Preference and performance of Hypena opulenta on Vincetoxicum rossicum foliage from sun versus shade habitats

Abstract

Characteristics of individual plants from the same species can differ significantly between habitats based on abiotic factors such as light intensity and temperature. In turn, these differences in plant quality can affect herbivores that feed on the plant. Here, we examined the effects of habitat on leaf characteristics for the invasive vine Vincetoxicum rossicum, as well as the preference and performance of its biological control agent, Hypena opulenta, on sun versus shade foliage. V. rossicum leaves grown in sunny habitats were tougher, thicker, and had lower water content than shade leaves. H. opulenta larvae consumed greater amounts of shaded foliage than sun foliage and were predominately night-active. H. opulenta larval development did not differ between sun and shade foliage diets; however, females preferred to oviposit on sun foliage. The underlying mechanisms of these results are discussed, as well as their implications for the biological control of Vincetoxicum species.iii

Biology of Invasive Plants 3. Vincetoxicum nigrum (L.) Moench and Vincetoxicum rossicum (Kleopow) Barbarich

“…In the United States, H. opulenta has been annually released since 2017 (Connecticut, Massachusetts, Michigan, New York, Rhode Island), but establishment has yet to be reported for these release sites or additional Canadian sites (Alred 2021;Alred et al 2022b;Livingstone et al 2020b; LRM, personal observation). Although larvae will feed nocturnally on V. rossicum in high-light (meadow) environments in which they are released, they appear to prefer the shaded conditions of low-light (forest understory) habitats (Livingstone et al 2020b;Rochette 2019). A field cage study showed that H. opulenta defoliation of V. nigrum was higher in a shaded environment, relative to a sunny environment, but the low levels of defoliation did not reduce V. nigrum fitness in either environment (Alred et al 2022b).…”

“…Vincetoxicum rossicum is found in a variety of environments, but generally achieves higher survival, growth, and reproduction under high light (see "Habitat"; "Reproduction: Seed Production and Dispersal"; Hotchkiss et al 2008;Milbrath 2008;Milbrath et al 2017). Ambient light levels help determine specific leaf area in V. rossicum (Rochette 2019;Yasui 2016). Smith et al (2006) reported that V. rossicum plants grown under low light exhibited a classic shade phenotype (taller, thicker stems and larger, thinner leaves) that resulted in an increased tendency to climb over nearby plants.…”