Ecology of beetle assemblages in a Panamanian tropical forest with taxonomic notes on Curculionidae and Histeridae

Beetles (Insecta, Coleoptera) contribute the most to global species richness of multicellular organisms with approximately one-fourth of all described species, the highest proportion of which can be found in tropical regions where many remain to be discovered and described. However, biodiversity in tropical regions is threatened by land use change and conversion of forests for agriculture, pasture and other uses. In this thesis I focus on tropical beetles as their ecological diversity, high richness and abundance, makes them suitable for a variety of studies that can add to our understanding of biodiversity and practical applications in management and conservation.;The study was carried out in a natural moist tropical forest in the San Lorenzo Protected Area, next to the community of Achiote, Colón Province, Republic of Panama. Thirty flight intercept traps were placed in six transects at five distances from the forest edge (0, 10, 50, 100, 250 m) to sample beetles at six periods between May 2007 and May 2008. Over 40,000 beetles were collected and identified to the level of family, and two families were selected and further identified to species level (Curculionidae, 2079 individuals from 355 species; Histeridae, 3022 individuals from 112 species).;I investigated the influence of distance and adjacent habitat (low or high contrasting habitat) on beetle assemblages along six transects from the edge towards the interior of the forest. I found that the relative abundance of beetles decreased at the edges in comparison to the interior of the forest. The sites adjacent to low contrasting habitats (i.e. coffee plantations) had a higher relative abundance of beetles than sites adjacent to high contrasting habitats (i.e. pastures). The β-diversity of beetle assemblages was found to differ significantly among sites adjacent to either coffee plantations or pastures and at the edges of the forest. The β-diversity within edges was higher for sites adjacent to pastures than those adjacent to coffee plantations. This study highlights the influence of the adjacent habitat with low contrast to the forest in diminishing the harsh effects of edges on biodiversity.;I further investigated the seasonal influence of precipitation on beetle assemblages collected between May 2007 and May 2008. The highest relative abundance and species richness of beetles were found early in the wet season. I also found a high turnover (β- diversity) between the early wet and the late wet seasons. I detected, using PerMANOVA, that the turnover of beetle assemblages was correlated significantly with the amount of precipitation. I conclude that the high β-diversity throughout the seasons might be related to different resources available and different assemblages of beetles exploiting those resources.;In this thesis, I also provide the first dichotomous key to the subfamilies Curculionidae known from Central America based on the latest classification of the family. This work presents a synthesis of information about each subfamily. In the last chapter three new species belonging to the tribe Nymphistrini of the obligate myrmeco- and termitophilous subfamily Haeteriinae (Coleoptera: Histeridae) are described from Central America: Nymphister rettenmeyeri (Costa Rica and Panama), Trichoreninus carltoni (Belize and Honduras) and T. neo (Costa Rica and Panama).