Abstract

Oil palm (Elaeis guineensis) is native to West Africa and has been cultivated for thousands of years. It is an essential part of the local cuisine and critical for food security. In Southeast Asia, oil palm plantations have been accused of being the main cause of deforestation and biodiversity loss. However, several recent studies assessing the impact of oil palm plantations have suggested that the conversion of primary forests to oil palm plantations has no negative impact on butterfly diversity or abundance. Permanent transects were established along a gradient of six land-use types (primary forests, secondary forests, farm-bush with few oil palms, farm-bush with a high density of palms, low-intensity oil palm plantations, and high-intensity oil palm plantations) to investigate the richness of butterfly assemblages. Butterfly species were recorded on eight occasions during both the wet and dry seasons over a two-year period using the walk-and-capture method and fruit bait trapping. All sites were within 50 km of each other in the Eastern Province of Sierra Leone. Three species parameters—Margalef’s Richness Index, Shannon-Wiener diversity index, and Pielou’s Evenness Index—were computed to describe richness, diversity, and evenness at the six sampling areas. A total of 2,502 individuals from 167 species, 60 genera, and 4 families were identified. The family Nymphalidae was the most widespread, accounting for 46.9% of all sampled butterflies. Eurema senegalensis (Pieridae), Junonia oenone (Nymphalidae), and Colotis euippe (Pieridae) were the species with the highest number of individuals. Butterfly species composition and diversity were higher in the forest (primary and secondary) than in any of the other land-use types. The oil palm plantations recorded the lowest number of individuals and species, with only four species restricted to this habitat. This result indicates that converting primary and secondary forests into oil palm plantations has a significant and detrimental effect on butterfly species composition and diversity.

Key words: Butterfly, LULC, oil palm.