Diversity of Bark Beetles (Coleoptera: Scolytinae) in Tropical Timber Plantations of Ondo State, South West Nigeria

This study documents the diversity and host associations of bark beetles (Subfamily Scolytinae) in tropical timber plantations in Ondo State, located in Nigeria's South West geopolitical zone. Bark beetles are economically important forest pests capable of causing significant tree mortality in monoculture plantations, and their species composition in Nigerian commercial plantations is poorly characterised. Sampling was conducted using multiple-funnel intercept traps baited with ethanol and alpha-pinene deployed at five timber plantation sites (Gmelina arborea, Tectona grandis, Eucalyptus camaldulensis, and Pinus caribaea) over four months. Additional specimens were obtained by splitting infested bark samples. A total of 24 Scolytinae species from nine genera were recorded. Xylosandrus germanus and Hypothenemus hampei (coffee berry borer) were the most abundant species. Gallery architecture and associated fungal growth were documented for the five most common species. Gmelina arborea plantations supported the highest species richness (18 species) compared to Eucalyptus plantations (9 species). Host specificity was high among several gallery-forming species. Freshly felled log piles attracted significantly higher scolytine densities than standing trees, suggesting that log removal speed is a critical management variable. The study recommends prompt log extraction, stump removal, and targeted pheromone-based monitoring for early detection of damaging species in commercial plantations. Keywords: bark beetles, Scolytinae, timber plantations, Ondo State, forest pests.