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Hiltpold, Ivan

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Hiltpold, Ivan
Affiliation principale
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https://libra.unine.ch/handle/123456789/605

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  • Publication
    Métadonnées seulement
    Capsules containing entomopathogenic nematodes as a Trojan horse approach to control the western corn rootworm
    (2012)
    Hiltpold, Ivan 
    ;
    Hibbard, Bruce Elliott
    ;
    French, B. W.
    ;
    Turlings, Ted 
    Aims The use of entomopathogenic nematodes in the biological control of soil insect pests is hampered by the costly and inadequate application techniques. As a possible solution we evaluated a nematode encapsulation approach that offers effective application and may possibly attract the pest by adding attractants to the capsule shell. Methods Heterorhabditis bacteriophora nematodes, which show high virulence against the maize root pest Diabrotica virgifera virgifera, were encapsulated in a polysaccharide shell derived from the algae Laminaria ssp. Shells of varying thickness and composition were evaluated. Results Nematodes readily survived the encapsulation process and were able, varying with shell thickness and temperature, to break through the shell and subsequently infect hosts. The added attractants and feeding stimulants to the shell attracted the pest larvae as much as maize roots. In field trials, encapsulated H. bacteriophora nematodes were more effective in controlling D. v. virgifera than those sprayed in water over the soil surface, but in these trials the addition of stimulants did not increase the control efficiency. Conclusions The study demonstrates that nematodes can be successfully applied in capsules in the field. Further improvements are needed to make the capsules a cost effective alternative to conventional field application of nematodes.
  • Publication
    Métadonnées seulement
    Selection of entomopathogenic nematodes for enhanced responsiveness to a volatile root signal helps to control a major root pest
    (2010)
    Hiltpold, Ivan 
    ;
    Baroni, Mariane
    ;
    Toepfer, Stefan
    ;
    Kuhlmann, Ulrich
    ;
    Turlings, Ted 
    The efficacy of natural enemies as biological control agents against insect pests can theoretically be enhanced by artificial selection for high responsiveness to foraging cues. The recent discovery that maize roots damaged by the western corn rootworm (WCR) emit a key attractant for insect-killing nematodes has opened the way to explore whether a selection strategy can improve the control of root pests. The compound in question, (E)-beta-caryophyllene, is only weakly attractive to Heterorhabditis bacteriophora, one of the most infectious nematodes against WCR. To overcome this drawback, we used a six-arm below-ground olfactometer to select for a strain of H. bacteriophora that is more readily attracted to (E)-beta-caryophyllene. After six generations of selection, the selected strain responded considerably better and moved twice as rapidly towards a (E)-beta-caryophyllene source than the original strain. There was a minor trade-off between this enhanced responsiveness and nematode infectiveness. Yet, in subsequent field tests, the selected strain was significantly more effective than the original strain in reducing WCR populations in plots with a maize variety that releases (E)-beta-caryophyllene, but not in plots with a maize variety that does not emit this root signal. These results illustrate the great potential of manipulating natural enemies of herbivores to improve biological pest control.
  • Publication
    Accès libre
    Restoring a maize root signal that attracts insect-killing nematodes to control a major pest
    (2009)
    Degenhardt, Jörg
    ;
    Hiltpold, Ivan 
    ;
    Köllner, Tobias G.
    ;
    Frey, Monika
    ;
    Gierl, Alfons
    ;
    Gershenzon, Jonathan
    ;
    Hibbard, Bruce E.
    ;
    Ellersieck, Mark R.
    ;
    Turlings, Ted 
    When attacked by herbivorous insects, plants emit volatile compounds that attract natural enemies of the insects. It has been proposed that these volatile signals can be manipulated to improve crop protection. Here, we demonstrate the full potential of this strategy by restoring the emission of a specific belowground signal emitted by insect-damaged maize roots. The western corn rootworm induces the roots of many maize varieties to emit (E)-β-caryophyllene, which attracts entomopathogenic nematodes that infect and kill the voracious root pest. However, most North American maize varieties have lost the ability to emit (E)-β-caryophyllene and may therefore receive little protection from the nematodes. To restore the signal, a nonemitting maize line was transformed with a (E)-β-caryophyllene synthase gene from oregano, resulting in constitutive emissions of this sesquiterpene. In rootworm-infested field plots in which nematodes were released, the (E)-β-caryophyllene-emitting plants suffered significantly less root damage and had 60% fewer adult beetles emerge than untransformed, nonemitting lines. This demonstration that plant volatile emissions can be manipulated to enhance the effectiveness of biological control agents opens the way for novel and ecologically sound strategies to fight a variety of insect pests.