Biological control of Hydrocotyle ranunculoides in the United Kingdom
Hydrocotyle ranunculoides (Araliaceae: EPPO A2 List) is an aquatic plant species native to the Americas. In the EPPO region it can invade habitats such as slow-flowing and eutrophic water bodies, especially ponds, ditches, lakes, and streams. H. ranunculoides can have a negative impact on the habitat it invades where it transforms the habitat as a result of its matt forming behaviour. This can alter the chemical composition of the waterbody which in turn can have a negative impact on native plant biodiversity and associated ecosystem services. Traditional management options, such as chemical and manual control, are difficult to implement due to the habitat where the plant occurs. Since 2011, research has been conducted on the classical biological control of H. ranunculoides in the United Kingdom. Through natural enemy surveys in South America (Argentina and Paraguay) and subsequent host specificity testing, the weevil Listronotus elongatus (Coleoptera: Curculionidae) was identified as a biological control agent for the control of H. ranunculoides. Following the assessment of a pest risk analysis and stakeholder consultation, the weevil was released in a number of sites in the United Kingdom and a monitoring programme will evaluate the establishment, over wintering, and impact of the weevil on H. ranunculoides.
Sources
CABI Invasive Species Compendium. Hydrocotyle ranunculoides. https://www.invasive-species.org/species/floating-pennywort/