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Classical niche theory explains the coexistence of species through their exploitation of different resources. Assemblages of herbivores coexisting on a particular plant species are thus expected to be dominated by species from host-specific guilds with narrow, coexistence- facilitating niches rather than by species from generalist guilds. Exactly the opposite pattern is observed for folivores feeding on trees in New Guinea. The least specialized mobile chewers were the most species rich, followed by the moderately specialized semiconcealed and exposed chewers. The highly specialized miners and mesophyll suckers were the least species-rich guilds. The Poisson distribution of herbivore species richness among plant species in specialized guilds and the absence of a negative correlation between species richness in different guilds on the same plant species suggest that these guilds are not saturated with species. We show that herbivore assemblages are enriched with generalists because these are more completely sampled from regional species pools. Herbivore diversity increases as a power function of plant diversity, and the rate of increase is inversely related to host specificity. The relative species diversity among guilds is thus scale dependent, as the importance of specialized guilds increases with plant diversity. Specialized insect guilds may therefore comprise a larger component of overall diversity in the tropics (where they are also poorly known taxonomically) than in the temperate zone, which has lower plant diversity. © 2012 by The University of Chicago.

Fig pollination is a well‐known example of obligate mutualism involving specialized fig wasps (Hymenoptera, Agaonidae) and Ficus (Moraceae). However, pollination is poorly understood in Castilleae, the recently identified sister group to Ficus. Here we report the first record of thrips pollination in a member of the paleotropical Castilleae. We used phenological measurements, insect trapping, and pollinator exclusion experiments to investigate the mode of pollination in Antiaropsis decipiens, a monotypic dioecious tree of lowland rainforests in New Guinea. We recorded a new species, described here as Thrips antiaropsidis (Thysanoptera, Thripidae), feeding on Antiaropsis pollen, breeding in the staminate inflorescences, and pollinating the carpellate inflorescences. It appears that thrips are lured from staminate to carpellate inflorescences by deceit. We combine these observations with evidence from the Neotropical Castilleae to suggest that thrips pollination may be common in the sister group to figs. We...