Herbivore-Induced Plant Volatiles Can Serve as Host Location Cues for a Generalist and a Specialist Egg Parasitoid M. F.G. V. Peñaflor & M. Erb & L. A. Miranda & A. G. Werneburg & J. M. S. Bento Received: 30 September 2011 /Revised: 28 November 2011 /Accepted: 4 December 2011 /Published online: 15 December 2011 # Springer Science+Business Media, LLC 2011 Abstract Herbivore-induced plant volatiles are important host finding cues for larval parasitoids, and similarly, insect oviposition might elicit the release of plant volatiles func- tioning as host finding cues for egg parasitoids. We hypoth- esized that egg parasitoids also might utilize HIPVs of emerging larvae to locate plants with host eggs. We, there- fore, assessed the olfactory response of two egg parasitoids, a generalist, Trichogramma pretiosum (Tricogrammatidae), and a specialist, Telenomus remus (Scelionidae) to HIPVs. We used a Y-tube olfactometer to tests the wasps’ responses to volatiles released by young maize plants that were treated with regurgitant from caterpillars of the moth Spodoptera frugiperda (Noctuidae) or were directly attacked by the caterpillars. The results show that the generalist egg parasitoid Tr. pretiosum is innately attracted by volatiles from freshly- damaged plants 0–1 and 2–3 h after regurgitant treatment. During this interval, the volatile blend consisted of green leaf volatiles (GLVs) and a blend of aromatic compounds, mono- and homoterpenes, respectively. Behavioral assays with syn- thetic GLVs confirmed their attractiveness to Tr. pretiosum. The generalist learned the more complex volatile blends re- leased 6–7 h after induction, which consisted mainly of ses- quiterpenes. The specialist T. remus on the other hand was attracted only to volatiles emitted from fresh and old damage after associating these volatiles with oviposition. Taken to- gether, these results strengthen the emerging pattern that egg and larval parasitoids behave in a similar way in that general- ists can respond innately to HIPVs, while specialists seems to rely more on associative learning. Key Words Tritrophic interaction . Egg parasitoids . Natural enemies . Fall armyworm . Induced defense Introduction Volatiles released by plants under herbivore attack are im- portant chemical cues for parasitoids and predators to locate their host and/or prey (Dicke et al., 1990; Turlings et al., 1990). Attraction to herbivore-induced plant volatiles (HIPVs) has been observed for many larval parasitoids and arthropod predators (Mattiacci et al., 1995; Ngi Song et al., 1996; De Moraes et al., 1998; Dicke, 1999; Kessler and Baldwin, 2001). Besides herbivory, deposition of insect eggs also can induce the production of volatiles or change leaf chemistry in a way that the plants attract and/or arrest certain egg parasitoids (Meiners and Hilker, 1997; Hilker et al., 2002; Mumm et al., 2003; Fatouros et al., 2008; Tamiru et M. F. G. V. Peñaflor : A. G. Werneburg : J. M. S. Bento (*) Department of Entomology and Acarology, Laboratory of Chemical Ecology and Insect Behavior, University of São Paulo, Escola Superior de Agricultura “Luiz de Queiroz”, Av. Pádua Dias, 11, CP 09, 13418-900 Piracicaba, SP, Brazil e-mail: jmsbento@usp.br M. Erb : L. A. Miranda Laboratory of Fundamental and Applied Research in Chemical Ecology (FARCE), University of Neuchâtel, Institute of Biology, Rue Emile-Argand, 11, CP 158, CH-2009 Neuchâtel, Switzerland M. Erb Department of Molecular Ecology, Max Planck Institute for Chemical Ecology, Hans-Knöll-Str. 8, 07745 Jena, Germany J Chem Ecol (2011) 37:1304–1313 DOI 10.1007/s10886-011-0047-9