Patterns of insect herbivory, growth, and survivorship in juveniles of a Neotropical liana
Patterns of insect herbivory, growth, and survivorship were studied for 3 yr in the shadeâ€šÃ„Ã®tolerant liana Connarus turczaninowii. The percent damage to young leaves (Â¬âˆž2 mo) ranged from 2.9% in 1981 to 7.5% in the census following an El Nino event (January 1984). Although the median leaflet lifetime was 2.5 yr, Â¬âˆž33% of the lifetime damage by herbivores occurred during the first 2 mo. Annual rates of insect damage to mature leaves varied from 2.8% in 1982 to 6.0% in 1984. The most common herbivore observed on mature leaves was the beetle Demotispa sp. nov. The proportion and actual quantity of damage by this species was minimal on young leaves, but increased with leaf age. Compared with leaves in extremely low light, leaves from plants in extremely high light had lower concentrations of water and nitrogen, and more condensed tannins. Leaves from high light environments were also tougher. Although these charateristics have been shown to affect host choice or feeding in other species, no differences in rates of insect damage were detected among plants that occurred across a continuum of light environments. Plant growth increased with canopy openness, and, in one year, decreased with an increase in insect herbivory. Even though damage rates were high folowing El Nino, growth was high. We hypothesize that juvenile growth responded positively to the duration of the previous dry season because of increased light in the understory and a decrease in water loss from the soil due to the increased level of deciduousness of large canopy trees.