295

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Parasitic plants are important sources of stress and can strongly impact their host plants through direct and indirect associations with other associated organisms such as insect herbivores, ants and pollinators. We investigated the direct and indirect influences of multiple partners involved in interactions between the mistletoe Psitachantus robustus and its main host tree, Vochysia thyrsoidea and herbivore insects, ants, and pollinators. We hypothesized that the presence of the mistletoe could modify the herbivory patterns of its host by altering the diversity of associated insects. Additionally, we hypothesized that associations between fluid-feeding insects and ants should indirectly decrease mistletoe reproduction by repelling pollinators and directly by reducing seed size, germination, and establishment of plants presenting denser herbivore aggregations. We found that the mistletoes' influence on the insect herbivores was related to their feeding guild. In addition, we found a decrease in leaf-chewing insects, but an increase of levels of herbivory damage in parasitized plants. While the mistletoes' presence did not influence the hemipteran sap-sucking insects, this herbivore guild directly responded to the abundance of their associated ants. Meanwhile, the ant’s presence on inflorescences did not affect the visitation rates of its main pollinator, the hummingbird Eupetomena macroura. Nevertheless, we observed a significant reduction in seed size in those plants hosting larger aggregations of fluid-feeding herbivores. By exposing the distinct effects of the different partners involved, our results shed light on the intricated interactions mediated by parasitic plants and multitrophic interactions, opening the path for new investigations.

Keywords:

Campo rupestre
Ants
interspecific interactions
Loranthaceae
Pollination
insect herbivores

Frederico Neves

Presentation within symposium:

S-2 Plant-Insect interactions in the Anthropocene: patterns, mechanisms and challenges in the Neotropics

Not everything is what it seems to be: interactions among mistletoes, host plants and insects in a changing world

-Review-