The Mexican bean beetle (Epilachna varivestis) regurgitome and insights into beetle-borne virus specificity

PLoS One. 2018 Jan 29;13(1):e0192003. doi: 10.1371/journal.pone.0192003. eCollection 2018.

Abstract

For nearly 400 million years, insects and plants have been embattled in an evolutionary arms race. Insects have developed diverse feeding strategies and behaviors in an effort to circumvent and overcome an extensive collection of plant defense tactics. Sap-sucking insects often inject saliva into hosts plants, which contains a suite of effector proteins and even microbial communities that can alter the plant's defenses. Lacking salivary glands, leaf-feeding beetles represent an interesting group of phytophagous insects. Feeding beetles regurgitate onto leaf surfaces and it is thought that these oral secretions influence insect-plant interactions and even play a role in virus-vector specificity. Since the molecular and biological makeup of the regurgitant is virtually unknown, we carried out RNA sequencing and 16S rDNA analysis on a major soybean pest, Epilachna varivestis, to generate the first ever beetle "regurgitome" and characterize its microbiome. Interestingly, the regurgitant is comprised of a rich molecular assortment of genes encoding putative extracellular proteins involved in digestion, molting, immune defense, and detoxification. By carrying out plant inoculation assays, we reinforced the fundamental role of the regurgitant in beetle-borne virus specificity. Ultimately, these studies begin to characterize the importance of regurgitant in virus transmission and beetle-plant interactions.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Coleoptera / genetics
  • Coleoptera / metabolism*
  • Coleoptera / physiology
  • Coleoptera / virology
  • Genes, Insect
  • Transcriptome

Grants and funding

Funding for the project was provided by Natural Sciences and Engineering Research Council of Canada (NSERC) Discovery Grants Program awarded to Bryan Cassone (RGPIN-2016-04335). The funder had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.