Effects of Sub-lethal Doses of Glyphosate On Honeybee Navigation

The Journal of Experimental Biology   Accepted July 2, 2015

Research Article/Abstract

Glyphosate (GLY) is a herbicide that is widely used in agriculture for weed control. Although reports about the impact of GLY in snails, crustaceans and amphibians exist, few studies have investigated its sub-lethal effects in non-target organisms such as the honeybeeApis mellifera, the main pollen vector in commercial crops. Here, we tested whether exposure to three sub-lethal concentrations of GLY (2.5, 5 and 10 mg/L corresponding to 0.125, 0.250 and 0.500 µg/animal) affects the homeward flight path of honeybees in an open field. We performed an experiment in which forager honeybees were trained to an artificial feeder, and then captured, fed with sugar solution containing GLY traces and released from a novel site (the release site, RS) either once or twice. Their homeward trajectories were tracked using harmonic radar technology. We found that honeybees that had been fed with solution containing 10 mg/L GLY spent more time performing homeward flights than control bees or bees treated with lower GLY concentrations. They also performed more indirect homing flights. Moreover, the proportion of direct homeward flights performed after a second release at the RS increased in control bees but not in treated bees. These results suggest that, in honeybees, exposure to GLY doses commonly found in agricultural settings impairs the cognitive capacities needed to retrieve and integrate spatial information for a successful return to the hive. Therefore, honeybee navigation is affected by ingesting traces of the most widely used herbicide worldwide, with potential long-term negative consequences for colony foraging success.

Read at: http://jeb.biologists.org/content/early/2015/07/09/dev.117291.abstract

Honeybee Navigation and Communication

World Organic News    By Mary MacGregor Reid   March 22, 2015

Honeybees navigate according to a map-like spatial memory

Using radar scientists tracked the flight paths of displaced bees – the bees are captured leaving the hive or a feeder they are familiar with and are released in unexpected sites in their general territory. Behavioural routines are recorded:

1) Straight flights in which they fly the course that they were on when they were captured on a foraging flight or that they learned from directions given from bee dances (those are called recruited bees).
2) Slow search flights where they fly with frequent direction changes in order to get their bearings.
3) Straight rapid flights to the hive or the feeder even from unexpected places in their territory where they have no visual connection to either hive or feeder.

“Two essential criteria of a map-like spatial memory are met by these results: bees can set course at any arbitrary location in their familiar area, and they can choose between at least two goals. This finding suggests a rich, map-like organization of spatial memory in navigating honey bees.”

Menzel, R. et al (2004) Proceedings of the National Academy of Science of the United States of America (website) http://www.pnas.org/content/102/8/3040.abstract

F3.medium

Diagram showing homing flights via the feeder (Fs) to the hive (H)

It is commonly accepted that bees use the sun as a reference point in both communication (waggle dance) and navigation, and that this is an innate understanding. Attempts to model this have apparently been unsuccessful.

Karl Von Frisch received the Nobel Prize for discovering one of the most difficult to fathom complexities of honeybee behaviour; their ability to ‘talk’ to each other abstractly through the Figure 8 Dance of the honeybee. The direction the bee moves in relation to the hive indicates direction pf pollen source. If it moves vertically upwards the direction to the source is directly towards the sun. The duration of the waggle signifies the distance. A waggle dance consists of one to 100 or more circuits, each of which consists of two phases: the waggle phase and the return phase. A worker bee’s waggle dance involves running through a small figure-eight pattern: a waggle followed by a turn to the right to circle back to the starting point (return phase), another waggle run, followed by a turn and circle to the left, and so on in a regular alternation between right and left turns after waggle runs. Waggle-dancing bees produce and release two alkanes that also seem to act as additional communication.

Unusual fact: Apparently honeybees cannot see white, hence the colour of beekeeping suits.

Read at: http://www.worldorganicnews.com/?p=13667 
http://marymacgregor-reid.com/2015/03/22/honeybee-navigation-and-communication/