THE EARLY HISTORY OF SEED PREDATORS ON COCONUTS: MORE TROUBLE IN PARADISE

Seed predation is a plant–animal interaction in which an animal, often an insect, feeds on a seed or analogous plant reproductive disseminule resulting in a damaged structure and frequently a nonviable embryo. Two distinct examples of seed predation on separate specimens come from the middle–late Paleocene Cerrejón Formation (58–60 Ma) of northeastern Colombia. The plant host is referable to Cocos, a coconut palm (Arecaceae: Cocoseae). The first interaction, assigned to DT172, consists of seed predators is indicated by larval borings of a palm seed beetle (Coleoptera: Chrysomelidae: Pachmerini), representing a seed beetle lineage probably similar to extant Pachymerus on coconut. The second interaction, assigned to DT391, is a seed predator suggestive of piercing-and-sucking damage indicating a nymphal or adult coconut bug (Hemiptera: Coreidae: Coreinae), representing a leaf-footed bug lineage likely similar to extant Pseudotheraptus on coconut. We interpret the borings of palm seed beetles and the punctures by coconut bugs based on the size, incidence number, and position, of the damage, as well as plant reaction tissue, and plant-host selectivity. These occurrences provide the earliest record of an ecological interaction between a palm seed beetle, a coconut bug, and its coconut palm host, from which we infer that these host-specific interactions have been consistently maintained for approximately 60 million years. Inferences regarding the coevolutionary origins among plant hosts and their insect associates historically have been based on divergence-age estimates of extant plant hosts and their herbivores. Nevertheless, seldom are such associations established and calibrated from dated fossil occurrences of well-preserved interactions. Notably, these two, distinct, insect associations are documented on the same host-plant taxon from the same mid Paleocene deposit, suggesting that in the wake of the end-Cretaceous ecological event, there were multiple opportunities for associations with the same host from two, unrelated insect seed-predator lineages.