First record of a new microsporidium pathogenic to Gonipterus platensis in Brazil

Authors: JORDAN, CAROLINA - Sao Paulo State University (UNESP); DE CARVALHO, VANESSA RAFAELA - Sao Paulo State University (UNESP); MASCARIN, GABRIEL MOURA - Embrapa; DOS SANTOS OLIVEIRA, LEILIANE RODRIG - Sao Paulo State University (UNESP); Dunlap, Christopher; WILCKEN, CARLOS FREDERIC - Sao Paulo State University (UNESP)

Submitted to: Scientific Reports
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/12/2021
Publication Date: 5/26/2021
Citation: Jordan, C., de Carvalho, V., Mascarin, G., Dos Santos Oliveira, L., Dunlap, C.A., Wilcken, C. 2021. First record of a new microsporidium pathogenic to Gonipterus platensis in Brazil. Scientific Reports. 11. Article 10971. https://doi.org/10.1038/s41598-021-90041-9.
DOI: https://doi.org/10.1038/s41598-021-90041-9

Interpretive Summary: ARS researcher from Peoria, IL collaborated with scientists from Brazil to identify a fungal pathogen infecting eucalyptus snout beetles, a pest insect of eucalyptus plantations. The study investigates the basic characteristics of the pathogen and its occurrence in field and laboratory colony insects. Understanding the natural pathogen pressures on insects is important to developing control strategies for these pests. The presence of natural pathogens may positively or negatively impact the efficacy of pest control products and need to be understood for predictable insect management. The current study enhances our knowledge by identifying an unknown natural pathogen infecting a forest pest, which can be further evaluated to determine its impact on pest control products and strategies.

Technical Abstract: Microsporidia are naturally occurring fungal-related parasites that can infect nearly all animal hosts, but their biocontrol potential of insect pests is routinely overlooked in agriculture and forestry. This research brings the first report describing the natural occurrence of a microsporidium causing disease in field-collected populations of the invasive eucalyptus snout beetle, Gonipterus platensis (Coleoptera: Curculionidae), a major destructive pest of eucalyptus plantations in Brazil. Adult beetles were collected during field surveys in commercial eucalyptus plantations in southern Brazil to be examined and dissected with typical symptoms to verify presence of microsporidian spores in haemolymph. From 14 plantations in different sites, the natural infection occurrence in these populations ranged from 0 to 65%, while a lab colony exhibited an infection incidence of 70%. Spore density in haemolymph of symptomatic insects averaged 2.1 (±'0.4)'×'107 spores/beetle. Symptoms in infected adults were identified by an abnormal abdomen with malformation of the second pair of wings, impairing their flight activity. Electron transmission microscopy of the pathogen showed morphological features similar to species belonging to the genus Nosema or Vairimorpha. Phylogenetic analysis of the full-length small subunit ribosomal RNA gene suggests this pathogen’s placement in the genus Vairimorpha, but with a sequence identity of'~'94% with the nearest neighbours. The low level of sequence identity suggests this pathogen may represent a novel taxon in the genus and further requires whole genome sequencing for definitive taxonomic resolution. These findings provide insights on the natural occurrence of this novel pathogen of this invasive pest in Eucalyptus plantations in Brazil. Further studies are needed to determine potential of this microsporidium in the design of conservative or augmentative biological control programs for this invasive pest.