Morphological and molecular identification of Xylocoris flavipes (Hemiptera: Anthocoridae) in southern China

During the investigation of natural enemy insects in grain depots, we've found an Anthocoridae insect accounted for a high proportion of natural enemy insects. We identify the enemy insects from morphology and molecular biology, so as to realize more accurate and effective control of storage pests by using the enemy insect. The images of the insects under the ultra-depth microscope (VHX-5000) showed that the insect adults were black brown in colour; the antennas of both the female and male had four segments, which increase in length sequentially from the base to the end, and had a length of 756.2 μm for the female and 741.1 μm for the male. The rostrums of both the female and the male insects were composed of three segments, the male's rostrum (596.8 μm) were shorter than the female's (734.6 μm), and the former two segments of the female's rostrum were significantly longer than the male's. The abdomen of the insect was bilaterally symmetrical, the female's abdomen was wider than the male, and the male insect had a dent between its eighth and ninth segments of the left abdomen, in which its male genitalia was located. In addition, the nymphs as a whole were tangerine in colour, and the eggs were elliptic with creamy white gloss and gridding patterns on the surface. The cytochrome C oxidase I (COI)  gene sequences of the insects were identified by DNA barcoding technique, and the determined COI sequences were then submitted to the Genbank database for Blast alignment, and the results showed that the COI gene sequences had a high degree of similarity (99%) with X. flavipes records in the Genbank database. Therefore, we could determine that the insect was X. flavipes. In addition, the neighbor joining (NJ) was used to construct the evolutionary tree, and 1,000 repeated tests were conducted on the confidence levels of each branch. Based on the phylogenetic tree, we've found that X. flavipes belongs to Xylocoris genus. Based on morphology and COI sequence identification, we confidentiy determined that the collected natural enemy insect was X. flavipes. This is the first time that the identification of X. flavipes is being investigated from morphology and molecular biology. The research results are helpful to identify and distinguish the species of flower bugs, and beneficial for the better application of X. flavipes in biological control.