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Front. Ecol. Evol. | doi: 10.3389/fevo.2018.00055

Parasitic wasps can reduce mortality of teosinte plants infested with fall armyworm: support for a defensive function of herbivore-induced plant volatiles

 Elvira S. De Lange1,  Kevin Farnier1, Thomas Degen1, Benjamin Gaudillat1, Rafael Aguilar-Romero2, Fernando Bahena-Juárez3,  Ken Oyama2 and  Ted Turlings1*
  • 1Institute of Biology, University of Neuchâtel, Switzerland
  • 2Escuela Nacional de Estudios Superiores Unidad Morelia, Universidad Nacional Autónoma de México, Mexico
  • 3Campo Experimental Uruapan, Instituto Nacional de Investigaciones Forestales, Agrícolas y Pecuarias (INIFAP), Mexico

Many parasitic wasps use volatiles emitted by plants under herbivore attack to find their hosts. It has therefore been proposed that these inducible plant volatiles serve an indirect defense function by recruiting parasitoids and other natural enemies. This suggested function remains controversial because there is little evidence that, in terms of fitness, plants benefit from the actions of natural enemies, particularly parasitoids, which do not immediately kill their hosts. We aimed to address this controversy in a semi-natural field experiment in Mexico, where we used large screen tents to evaluate how parasitoids can affect plant performance. The tritrophic study system comprised teosinte (Zea spp.), the ancestor of maize, Spodoptera frugiperda Smith (Lepidoptera: Noctuidae) and Campoletis sonorensis Cameron (Hymenoptera: Ichneumonidae), which have a long evolutionary history together. In tents without parasitoids, S. frugiperda larvae inflicted severe damage to the plants, whereas in the presence of parasitoid wasps, leaf damage was reduced by as much as 80%. Parasitoids also mitigated herbivore-mediated mortality among young teosinte plants. Although these findings will not resolve the long-standing debate on the adaptive function of herbivore-induced plant volatiles, they do present strong support for the hypothesis that plants can benefit from the presence of parasitoid natural enemies of their herbivores.

Keywords: Campoletis sonorensis, Parasitoid wasp, Spodoptera frugiperda, Tritrophic interactions, volatiles, Zea mays

Received: 27 Oct 2017; Accepted: 16 Apr 2018.

Edited by:

Marie Bengtsson, Swedish University of Agricultural Sciences, Sweden

Reviewed by:

Antonino Cusumano, Wageningen University & Research, Netherlands
Amanuel Tamiru, International Centre of Insect Physiology and Ecology, Kenya  

Copyright: © 2018 De Lange, Farnier, Degen, Gaudillat, Aguilar-Romero, Bahena-Juárez, Oyama and Turlings. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

* Correspondence: Prof. Ted Turlings, University of Neuchâtel, Institute of Biology, Rue Emile-Argand 11, Neuchâtel, 2000, Neuchâtel, Switzerland, ted.turlings@unine.ch