Data and code from: Trapped honey bees reduce floral visitation on milkweed flowers

Trapped arthropods have been shown to benefit plants in several ways, but
few studies have examined the potential costs of arthropod entanglement.
Milkweeds (Asclepias spp.) have an unusual pollination system that
requires relatively large packets of pollen (pollinia) to become attached
to the appendages of insect pollinators and be pulled through a narrow
opening in the flower. Honey bees (Apis mellifera) commonly become trapped
and die with their legs still attached to milkweed flowers. In this study,
we conducted a field experiment to examine how dead trapped honey bees
affect floral visitation. We expected that the presence of a dead trapped
bee would reduce floral visitation via two non-mutually exclusive
pathways: 1) a direct deterrent effect on floral visitors, and 2) an
indirect deterrent effect mediated by an increased abundance of scavenging
predators such as ants. The presence of a dead bee reduced floral
visitation by 37% compared with controls, and this effect was more robust
for honey bee visitors than non-Apis visitors. While ant densities were
51% higher on floral umbels with a dead bee, and ants reduced floral
visitation by 30%, our path analysis indicated that the direct deterrent
pathway explained 91% of the total effect, consistent with an aversion to
dead conspecifics among honey bees. Our results suggest that the lethal
entanglement of honey bees is likely to incur an ecological cost for
milkweed flowers, although the deterrence of honey bees could also shift
the pollinator communities on milkweeds with unexpected consequences.