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ARS Home » Southeast Area » Fort Lauderdale, Florida » Invasive Plant Research Laboratory » Research » Publications at this Location » Publication #435897
Research Project: Development and Implementation of Biological Control Programs for Natural Area Weeds in the Southeastern United States

Location: Invasive Plant Research Laboratory

Title: Photosynthetic performance of water hyacinth as affected by Neochetina spp. and Megamelus scutellaris herbivory

Author
item MOHAMMED, USMAN - University Of Florida
item ZAMBON, FLAVIA - University Of Florida
item VAN SANTEN, EDZARD - University Of Florida
item LAHIRI, SRIYANKA - University Of Florida
item Smith, Melissa
item MINTEER-KILIAN, CAREY - University Of Florida

Submitted to: Biocontrol Science and Technology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/22/2026
Publication Date: 7/8/2026
Citation: Mohammed, U., Zambon, F., Van Santen, E., Lahiri, S., Smith, M., Minteer-Kilian, C.R. 2026. Photosynthetic performance of water hyacinth as affected by Neochetina spp. and Megamelus scutellaris herbivory. Biocontrol Science and Technology. 36(9):1092-1107. https://doi.org/10.1080/09583157.2026.2695282.
DOI: https://doi.org/10.1080/09583157.2026.2695282

Interpretive Summary: Understanding leaf-level effects of herbivory on invasive water hyacinth can help to elucidate impacts and mechanisms for control. We measured the leaf-level photosynthetic parameters on waterhyacinth (including chlorophyll fluorescence, gas exchange, intercellular CO2, and leaf conductance), and found that herbivory, exposure time, and their interaction had no significant effect on these parameters. The combined treatments of Neochetina spp. and M. scutellaris resulted in greater physical damage and plant mortality compared to the individual treatments. Despite this, gas exchange results showed no significant difference in net photosynthetic rate among treatments, suggesting a non-additive interaction, potentially negative interaction at the physiological level.

Technical Abstract: Water hyacinth, Pontederia crassipes Mart. Solms, is invasive throughout tropical and subtropical freshwater bodies. Multiple tools are utilized to control water hyacinth including classical biocontrol with the agents, Neochetina eichhorniae, N. bruchi and Megamelus scutellaris. These have been released in several countries including the United States, where they are widely established. Post-release evaluations of impacts understandably focused on plant metrics indicative of impact including biomass, reproduction, and coverage. These metrics are coarse and may not fully capture the plant and leaf-level impacts of herbivores on their host. This study focused on leaf-level physiological parameters to evaluate the impact of M. scutellaris and its combined interaction with Neochetina spp. Leaf-level gas exchange and chlorophyll fluorescence were measured after two and four weeks of exposure to herbivory using a portable photosynthetic gas exchange system (LiCoR LI 6800). Treatment (herbivore type × infestation level) and exposure time have significant reduction on transpiration rate and leaf conductance. However, there was no significant reduction on net photosynthetic rate or intercellular CO2 concentration. Similarly, no significant interaction was observed between treatment and exposure time across all parameters. For fluorescence, exposure time significantly reduced maximal fluorescence, maximum quantum efficiency of PSII photochemistry, and performance index, but not minimal fluorescence. However, treatment and their interactions with exposure time were not significant across all fluorescence parameters. The findings of this study indicate that gas exchange and chlorophyll fluorescence parameters are effective metrics for understanding the impact of biological control on invasive species.