Exploring the interactions between resource availability and the utilisation of semi-natural habitats by insect pollinators in an intensive agricultural landscape

Intensification of agriculture and associated loss of habitat heterogeneity is a key driver of global declines in insect pollinators. Pollinators utilise different habitats to meet resource requirements throughout their life-span and it is widely accepted that their conservation requires a landscape-scale approach. Information on the mechanisms driving insect pollinators at the landscape scale is, however, lacking. To fill this knowledge gap, this novel study explores how pollinators utilise different habitats within a landscape and how utilisation changes over the season. Floral resources and insect pollinators (i.e. bumblebee, butterflies and hoverflies) were monitored during peak pollinator activity periods on a wide range of agricultural and semi-natural habitats in an intensive grassland landscape. The availability of key foraging resources differed between semi-natural habitats and this was strongly linked to their utilisation by pollinators. Floral resources were most abundant and diverse in road verges, riparian buffer strips and open scrub. These were key habitats for butterflies, with road verges and buffer strips also being important for hoverflies and bumblebees. The relative value of semi-natural habitats in providing floral resources changed throughout the season. Pollinators appeared to respond to changes in key floral resources, dynamically using different semi-natural habitats to meet their requirements. Maintaining landscape heterogeneity and improving the quality of semi-natural habitats to ensure resource diversity and continuity is fundamental to pollinator conservation. Regionally targeting agri-environment spending could result in the simplification of agricultural landscapes with consequences on insect pollinators and biodiversity as a whole.