Interactive effects of light environment and herbivory on growth and productivity of an invasive annual vine, Persicaria perfoliata

Abstract

Plant populations often exist in spatially heterogeneous environments with varying light levels, which can affect plant growth directly through resource availability or indirectly by altering behavior or success of herbivores. The plant vigor hypothesis predicts that herbivores are more likely to attack vigorously growing plants than those that are suppressed, for example in more shaded conditions. Plant tolerance of herbivory can also vary under contrasting resource availability. Observations suggest that damage by Rhinoncomimus latipes Korotyaev (Coleoptera: Curculionidae), introduced into the United States in 2004 as a biological control agent for mile-a-minute weed (Persicaria perfoliata [L.] H. Gross), is greater in the sun than in shade. We compared weevil densities and plant growth in paired plots in full sun or under shade cloth; a second experiment included insecticide-treated plots in sun and shade, to assess the ability of the plant to compensate for herbivore damage. Greater density of weevils and more node damage (indicating internal larval feeding) were found on P. perfoliata plants growing in sun than on those in shade. Nodes were 14% thicker in the sun, which may have provided better larval habitat. Biomass produced by plants without weevils in the sun was about twice that produced in any other treatment. Herbivory had a greater effect on plant growth in the high-light environment than in the shade, apparently because of movement into the sun and increased feeding there by the monophagous herbivore, R. latipes. Results support the plant vigor hypothesis and suggest that high weevil densities in the sunny habitats favored by P. perfoliata can suppress plant growth, negating the resource advantage to plants growing in the sun.

Integrating Management Techniques to Restore Sites Invaded by Mile‐a‐Minute Weed, Persicaria perfoliata

“…This experiment did not test the effectiveness of the biological control agent, which was present in all plots; however, weevil densities observed here were comparable to those in other studies where mile‐a‐minute growth and seed production were shown to be suppressed by the insect (Hough‐Goldstein et al ; Lake et al ; Hough‐Goldstein & LaCoss ; Cutting & Hough‐Goldstein ). Feeding damage by R. latipes decreases the competitive ability of mile‐a‐minute by stressing the plant and altering plant architecture (Hough‐Goldstein et al 2008 b ).…”

Mile-a-minute weed (Persicaria perfoliata) and weevil (Rhinoncomimus latipes) response to varying moisture and temperature conditions

“…In other studies, the biomass of P. perfoliata was reduced by R. latipes herbivory (Cutting and Hough-Goldstein, 2013; Hough-Goldstein and LaCoss, 2012), and also by light limitation (Hough-Goldstein and LaCoss, 2012;Smith and HoughGoldstein, 2013). A meta-analysis of plant responses to herbivory under low or high resource conditions (light, water, or nutrients) found that typically the main effects of the treatments were most important, with fewer seeds and lower biomass produced under herbivory and low resources compared to no herbivory and high resources (Hawkes and Sullivan, 2001).…”

“…Feeding damage by R. latipes has been shown to reduce P. perfoliata percent cover and biomass, and delay and reduce seed production (Cutting and Hough-Goldstein, 2013;Hough-Goldstein and LaCoss, 2012;Hough-Goldstein et al, 2008, 2009Lake et al, 2011). However, the impact of R. latipes on mile-a-minute populations has varied from year to year.…”

Aerial release of Rhinoncomimus latipes (Coleoptera: Curculionidae) to control Persicaria perfoliata (Polygonaceae) using an unmanned aerial system

“…using broad‐spectrum herbicides). Biological control using an introduced insect has become a key management tactic since the mile‐a‐minute weevil, Rhinoncomimus latipes Korotyaev (Coleoptera: Curculionidae), was introduced to North America in 2004 …”