Mixed-species system and native vegetation cover shape bee community in tomato crops

ContextChanges in landscape structure resulting from intensive land use along with low plant diversity in agroecosystems can negatively affect pollination services, but it is still poorly understood how the underlying processes can affect wild pollinators in tomato crops.ObjectivesWe investigated to what extent tomato crop management (mixed-species system versus monoculture) and landscape structure are related to community metrics of flower-visiting bees (species composition, richness, abundance, and flower visitation rate) at two different scales (buffers of 500 and 2000 m).MethodsThe research was conducted in ten commercial tomato fields located in Southeastern Brazil. In five fields, management was based on a mixed-species system, and the other five tomato crops used a monoculture system. In the core area of each field, we deployed two adjacent transects of 100 m that were sampled at the same time by two independent trained observers. Every hour, from 7 to 14 h, a 30-min observation was conducted in each transect. The bees was observed or collected during their flower visitation.ResultsThe differences in species composition were significantly driven by the abundance of Apis mellifera (the only exotic species; 14% of bee observations), which was higher in crops with lower native cover, and the abundance of Paratrigona lineata (the most abundant species; 55% of bee observations), which was higher in the mixed-species system. Mixed crops and a higher percentage of natural vegetation positively affected the occurrence of native bees, while the percentage of exotic species tends to be higher in monocultures and non-native landscapes. The relative importance of landscape structure decreased for some bee community metrics in the 2000 m buffer.ConclusionsOur results reinforce that the mixed-species system and the conservation of natural habitats are important for maintaining the diversity of wild bees and the pollination service that they provide to both crops and native vegetation.

Automated summary

Through studying the relationship between tomato crop management and landscape structure and community metrics of flower-visiting bees, it was found that mixed-species system and conservation of natural habitats are crucial for maintaining the diversity of wild bees and providing pollination services to both crops and native vegetation.