2. Behavioral Biology TALKS - Deutsche Zoologische Gesellschaft

����138 Hannah Burger
Have specialized bees evolved neural adaptations to locate their host plants?
Authors: Hannah Burger 1 , Giovanni Galizia, Stefan Dötterl, Sabine Kreissl, Manfred
Ayasse
Affiliation: 1 University of Ulm, Institute of Experimental Ecology
Specialized (oligolectic) bees rely on a small range host plants for their pollen
collection, in strong contrast to bees like honeybees which forage on a broad and
generalized flower spectrum. As compared to generalists, the specialists might have
evolved neural adaptations allowing them to effectively locate their specific host
flowers. In particular, olfactory cues might be suited for identifying host flowers. To
investigate how host odours are processed in their brains, we used calcium imaging
experiments and recorded odour-evoked activity patterns in the antennal lobe for
the specialist Andrena vaga and, for comparison, in the generalist honeybee Apis
mellifera. Our investigations show that A. vaga bees, but not the honeybee A.
mellifera, had a particularly high sensitivity for a main component of the host-flower
odour. Our experiments suggest that A. vaga females show correlates between
neural organization and host-plant finding behaviour.
����139 Peter Christ
Activity dependent plasticity in the olfactory system of adult Tribolium castaneum
Authors: Peter Christ 1 , Martin Kollmann 1 , Joachim Schachtner 1
Affiliation: 1 Philipps-University Marburg, Dept. Biology, Animal Physiology
Tribolium castaneum offers an excellent system to study development and plasticity
of the olfactory system. A previous work on volume of distinct neuropils revealed a
pronounced increase of brain volume incl. antennal lobes (ALs) and mushroom
bodies (MBs) within the first days of adult life, indicating a pronounced sensitive
phase. To further reveal this mechanism, we examined neuropeptidespossibly
involved in this postmetamorphic plasticity. We compared the numbers of
tachykinin-immunoreactive (TK-ir) AL neurons of females and males directly (A0) and
seven days after molt (A7). We found a sexual dimorphism at A0 concerning numbers
of TK-ir cells, with females having more TK-ir AL neurons than males. In both sexes,
the numbers of AL TK-ir cells increased from A0 to A7. Females, isolated shortly
before adult molt and raised to A7, showed no increase in the number of TK-ir cells,
in contrast to males held under same conditions. As in T. castaneummales are the
main source of pheromone, we concluded, increase in TK-ir cell number can be
induced by perception of pheromones. To extend these findings, we added the
pheromone Dimethlydecanal (DMD), a food-related odor (cis-3-Hexen-1-ol) or a
perception disturbing substance (Deet) to isolated beetles. The pheromone as well as
the food related odor led to an increase in number of TK-ir cells in both sexes, while
Deet addition prevented an increase in cell number.
This result suggests that the increase of TK-ir cells between A0 and A7 depends on
the perception of odor signals and favors an activity dependent mechanism for the
maturation of a peptidergic system in the AL of the red flour beetle.
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