Data from: The carry-over effects of pollen shortage decrease the survival of honeybee colonies in farmlands

Many studies have reported honeybee colony losses in human-dominated
landscapes. While bee floral food resources have been drastically reduced
over past decades in human-dominated landscapes, no field study has yet
been undertaken to determine whether there is a carry-over effect between
seasonal disruption in floral resource availability and high colony
losses. We investigated if a decline in the harvest of pollen by honeybees
in spring affected managed honeybee colony dynamics (brood size, adult
population and honey reserves) and health (Varroa mite loads and colony
survival) throughout the beekeeping season. A decline in pollen harvest
was associated with a direct reduction in brood production, leading to a
negative effect on the adult population size later in the season, and
lower honey reserves before the onset of winter. Furthermore, the decline
in pollen harvest negatively impacted the health of the colony, resulting
in higher Varroa mite loads and higher seasonal and winter colony losses.
Early-warning signs of these carry-over effects were identified, showing
that preferential investment in honey reserves instead of brood production
early in the season increased the decline in pollen harvest and its
associated carry-over effects. Synthesis and applications. The results
suggest that the decline in pollen harvest may have been overlooked as a
cause of pollen shortage and associated bee colony losses. Strategies to
avoid such losses in intensive farmland systems include (i) limiting or
avoiding honey harvests in spring, (ii) monitoring colonies for
early-warning signals of colony failure and (iii) increasing the amount of
floral resources available through wise land-use management.