Behavioural data of the differentially conditioned honey bees: hissing, escapes from odour and combination of these two.

<p>a) Hissing of bees during odour presentation (during section)—same data as in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0118708#pone.0118708.g003" target="_blank">Fig. 3b</a>. b) Escapes by the bees from odour. Left panel: acquisition, right panel: recall test. Bees learned to escape from the odour during conditioning and escaped with a higher probability from the CS+ than from the CS- from the second trial on. This difference remained stable throughout the recall test. c) Proportion of bees that both hissed and escaped from the odour. Although only few bees exhibited both behaviours, there is a very clear difference between CS+ and CS-: almost no bees responded with hissing and escape to the CS- (2%), whereas 24.2% of the bees responded to the CS+ with both behaviours at the same time during the test. Solid lines and bars: CS+, dashed lines and shaded bars: CS-. Asterisks indicate statistically significant difference (RM-ANOVA followed by Fisher LSD-post hoc test, p<0.0001); error bars denote 95% confidence interval. d, e) Proportion of bees hissing, escaping, doing both or none of these responses upon presentation of CS+ (d) and CS- (e). The dashed line separates the conditioning phase (trial 1–4) from the recall test phase (trial 5 and 6).</p

The Automatic Performance Index System and the protocol used.

<p>a) APIS is 148 mm long, 20 mm wide and 6 mm high, enabling unhindered walking on either floor or ceiling for the honey bee (black arrow). The interior is covered with an electrifiable metallic grid, and infrared-sensors constantly record the bee’s position. Odours were injected from either end of the chamber via computer-controlled valves. The bee’s hissing was recorded via the microphone attached to an opening in the chamber (top, white arrowhead). b) In order to quantify the bees’ hissing response, we analysed three sections of the recording for each trial: the two seconds before onset of the odours (before); the two seconds following the odour onset termed during (corresponding to the ISI in case of the CS+); and the first two seconds of the CS delivery after the ISI (after). Bees received 5 shocks (yellow lightening bolts) every 950 ms during the shock period in case of the CS+.</p

Coincidence of pheromone and plant odor leads to sensory plasticity in the heliothine olfactory system

<div><p>Male moths possess a highly specialized olfactory system comprised of two segregated sub-arrangements dedicated to processing information about plant odors and pheromones, respectively. Communication between these two sub-systems has been described at the peripheral level, but relatively little is known about putative interactions at subsequent synaptic relays. The male moth faces the challenge of seeking out the conspecific female in a highly dynamic odor world. The female-produced pheromone blend, which is a limited resource serving as guidance for the male, will reach his antennae in intermittent pockets of odor filaments mixed with volatiles from various plants. In the present study we performed calcium imaging for measuring odor-evoked responses in the uni-glomerular antennal-lobe projection neurons (analog to mitral cells in the vertebrate olfactory bulb) of <i>Helicoverpa armigera</i>. In order to investigate putative interactions between the two sub-systems tuned to plant volatiles and pheromones, respectively, we performed repeated stimulations with a selection of biologically relevant odors. We found that paired stimulation with a plant odor and the pheromone led to suppressed responses in both sub-systems as compared to those evoked during initial stimulation including application of each odor stimulus alone. The fact that the suppression persisted also after pairing, indicates the existence of a Hebbian-like plasticity in the primary olfactory center established by temporal pairing of the two odor stimulation categories.</p></div

The Sound and the Fury—Bees Hiss when Expecting Danger

<div><p>Honey bees are important model systems for the investigation of learning and memory and for a better understanding of the neuronal basics of brain function. Honey bees also possess a rich repertoire of tones and sounds, from queen piping and quacking to worker hissing and buzzing. In this study, we tested whether the worker bees’ sounds can be used as a measure of learning. We therefore conditioned honey bees aversively to odours in a walking arena and recorded both their sound production and their movement. Bees were presented with two odours, one of which was paired with an electric shock. Initially, the bees did not produce any sound upon odour presentation, but responded to the electric shock with a strong hissing response. After learning, many bees hissed at the presentation of the learned odour, while fewer bees hissed upon presentation of another odour. We also found that hissing and movement away from the conditioned odour are independent behaviours that can co-occur but do not necessarily do so. Our data suggest that hissing can be used as a readout for learning after olfactory conditioning, but that there are large individual differences between bees concerning their hissing reaction. The basis for this variability and the possible ecological relevance of the bees’ hissing remain to be investigated.</p></div

Hissing of honey bees during differential conditioning and recall test.

<p>Left: Acquisition curve. Right: Recall test five minutes after the end of conditioning. Shown are the three sections before and during odour presentation: a) before section, b) during section, c) after section. Solid lines and bars: CS+, dashed lines and shaded bars: CS-. Bees do not respond differently to CS+ and CS- before onset of the odour (a), but after onset of the odour, they respond more often to the CS+ than to the CS- with hissing (b, c). There is no clear distinction between CS+ and CS- during the conditioning phase in the during section (b, left panel, only the first and the last conditioning trial show a significant difference), bees hiss more often during the shocked phase (after section) of the CS+ (c, upper curve) compared to the CS- (c, lower curve). Asterisks indicate statistical difference, RM-ANOVA followed by Fisher LSD-post hoc test, p<0.0001. Error bars show the 95% confidence interval.</p