DNA Barcoding Subtropical Aphids and Implications for Population Differentiation.

Qiang Li,Zhentao Cheng,Linda Zeng,Jun Deng,Xiaolan Lin,Cui Chen,Gexia Qiao,Xiaolei Huang

doi:10.3390/insects11010011

Abstract

DNA barcoding has proven its worth in species identification, discovering cryptic diversity, and inferring genetic divergence. However, reliable DNA barcode reference libraries that these applications depend on are not available for many taxonomic groups and geographical regions. Aphids are a group of plant sap sucking insects, including many notorious pests in agriculture and forestry. The aphid fauna of the subtropical region has been understudied. In this study, based on extensive sampling effort across main subtropical areas, we sequenced 1581 aphid specimens of 143 morphospecies, representing 75 genera, and 13 subfamilies, to build the first comprehensive DNA barcode library for subtropical aphids. We examined the utility of DNA barcodes in identifying aphid species and population differentiation and evaluated the ability of different species delimitation methods (automatic barcode gap discovery (ABGD), generalized mixed Yule-coalescent (GMYC), and Bayesian Poisson tree processes (bPTP)). We found that most aphid species demonstrated barcode gaps and that a threshold value of 2% genetic distance is suitable for distinguishing most species. Our results indicated that ten morphospecies may have species divergence related to factors such as host plant or geography. By using two pest species Aphis spiraecola and A. gossypii as examples, we also discussed the effect of the sampling scale of host plants on the results and reliability of DNA barcoding of phytophagous insects. This DNA barcode library will be valuable for future studies and applications.

Highlights

Since DNA barcoding was formally proposed at a large scale in 2003 [1], it has been widely used in different fields, for example species delimitation [2,3], cryptic diversity discovering [4,5], investigating host–parasitoid interactions [6,7], pest quarantine, and environmental monitoring [8,9,10]
A first DNA barcode reference library for subtropical aphids has been built. Based on this reference database, we examined the utility of DNA barcoding in species identification, tested the accuracy of different species delimitation methods (automatic barcode gap discovery (ABGD), generalized mixed Yule-coalescent (GMYC), and Bayesian Poisson tree processes), and revealed several cases of the population differentiation of aphid pests
A total of 1581 aphid specimens was successful sequenced in our study and identified as 143 morphological species, representing 13 subfamilies and 75 genera, collected from 244 host plant species in subtropical areas of southern China

Summary

Introduction

Since DNA barcoding was formally proposed at a large scale in 2003 [1], it has been widely used in different fields, for example species delimitation [2,3], cryptic diversity discovering [4,5], investigating host–parasitoid interactions [6,7], pest quarantine, and environmental monitoring [8,9,10]. A fragment of the mitochondrial cytochrome oxidase subunit I (COI) gene has been proven to be a standard DNA barcode region for animal species identification and detecting molecular operational taxonomic units (MOTUs) [11,12]. The usability of DNA barcoding has been reported in many groups, for instance. The power and accuracy of DNA barcoding, as well as unambiguous species identification may depend on sampling scales [18,19]. For many organisms including plant feeding insects, their species differentiation processes have been influenced by geography, and by other factors (e.g., host plant for phytophagous insect)

Methods

Results

Discussion

Conclusion