Protected areas (PAs) are vital in the global effort to preserve biodiversity, particularly for disturbance-intolerant pollinator species in the tropics. As there is little information on the potential of PAs for pollinator conservation in sensitive tropical ecosystems, we assessed here insect pollinator diversity in protected vs. unprotected areas in two vegetation zones in Nigeria, within the West African Guinea Biodiversity Hotspot. We selected two land-use types based on predominant canopy cover type (open and tree-shaded habitats) and these were sampled in both protected and unprotected areas of tropical rain forest and savanna vegetation zones. Pollinator composition varied significantly between protected vs. unprotected areas in each vegetation zone, signifying both areas support unique assemblages of insect pollinators. However, pollinator diversity varied according to land-use type (open vs. shaded habitats) rather than protected area per se, such that pollinators were more abundant and species-rich in open habitat than shaded habitat. These findings emphasize that beyond the protection of ecosystems, fine scale habitat management promoting the availability of adequate floral resources in natural areas is critical for ensuring conservation of these pollinators in tropical ecosystems.   

Sampling of insect pollinators was carried out four times between August 2018 and July 2019 on each sampling plot. The sampling times were during early rain (May/June), late rain (September/October), early dry (January) and late dry (March) seasons within the one-year sampling period to cover the variation during the prolonged flowering season (Kaiser-Bunbury et al., 2017). The sampling of flowering plants in the study plots was carried out only after insect sampling to avoid disturbing the insect flower visitors. A 1 m × 1 m quadrat was randomly thrown ten times in each 25 m × 25 m plot. All flowering plants were shrubs and herbs with a maximum height of approximately 1m above ground level. Species richness and abundance of the flowering plants were estimated within the quadrats. The abundance and species richness of the different taxa (bees, wasps, beetles, butterflies, and flies) recorded in each vegetation zone from all sampling periods were pooled per insect taxon for the analyses. Species richness was estimated as the number of species recorded in each observation plot during the sampling period.  

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