Transcriptome sequencing of an ecologically important graminivorous sawfly: a resource for marker development

Sawfly larvae (Hymenoptera: Symphyta) are an important, highly nutritious, invertebrate food source for farmland birds. Reduced numbers of farmland invertebrates are a possible factor contributing to the observed declines in many farmland bird populations associated with post-1950s intensification of agriculture. To date, studies on sawfly populations have been census-based and, therefore, the genetic factors underlying their declines are unknown. We have produced the first genetic resource for any sawfly species in the form of a de novo transcriptome assembly comprising 18,539 contiguous sequences (contigs) and 260 singletons. The assembly was sequenced using 454 pyrosequencing technology and produced 1,284 microsatellite markers for the common farmland sawfly Dolerus aeneus, which may also be useful in other closely-related species. These markers will facilitate monitoring of changes in genetic diversity and gene flow in sawfly populations therefore helping to predict extinction risk.