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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
    The role of fresh versus old leaf damage in the attraction of parasitic wasps to herbivore-induced maize volatiles
    (2005)
    Hoballah, Maria Elena
    ;
    Turlings, Ted 
    The odor produced by a plant under herbivore attack is often used by parasitic wasps to locate hosts. Any type of surface damage commonly causes plant leaves to release so-called green leaf volatiles, whereas blends of inducible compounds are more specific for herbivore attack and can vary considerably among plant genotypes. We compared the responses of naive and experienced parasitoids of the species Cotesia marginiventris and Microplitis rufiventris to volatiles from maize leaves with fresh damage (mainly green leaf volatiles) vs. old damage (mainly terpenoids) in a six-arm olfactometer. These braconid wasps are both solitary endoparasitoids of lepidopteran larvae, but differ in geographical origin and host range. In choice experiments with odor blends from maize plants with fresh damage vs. blends from plants with old damage, inexperienced C. marginiventris showed a preference for the volatiles from freshly damaged leaves. No such preference was observed for inexperienced M. rufiventris. After an oviposition experience in hosts feeding on maize plants, C. marginiventris females were more attracted by a mixture of volatiles from fresh and old damage. Apparently, C. marginiventris has an innate preference for the odor of freshly damaged leaves, and this preference shifts in favor of a blend containing a mixture of green leaf volatiles plus terpenoids, after experiencing the latter blend in association with hosts. M. rufiventris responded poorly after experience and preferred fresh damage odors. Possibly, after associative learning, this species uses cues that are more directly related with the host presence, such as volatiles from host feces, which were not present in the odor sources offered in the olfactometer. The results demonstrate the complexity of the use of plant volatiles by parasitoids and show that different parasitoid species have evolved different strategies to exploit these signals.
  • Publication
    Accès libre
    The composition and timing of flower odour emission by wild Petunia axillaris coincide with the antennal perception and nocturnal activity of the pollinator Manduca sexta
    (2005)
    Hoballah, Maria Elena
    ;
    Stuurman, Jeroen
    ;
    Turlings, Ted 
    ;
    Guerin, Patrick 
    ;
    Connétable, Sophie
    ;
    Kuhlemeier, Cris
    In the genus Petunia, distinct pollination syndromes may have evolved in association with bee-visitation (P. integrifolia spp.) or hawk moth-visitation (P. axillaris spp). We investigated the extent of congruence between floral fragrance and olfactory perception of the hawk moth Manduca sexta. Hawk moth pollinated P. axillaris releases high levels of several compounds compared to the bee-pollinated P. integrifolia that releases benzaldehyde almost exclusively. The three dominating compounds in P. axillaris were benzaldehyde, benzyl alcohol and methyl benzoate. In P. axillaris, benzenoids showed a circadian rhythm with an emission peak at night, which was absent from P. integrifolia. These characters were highly conserved among different P. axillaris subspecies and P. axillaris accessions, with some differences in fragrance composition. Electroantennogram (EAG) recordings using flower-blends of different wild Petunia species on female M. sexta antennae showed that P. axillaris odours elicited stronger responses than P. integrifolia odours. EAG responses were highest to the three dominating compounds in the P. axillaris flower odours. Further, EAG responses to odour-samples collected from P. axillaris flowers confirmed that odours collected at night evoked stronger responses from M. sexta than odours collected during the day. These results show that timing of odour emissions by P. axillaris is in tune with nocturnal hawk moth activity and that flower-volatile composition is adapted to the antennal perception of these pollinators.
  • Publication
    Accès libre
    The Role of Fresh versus Old Leaf Damage in the Attraction of Parasitic Wasps to Herbivore-Induced Maize Volatiles
    (2005)
    Hoballah, Maria Elena
    ;
    Turlings, Ted 
    The odor produced by a plant under herbivore attack is often used by parasitic wasps to locate hosts. Any type of surface damage commonly causes plant leaves to release so-called green leaf volatiles, whereas blends of inducible compounds are more specific for herbivore attack and can vary considerably among plant genotypes. We compared the responses of naïve and experienced parasitoids of the species Cotesia marginiventris and Microplitis rufiventris to volatiles from maize leaves with fresh damage (mainly green leaf volatiles) vs. old damage (mainly terpenoids) in a six-arm olfactometer. These braconid wasps are both solitary endoparasitoids of lepidopteran larvae, but differ in geographical origin and host range. In choice experiments with odor blends from maize plants with fresh damage vs. blends from plants with old damage, inexperienced C. marginiventris showed a preference for the volatiles from freshly damaged leaves. No such preference was observed for inexperienced M. rufiventris. After an oviposition experience in hosts feeding on maize plants, C. marginiventris females were more attracted by a mixture of volatiles from fresh and old damage. Apparently, C. marginiventris has an innate preference for the odor of freshly damaged leaves, and this preference shifts in favor of a blend containing a mixture of green leaf volatiles plus terpenoids, after experiencing the latter blend in association with hosts. M. rufiventris responded poorly after experience and preferred fresh damage odors. Possibly, after associative learning, this species uses cues that are more directly related with the host presence, such as volatiles from host feces, which were not present in the odor sources offered in the olfactometer. The results demonstrate the complexity of the use of plant volatiles by parasitoids and show that different parasitoid species have evolved different strategies to exploit these signals.
