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Turlings, Ted

Nom
Turlings, Ted
Affiliation principale
Fonction
Professeur ordinaire
Email
ted.turlings@unine.ch
Identifiants
https://libra.unine.ch/handle/123456789/330

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  • Publication
    Métadonnées seulement
    Antennal electrophysiological responses of three parasitic wasps to caterpillar-induced volatiles from maize (Zea mays mays), cotton (Gossypium herbaceum), and cowpea (Vigna unguiculata)
    (2005)
    Gouinguene, Sandrine 
    ;
    Pickett, John A
    ;
    Wadhams, Lester J.
    ;
    Birkett, Michael A
    ;
    Turlings, Ted 
    Many parasitic wasps are attracted to volatiles that are released by plants when attacked by potential hosts. The attractiveness of these semiochernicals from damaged plants has been demonstrated in many tritrophic systems, but the physiological mechanisms underlying the insect responses are poorly understood. We recorded the antennal perception by three parasitoids (Cotesia marginiventris, Microplitis rufiventris, and Campoletis sonorensis) to volatiles emitted by maize, cowpea, and cotton plants after attack by the common caterpillar pest Spodoptera littoralis. Gas chromatography-electroantennography (GC-EAG) recordings showed that wasps responded to many, but not all, of the compounds present at the physiologically relevant levels tested. Interestingly, some minor compounds, still unidentified, elicited strong responses from the wasps. These results indicate that wasps are able to detect many odorant compounds released by the plants. It remains to be determined how this information is processed and leads to the specific behavior of the parasitoids.
  • Publication
    Métadonnées seulement
    High genetic variability of herbivore-induced volatile emission within a broad range of maize inbred lines
    (2004)
    Degen, Thomas 
    ;
    Dillmann, Christine
    ;
    Marion-Poll, Frédéric
    ;
    Turlings, Ted 
    Maize plants (Zea mays) attacked by caterpillars release a mixture of odorous compounds that attract parasitic wasps, natural enemies of the herbivores. We assessed the genetic variability of these induced volatile emissions among 31 maize inbred lines representing a broad range of genetic diversity used by breeders in Europe and North America. Odors were collected from young plants that had been induced by injecting them with caterpillar regurgitant. Significant variation among lines was found for all 23 volatile compounds included in the analysis: the lines differed enormously in the total amount of volatiles emitted and showed highly variable odor profiles distinctive of each genotype. Principal component analysis performed on the relative quantities of particular compounds within the blend revealed clusters of highly correlated volatiles, which may share common metabolic pathways. European and American lines belonging to established heterotic groups were loosely separated from each other, with the most clear-cut difference in the typical release of (E)-beta-caryophyllene by European lines. There was no correlation between the distances among the lines based on their odor profiles and their respective genetic distances previously assessed by neutral RFLP markers. This most comprehensive study to date on intraspecific variation in induced odor emission by maize plants provides a further example of the remarkably high genetic diversity conserved within this important crop plant. A better understanding of the genetic control of induced odor emissions may help in the development of maize varieties particularly attractive to parasitoids and other biological control agents and perhaps more repellent for herbivores.
  • Publication
    Métadonnées seulement
    Induction of volatile emissions in maize by different larval instars of Spodoptera littoralis
    (2003)
    Gouinguene, Sandrine 
    ;
    Alborn, Hans
    ;
    Turlings, Ted 
    Maize plants under attack by caterpillars emit a specific blend of volatiles that is highly attractive to parasitic wasps. The release of these signals is induced by elicitors in the caterpillar regurgitant. Studies suggest that plants respond differently to different herbivore species and even to different herbivore stages, thus providing parasitoids and predators with specific signals. We tested if this is the case for different larval instars of the noctuid moth Spodoptera littoralis when they feed on maize plants. Cut maize plants were incubated in diluted regurgitant from second, third, or fifth instar caterpillars. There were no differences in total amount released after these treatments, but there were small differences in the release of the minor compounds phenethyl acetate and alpha-humulene. Regurgitant of all three instars contained the elicitor volicitin. To test the effect of actual feeding by the larvae, potted plants were infested with caterpillars of one of the three instars, and volatiles were collected the following day. The intensity of the emissions was correlated with the number of larvae feeding on a plant, and with the amount of damage inflicted, but was independent of the instar that caused the damage. We also used artificial damage to mimic the manner of feeding of each instar to test the importance of physical aspects of damages for the odor emission. The emission was highly variable, but no differences were found among the different types of damage. In olfactometer tests, Microplitis rufiventris, a parasitoid that can only successfully parasitize second and early third instar S. littoralis, did not differentiate among the odors of maize plants attacked by different instar larvae. The odor analyses as well as the parasitoid's responses indicate that maize odors induced by S. littoralis provide parasitoids with poor information on the larval developmental stage. We discuss the results in the context of variability and lack of specificity in odorous plant signals.
