Molecular identification and cryptic species diversity of armored scale insects

Armored scale insects (Hemiptera: Coccoidea: Diaspididae) are highly invasive and economically damaging pests that are frequently intercepted in quarantine on diverse plant material. Rapid and accurate identification of intercepted material is required. Currently, identification is based on morphological characters of slide-mounted adult females. This method is always time-consuming, and many samples -- for instance, immature individuals -- are unidentifiable. Potentially, a DNA-based system of identification could be more rapid, more accurate, and applicable to a wider range of samples. Here we report on a project that lays the groundwork for DNA identification of armored scale insects. We purify DNA from individual specimens, mount their cuticles on microscope slides, and evaluate the quality of each cuticle as a morphological voucher specimen. High-quality specimens are identified morphologically by experts and three loci are sequenced from each (28S rDNA, elongation factor -1 alpha, and cytochrome c oxidase I-II). This results in matrices of sequences tied to morphological specimens and species names. We add sequences from unidentified specimens to these matrices and analyze them phylogenetically to yield estimates of species identity. We also use these matrices to estimate interspecific phylogeny of armored scale insects, and in many instances our results provide evidence for the occurrence and distribution of cryptic species.