BuehlmannHanssonKnaden_RawData

The file provides the raw data (xy coordinates) of foraging ants under different experimental conditions

Individual test runs of homing ants.

<p>Schematic nest searches of ants trained and tested with a nest-defining landmark that was either a magnetic, vibrational, visual or olfactory cue (red), control ants trained and tested without landmark (black) or naïve ants that experienced the landmark in the test for the first time (blue). Blue dashed line, nest position as defined by path integration; red dashed line, nest position as defined by landmark; point of release for each homing run at position -2 m from nest-defining cue. The first six turning points after the ants had passed the landmark for the first time were analyzed for their median position.</p

Experimental procedure.

<p>(A) The ants' nest was connected with a tube to the training channel where the ants were trained to visit a feeder 1 m away from the nest entrance that was marked with either a magnetic, vibrational, visual, olfactory or no landmark. For size and shape of the solenoid, and for the application of the massaging rod next to the channel see <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0033117#s3" target="_blank">Material and Methods</a>. (B) Trained ants were displaced from the feeder of the training channel into the parallel test channel (displacement shown by dashed arrow) where the homing runs and nest searches of the tested ants were tracked and recorded. Blue filled circle, nest entrance; black filled circle, feeder; black empty circle, release point; blue empty circle, fictive nest position, red rectangle, landmark; blue dashed line, nest position as defined by path integration, red dashed line, nest position as defined by landmark. Nest-to-feeder distance, 1 m; landmark was 1 m behind fictive nest position in test channel. (C) Exemplar homing run and nest search. We analyzed the first six turning points (TP1–TP6) after the ants had crossed the nest-defining cue for the first time.</p

Schematic drawing of the wind tunnel (length, 250 cm; width, 90 cm; height, 90 cm).

<p>Females were released from a platform 50(distance between sources, 20 cm) were placed at the upwind entrance to the wind tunnel. These consisted of filter papers loaded with synthetic flower odors. Headspace volatiles from non-flowering plants placed in a glass cylinder outside the tunnel were released close to the source of flower volatiles.</p

Attraction of <i>M. sexta</i> females to plant and flower odors.

<p>(a) No-choice experiment: Percentage of moths that flew upwind towards the presented odor source (duf) and reached the source with extended proboscis (sc). (b) Two-choice experiment with two single odor sources presented in the wind tunnel (20 cm apart). (b-i) Number of first source contacts. (b-ii) Total number of approaches per moth within 5 min. (c) Two-choice experiment, presenting a single flower blend stimulus and a combined flower and plant odor. (c-i) Number of first source contacts. (c-ii) Total number of approaches per moth within 5 min. Error bars depict the standard deviation.</p

Host Plant Odors Represent Immiscible Information Entities - Blend Composition and Concentration Matter in Hawkmoths

<div><p>Host plant choice is of vital importance for egg laying herbivorous insects that do not exhibit brood care. Several aspects, including palatability, nutritional quality and predation risk, have been found to modulate host preference. Olfactory cues are thought to enable host location. However, experimental data on odor features that allow choosing among alternative hosts while still in flight are not available. It has previously been shown that <i>M. sexta</i> females prefer <i>Datura wrightii</i> compared to <i>Nicotiana attenuata</i>. The bouquet of the latter is more intense and contains compounds typically emitted by plants after feeding-damage to attract the herbivore’s enemies. In this wind tunnel study, we offered female gravid hawkmoths (<i>Manduca sexta</i>) odors from these two ecologically relevant, attractive, non-flowering host species. <i>M. sexta</i> females preferred surrogate leaves scented with vegetative odors form both host species to unscented control leaves. Given a choice between species, females preferred the odor bouquet emitted by <i>D. wrightii</i> to that of <i>N. attenuata</i>. Harmonizing, i.e. adjusting, volatile intensity to similar levels did not abolish but significantly weakened this preference. Superimposing, i.e. mixing, the highly attractive headspaces of both species, however, abolished discrimination between scented and non-scented surrogate leaves. Beyond ascertaining the role of blend composition in host plant choice, our results raise the following hypotheses. (i) The odor of a host species is perceived as a discrete odor ‘Gestalt’, and its core properties are lost upon mixing two attractive scents (ii). Stimulus intensity is a secondary feature affecting olfactory-based host choice (iii). Constitutively smelling like a plant that is attracting herbivore enemies may be part of a plant’s strategy to avoid herbivory where alternative hosts are available to the herbivore.</p> </div

Effects of host blend composition and intensity on host choice in <i>M. sexta</i>.