  • Publication
    Métadonnées seulement
  • Publication
    Accès libre
    Costs of induced volatile production in maize
    (2004)
    Hoballah, Maria Elena
    ;
    Köllner, Tobias G.
    ;
    Degenhardt, Jörg
    ;
    Turlings, Ted 
    Herbivore-induced plant volatiles have been shown to serve as indirect defence signals that attract natural enemies of herbivores. Parasitoids and predators exploit these plant-provided cues to locate their victims and several herbivores are repelled by the volatiles. Recently, benefits, in terms of plant fitness, from the action of the parasitoids were shown for a few systems. However, the cost of production of herbivore-induced volatiles for the plant remains unknown. Here, we estimate the fitness cost of the production of induced volatiles in maize, Zea mays. Plants were treated with regurgitant of Spodoptera littoralis or with the elicitor volicitin and we measured dry weight of plant parts at specific times after treatments. After a two-week treatment period, the dry-weight of leaves of induced plants was lower than that of un-induced plants, suggesting a metabolic cost for induced defence. However, maize plants seem to compensate for this loss during subsequent growth, since seed production at maturity was not different for unharmed plants and plants treated with caterpillar regurgitant. For volicitin treated plants a small but significant reduction in seed production was found. It is likely that the treatments also induced the production of other defence compounds, which will contribute to the cost. Yet, a comparison of six maize inbred lines with distinct differences in volatile emissions showed a strong correlation between the intensity of induced emissions and reduction in plant performance. An analysis of the terpenoids that accumulated in the leaves of the inbred lines revealed non-volatilised compounds are constitutively present in maize and only the volatilised compounds are induced. Interestingly, the lines that released the largest amounts of induced volatiles also contained more of the non-volatile terpenoids. Based on these results and results from a previous study on the benefits of attracting parasitoids, we conclude that costs of induced volatile production in plants are counterbalanced by the benefits as long as natural enemies of the herbivores are present in the environment.
  • Publication
    Accès libre
    Occurrence and direct control potential of parasitoids and predators of the fall armyworm (Lepidoptera: Noctuidae) on maize in the subtropical lowlands of Mexico
    (2004)
    Hoballah, Maria Elena
    ;
    Degen, Thomas 
    ;
    Bergvinson, David
    ;
    Savidan, Anita
    ;
    Tamò, Cristina
    ;
    Turlings, Ted 
    1 Native natural enemies have the potential to control fall armyworm Spodoptera frugiperda (Smith) in tropical maize grown in Mexico, where this insect pest causes severe economic losses to farmers. It has been proposed that enhancing herbivore-induced volatile emissions in maize plants may help to increase the effectiveness of natural enemies, which use these volatiles to locate their prey. This will only be of immediate benefit to farmers if the activity of the natural enemies results in a direct reduction in herbivory. Here we report on field surveys for the most common natural enemies in a tropical maize-growing region in Mexico and the potential effects of these enemies on herbivory by fall armyworm.
    2 Caterpillars were collected in maize fields near Poza Rica in the state of Veracruz during January and February 1999, 2000 and 2001. Plants were either naturally infested by S. frugiperda, or artificially infested with laboratory-reared larvae. Ten species of parasitoids emerged from the collected larvae and eight species of predators that are known to feed on larvae and eggs were observed on the plants. Campoletis sonorensis (Cameron) (Hymenoptera: Ichneumonidae) was the dominant parasitoid species, in 1999 and 2001.
    3 Of the nine larval parasitoids collected, six (all solitary) are known to reduce herbivory, whereas one causes the host to eat more (for two species this is not known). This implies that enhancing the effectiveness of solitary endoparasitoids may benefit subsistence farmers in developing countries by immediately reducing herbivory. The overall benefit for the plant resulting from parasitoid activity also has important implications for the evolutionary role of parasitoids in contributing to selection pressures that shape indirect defences in plants.
