APIS—a novel approach for conditioning honey bees

Abstract

Honey bees perform robustly in different conditioning paradigms. This makes them excellent candidates for studying mechanisms of learning and memory at both an individual and a population level. Here we introduce a novel method of honey bee conditioning: APIS, the Automatic Performance Index System. In an enclosed walking arena where the interior is covered with an electric grid, presentation of odors from either end can be combined with weak electric shocks to form aversive associations. To quantify behavioral responses, we continuously monitor the movement of the bee by an automatic tracking system. We found that escapes from one side to the other, changes in velocity as well as distance and time spent away from the punished odor are suitable parameters to describe the bee's learning capabilities. Our data show that in a short-term memory test the response rate for the conditioned stimulus (CS) in APIS correlates well with response rate obtained from conventional Proboscis Extension Response (PER)-conditioning. Additionally, we discovered that bees modulate their behavior to aversively learned odors by reducing their rate, speed and magnitude of escapes and that both generalization and extinction seem to be different between appetitive and aversive stimuli. The advantages of this automatic system make it ideal for assessing learning rates in a standardized and convenient way, and its flexibility adds to the toolbox for studying honey bee behavior.

The Sound and the Fury—Bees Hiss when Expecting Danger

“…APIS has been described in detail elsewhere [ 20 ]. In brief, it consists of a conditioning chamber (148 mm long, 20 mm wide and 6 mm high), covered with a metallic grid which can be electrified ( Fig.…”

“…Example movement traces can be found in S1 Fig ., a-c. To quantify the bees’ responses towards the injected odours, we assessed the performance variable “Escape” [ 20 ] for each odour stimulus. Whenever a bee was repelled by the odour and located in the chamber’s half opposite to the odour stimulus 2 seconds after the stimulus onset, it was counted as a successful “Escape”.…”

“…We recently introduced APIS (Automatic Performance Index System, Fig. 1a ) as a new tool to investigate learning in honey bees [ 20 ]. It consists of a walking arena, where the bee can freely move and where odours can be introduced and paired with electric shocks via an electric grid covering both floor and ceiling of the chamber.…”

“…It consists of a walking arena, where the bee can freely move and where odours can be introduced and paired with electric shocks via an electric grid covering both floor and ceiling of the chamber. Bees quickly learn to avoid the side from which an odour is given after it has been associated with punishment (escape behaviour, see [ 20 ]). In those experiments, we observed that bees often produced a noise (which we termed “hissing", see discussion ), presumably by moving their wings, during the electric shocks, and that many bees appeared to hiss also during the test upon presentation of the odour alone.…”

Different Roles for Honey Bee Mushroom Bodies and Central Complex in Visual Learning of Colored Lights in an Aversive Conditioning Assay

“…This system was an adapted version of the one used for aversive olfactory conditioning (Kirkerud et al, 2013; Schott et al, 2015; Wehmann et al, 2015). In the APIS assay bees are able to move freely in a conditioning chamber, which is equipped with LEDs to provide visual stimuli of different wavelengths and intensities.…”