Resource use of insect seed predators during general flowering and seeding events in a Bornean dipterocarp rain forest

Insect seed predators of 24 dipterocarp species (including the genera of Dipterocarpus, Dryobalanops and Shorea) and five species belonging to the Moraceae, Myrtaceae, Celastraceae and Sapotaceae were investigated. In a tropical lowland dipterocarp forest in Sarawak, Malaysia, these trees produced seeds irregularly but intensely during general flowering and seeding events in 1996 and/or 1998. Dipterocarp seeds were preyed on by 51 insect species (11 families), which were roughly classified into three taxonomic groups: smaller moths (Tortricidae, Pyralidae, Crambidae, Immidae, Sesiidae and Cosmopterigidae), scolytids (Scolytidae) and weevils (Curculionidae, Apionidae, Anthribidae, and Attelabidae). Although the host-specificity of invertebrate seed predators has been assumed to be high in tropical forests, it was found that the diet ranges of some insect predators were relatively wide and overlapped one another. Most seed predators that were collected in both study years changed their diets between general flowering and seeding events. The results of cluster analyses, based on the number of adults of each predator species that emerged from 100 seeds of each tree species, suggested that the dominant species was not consistent, alternating between the two years.