Fire benefits flower beetles in a Mediterranean ecosystem

Despite the abundance of plants that benefit from fire in Mediterranean ecosystems, little is known about the possible presence of fire-favoured insects (other than bark beetles). For two years we sampled invertebrates after two large wildfires in eastern Spain and demonstrate that two flower beetle species, Protaetia morio and P. oblonga (Cetoniidae), show a pyrophilous behaviour. These beetles were much more numerous after the fires than in unburnt plots around the fire perimeter; in addition, these species tended to increase in number with the distance from the fire perimeter and with fire recurrence, especially P. morio. These results were maintained for the two postfire years sampled. The results for the beetles do not support the hypothesis of postfire colonization, but that local populations survived the fire as eggs or larvae protected in the soil (endogenous persistence). We propose that the increase in population size (compared with unburnt zones) could be driven by the reduction of their predator populations, as vertebrates that feed on these beetles were disfavoured by fire. That is, the results suggest that these flower beetle species benefit from fire because fire disrupts antagonistic interactions with their predators (predation release hypothesis). Given the omnipresence of small mammals, soil insects, and fires, the processes described here are likely to be general but unexplored.