The factors that determine the relationship between a mistletoe species (Psittacanthus plagiophyllus), its only local host (Anacardium occidentale) and a seed predator beetle (Hypothenemus obscurus), which bore both into the host and the mistletoe seeds, are poorly known. In this study, we aim specifically to investigate how host characteristics influence colonization by these beetles, relating the infestation patterns with predation of mistletoe seeds. We sampled 58 hosts in two study sites (Muretá and Piraoca) near to Alter-do-Chão village, Para state, Brazil. Ten branches of each host were marked to determinate the phenology of beetle infestation. We measured host characteristics (height, diameter at soil height, gum production and the number of neighbor trees) to evaluate their relationship with both intensity and prevalence of infestation. Besides this, we also captured beetles using a bait-trap during five months. Finally, 2,000 seeds of the mistletoe were hand-inoculated on host branches to compare seed predation between sites. We show that beetle infestation of host trees peaked in June-July, in the beginning of the dry season, which also coincides with the peak of the mistletoe fruiting period. Only host size influenced beetle infestation significantly, with smaller hosts harboring higher beetle infestation than larger hosts. The site with higher intensity and prevalence of infestation (Piraoca) had the lower beetle abundance. The predation of mistletoe seeds was lower in Piraoca than in the Muretá, suggesting that beetles could also bore into seeds after they become attached to host branches. The hypothesis that local specialization in this mistletoe species is due to enemy-free-space proportioned by the mechanism of host defense, need to be reviedwed.
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