Oviposition Induced Volatile Emissions from African Smallholder Farmers’ Maize Varieties
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Maize (corn), Zea mays, is a genetically diverse crop, and we have recently shown that certain open pollinated varieties (OPVs) of Latin American origin possess a trait not present in mainstream commercial 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-nonatriene (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.
KeywordsInsect-plant interaction Oviposition Induced defense Plant volatiles Multitrophic interaction
We thank local farmers in Mbita for contributing seed and Amos Gadi, Jacob Odhiambo and Silas Ouko for assistance with insect rearing and screen house operations. This work was supported by an International Foundation for Science (IFS) and a Rothamsted International African Fellows award to AT and the Kilimo Trust and European Union funded ADOPT Project (DCI-FOOD⁄2010⁄230224). Rothamsted Research receives grant-aided support from the Biotechnology and Biological Sciences Research Council of the UK.
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