Predicting how a plant will respond to herbivory is complex but often related to the timing and type of herbivory, plant competition, and nutrient availability. The invasive tree Melaleuca quinquenervia, for instance, is a long lived perennial that is competitively superior to native vegetation and occurs in the nutrient rich wetlands of south Florida. The introduced weevil Oxyops vitiosa is a host specific natural enemy of M. quinquenervia and feeds exclusively on developing foliage at branch apices, which consists of <1% of the plants total biomass. When considering the seemingly ideal growing conditions in the weed’s adventive range and the level of feeding damage, we questioned if the indirect effects of herbivory by O. vitiosa negatively impacts the reproductive potential of M. quinquenervia. When comparing plant reproductive performance in replicated melaleuca stands, trees incurring four consecutive years of damage by O. vitiosa had a lower probability of flowering across the entire range of tree sizes evaluated. Herbivory also delayed the reproductive maturity of saplings. Similarly, herbivory influenced biomass allocation, with damaged trees producing more secondary (terminal) branches and fewer fruit compared to undamaged trees. In a separate weevil exclusion experiment with uniform tree sizes, a single herbivory event resulted in an 80% reduction in the number of flowers produced per tree; however seed viability (germiniability+dormancy) from the few fruits that developed on damaged trees was not different when compared to undamaged controls. These findings suggest that, although M. quinquenervia grows under highly favorable conditions, the invasive tree undercompensates reproductively in response to herbivory by O. vitiosa.
Species 1: Coleoptera Curculionidae Oxyops vitiosa (Melaleuca snout beetle)
Keywords: Weed biological control, folivory
Back to Ten-Minute Papers, Section Cc. Insect Vectors in Relation to Plant Disease, Ce. Insect Pathology and Microbial Control, Ca. Biological Control
Back to Ten-Minute Papers, Section Ca, Cb, Cc, Cd, Ce, and Cf
Back to The 2003 ESA Annual Meeting and Exhibition