| 1. |
- Plepys, Dainius
(författare)
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Odour-mediated nectar foraging in the silver Y moth, Autographa gamma
- 2001
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- It is well established that floral odours play a significant role in the nectar foraging behaviour in Lepidoptera and other insect orders. Floral odour may elicit searching, alighting and feeding behaviours alone or in concert with visual stimuli. The goal of the present project was to investigate attractiveness of different species of flowers to the silver Y moth, to identify constituents of volatile floral components responsible for this attraction, and to study how they are processed in the peripheral nervous system. Moth's foraging as well as mate-finding behaviour is altered by the risk of bat predation. Thus I also studied if males and females take different risks when preyed upon, and if male risk taking depends on the nature of stimuli. Attractivity of six flower species differed in the flight tunnel assay. This difference can be explained by a difference in the emission rate of volatiles, by difference in innate preferences for specific compounds or by a combination of both factors. Gas chromatographic–electroantennographic analysis demonstrated the absence of a common volatile compound present in flowers of different plants visited by A. gamma. Forty-four electrophysiologically active compounds were identified. Employing the single sensillum recording method I found that these compounds are detected with high selectivity and sensitivity by the olfactory receptor neurones (ORNs) of the moth. Eleven ORN types were identified. ORNs responding to lilac aldehydes, cinnamyl alcohol, a-farnesene and cis-trans-nepetalactone were the most abundant. A flight tunnel assay revealed that lilac aldehyde(s) are the major attractive compound(s) responsible for the attraction of moths to the flowers of an orchid Platanthera bifolia. To test attractivity of extracts, blends and individual compounds an ultrasonic sprayer was used for release of stimuli. Noctuid moths are able to hear the ultrasound emitted by the sprayer that affects their behaviour. The sprayer was improved to eliminate the negative sound effect by introducing a new piezo ceramic transducer able to generate 300 kHz frequency sound that is beyond the hearing threshold of the moth. Males did not take a higher risk under the simulated bat predation than females; neither male risk taking was dependent on whether they were stimulated by floral odour or a pheromone.
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| 2. |
- Plepys, Dainius, et al.
(författare)
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Odour-mediated nectar foraging in the silver Y moth, Autographa gamma (Lepidoptera : Noctuidae): behavioural and electrophysiological responses to floral volatiles
- 2002
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Ingår i: Oikos. - : Wiley. - 1600-0706 .- 0030-1299. ; 99:1, s. 75-82
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Tidskriftsartikel (refereegranskat)abstract
- Naive male and female silver Y moths, Autographa gamma (Lepidoptera: Noctuidae), were attracted in a flight tunnel assay to potted creeping thistle, Cirsium arvense (Asteraceae), butterfly-orchid, Platanthera bifolia (Orchidaceae), soapwort, Saponaria officinalis (Caryophyllaceae), greater knapweed, Centaurea scabiosa (Asteraceae), red clover, Trifolium pratense (Fabaceae), and catnip, Nepeta faasseni (Labiatae), plants with flowers. The most attractive plants were C. arvense, P. bifolia and S. officinalis that elicited 87, 78 and 65%, source contacts, respectively. C. scabiosa was less attractive eliciting 43%, response. T. pratense and N. faasseni showed the least attraction eliciting 28 and 26% source contacts, respectively. A cotton plant used as control, was not attractive. Floral volatiles from the investigated plant species were collected using headspace sampling technique. Samples were analysed using gas chromatography coupled with electroantennographic detection, and electrophysiologically active compounds were identified by coupled gas chromatography/mass spectrometry. Consistent electrophysiological responses were elicited by twelve compounds from headspace of C. arvense, thirteen compounds from P. bifolia, eleven compounds from S. officinalis, nine from C. seabiosa, ten from T. pratense and two from N. faasseni. Most of the active compounds were specific for one or two species, while benzyl benzoate was present in four and benzaldehyde and benzyl alcohol in three species. Floral scents of C. arvense, P. bifolia and S. officinalis, the most attractive flowers, were dominated by aromatic compounds that were not abundant in the scent of other flowers. To conclude, the results demonstrate the absence of a common denominator of odours present in flowers of different plants visited by A. gamma.
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| 3. |
- Plepys, Dainius, et al.
