Habitat Fragmentation on Bee (Hymenoptera: Apoidea) Diversity, Food Niches, and Bee–Plant Interaction Networks

Habitat fragmentation poses a serious threat to bee communities, which are essential for pollination and biodiversity conservation. This study evaluated how habitat fragmentation in an oak forest in Zapopan, Mexico affected bee diversity, abundance, feeding niches, and bee–plant interaction networks. We compared a protected natural area with a nearby forest fragment that has been isolated from the main forest by urbanization for the past 10 years. Wild bee abundance and species richness in the fragmented area decreased by 74% and 70%, respectively, compared to the natural area, accompanied by a significant reduction in diversity. Community composition shifted mainly due to species loss; furthermore, there was persistence of generalist species such as Apis mellifera, which became more abundant in the forest fragment. Feeding niches in the fragmented area were narrower according to the Levin index, reflecting more restricted diets and increased interspecific competition. Interaction networks were simplified, showing fewer interactions, loss of specialist bees, and decreased equitability, although network specialization remained stable, and an almost-total turnover in interactions indicated a reconfiguration of pollination patterns. These findings suggest that fragmentation negatively affects bee community structures and their interactions with plants, potentially compromising pollination and ecosystem services. Conservation of protected areas and restoration of disturbed sites with native plants are recommended to support the recovery and stability of bee communities and their ecological interactions.