<p>(A) Choice experiments with gravid <i>M. sexta</i> females were performed in a wind tunnel. Plants were placed in glass boxes outside the wind tunnel where they could not be seen by the moths. Pumps delivered plant headspace to two surrogate leaves serving as visual stimuli inside the wind tunnel. Two host plants, <i>D. wrightii</i> and <i>N. attenuata</i>, were tested (I) against a clean air control, (II) with their plant headspaces mixed together 1:1 against a clean air control, (III) against a conspecific plant whose headspace was diluted with clean air, and (IV) against each other, with <i>N. attenuata</i> headspace either not manipulated or diluted with clean air. Plant headspace and clean air were mixed in a 1:4 (vol/vol) ratio resulting in a 5-fold dilution. (B) The percentage of first choices made in the corresponding experiments. Sample size is given next to each experiment. Asterisks denote significant differences between sources (Binomial Test, *** p<0.001; ** p<0.01; *p<0.05). (C) Boxplots depict preference indices calculated from the number of contacts to each source. Values close to 1/-1 represent a high preference for one source; 0 means no preference. The black line delineates the median; color distribution within the box represents the percentage of contacts to each source. Asterisks above the boxes denote indices significantly different from 0 (Wilcoxon Signed Ranks Test, *** p<0.001; ** p<0.01; * p<0.05). Preference indices resulting from experiments in which the plant headspace of both species is offered superimposed or separately against clean air differed significantly (Kruskal-Wallis Test, p<0.0001, and Dunn’s post hoc test, ** p<0.01, * p<0.05). Furthermore, preference indices derived from interspecific choice experiments were significantly different from each other (Mann-Whitney U Test, p<0.05).</p

<i>Drosophila</i> Avoids Parasitoids by Sensing Their Semiochemicals via a Dedicated Olfactory Circuit

<div><p>Detecting danger is one of the foremost tasks for a neural system. Larval parasitoids constitute clear danger to <i>Drosophila</i>, as up to 80% of fly larvae become parasitized in nature. We show that <i>Drosophila melanogaster</i> larvae and adults avoid sites smelling of the main parasitoid enemies, <i>Leptopilina</i> wasps. This avoidance is mediated via a highly specific olfactory sensory neuron (OSN) type. While the larval OSN expresses the olfactory receptor Or49a and is tuned to the <i>Leptopilina</i> odor iridomyrmecin, the adult expresses both Or49a and Or85f and in addition detects the wasp odors actinidine and nepetalactol. The information is transferred via projection neurons to a specific part of the lateral horn known to be involved in mediating avoidance. <i>Drosophila</i> has thus developed a dedicated circuit to detect a life-threatening enemy based on the smell of its semiochemicals. Such an enemy-detecting olfactory circuit has earlier only been characterized in mice and nematodes.</p></div

The ab10B neuron detects parasitoid odors.

<p>(<b>A</b>) Example spike traces of GC-coupled SSR with all <i>D</i>. <i>melanogaster</i> OSN types and the headspace of <i>L</i>. <i>boulardi</i> (note that the amount of odors within headspace is too low to be detected and analyzed by GC, but is still detected by ab10B). FID, flame ionization detector. (<b>B</b>) GC-coupled SSR with the ab10B neuron and the wash of <i>L</i>. <i>boulardi</i> (1st panel), as well as the identified active compounds (2nd–4th panel). (<b>C</b>) SSR dose-response curves of the ab10B neuron tested with active compounds. (<b>D</b>) GC-coupled SSR with mutant ab3A neuron ectopically expressing either Or49a or Or85f. Blue, green, and red lines indicate active compounds. (<b>E</b>) Tuning breadths of Or49a and Or85f. 232 odorants are displayed along the <i>x</i>-axis according to strengths of responses they elicit from each receptor. Odorants eliciting strongest responses are placed near the center of distribution. Negative values indicate inhibitory responses. For a list of compounds, see <a href="http://www.plosbiology.org/article/info:doi/10.1371/journal.pbio.1002318#pbio.1002318.s005" target="_blank">S4 Fig</a>; for raw data see <a href="http://www.plosbiology.org/article/info:doi/10.1371/journal.pbio.1002318#pbio.1002318.s001" target="_blank">S1 Data</a>. (<b>F</b>) Identification of glomeruli activated by parasitoid odors (-)-iridomyrmecin, (<i>R</i>)-actinidine, and nepetalactol (a mixture of 1S4aR7R7aS, 1R4aS7S7aS-nepetalactol and their enantiomers). 1st to 3rd columns, false color-coded images showing odorant-induced calcium-dependent fluorescence changes in OSNs expressing Or49a or PNs labeled by GH-146-Gal4 at the antennal lobe (AL) level. Flies express UAS-GCaMP3.0 under control of either Or49a-Gal4, or the GH146-Gal4 driver line. (<b>G</b>) GC-coupled extracellular recordings from larval dorsal organ and wash of <i>L</i>. <i>boulardi</i>. (for more GC-SSR traces of wildtype ab10B neurons and mutant ab3A neurons expressing Or49a or Or85f see <a href="http://www.plosbiology.org/article/info:doi/10.1371/journal.pbio.1002318#pbio.1002318.s004" target="_blank">S3 Fig</a>)</p

Larvae and ovipositing flies are repelled by parasitoid odor.

<p>(<b>A</b>) Larval choice assay and preference indices when larvae were exposed to the wash of <i>L</i>. <i>boulardi</i>. (<b>B</b>) Different choice assays (T-maze, Trap assay, Oviposition assay) for adult flies and resulting preference indices when exposed to the wash of <i>L</i>. <i>boulardi</i>. PI = (number of larvae, flies, or eggs in odor side − number in control side) / total number. Bar plots indicate minimum and maximum values (whiskers), the upper and lower quartiles (boxes) and the median values (bold black line). Deviation of the indices against zero was tested with Wilcoxon rank sum test.</p