This paper links ecological theory to the biological control of insect pests in banana plantations. Through an established predictive approach, ecological data on tritrophic interactions from natural systems were used to formulate simple recommendations for biological control in banana plantations. The specific goals were (1) to determine the most effective parasitoid enemies for biological control of lepidopteran larvae in banana plantations and (2) to examine the impact of nematicides on enemy populations. To assess percent parasitism, we reared 1,121 lepidopteran larvae collected from six plantations managed under two nematicide regimens. Attack by parasitoids in the families Tachinidae (Diptera), Braconidae, Eulophidae, and Chalcididae (Hymenoptera) closely paralleled rates reported for species with similar characteristics in lowland wet forests, and statistical models predicted the relative importance of these parasitoids as sources of mortality. We found that tachinid flies were the most important source of early instar larval parasitism in banana plantations, and their importance increased with more intensive nematicide applications. The statistical models that we derived from data on natural systems were useful in predicting which parasitoids would be important in banana and which larval characteristics they would preferentially attack. This approach could be used in other managed ecosystems where the identification of effective biological control agents is needed.