Different pollinator sampling methods measure distinct pollinator communities in a mass-flowering crop, which respond differently to the composition of the surrounding landscape

Abstract

Pollinator insects are essential for the pollination of many crops and wild plants. Recent declines in insect population pose significant challenges for maintaining pollination services. Habitat loss and landscape homogenization are among the primary drivers of these declines. In order to monitor and assess populations of pollinating insects, precise and accurate methods are required. A common method to collect pollinators is pan traps, but this method suffers from a bias due to surrounding flower frequency, yet this remains untested at the large spatial scale such as the landscape. Understanding how different pollinator sampling methods reflect the impact of landscape composition on pollinator communities is critical for designing robust monitoring schemes that can lead to effective conservation strategies. This study investigates how two common pollinator sampling methods - insect nets and pan traps - measure the abundance, diversity, and composition of pollinator communities in sweet-cherry orchards (Prunus avium) in Belgium. The study also examines how pollinator data obtained by these methods relate to the surrounding landscape, specifically the amount of seminatural habitat and intensive fruit cultivation. We conclude that both methods provided similar sampling efficiencies, yet they captured different subsets of the pollinator community. Insect nets caught a higher abundance and species richness of bumblebees, while pan traps caught higher solitary bee abundance, and hoverfly abundance and richness were unaffected. The pollinator data also exhibited different responses to landscape composition as a function of the sampling method. These findings suggest that different sampling methods yield complementary insights into pollinator communities and their interactions with the landscape. Therefore, integrating both methods in future monitoring schemes is recommended to obtain comprehensive data on pollinator diversity and abundance, aiding in the assessment of pollinator population trends and the development of evidence-based conservation strategies.