Insect Herbivory on a Tropical Understory Tree: Effects of Leaf Age and Habitat

Abstract

Differences in chemical and nutritional traits among leaves of different ages and from plants in different habitats are expected to influence patterns of herbivore foraging and damage. Variability in the extent and patterns of insect herbivory on leaves of the understory tree Pentagonia donnell-smithii (Rubiaceae) was quantified with respect to leaf age and habitat type (sites) in lowland tropical wet forest in Costa Rica. Rates of herbivory were higher for young leaves than for mature leaves. The common leaf beetle, Phanaeta sp. (prob. ruficollis, Chrysomelidae) preferred young leaves to mature leaves, but another herbivore (the seed bug, Nicuesa speciosa) preferred mature leaves in a choice test. Total rates of herbivory over a 10-day period were higher in a secondary forest site than in successional plots 1-5 yr old. Laboratory choice tests suggested that Phanaeta sp. responded differentially to leaves from trees in three forest sites. Their apparent preference for leaves from younger, more open sites was not explained by either leaf toughness or leaf water content.