The impact of forest successional status on the abundance, diversity, and host specificity of neotropical cerambycid beetles (Cerambycidae)

Intact rain forests sustain biodiversity and maintain global climates. This project examines how forest successional status affects community composition of saproxylic (dead-wood associated) beetles, with a special focus on Cerambycidae, which include early colonists of dying trees. Beetle abundance and species richness were expected to be similar in primary and secondary forest, however vertical stratification and host specificity were expected to be less pronounced in secondary forest. Thirty-nine trees (from eight species in five plant families) were sampled in the lowland rain forest of the Osa Peninsula, Costa Rica. Bait branches were placed at ground and canopy stratum in primary and secondary forest and exposed for three months, then placed in rearing cages. A total of 2886 adult cerambycids in 45 morphospecies were collected. Species richness was similar in the two forest types, although abundance was higher than expected in primary forest.  There was little evidence of stratification in either forest type; over 90% of the species were reared at both strata. Almost 25% of the cerambycids were host specialists that were found in primary forest; another 11% were host specialists found in secondary forest. This study suggests that even small areas of secondary forest can act as barriers to the dispersal of primary forest species. This is consistent with observations that deforestation and changes in land use are closely linked to the reduction of biodiversity, including the loss of host-specific species that play critical roles in forest nutrient cycling.