Molecular Resources for the Stored Grain Cryptolestes Cryptic Pest Species (Coleoptera: Laemophloeidae)

Recent evolutionary genetics and molecular characterisation of Cryptolestes (Ganglbauer) stored grain pest beetle species revealed gaps in public DNA databases that resulted in molecular diagnostic inconsistencies in publicly available sequence databases. We report the characterisation of mitochondrial DNA cytochrome oxidase I (mtCOI) genes from specimens intercepted during Australia’s border biosecurity inspections, and surveys of public mtCOI gene sequences, for Cryptolestes species status re-assessment. We identified and characterised a new putative Cryptolestes species (C. sp. ‘WTT-2016’) and demonstrated the close evolutionary relationships between C. ferrugineus (Stephens)/C. pusilloides (Steel and Howe) and between C. pusillus (Schonherr) and the previously identified C. sp. ‘WTT-2013’ cryptic species. Confusion between C. ferrugineus, C. pusiolloides, C. pusillus, C. sp. ‘WTT-2013’, and C. sp. ‘WTT-2016’ highlighted a substantial and persistent taxonomic challenge within Cryptolestes, while low C. spartii (Curtis)/C. corticinus (Reitter) inter-specific genetic distances suggested they were the same species. Assembled and annotated mitochondrial DNA genomes (mitogenomes) of six Cryptolestes species identified assembly errors in published mitogenomes of C. ferrugineus and C. turcicus (Grouvelle) and misidentification of C. pusillus. Based on re-evaluation of genetic distances and phylogeny congruence, we proposed a Cryptolestes ‘operational species-level genetic gap’ at approximately 5% to help define Cryptolestes species boundaries, thereby contributing to improving agricultural biosecurity preparedness associated with this important stored grain beetle species. Our work also provides an evolutionary framework that will contribute to future understanding of ecological and environmental impact posed by this highly invasive cryptic beetle species complex.