Seed viability of an invasive weed species

Smith, Jeffrey
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University of Delaware
Persicaria perfoliata, commonly known as mile-a-minute weed, is an aggressive invasive vine throughout the Mid-Atlantic and Northeastern United States. The plant has been shown to be highly problematic in both natural and agricultural areas, prompting extensive research into potential control methods. As an annual plant that reproduces primarily through seeds, specific attention has focused on ways to reduce the reproductive potential of P. perfoliata. In addition to a regimen of physical and mechanical controls, a classical biological control agent was identified and introduced in 2004. This insect, Rhinoncomimus latipes, is entirely host specific on P. perfoliata with the adults feeding primarily on leaves and the larvae boring into stems. Previous studies have shown that R. latipes reduces both the percent cover and number of seeds produced by P. perfoliata. My first study aimed to identify how seed viability is affected by the maturity status of the fruit surrounding the seed and the time of year of seed collection. In order to do this, seeds were collected from five field sites in the Mid-Atlantic and returned to the lab where their viability was assessed using a chemical assay. The second study aimed to quantify the impact of R. latipes on the reproductive potential of P. perfoliata, both by determining the reduction in number of seeds produced and the proportion of resultant seeds which are viable. One experiment in this study solely investigated the effects of adult weevils confined to developing seed clusters while the other tested the effects of feeding by larvae and adults on the entirety of a P. perfoliata plant.