Landscape genomics and evolutionary history of Megamelus scutellaris, a biocontrol agent of the invasive water hyacinth (Pontederia crassipes)

Authors: SALINAS, NICOLAS - Consejo Nacional De Investigaciones Científicas Y Técnicas(CONICET); SOSA, ALEJANDRO - Consejo Nacional De Investigaciones Científicas Y Técnicas(CONICET); POVEDA-MARTINEZ, DAVID - Fuedei; MARIANA, ROXANA - National University Of La Plata; RODRIGUERO, MARCELA - Consejo Nacional De Investigaciones Científicas Y Técnicas(CONICET); LENICOV, ANA M MARINO - Consejo Nacional De Investigaciones Científicas Y Técnicas(CONICET); Smith, Melissa

Submitted to: Evolutionary Applications
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/27/2026
Publication Date: 2/18/2026
Citation: Salinas, N., Sosa, A., Poveda-Martinez, D., Mariana, R., Rodriguero, M., Lenicov, A., Smith, M. 2026. Landscape genomics and evolutionary history of Megamelus scutellaris, a biocontrol agent of the invasive water hyacinth (Pontederia crassipes). Evolutionary Applications. 19(2). Article e70208. https://doi.org/10.1111/eva.70208.
DOI: https://doi.org/10.1111/eva.70208

Interpretive Summary: The waterhyacinth planthopper, Megamelus scutellaris, is effectively used as a biological control agent for waterhyacinth (Pontederia crassipes) throughout the world. Several populations have been targeted for use based on their location. To determine how these populations are structured in the native range, we used nuclear and mitochondrial DNA to investigate genetic structure, evolutionary history, and environmental factors that affect the species. Megamelus scutellaris diverged during times of large-scale climatic changes in the Pleistocene and Holocene. Ecological and evolutionary processes drove populations to differentiate during isolation. This provides important insights into the many populations of M. scutellaris and their ecological differences.

Technical Abstract: Understanding the evolutionary history of biological control agents in their native ranges is crucial for improving their selection, establishment, and performance across environmentally diverse regions. Phytophagous insects that specialize on aquatic plants offer particularly valuable models, as their evolutionary trajectories may be shaped by a combination of climatic variation, host plant availability, and the fragmented nature of aquatic habitats. Megamelus scutellaris is a monophagous planthopper native to South America that has been introduced into the United States and South Africa as part of biological control programs targeting the highly invasive aquatic plant Pontederia crassipes. In this work, we combined nuclear SNP and mitochondrial sequence data to investigate the genetic structure, demographic history, and environmental drivers of population divergence in M. scutellaris across its native range in Argentina and Paraguay. We identified three main genetic lineages broadly associated with major river basins and ecoregions. Demographic modeling supported an early divergence, likely linked to Pleistocene climatic shifts and hydrological changes, followed by a more recent split dated to the early Holocene. Contemporary gene flow was asymmetric and varied in magnitude among lineages, reflecting differences in connectivity and environmental conditions. Lastly, landscape genomic analyses revealed a strong association between genetic differentiation and specific climatic variation, supporting models of isolation by environment and resistance. These findings highlight the role of evolutionary and ecological processes in shaping the genetic landscape of M. scutellaris and provide key insights for selecting source populations better suited to different environments.