Ecological modelling of the effects of water hyacinth nutrient composition on the performance of a biological control agent

Introduction: water hyacinth (Eichhornia crassipes) is the world’s most economically damaging aquatic weed species. The Delta, is a large (68,000-acres) complex and highly dynamic ecosystem with tidal influence, urban pollution, land subsidence (erosion), and agricultural runoff. Invasive infestations by water hyacinth are directly and indirectly associated with: clogged waterways, increase in evapotranspiration, reduction in biodiversity, threat to endemic aquatic species, loss of agricultural irrigation water, increased prevalence of the West Nile Virus mosquito vector.

Methods: Data a comprehensive water hyacinth monitoring program comprise bi-monthly sampling of water nutrients, leaf nutrients, weed population density and quantification of biological control insect damage (Neochetina bruchi, Curculionidae). Multivariate analyses and modelling approaches were used to analyze these data.

Results/Conclusion: We demonstrate that the nutrient composition of water hyacinth plants appears to be strongly associated with spatio-temporal dynamics of the weevil population dynamics. Thus, we discuss the importance of plant nutrients (through water nutrient management) as part of developing a successful management for this important aquatic weed.