Changes in leaf hardness and moisture content of water hyacinth, Eichhornia crassipes, following feeding by Neochetina eichhorniae Warner (Coleoptera: Curculionidae)

Feeding by adults of Neochetina eichhorniae Warner on water hyacinth, Eichhornia crassipes , significantly increased the hardness of the lamina of the youngest leaf and the petioles of the youngest three leaves, while the moisture content of the petioles and laminae was significantly reduced. However, variations in leaf hardness did not significantly affect feeding by the weevils, and leaf age was considered to have a greater effect. The results help explain field observations of the relative abundances of N. eichhorniae and the pyralid Sameodes albiguttalis (Warren), which also attacks water hyacinth.