Rapid identification of Henosepilachna vigintioctopunctata and Henosepilachna vigintioctomaculata based on species-specific mitochondrial cytochrome oxidase I primers

Objective: Henosepilachna vigintioctopunctata (Fabricius) and Henosepilachna vigintioctomaculata (Motschulsky), two kinds of phytophagous ladybeetles in China, are destructive pests causing great damage to solanaceous plants. They are difficult to distinguish based on external morphological characteristics, and it is therefore necessary to develop a rapid and accurate method to differentiate them. Method: We established a molecular identification technique using species-specific (SS) PCR primers based on the species-specificity of mitochondrial cytochrome oxidase I (mtCOI) of two ladybeetles. Two pairs of SS-mtCOI primers, Hvp and Hvm, were designed based on sequence variations in the mtCOI gene between H. vigintioctopunctata and H. vigintioctomaculata. Result: PCR amplifications were conducted using these two primers and both had species-specific amplifications. Sensitivity assays were conducted under different DNA concentrations, and the results showed that Hvp primers for H. vigintioctopunctata had a detectable amplification band at a DNA concentration of 3.13 mg/L, while Hvm primers for H. vigintioctomaculata had a detectable amplification band at a DNA concentration of 2.43 mg/L. The egg or 1st instar of H. vigintioctopunctata and H. vigintioctomaculata could also be accurately differentiated by Hvp and Hvm primers. Furthermore, six field populations of H. vigintioctopunctata collected from six provinces could be authenticated by the Hvp primers. Conclusion: These two pairs of SS-mtCOI primers can differentiate H. vigintioctopunctata and H. vigintioctomaculata rapidly, accurately and sensitively.