DNA barcoding: an innovative tool to identify internal lepidopterans in apples

Abstract: The identification of Lepidoptera larvae can be problematic when different species occur at the same time in crops and when their identification requires dissection or laboratory rearing. In Quebec, this is the case for three Tortricidae that feed synchronously in apples: the codling moth [Cydia pomonella (L.)], the lesser appleworm [Grapholita prunivora (Walsh)] and the oriental fruit moth [Grapholita molesta (Busck)]. Codling moth larvae can usually be distinguished from the two other species by their larger size and the absence of anal comb, but larvae of the lesser appleworm and oriental fruit moth are nearly indistinguishable.The objective of our study is to validate DNA barcoding as a method for identifying major lepidopteran larval pest insects occurring in apple orchards in Quebec. This molecular method uses primers common to all Lepidoptera that target a 658 bp gene fragment coding for cytochrome oxydase I, which are specific to each lepidopteran species. 140 adult moths of the three species were collected in 2011 from six apple-producing regions in Quebec to establish a DNA sequence library that would be included in the “Barcode of Life Data Systems”. Lepidoptera larvae were sampled in the 2012 summer season in orchards of Quebec to assess the effectiveness of the molecular method for larval identification. When validated, this method will become a useful identification tool for laboratories specialized in plant pest identification.