Morphometric analysis and deoxyribonucleic acid barcoding of new grapevine pest, Stromatium barbatum (Fabricius) (Coleoptera: Cerambycidae) in India

Abstract

Deoxyribonucleic acid barcoding, using mitochondrial cytochrome c oxidase-1 sequence, is an accurate and rapid identification method for insect-taxa and independent of life-stages, sex and polymorphism. The present study aimed at providing deoxyribonucleic acid barcode for the correct identification of Stromatium barbatum (Fabricius), a new pest of grapevines in India. Morphometric analysis and pictorial illustrations of important morphological features and life-stages were also documented for future reference. Average length and breadth (in mm) were 1.012 ± 0.10 and 0.49 ± 0.07 for egg, 1.52 ± 0.15 and 0.50 ± 0.04 for neonate-grub, 35.12 ± 0.47 and 7.08 ± 0.12 for fully matured grub, 26.0 ± 0.25 and 8.64 ± 0.12 for pupa, 21.20 ± 2.51 and 6.02 ± 0.62 for adult-male, and 22.47 ± 2.26 and 6.67 ± 0.75 for adult-female, respectively. Antennae was filiform which was longer in males (30.63 ± 5.89 mm) than females (22.55 ± 4.84 mm). The barcode showed 86% match with closely related S. longicorne and in Neighbor Joining analysis formed monophyletic clade with S. longicorne suggesting correct genus-level identification. Specimens used for sequencing were morphologically identified by an expert taxonomist and compared with type specimens before barcoding and sequences were submitted to National Center for Biotechnology Information. The barcode was put to test for confirmation of size-polymorphism. Cytochrome c oxidase-1 regions were sequenced for morphologically identified S. barbatum large male (2.6 cm), large female (2.9 cm), small male (1.6 cm) and small female (1.8 cm). These sequences showed B2.5% divergence among each other and B2.5 divergence with the DNA barcode confirming that the four specimens of different sizes belonged to same species and variation was due to size-polymorphism.