Differences in bark beetle (Coleoptera : Curculionidae) community composition within Cecropia obtusifolia (Cecropiaceae) petioles in two habitats in Monteverde, Costa Rica

Cecropia obtusifolia trees shed leaves daily throughout the year, regularly dropping large, woody leaf petioles. These petioles serve as the perfect habitat for Scolytine bark beetles, which burrow in, lay their eggs, and feed on the moist, fibrous pith of the petiole (Wood 1983). Cecropia spp. are known to thrive in fragmented, edge habitats altered by human land use transformation (Bello et al 1996) but success rates of associated fauna, including Azteca spp. ants, scale insects and Scolytine beetles, are less understood. This study examined the bark beetle community composition, morphospecies richness, and abundance inside C. obtusifolia petioles. It also investigated the rate of petiole colonization by Scolytine beetles, comparing two habitats: a C. obtusifolia population occurring in a forest tree fall light gap, and a population occurring along a neighborhood road. Both populations were located in Monteverde, Costa Rica. Fallen, dead petioles were collected and dissected from each habitat type, and all fauna found inside the woody petioles were removed, identified, and recorded. They were identified as either a Scolytine larva, one of five observed Scolytinae morphospecies, or a non-Scolytine organism. Differences between observed beetle communities in the two studied habitats were then compared. This revealed equal species richness and equal rates of petiole colonization for beetle communities at each site. The human disturbed habitat had greater Scolytinae abundance, while the forest light gap habitat had greater diversity due to higher evenness of morphospecies abundances. This is explained by the particularly high abundance of one morphospecies in disturbed habitat beetle communities. Overall, there were few evident differences between Scolytinae communities in the two examined habitats, indicating that observed Scolytinae populations are adaptable to human-caused habitat alterations and can disperse to fragmented C. obtusifolia trees. Their maintained survival and reproduction rates indicate that C. obtusifolia associated Scolytinae beetles are poor indicators for biodiversity loss and impacts on species relationships that result from continued global deforestation and habitat degradation. Este estudio examina la composición en la comunidad de los escarabajos de corteza en cuanto a número de morfoespecies y abundancia de individuos dentro de los pecíolos de la especie C. obtusifolia. También se investiga el rango de colonización de los peciolos colonizado por los escarabajos de la subfamilia Scolytine comparando dos hábitats entre los individuos encontrados en poblaciones en los claros del bosque y las poblaciones encontradas en las orillas de los caminos. Ambas poblaciones fueron encontradas en Monteverde, Costa Rica.https://digitalcommons.usf.edu/tropical_ecology/1041/thumbnail.jp