Presentation Title

St. John's Wort (Hypericum perforatum): An Investigative Approach to Biocontrol Resistance

Format of Presentation

Poster to be presented Friday March 31, 2017

Abstract

St. John’s wort (Hypericum perforatum) is a perennial plant native to Europe that can reproduce and spread aggressively, particularly in disturbed sites and rangelands. Recently, St. John’s wort appears to be resurging on the landscape, and the biological control agents (Chrysolina sp.) are not performing as well as they have historically. The purpose of this research was to determine if there exists evidence of biocontrol resistance within a population of St. John’s wort located in the West Kootenay region of British Columbia. Ten suspected resistant plants and ten susceptible plants were collected from the field. Leaves were randomly selected, and the number of dark coloured and translucent leaf glands (the locations of where the toxins hypericin and hyperforin accumulate) were tallied for each of the suspected resistant plants versus susceptible plants. Further experiments included single-choice and no-choice tests. Our results indicate that the suspected resistant St. John’s wort plants had greater densities of dark leaf glands (p=.043, α=.05) and translucent leaf glands (p=.001, α=.05). Although not significant, there appeared to be more leaves defoliated on the susceptible plants than on the resistant plants in the single-choice test (p=0.326, α=0.05). Additionally, 54.5% of the suspected resistant leaves were not eaten, while 66.7% of the susceptible leaves were eaten in the no-choice test. The results of this research suggest that there may be resistance developing within certain populations of St. John’s wort. This experiment should be repeated with more sites added to determine how widespread possible resistance may be across the province.

Department

Natural Resource Science

Faculty Advisor

Catherine Tarasoff

This document is currently not available here.

Share

COinS
 

St. John's Wort (Hypericum perforatum): An Investigative Approach to Biocontrol Resistance

St. John’s wort (Hypericum perforatum) is a perennial plant native to Europe that can reproduce and spread aggressively, particularly in disturbed sites and rangelands. Recently, St. John’s wort appears to be resurging on the landscape, and the biological control agents (Chrysolina sp.) are not performing as well as they have historically. The purpose of this research was to determine if there exists evidence of biocontrol resistance within a population of St. John’s wort located in the West Kootenay region of British Columbia. Ten suspected resistant plants and ten susceptible plants were collected from the field. Leaves were randomly selected, and the number of dark coloured and translucent leaf glands (the locations of where the toxins hypericin and hyperforin accumulate) were tallied for each of the suspected resistant plants versus susceptible plants. Further experiments included single-choice and no-choice tests. Our results indicate that the suspected resistant St. John’s wort plants had greater densities of dark leaf glands (p=.043, α=.05) and translucent leaf glands (p=.001, α=.05). Although not significant, there appeared to be more leaves defoliated on the susceptible plants than on the resistant plants in the single-choice test (p=0.326, α=0.05). Additionally, 54.5% of the suspected resistant leaves were not eaten, while 66.7% of the susceptible leaves were eaten in the no-choice test. The results of this research suggest that there may be resistance developing within certain populations of St. John’s wort. This experiment should be repeated with more sites added to determine how widespread possible resistance may be across the province.