Oviposition Induced Volatile Emissions from African Smallholder Farmers’ Maize Varieties Amanuel Tamiru & Toby J. A. Bruce & Charles A. O. Midega & Christine M. Woodcock & Michael A. Birkett & John A. Pickett & Zeyaur R. Khan Received: 7 February 2012 / Revised: 13 February 2012 / Accepted: 14 February 2012 / Published online: 25 February 2012 # Springer Science+Business Media, LLC 2012 Abstract Maize (corn), Zea mays, is a genetically di- verse crop, and we have recently shown that certain open pollinated varieties (OPVs) of Latin American origin possess a trait not present in mainstream com- mercial varieties: they produce volatiles in response to stemborer oviposition that are attractive to stemborer parasitoids. Here, we tested whether a similar tritrophic effect occurs in the African OPVs ‘ Nyamula’ and ‘Jowi’. Herbivore induced plant volatiles (HIPVs) were collected from plants exposed to egg deposition by the stemborer Chilo partellus. In a four-arm olfactometer bioassay, the parasitic wasp Cotesia sesamiae preferred samples containing HIPVs from plants with eggs to samples collected from plants without eggs. EAG- active compounds, including (E)-4,8-dimethyl-1,3,7-non- atriene (DMNT), were released in higher amounts from the egg induced headspace samples. Our results suggest that this oviposition trait is not limited to S. American Z. mays germplasm, and that it could be used to increase indirect defense against attack by stemborers. Keywords Insect-plant interaction . Oviposition . Induced defense . Plant volatiles . Multitrophic interaction Introduction Plants have evolved sophisticated defense mechanisms that protect against insect attack. Some of these mechanisms directly affect the herbivore due to their toxic or deterrent properties, while others involve recruitment of the herbi- vore’ s natural enemies and are based on plant secondary metabolites. The latter is termed indirect defense (Turlings et al., 1990; Heil, 2008) and involves the plant responding to insect attack by releasing a blend of herbivore induced volatiles (HIPVs) that serve as foraging cues for parasitoids. Production of HIPVs often is triggered on feeding damage by herbivorous larvae. However, a number of recent studies have shown plant responses to an earlier stage of insect attack, i.e., egg deposition (Colazza et al., 2004; Hilker and Meiners, 2006; Bruce et al., 2010; Tamiru et al., 2011). Defenses elicited by the presence of eggs benefit plants because they enable defense to be switched on early, before leaf or stem damage is caused by larvae (Hilker and Meiners, 2006; Bruce et al., 2010). The spotted stemborer, Chilo partellus Swinhoe (Crambi- dae), is the most damaging pest of maize in eastern and southern Africa and South Asia, causing severe yield losses that can reach 88% (Seshu Reddy and Walker, 1990; Kfir et al., 2002). In sub-Saharan Africa, maize is an important staple and cash crop (Odendo et al., 2001) and is grown mainly by resource-poor farmers under low-input smallholder systems. Effective control of C. partellus is difficult, largely due to the protection provided by the plant stem for immature pest stages, and insecticides often are neither practical nor eco- nomical for smallholder farmers. The ecology of tritrophic interactions thus presents an opportunity for development of cost effective and environmentally benign pest control approaches that make use of innate plant defenses, which would be relevant for resource-poor African farmers. T. J. A. Bruce : C. M. Woodcock : M. A. Birkett : J. A. Pickett (*) Department of Biological Chemistry, Rothamsted Research, Harpenden, Herts AL5 2JQ, UK e-mail: john.pickett@rothamsted.ac.uk A. Tamiru : C. A. O. Midega : Z. R. Khan Habitat Management Programme, International Centre of Insect Physiology and Ecology, P.O. Box 30, Mbita Point, Kenya J Chem Ecol (2012) 38:231–234 DOI 10.1007/s10886-012-0082-1