High-Throughput Sequencing to Investigate Phytopathogenic Fungal Propagules Caught in Baited Insect Traps.

Émilie D Tremblay,Guillaume J Bilodeau,Troy Kimoto,Jean A Bérubé

doi:10.3390/jof5010015

Émilie D Tremblay, Guillaume J Bilodeau + Show 2 more

Open Access

https://doi.org/10.3390/jof5010015

Copy DOI

Abstract

Studying the means of dispersal of plant pathogens is crucial to better understand the dynamic interactions involved in plant infections. On one hand, entomologists rely mostly on both traditional molecular methods and morphological characteristics, to identify pests. On the other hand, high-throughput sequencing (HTS) is becoming the go-to avenue for scientists studying phytopathogens. These organisms sometimes infect plants, together with insects. Considering the growing number of exotic insect introductions in Canada, forest pest-management efforts would benefit from the development of a high-throughput strategy to investigate the phytopathogenic fungal and oomycete species interacting with wood-boring insects. We recycled formerly discarded preservative fluids from the Canadian Food Inspection Agency annual survey using insect traps and analysed more than one hundred samples originating from across Canada. Using the Ion Torrent Personal Genome Machine (PGM) HTS technology and fusion primers, we performed metabarcoding to screen unwanted fungi and oomycetes species, including Phytophthora spp. Community profiling was conducted on the four different wood-boring, insect-attracting semiochemicals; although the preservative (contained ethanol) also attracted other insects. Phytopathogenic fungi (e.g., Leptographium spp. and Meria laricis in the pine sawyer semiochemical) and oomycetes (mainly Peronospora spp. and Pythium aff. hypogynum in the General Longhorn semiochemical), solely associated with one of the four types of semiochemicals, were detected. This project demonstrated that the insect traps’ semiochemical microbiome represents a new and powerful matrix for screening phytopathogens. Compared to traditional diagnostic techniques, the fluids allowed for a faster and higher throughput assessment of the biodiversity contained within. Additionally, minimal modifications to this approach would allow it to be used in other phytopathology fields.

Highlights

The Era of Globalization has dramatically and consistently increased international cargo shipments since 1970 [1,2]
Taking advantage of a well-established, nationwide entomological survey, this project aimed to use a metagenomics approach to screen for the presence of phytopathogenic oomycetes and fungi contained in the preservative fluids originating from insect traps
Such an assessment was performed using the subtracted species datasets, in order to focus on microorganisms unique to the insect traps and, more likely to have been vectored by insects

Summary

Introduction

The Era of Globalization has dramatically and consistently increased international cargo shipments since 1970 [1,2]. Bark and wood-boring insects, such as bark beetles, long-horned beetles, wood wasps, jewel beetles, weevils, and ambrosia beetles are often intercepted in SWPM [2,3,4,5,6]. J. Fungi 2019, 5, 15 the spread of insects and diseases, live wood-boring insects are still intercepted in SWPM, at the Canadian and American borders [7,8]. The emerald ash borer (Agrilus planipennis), brown spruce long-horned beetle (Tetropium fuscum), sirex wood wasp (Sirex noctilio), and the pine shoot beetle (Tomicus piniperda), are just a few examples of species recently introduced and established in Canadian forests [9,10,11,12,13]

Objectives

Methods

Results

Discussion

Conclusion