Raw data and code for: Drivers of nocturnal and diurnal insect declines in urban landscapes

Insect pollinators are essential for the health and resilience of
terrestrial ecosystems, delivering key ecosystem services in the face of
anthropogenic disturbance. Urbanisation may be a key threat to pollinator
diversity and abundance.  However, the scale of the threat
remains unknown due to an overwhelming research emphasis on bees and a
lack of comparative studies of hyper-diverse taxa such as nocturnal moths.
Consequently, the question of which pollinator groups will be more
affected by urbanisation remains unknown, and the habitat features that
support key taxa remain controversial. We conducted the first large-scale
assessment of the negative effects of increasing urbanisation on the
diversity of bee, hoverfly and nocturnal moths across three cities. We
report up to a 43\% reduction in species richness along replicated
urbanisation gradients, suggesting that a wide range of pollinators are
limited due to abiotic stresses and limited resources in urban
environments. Landscape mapping indicated that these effects are driven by
the reduction of tree cover and semi-natural habitat; however, the
specific landscape drivers were taxon-specific, suggesting that urban
insect conservation depends on the preservation or expansion of habitat
features specific to different threatened taxa. In the first empirical
comparison of three major pollinator taxa, we show that, relative to bees,
moths and hoverflies are particularly sensitive to urbanisation, and we
highlight the importance of including these frequently overlooked
pollinator groups when assessing the biodiversity impacts of environmental
change.