LE3 .A278 2021

2021

Hillier, Kirk
Moreau, Debra

Acadia University

Master of Science

Masters

Biology

Biology

In 2012 there was an outbreak of strawberry decline disease (SDD) in Nova Scotia, resulting in crop failure. The disease was caused by Strawberry mild yellow edge virus (SMYEV) and Strawberry mottle virus (SMoV), and vectored by the aphid, Chaetosiphon fragaefolii. I nfected fields were tilled under and a provincial strawberry aphid and virusmonitoring program was implemented in Nova Scotia. New virus infections continued to occur leading to the hypothesis that there could be inoculum outside of infected fields. Fragaria and Potentilla species are known alternative host species of C. fragaefolii, and are suspected reservoirs of viruses. A new virus, Strawberry polerovirus 1 (SPV1), was identified during the outbreak. It is hypothesized that SPV1 aids in the transmission of SMYEV and vectored by C. fragaefolii. Aphid, alternative host, and virus surveys were conducted at six field sites throughout the Annapolis Valley of Nova Scotia, and worked related to the SPV1 transmission experiment was conducted in laboratory and greenhouse settings. Aphid surveys found C. fragaefolii was the dominant colonizing species in the field, but only represented a small minority of alate aphids collected from pan traps. We determined that pan traps samples are more representative of what aphid species are present in the surrounding environment, and leaf sampling is still necessary to determine what species are colonizing a host crop. From the alternative host study, Fragaria and Potentilla only had low numbers of C. fragaefolii, and wild Fragaria species were infected with SMYEV and SPV1, but no virus infections were found from Potentilla species. We determined that alternative hosts do not act as significant reservoirs of SDD. Implementing different production systems and shorter cropping cycles could significantly reduce the risks associated with SDD. The SPV1 transmission experiment was not completed due to continued issues with confirming virus infections in daughter plants produced from virus infected mother plants. Research still needs to be completed to experimentally demonstrate that SPV1 is transmitted by C. fragaefolii, and determine its role in the SDD complex.

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https://scholar.acadiau.ca/islandora/object/theses:3646