5 research outputs found
Behavioral and genetic correlates of heterogeneity in learning performance in individual honeybees, Apis mellifera
Learning an olfactory discrimination task leads to heterogeneous results in honeybees with some bees performing very well and others at low rates. Here we investigated this behavioral heterogeneity and asked whether it was associated with particular gene expression patterns in the beeâs brain. Bees were individually conditioned using a sequential conditioning protocol involving several phases of olfactory learning and retention tests. A cumulative score was used to differentiate the tested bees into high and low performers. The rate of CS+ odor learning was found to correlate most strongly with a cumulative performance score extracted from all learning and retention tests. Microarray analysis of gene expression in the mushroom body area of the brains of these bees identified a number of differentially expressed genes between high and low performers. These genes are associated with diverse biological functions, such as neurotransmission, memory formation, cargo trafficking and development
Hinweise anhand Verhaltens- und physiologischen Experimenten
Honeybees have superior abilities to learn and discriminate between enormous
number of odors with different carbon chain length and functional group. They
learn odors outside the colony during foraging as well as inside the colony
while communicating with the hive comrades. Bees can be trained to learn odors
in the laboratory in simple and complex forms of learning assays using the
popular conditioning paradigm namely, the olfactory conditioning of proboscis
extension reflex (PER). I used the same olfactory PER conditioning assay and
investigated the influences of different learning and memory related features
on the overall performance of bees in complex form of olfactory learning. In
addition, I recorded physiological responses from the olfactory neurons in
honeybee brain to understand the olfactory coding in presence of the complex
background odor used for adaptation. In the first chapter of this dissertation
I investigated the role of olfaction in honeybees to detect the presence of
pathogenic Varroa mite inside the brood cells. Results showed that bees with
higher resistance against the Varroa mitewere able to distinguish between the
odors of the healthy and infected brood better than the less resistant bees.
This strongly indicated that resistant bees possibly detect the Varroa
parasitized brood through recognizing their abnormal odors in the colony. This
also indicated that honeybees can possibly learn the odors associated with the
Varroa infection in presence of the adapting background odor of the honeybee
colony. In the second chapter a cumulative form (complex form) of olfactory
conditioning assay was used to train bees to identify and understand the
behavioral characteristics of the different types of learning related
performer classes present in the population of honeybee. I found that speed of
odor learning and odor discriminability were the two most important features
that strongly influenced the overall performances of all types of performer
classes in honeybee. Furthermore, in the third chapter I used the popular
neurophysiological technique of in vivo calcium imaging and investigated the
effects of olfactory adaptation on the odor coding of the antennal lobe
glomeruli. My results showed that adaptation with the background of complex
odor stimuli changed the response strengths and representation patterns of
odor in the glomeruli which together confirmed the change in odor coding
scheme of the glomerular coding space. These results altogether contributed
further to the understanding of neural coding and behavioral learning of odor
information in honeybee.Honigbienen besitzen die FĂ€higkeit eine Vielzahl von DĂŒften anhand von
unterschiedlich langen Kohlenstoffketten und unterschiedlichen funktionalen
Gruppen zu unterscheiden. DĂŒfte sind fĂŒr diese Tiere wĂ€hrend der Futtersuche
und im Stock zur Kommunikation von höchster Wichtigkeit. Bienen lernen DĂŒfte
im Labor in unterschiedlich komplexen Lernexperimenten. HierfĂŒr bedient man
sich der olfaktorischen Konditionierung des Proboscisstreckungsreflexes (PER).
Mit Hilfe solcher Konditionierungsexperimente untersuchte ich die EinflĂŒsse
von verschiedenen Lern- und GedÀchtniseigenschaften auf die Performance von
Bienen in komplexen Formen olfaktorischen Lernens. ZusÀtzlich habe ich
(opto-)physiologische Messungen an olfaktorischen Neuronen im Bienengehirn
vorgenommen, um den olfaktorischen Code in Gegenwart von komplexen
HintergrunddĂŒften zu untersuchen. Im ersten Kapitel dieser Dissertation
untersuchte ich die Rolle von Olfaktion bei der AufspĂŒrung der pathogenen
Milbe Varroa in den Brutzellen von Honigbienen. Die Ergebnisse zeigen, dass
Bienen mit einer höheren Resistenz gegen Varroa-Milben besser zwischen den
DĂŒften von gesunder und infizierter Brut unterscheiden konnten. Dies deutet
stark darauf hin, dass resistente Bienen von Varroa parasitierte Brut durch
olfaktorische Merkmale erkennen können. Im zweiten Kapitel wurden die Bienen
mit Hilfe einer kumulativen (komplexen) Form der olfaktorischen
Konditionierung trainiert um die Ergebnisse der verschiedenen Typen von
lernbezogenen Performerklassen interpretieren zu können. Ich fand heraus, dass
die Geschwindigkeit des Duftlernens und Duftunterscheidbarkeit die beiden
Eigenschaften sind, die die Performance von allen Typen von Performerklassen
am meisten beeinflussen. Im letzten Kapitel untersuchte ich unter Anwendung
der opto-physiologischen Technik in vivo Calcium Imaging die Effekte von
olfaktorischer Adaption auf den Duftcode im Antennallobus. Meine Ergebnisse
zeigen, dass Adaption an einen komplexen Hintergrundduft die AntwortstÀrke
erhöht und das glomerulare AktivitÀtsmuster von zusÀtzlich prÀsentierten
EinzeldĂŒften verĂ€ndert. Diese Ergebnisse tragen dazu bei, die Rolle von
HintergrunddĂŒften in der Umgebung beim neuronalen Coding und das Lernverhalten
von Duftinformation in der Honigbiene besser zu verstehen
Odor learning and odor discrimination of bees selected for enhanced hygienic behavior
International audienceAbstractOdor learning and odor discrimination were tested in a line of honeybees selected for increased hygienic behavior (HB) against the Varroa mite and compared with control bees (CB). Olfactory proboscis extension conditioning was used to quantify learning, discrimination, and generalization. Retention tests were performed after 1Â h and after 1Â day to probe the stability of memory. HB and CB did not differ in their learning, discriminating, generalizing, and remembering behavior when pairs of floral odors and pairs of sting pheromone and floral odor were tested. Colony odor used as a background odor during learning and discrimination reduced the performance in both groups, possibly due to an adaptation effect. This effect was found to be particularly strong in CB. In both groups of test bees, no learning was found if wax caps of Varroa-infected and Varroa-uninfected cells were used as test stimuli, possibly because of the common odors. Volatile odors from Varroa-infected and noninfected pupae, however, were learned and discriminated indicating that the volatile signals are strong enough to override the similar cues of pupae. HB performed somewhat better than CB when infected pupae were used as the rewarded stimulus, but the difference between the two groups of test bees was small. Taken together, we conclude that odor learning and discrimination do not differ between HB and CB as long as general odors are involved, but when specific odor profiles from infected pupae are used as the reinforced signal, then a slightly better performance is seen in HB