Spiders do not affect fruit set in Byrsonima intermedia (Malpighiaceae)
Considering the theoretical background of trait-mediated interactions, this investigation used artificial spiders to test for indirect effects of predator presence on fruit set in Byrsonima intermedia shrubs. The presence of models simulating a predation risk for insect visitors did not affect fruit set. Characteristics of the plantâ€™s reproductive system, such as self-compatibility, local availability of visitors, and visitor behavior regulate the outcome of these interactions, potentially explaining the results obtained. For instance, regardless of the number of cross-pollination events â€“ which are influenced by the presence of model spiders â€“ the number of fruits remains unchanged because of self-pollination events. Moreover, this type of interaction requires the availability of a particular group of species in the community (i.e., a specific plant and its pollinators, which in turn have specific predators) â€“ a combination of elements expected to render
this occurrence uncommon. Trophic cascade effects caused by the presence of carnivores may therefore end up being overestimated due the lack of reports that describe the absence of this effect, which could bias our expectations about the generality of this kind of effect in nature.