Climate change and biocontrol: forecasting the potential range and overlap of Hydrilla verticillata and its herbivore Parapoynx diminutalis.

Abstract

Climate change can alter species distribution patterns by modifying environmental conditions across ecosystems. In continental aquatic environments, the submerged macrophyte Hydrilla verticillata, characterized by high ecological plasticity and efficient vegetative reproduction, and the aquatic moth Parapoynx diminutalis, whose larvae feed on plant tissues, establish an ecological interaction based on herbivory with potential for biological control. The effectiveness of this interaction depends on spatial co-occurrence and life-cycle synchrony between the species, and may be influenced by environmental variability. Thus, this study investigated the effects of climate change on the potential distribution of H. verticillata and P. diminutalis, as well as their spatial overlap at a global scale. To this end, an ecological niche modeling approach using multiple algorithms was applied to estimate environmental suitability under future climate scenarios. Mean annual river discharge was the main predictor for H. verticillata, whereas distance to river mouth was more important for P. diminutalis, with isothermality being relevant for both species. Although large areas currently present suitable conditions, projections for 2050 and 2090 indicate a predominance of spatial stability, with slight increases in suitability at mid-latitudes of the Northern Hemisphere and localized reductions in subtropical regions of the Southern Hemisphere. The potential overlap, currently concentrated in tropical regions, is expected to remain relatively stable, with marginal reductions at the edges and no significant expansions. Overall, the results obtained indicate a probability of gradual adjustments in environmental suitability, without substantial changes in the global patterns of distribution and co-occurrence of these species.