest status has been available. RADseq was performed for 52 P. australiana and 47 P. xylostella individuals that coexisted at five collection locations. Genome-wide nuclear SNP markers were generated and used to compare nuclear genomes. A major objective of the study was to determine the extent to which Plutella australiana is an agricultural pest and the need for specific management of the two Plutella species. The RAD sequencing work was accompanied by crossing experiments, insecticide bioassays, investigation of mtDNA haplotypes and screening of Wolbachia infections. The study revealed strong genomic and phenotypic divergence between the species, despite their capacity to hybridize in laboratory crosses.