(författare)
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Volatiles from flowers of Platanthera bifolia (Orchidaceae) attractive to the silver Y moth, Autographa gamma (Lepidoptera : Noctuidae)
- 2002
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Ingår i: Oikos. - : Wiley. - 1600-0706 .- 0030-1299. ; 99:1, s. 69-74
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Tidskriftsartikel (refereegranskat)abstract
- We examined the attractiveness of a natural headspace sample of [i]Platanthera bifolia[/i blossoms, synthetic blends and Single compounds to the silver Y moth, Autographa gamma, in a flight tunnel. The synthetic blend consisted of previously identified electrophysiologically active compounds from P. bifolia: benzyl benzoate, benzyl salicylate, cinnamyl alcohol, lilac aldehydes, methyl benzoate and methyl salicylate. This blend had a similar attractivity as the natural headspace sample. Subtraction of lilac aldehydes significantly decreased attractiveness of the synthetic blend. When a mixture of lilac aldehydes was tested alone. it showed attractiveness similar to that of the synthetic blend. One or a mixture of lilac aldehydes accounts for the attraction of moths to P. bifolia. All other Compounds elicited significantly lower responses. Results are discussed in relation to the pollination biology of P. bifolia.
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| 4. |
- Skals, Niels, et al.
(författare)
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Foraging and mate-finding in the silver Y moth, Autographa gamma (Lepidoptera : Noctuidae) under the risk of predation
- 2003
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Ingår i: Oikos. - : Wiley. - 1600-0706 .- 0030-1299. ; 102:2, s. 351-357
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Tidskriftsartikel (refereegranskat)abstract
- Animal foraging and reproductive behaviour is influenced by other simultaneous demands such as predator avoidance. The trade-offs between these demands may depend on sex or mating experience. This study demonstrates that the olfactory-mediated foraging and mate-seeking behaviours in the silver Y moths, Autographa gamma, are affected by auditory cues mimicking their bat predators. Both males and females changed their foraging behaviour under simulated predation risk. Fewer moths reached the odour source following sound stimulation and the time to find the odour source increased by up to 250%. However. there were no significant differences between male and female ability to reach the plant odour source or the duration of the flight towards the source when stimulated with ultrasound. Hence females are not more cautious than males when observed in the same behavioural context. Risk-taking in males was independent of whether they were flying toward a flower odour or sex pheromones having equal attractive value. This indicates that the trade-off between olfactory and acoustic cues is independent the type of odour. Mated females were not as strongly affected by sound as non-mated, indicating that flower odours have a higher adaptive value for mated females, suggesting that some processes following mating experience influence the trade-off between flower odours and simulated bat sounds.
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| 5. |
- Skals, Niels, et al.
(författare)
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Quantitative analysis of the effects of ultrasound from an odor sprayer on moth flight behavior
- 2003
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Ingår i: Journal of Chemical Ecology. - 1573-1561. ; 29:1, s. 71-82
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Tidskriftsartikel (refereegranskat)abstract
- A piezoelectric sprayer was recently developed for precision release of odor stimuli in olfactory research. The device replaces conventional dispensers used to release semiochemicals in studies of moth flight toward odor sources. However, the device generates high-frequency sounds in the range that some moths can hear. Ultrasound from the standard set-up sprayer had a considerable impact on flight behavior of the silver Y moth, Autographa gamma, tested in a flight tunnel. It was affected at all behavioral stages when the dispenser was driven at 120 kHz. Only 5% of the moths reached the source when exposed to 120-kHz sound from the dispenser compared to 65% in the control group without sound. The proportion taking flight was also reduced. Hearing threshold curves obtained electrophysiologically revealed that moths were sensitive to the frequency range at which the sprayer was operated and that sound intensity from the sprayer was up to 40 dB above the moths' electrophysiological hearing threshold. The audiogram for A. gamma was similar to audiograms obtained for other noctuids. Hearing sensitivity was highest at around 15 kHz, where the threshold was 35 dB SPL (sound pressure level). The threshold increased with frequency up to 94 dB SPL at 160 kHz. We improved the sprayer to operate at 300 kHz, which is beyond the hearing ability of most insects with ears. At this high frequency, the moths' sensitivity to ultrasound is reduced considerably, and we did not observe any effect on flight behavior compared to a control group without sound. Accordingly, this new piezoelectric sprayer can be used with ultrasound-sensitive insects and insensitive insects alike.
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