Neonicotinoids Interfere with Specific Components of Navigation in Honeybees

Abstract

Three neonicotinoids, imidacloprid, clothianidin and thiacloprid, agonists of the nicotinic acetylcholine receptor in the central brain of insects, were applied at non-lethal doses in order to test their effects on honeybee navigation. A catch-and-release experimental design was applied in which feeder trained bees were caught when arriving at the feeder, treated with one of the neonicotinoids, and released 1.5 hours later at a remote site. The flight paths of individual bees were tracked with harmonic radar. The initial flight phase controlled by the recently acquired navigation memory (vector memory) was less compromised than the second phase that leads the animal back to the hive (homing flight). The rate of successful return was significantly lower in treated bees, the probability of a correct turn at a salient landscape structure was reduced, and less directed flights during homing flights were performed. Since the homing phase in catch-and-release experiments documents the ability of a foraging honeybee to activate a remote memory acquired during its exploratory orientation flights, we conclude that non-lethal doses of the three neonicotinoids tested either block the retrieval of exploratory navigation memory or alter this form of navigation memory. These findings are discussed in the context of the application of neonicotinoids in plant protection.

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

“…2012; Fischer et al . 2014; Thompson et al . 2016a), we know nothing about potential effects of neonicotinoid exposure on homing abilities of bumblebees.…”

Weight of evidence evaluation of a network of adverse outcome pathways linking activation of the nicotinic acetylcholine receptor in honey bees to colony death

“…In preparation for foraging, a new forager embarks on a number of orientation flights to identify and learn landmarks for navigation to and from the hive (Capaldi et al, 2000). Such navigational information includes using the sun azimuth as a visual compass and for estimating distance (Fischer et al, 2014). Successful foragers and scouts will recruit nest mates to profitable food collection locations using an intricate behavior termed the waggle dance.…”

“…In order to establish a link between learning and memory and chemical impacts on foraging, studies typically train bees to feed from an artificial feeder (with or without a conditioned stimulus, typically an odor) and ensure bees return to a specific feeding site (pre-exposure), expose the bees to a test chemical, and then evaluate changes in parameters associated with foraging success (post-exposure). For example, honey bees orally treated with 1.3 ng thiacloprid/bee demonstrated significantly delayed initiation of flight back to the hive from specified forage sites compared to initiation of return flights pre-exposure (Fischer et al, 2014). Additionally, those treated with either 11.3 ng imidacloprid/bee or 1.3 ng thiacloprid/bee showed a significant increase in failure to return home and exhibited directional changes in the flight vector leading back to the hive, while exposure to 2.5 ng clothianidin/bee led to significantly longer total flight paths during the homing phase (Fischer et al, 2014).…”

“…For example, honey bees orally treated with 1.3 ng thiacloprid/bee demonstrated significantly delayed initiation of flight back to the hive from specified forage sites compared to initiation of return flights pre-exposure (Fischer et al, 2014). Additionally, those treated with either 11.3 ng imidacloprid/bee or 1.3 ng thiacloprid/bee showed a significant increase in failure to return home and exhibited directional changes in the flight vector leading back to the hive, while exposure to 2.5 ng clothianidin/bee led to significantly longer total flight paths during the homing phase (Fischer et al, 2014).…”

“…Another study using radar tracking of honey bee flights following exposure to several different neonicotinoids (2.5 ng clothianidin/bee, or 11.25 μg imidacloprid/bee or 1.25 μg thiacloprid/bee) also reported adverse effects on homing, where the rate of bees returning to the hive was significantly lower than controls (Fischer et al, 2014). Visitation intervals to an artificial feeding site were also delayed when honey bees were fed a one-time dose of 50 μg imidacloprid/L sucrose solution (1 .82-4.33 ng/bee based on consumption data) (Yang et al, 2008).…”