Morphometric and molecular discrimination of the sugarcane aphid, Melanaphis sacchari, (Zehntner, 1897) and the sorghum aphid Melanaphis sorghi (Theobald, 1904)

PLoS One. 2021 Mar 25;16(3):e0241881. doi: 10.1371/journal.pone.0241881. eCollection 2021.

Abstract

Melanaphis sacchari (Zehntner, 1897) and Melanaphis sorghi (Theobald, 1904) are major worldwide crop pests causing direct feeding damage on sorghum and transmitting viruses to sugarcane. It is common in the scientific literature to consider these two species as synonyms, referred to as the 'sugarcane aphid', although no formal study has validated this synonymy. In this study, based on the comparison of samples collected from their whole distribution area, we use both morphometric and molecular data to better characterize the discrimination between M. sacchari and M. sorghi. An unsupervised multivariate analysis of morphometric data clearly confirmed the separation of the two species. The best discriminating characters separating these species were length of the antenna processus terminalis relative to length of hind tibia, siphunculus or cauda. However, those criteria sometimes do not allow an unambiguous identification. Bayesian clustering based on microsatellite data delimited two clusters, which corresponded to the morphological species separation. The DNA sequencing of three nuclear and three mitochondrial regions revealed slight divergence between species. In particular, the COI barcode region proved to be uninformative for species separation because one haplotype is shared by both species. In contrast, one SNP located on the nuclear EF1-α gene was diagnostic for species separation. Based on morphological and molecular evidence, the invasive genotype damaging to sorghum in the US, Mexico and the Caribbean since 2013 is found to be M. sorghi.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Animals
  • Aphids / genetics*
  • Aphids / physiology
  • Arthropod Antennae / physiology
  • Bayes Theorem
  • Cluster Analysis
  • DNA-Binding Proteins / chemistry
  • DNA-Binding Proteins / genetics
  • DNA-Binding Proteins / metabolism
  • Electron Transport Complex IV / chemistry
  • Electron Transport Complex IV / genetics
  • Electron Transport Complex IV / metabolism
  • Genotype
  • Haplotypes
  • Insect Proteins / chemistry
  • Insect Proteins / genetics
  • Insect Proteins / metabolism
  • Microsatellite Repeats
  • Mitochondria / genetics
  • Polymorphism, Single Nucleotide
  • Sequence Analysis, DNA
  • Sorghum*

Substances

  • DNA-Binding Proteins
  • Insect Proteins
  • Electron Transport Complex IV

Grants and funding

This work was co-funded by the European Union: Agricultural Fund for Rural Development (https://ec.europa.eu/agriculture/cap-funding_en), by the Conseil Départemental de La Réunion (http://www.cg974.fr), by the Conseil Régional de La Réunion (https://www.regionreunion.com) and by the Centre de Coopération internationale en Recherche agronomique pour le Développement (www.cirad.fr), as well as by the National Institute of Food and Agriculture, U.S. Department of Agriculture Hatch Program (TEX09185 to R. F. M), and was carried out in part on the Plant Protection Platform which is co-financed by the Groupe d'Intérêt Scientifique "Infrastructures en Biologie Santé et Agronomie" (www.ibisa.net). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.