2026/01/01 by Ian Jones, Ian M. Jones, Brent J. Sinclair +3
Agricultural and Biological Sciences · Environmental Science · #Biological Control of Invasive Species #Aquatic Ecosystems and Phytoplankton Dynamics #Insect-Plant Interactions and Control
paper · pdf · doi:10.4039/tce.2026.10062
Abstract Hypena opulenta (Lepidoptera: Erebidae) has been introduced to control invasive swallow-worts (Apocynaceae) in North America. However, population densities remain too low to suppress weed populations. We examined winter cold and soil moisture as potential factors limiting H. opulenta population growth in Canada. We characterised cold-tolerance strategy, susceptibility to inoculative freezing (freezing initiated by external ice formation at higher subzero temperatures), and examined the effects of prolonged cold exposures on H. opulenta survival. Finally, we conducted a laboratory experiment to determine whether soil moisture content affects the cold hardiness of H. opulenta pupae. Hypena opulenta pupae are freeze-tolerant, but only 22% survived prolonged exposure to –15 °C for 15 hours. After 1-hour cold exposures, survival of pupae in which freezing was inoculated at high temperatures (25%) was lower than that of untreated pupae (62%). After 15-hour cold exposures, however, there was no difference in survival between inoculated and untreated pupae. Pupal mortality was not affected by cold-exposure duration or inoculative freezing in soil, but male pupae had higher survival than females. These results suggest that H. opulenta has the potential to continue to survive, grow, and eventually impact swallow-wort populations in Canada without being limited by winter conditions.