Genome sequencing of gall aphids
The aphid species Chaetogeoica ulmidrupa lives on its primary host plant Pistacia chinensis to form galls. In this study, the genome of C. ulmidrupa was sequenced by shotgun genome-skimming methods, and the complete mitochondrial genome was assembled and analyzed. The mitochondrial genome is 15,549 bp in length and consists of 13 protein-coding genes, 22 transfer RNA genes and two ribosomal RNA genes. The nucleotide composition is 45.9% A, 5.6% G, 10.0% C, and 38.5% T, showing a very high A+T bias (84.4%). All protein-coding genes initiate with ATN codon and stop with TAA, except for ND4 and COX1, which end with TAT and AAT, respectively. Based on the dataset of the concatenated protein-coding genes and rRNA sequences, we also constructed the maximum likelihood phylogenetic tree of Aphididae using the two species Adelges laricis and Adelges tsugae in the family Adelgidae as outgroup. The tree strongly supported the monophyly of three subfamilies, i.e., Hormaphidinae, Aphidinae, Eriosomatinae. The species C. ulmidrupa is sister to Chaetogeoica yunlongensis, and then clustered with Slavum lentiscoides as a group, these three species of which all feed on the primary host plant Pistacia chinensis to form galls.