  • Publication
    Métadonnées seulement
    The NCCR Plant Survival at the University of Neuchatel - The role of chemistry in an interdisciplinary Swiss research network
    (2003)
    Vogelgsang, Susanne
    ;
    Abou-Mansour, Eliane
    ;
    Guerin, Patrick 
    ;
    Hoballah, Maria Elena
    ;
    Turlings, Ted 
    ;
    Tabacchi, Raffaele 
    The survival of plants is of fundamental importance to guarantee the biodiversity in natural areas and a sustainable agriculture. The National Centre of Competence in Research 'Plant Survival in Natural and Agricultural Ecosystems' devotes its research efforts to the understanding of mechanisms of plant survival. The mechanisms that plants employ to adapt to their biotic and abiotic environment and to cope with important stress factors are investigated. This is achieved by interdisciplinary interaction of disciplines within the NCCR. The particular role played by natural products and analytical chemistry in seven different projects is summarized.
  • Publication
    Métadonnées seulement
    Differential attractiveness of induced odors emitted by eight maize varieties for the parasitoid Cotesia marginiventris: Is quality or quantity important?
    (2002)
    Hoballah, Maria Elena
    ;
    Tamo, Cristina
    ;
    Turlings, Ted 
    Herbivore-induced plant volatiles can function as indirect defense signals that attract natural enemies of herbivores. Several parasitoids are known to exploit these plant-provided cues to locate their hosts. One such parasitoid is the generalist Cotesia marginiventris, which is, among others, attracted to maize volatiles induced by caterpillar damage. Maize plants can be induced to produce the same blend of attractive volatiles by treating them with regurgitant of Spodoptera species. We collected and analyzed the regurgitant-induced emissions of two plant species (cowpea and maize) and of eight Mexican maize varieties and found significant differences among their volatile emissions, both in terms of total quantity and the quality of the blends. In a Y-tube olfactometer, the odors of the same artificially induced plant species and Mexican varieties were offered in dual choice experiments to naive mated females of C. marginiventris. Wasps preferred cowpea over maize odor and, in 3 of 12 combinations with the maize varieties, they showed a preference for the odors of one of the varieties. A comparison of the odor collection with results from the behavioral assays indicates that not only the quantity of the volatile emissions, but also the quality (composition) of the volatile blends is important for attraction of C. marginiventris. The results are discussed in the context of the possibility of breeding crop varieties that are particularly attractive to parasitoids.
  • Publication
    Accès libre
    Differential Attractiveness of Induced Odors Emitted by Eight Maize Varieties for the Parasitoid Cotesia marginiventris : Is Quality or Quantity Important ?
    (2002)
    Hoballah, Maria Elena
    ;
    Tamò, Cristina
    ;
    Turlings, Ted 
    Herbivore-induced plant volatiles can function as indirect defense signals that attract natural enemies of herbivores. Several parasitoids are known to exploit these plant-provided cues to locate their hosts. One such parasitoid is the generalist Cotesia marginiventris, which is, among others, attracted to maize volatiles induced by caterpillar damage. Maize plants can be induced to produce the same blend of attractive volatiles by treating them with regurgitant of Spodoptera species. We collected and analyzed the regurgitant-induced emissions of two plant species (cowpea and maize) and of eight Mexican maize varieties and found significant differences among their volatile emissions, both in terms of total quantity and the quality of the blends. In a Y-tube olfactometer, the odors of the same artificially induced plant species and Mexican varieties were offered in dual choice experiments to naïve mated females of C. marginiventris. Wasps preferred cowpea over maize odor and, in 3 of 12 combinations with the maize varieties, they showed a preference for the odors of one of the varieties. A comparison of the odor collection with results from the behavioral assays indicates that not only the quantity of the volatile emissions, but also the quality composition of the volatile blends is important for attraction of C. marginiventris. The results are discussed in the context of the possibility of breeding crop varieties that are particularly attractive to parasitoids.
  • Publication
    Métadonnées seulement
    Experimental evidence that plants under caterpillar attack may benefit from attracting parasitoids
    (2001)
    Hoballah, Maria Elena
    ;
    Turlings, Ted 
    Herbivore-induced plant volatiles have been suggested to function as indirect defence signals that attract natural enemies of herbivores. Several insect parasitoids are known to exploit such plant-provided cues to locate hosts. It is unclear if individual plants benefit from the action of parasitoids. We investigated this question in maize plants under attack by Spodoptera littoralis larvae and found that parasitization by the endoparasitoids Cotesia marginiventris and Campoletis sonorensis significantly reduced feeding and weight gain in the host larvae. As a result, young maize plants attacked by a single parasitized larva suffered much less feeding damage and, at maturity, produced about 30% more seed than plants that were attacked by an unparasitized larva. Such fitness benefits may have contributed to selection pressures that shaped the evolution of herbivore-induced indirect defence signals in plants.