Author
Ana C. Faltlhauser
anafaltlhauser@gmail.com
Fundación para el Estudio de Especies Invasivas (FuEDEI) / Consejo Nacional de Ciencia y Técnica (CONICET)
Hurlingham
Coauthors
Gianmarco Minuti, Vrije Universiteit Brussel (VUB), Brussels, Belgium
Pamela C Krug, Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Hurlingham, Argentina
Iris Stiers, Vrije Universiteit Brussel (VUB), Brussels, Belgium
Alejandro J Sosa, Fundación para el Estudio de Especies Invasivas (FuEDEI) /Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Hurlingham, Argentina
Abstract
Classical biological control (CBC) aims to reduce invasive alien plant populations using their coevolved natural enemies. The Enemy Release Hypothesis (ERH) provides its conceptual basis, proposing that invasive species may succeed due to the lack of specialised enemies in the introduced range. Ludwigia grandiflora subsp. hexapetala is native to South America and invasive across the Northern Hemisphere. To assess its performance and herbivore pressure across ranges, we compared morphological traits and herbivory in Argentina and Belgium. We quantified stem number, apical damage, reproductive structures, fruit and leaf herbivory, pathogen presence, and damage types during flowering and fruiting at 10 sites. Multivariate analyses revealed significant effects of country on both morphology (Pillai’s Trace=0.662, F(6,88)=28.77, p<2.2e-16) and herbivory variables (Pillai’s Trace = 0.69, F(5,89)=38.85, p<2.2e-16). Belgian plants were taller, less ramified, with larger leaves and significantly more flowers, but showed almost no foliar damage, pathogen infection or fruit herbivory. In contrast, native-range plants experienced consistent attack by different herbivores, with higher levels of apical damage, defoliation, pathogen incidence and fruit consumption. These patterns suggest that the absence of specialized enemies in the invaded range allows greater allocation to growth and reproduction, supporting ERH and reinforcing the rationale for CBC as a management option.
Keywords
Enemy Release Hypothesis
Herbivory
Ludwigia grandiflora subsp. hexapetala
Native
morphological traits
Highlights
Morphology and herbivory differ significantly between native and invaded ranges of Ludwigia.
Absence of specialised enemies in Belgium enables greater growth and reproduction.
Findings reinforce classical biological control as a management tool for invasive Ludwigia.