Host specificity and association patterns of weevil seed predators (Coleoptera: Curculionoidea): the Neotropical case

Studies of plant-insect interactions are essential for accurate estimations of global species richness, as these have been proven to be a major factor in diversification processes. Seed and fruit predators are of particular interest as they have been categorized as the most host specific guild within herbivorous insects, though one of the more poorly examined. We studied host associations of seed feeding weevils (Curculionoidea) in the neotropics based on seed/fruit rearings from more than 60 host plants. Molecular data of both mitochondrial (cox1 & 16S) and nuclear (28S) markers was obtained allowing species delimitation using a coalescence-based methodology. More than 90 species of weevils were associated with host plants collected, 76% being monophagous and 19% oligophagous (feeding on congeneric hosts); generalists were very rare in our samples, though some cases were found. Host specificity and weevil richness estimated using the "effective specialization" (considering potential hosts) showed no significant difference when increasing host species (potential hosts known in the area), supporting the accuracy of the host patterns found. Host associations obtained from the Neotropics were compared to previous studies from South East Asia and showed similar host specificity patterns. These tropical data were compared with temperate forests (based on UK records assembled for many years) and demonstrated that niches are not narrower in the tropics than in temperate counterparts. This conclusion is concordant with previous hypotheses stating higher insect diversity in the tropics over temperate forests might be driven by plant diversity, rather than by a difference in niche partitioning.