2. Behavioral Biology TALKS - Deutsche Zoologische Gesellschaft

differences of only 0.2 °C, and physiological measurements of one receptor neuron
type revealed an incredible resolution of only 0.005°C for temperature fluctuations
(Ruchty et al. (2010) J. Neurophysiology 104). Thermo-reception takes places in peg
and pit sensilla located at the tip of the ants’ antenna. Several studies in other insects
revealed that members of the TRPA subfamiliy are involved in thermo-reception.
Interestingly, the number of TRPA members is expanded in Hymenoptera (Matsuura
et al. 2009). Therefore, we hypothesize that the TRP channels are important for
thermo reception in ants, and that modulation and adaptation of diverse TRP
channels contribute to the highly evolved thermo-reception system. In order to
understand the underlying mechanism of thermo-reception, we address the
following questions: i) which members of the TRP family are expressed in the ants’
antenna, and ii) which sensilla types house the TRP expressing neurons?
Antennal transcriptome analysis revealed the expression of different TRP channels.
Based on these transcripts, we built TRP-specific probes for fluorescence in situ
hybridization (FISH). For establishing FISH, we used a specific probe for the olfactory
co-receptor ORCO, which is expressed in most of the antennal chemosensory
neurons. Currently, we are testing various probes on cryosections of the ants’
antenna to co-localize the expression of TRP channels with their specific sensilla
types.
����144 Judith Förster
Determining Mode of Action of Pymetrozine - From Single Cell to System Level
Authors: Judith Förster 1 , Ulrich Ebbinghaus-Kintscher 2 , AnsgarBüschges 1
Affiliation: 1 University of Cologne; 2 Bayer CropScience, Monheim
Pymetrozine is one selective insecticide against aphids. It induces a stretched posture
of the legs and proboscis. This effect vanishes over time after application.
Experiments in locusts indicate that pymetrozine affects gross sensitivity of sensory
neurons in the fCO (Ausborn et al., 2005; Kaufmann et al., 2004). However, the mode
of action of Pymetrozine is presently unknown. That means it is not known how
single sensory cells of the fCO are affected and which target sides in the fCO exist.
So far two possible explanations exist: (1) Pymetrozine affects the mechanoelectrical
transduction process or (2) affects transformation of receptor potential towards
action potentials.
The stick insect, Carausius morosus, that has well characterized sensory organs, is
also affected by Pymetrozine by lifting its legs. Potent concentrations of pymetrozine
start at 100nM. Single fCO sensory cells are sensitive to changes of position (P),
velocity (V) and/or acceleration (A) of the tibia (Hofmann et al., 1985). The reactions
of these sensory cells to pymetrozine can be recorded intracellularly in the segmental
ganglion (n=10). We show that P-sensitive (n=2) and V-sensitive (n=4) cells become
tonic during stimulation after pymetrozine application. Active sensory cells as well as
silent sensory cells become tonically active with pymetrozine treatment already in
the absence of fCO-stimulation. This was independent of cell type (P: n=2; V: n=5; A:
n=1). On average 25sec after the tonic activation, 70% of sensory cells became
inactive. These results suggest that pymetrozine influences the transformation of
receptor potentials into action potentials because the effect occurs without
mechanical stimulation.
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