Agricultural landscape influences on the solitary bees and wasps that nest in ecological restoration sites

Global initiatives to reforest degraded areas have intensified in recent years, arising from advances in agricultural frontiers that mainly alter natural landscapes and suppress vegetation. However, little is known about the influence of agricultural landscapes on the re-establishment of groups that perform key ecosystem services in restoration areas, such as pollination and pest control. Using trap nest methodology, we aimed to evaluate how aspects of the landscape influence the abundance, richness, diversity, and composition of trap-nesting bees and wasps as well as their natural enemies in restored areas located within highly managed landscapes. Samplings were conducted monthly from August 2018 to August 2019 in nine reforested areas of Seasonal Semideciduous forest older than 15 years. We found evidence of a negative influence of monoculture area (i.e., surrounding soybean/corn agriculture) on the abundance of wasps and their natural enemies, indicating a preference for more heterogeneous landscapes, possibly related to the greater availability of prey and lesser edge effect in this type of landscape. Bee diversity indicates a negative relationship with increasing distance from the edge of reforestation to the edges of the nearest forest fragment. Our results also suggest that some bee and wasp species are more affected by habitat loss than other species in general, which was indicated by a change in community composition. We conclude that the nesting of solitary bees and wasps in reforested areas was influenced by characteristics of the surrounding landscape, which should be considered in restoration projects to maximize the effectiveness of ecological services such as pollination and predation.

Automated summary

This study evaluated the influence of agricultural landscapes on the abundance and diversity of trap-nesting bees, wasps, and their natural enemies in restored areas. The results showed that monoculture agriculture had a negative impact on the abundance of wasps and their natural enemies, while bee diversity was negatively related to the distance from the edge of reforestation to the nearest forest fragment. The findings suggest that the characteristics of the surrounding landscape should be considered in restoration projects to maximize the effectiveness of ecological services.