Data from: Investigating the impacts of field-realistic exposure to a neonicotinoid pesticide on bumblebee foraging, homing ability and colony growth

The ability to forage and return home is essential to the success of bees
as both foragers and pollinators. Pesticide exposure may cause behavioural
changes that interfere with these processes, with consequences for colony
persistence and delivery of pollination services. We investigated the
impact of chronic exposure (5–43 days) to field-realistic levels of a
neonicotinoid insecticide (2·4 ppb thiamethoxam) on foraging ability,
homing success and colony size using radio frequency identification (RFID)
technology in free-flying bumblebee colonies. Individual foragers from
pesticide-exposed colonies carried out longer foraging bouts than
untreated controls (68 vs. 55 min). Pesticide-exposed bees also brought
back pollen less frequently than controls indicating reduced foraging
performance. A higher proportion of bees from pesticide-exposed colonies
returned when released 1 km from their nests; this is potentially related
to increased orientation experience during longer foraging bouts. We
measured no impact of pesticide exposure on homing ability for bees
released from 2 km, or when data were analysed overall. Despite a trend
for control colonies to produce more new workers earlier, we found no
overall impacts of pesticide exposure on whole colony size. Synthesis and
applications. This study shows that field-realistic neonicotinoid exposure
can have impacts on both foraging ability and homing success of
bumblebees, with implications for the success of bumblebee colonies in
agricultural landscapes and their ability to deliver crucial pollination
services. Pesticide risk assessments should include bee species other than
honeybees and assess a range of behaviours to elucidate the impact of
sublethal effects. This has relevance for reviews of neonicotinoid risk
assessment and usage policy world-wide.