  • Publication
    Métadonnées seulement
    The effects of abiotic factors on induced volatile emissions in corn plants
    (2002)
    Gouinguene, Sandrine 
    ;
    Turlings, Ted 
    Many plants respond to herbivory by releasing a specific blend of volatiles that is attractive to natural enemies of the herbivores. In corn (Zea mays), this induced odor blend is mainly composed of terpenoids and indole. The induced signal varies with plant species and genotype, but little is known about the variation due to abiotic factors. Here, we tested the effect of soil humidity, air humidity, temperature, light, and fertilization rate on the emission of induced volatiles in young corn plants. Each factor was tested separately under constant conditions for the other factors. Plants released more when standing in dry soil than in wet soil, whereas for air humidity, the optimal release was found at around 60%, relative humidity. Temperatures between 22degreesC and 27degreesC led to a higher emission than lower or higher temperatures. Light intensity had a dramatic effect. The emission of volatiles did not occur in the dark and increased steadily with an increase in the light intensity. An experiment with an unnatural light-dark cycle showed that the release was fully photophase dependent. Fertilization also had a strong positive effect; the emission of volatiles was minimal when plants were grown under low nutrition, even when results were corrected for plant biomass. Changes in all abiotic factors caused small but significant changes in the relative ratios among the different compounds (quality) in the induced odor blends, except for air humidity. Hence, climatic conditions and nutrient availability can be important factors in determining the intensity and variability in the release of induced plant volatiles.
  • Publication
    Métadonnées seulement
    Timing of induced volatile emissions in maize seedlings
    (1998)
    Turlings, Ted 
    ;
    Lengwiler, Urs
    ;
    Bernasconi, Marco
    ;
    Wechsler, Daniel
    Maize (Zea mays L.) releases specific volatiles in response to herbivory by caterpillars. These volatiles are known to serve as cues for parasitic wasps to locate the herbivores. In the present study the exact time of volatile emission after simulated herbivory (mechanical damage and treatment with caterpillar regurgitant) was measured for seedlings of the cultivars "Ioana Sweet Corn" and "LG11". Odours were collected every 0.5 h for a total of 12 h. Typical "green leaf odours", (Z)-3-hexenal, (E)-2-hexenal, (Z)-hexen-1-ol, and (Z)-3-hexen-1-yl acetate, were emitted immediately upon damage and their amounts dropped rapidly after the first collections. Several of the induced compounds were released within 2 h after treatment, while others (mainly sesquiterpenoids) started to be released after 4 h. The LG11 seedlings emitted several compounds (e.g. beta-myrcene, (Z)-beta-ocimene, benzyl acetate, beta-caryophyllene, (E,E)-alpha-farnesene) that were not detected for Ioana. (E, E)-alpha-farnesene was continuously emitted by LG11 seedlings, even by undamaged plants. Timing of the release of volatile compounds that the two varieties had in common did not differ significantly, with the exception of indole for which the peak production was considerably earlier for LG11. These findings are discussed in the context of biosynthetic pathways and mechanisms involved in induced emissions of plant volatiles and the exploitation of the resulting odour by parasitoids and predators of herbivores.