XVI International Botanical Congess

Herbivore populations in tropical rainforests are generally consideredto be resource limited. Investments in plant defenses are greater in the tropics as compared to the temperate zone, and levels of herbivory are highly negatively correlated with defenses. However, here I present evidence that top-down control of herbivores may also be important. Rates of predation on lepidopteran larvae in Panama are 10%/caterpillar/d and rates of parasitism are 27%. The susceptibility of caterpillars to predators and their commitment to defenses against the third trophic level are predictably related to the traits of their host plants. Prolonged dry seasons, such as those associated with El Niņo events may reduce populations of parasitoids, creating an enemy free space in which herbivore populations can grow.