Phoresy and interactions between Scotocryptus beetles and stingless bees

Abstract

Phoresy is an interaction between two organisms in which one species (the phoront) is transported by a host as a widespread means of dispersal or migration. For some arthropods, the costs and benefits of this process for hosts and phoronts remain unclear. Scotocryptus beetles are blind and flightless, relying on stingless bees for dispersal via phoresy. Here, we studied the phoretic behavior of Scotocryptus melitophilus on two stingless bee species: Melipona (Melipona) quadrifasciata anthidioides and Melipona (Michmelia) mondury. We investigated the longevity and climbing behavior of beetles in experimental arenas with bees of different species and ages (foragers and non-foragers). The sex ratio of beetles randomly sampled from bee colonies was 1:1, and beetles of both sexes climbed onto bees. Beetles survived for at least 15 days in the presence of bees in experimental arenas. The bees did not repel beetles in the arenas, even when the beetles climbed onto them. Beetles climbed onto bees more frequently in M. mondury than in M. quadrifasciata and more often on foragers than on non-foragers. Climbing behavior was concentrated on the bees' legs, particularly the corbicula. We cannot confirm whether the relationship between Scotocryptus beetles and stingless bees is mutualistic. However, the observed beetle behavior suggests that the evolution of phoresy was a crucial step in the development of symbiosis between these two arthropod groups.