In recent years, DNA barcoding has rapidly developed as a powerful tool in taxonomy, demonstrating its value in species identification and discovery of cryptic diversity. The number of barcoding sequences of various species continues to grow in the GenBank and BOLD databases; however, the accuracy of sequences and related raw information in public repositories is often questionable. In the present study, based on a dataset of 68,089 Hemiptera COI barcode sequences covering 3,064 species, 1,072 genera, and 48 families, we analyzed genetic differences within and between species and evaluated possible data errors in the insect barcodes. The results showed that errors in the barcode data are not rare, and most of them are due to human errors, such as specimen misidentification, sample confusion, and contamination. A significant portion of these errors can be attributed to inappropriate and imprecise practices in the DNA barcoding workflow. Herein, suggestions are provided to improve the practical operations and workflow of DNA barcoding to reduce human errors.

Insect mitochondrial genomes (mitogenomes) are of great interest in exploring molecular evolution, phylogenetics and population genetics. Only two mitogenomes have been previously released in the insect group Aphididae, which consists of about 5,000 known species including some agricultural, forestry and horticultural pests. Here we report the complete 16,317 bp mitogenome of Cavariella salicicola and two nearly complete mitogenomes of Aphis glycines and Pterocomma pilosum. We also present a first comparative analysis of mitochondrial genomes of aphids. Results showed that aphid mitogenomes share conserved genomic organization, nucleotide and amino acid composition, and codon usage features. All 37 genes usually present in animal mitogenomes were sequenced and annotated. The analysis of gene evolutionary rate revealed the lowest and highest rates for COI and ATP8, respectively. A unique repeat region exclusively in aphid mitogenomes, which included variable numbers of tandem repeats in a lineage-specific manner, was highlighted for the first time. This region may have a function as another origin of replication. Phylogenetic reconstructions based on protein-coding genes and the stem-loop structures of control regions confirmed a sister relationship between Cavariella and pterocommatines. Current evidence suggest that pterocommatines could be formally transferred into Macrosiphini. Our paper also offers methodological instructions for obtaining other Aphididae mitochondrial genomes.

Global climate warming has significant influence on individual development, population dynamics, and geographical distribution of many organisms, which has drawn much attention in recent years. As a large group of poikilotherms, insects whose life activities are closely linked with ambient temperature are supposed to be influenced by global warming. In order to test the consistency or difference of the effects of long-term climate warming on phytophagous insect pests in different geographical environments, this study collected historical data on the occurrence and population dynamics of three aphid pests (Myzus persicae, Aphis gossypii, and Sitobion avenae) in China, and systematically explored their phenological responses. We found that, during a period of about 60 years, in general, the first occurrence dates and the first migration dates of the three aphids almost moved earlier, while the end of the occurrence and the last migration dates were slightly delayed. However, these responses also represented geographical variation at a local scale. Basically, our results showed that the occurrence and migration seasons of these three aphid pests have been prolonged along with climate warming. This study based on historical literature data provides empirical evidence and valuable implications for understanding the impact of climate warming on insect pests and future management strategies.