Abstract
Plant density influences interspecific interactions such as pollination and herbivory. In denser populations, pollinators find flowers more easily, increasing reproductive success and population growth. However, the same floral attractiveness also favors floral herbivory, a relationship described by Janzen and Connell as negative density dependence, considered an important mechanism for maintaining tropical diversity. This study analyzed the reproduction of Peixotoa tomentosa A. Juss. (Malpighiaceae) and Byrsonima intermedia A. Juss. (Malpighiaceae), considering population density and its influence on pollinator and herbivore attraction. The central hypothesis was that density affects fruit production. We conducted two treatments with both species: high density and low density in a preserved Brazilian savanna. We investigated fruit production, reproductive system, floral visitation rates, and the florivory rates of each species on each treatment. Our results showed that fruiting increased with density in both species. Peixotoa tomentosa is an agamospermous species, while B. intermedia is self-incompatible and relies exclusively on pollinators. Bees visited only B. intermedia, and the high-density treatment received more visits. Herbivores attacked more isolated P. tomentosa flowers. We concluded that density influences both pollination and herbivory, affecting plant reproduction, with effects mediated by the plant's attractiveness in denser populations and by the size and quantity of flowers in single individuals.