The Genome of Plutella xylostella (Diamondback Moth) Three Ways

The diamondback moth, Plutella xylostella, is an important pest of brassica crops worldwide.  The overuse of pesticides and poor crop management has allowed the moth to develop resistance to multiple chemical and biological insecticides. RIDL technology developed by Oxitec has the potential to provide an alternative to traditional control methods. However, for the effective design of genetics-based control there was a need to produce a high-quality diamondback moth female genome and parallel tissue/sex-specific gene expression data. The genome was first published in 2013 using a combination of fosmid clones and whole genome shotgun using the Illumina sequencing platform. This resulted in a genome of 343 Mb (consisting of 36470 contigs, with an N50 of 20 kb) contains 18,071 protein-coding genes. However, this was a very labour-intensive approach that used >100 moths. Our approach was to construct sequencing libraries from single moths for sequencing on the Roche 454 and Illumina with a range of library inset sizes. The resulting assembly was 380 Mb. To improve the quality of this genome we have added long PACBIO reads. We have also produced a PACBIO only de novo assembly that has >2000 contigs and an N50 of 225 kb. We will discuss the pros and cons of these technologies to describe the sex chromosomes of Lepidoptera.