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Research Project: Disease Defense Responses Signaling in Maize

Location: Chemistry Research

Title: Contrasting insect attraction and herbivore-induced plant volatile production in maize

Author
item Block, Anna
item Hunter, Charles
item Rering, Caitlin
item Christensen, Shawn
item Meagher, Robert - Rob

Submitted to: Planta
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/29/2018
Publication Date: 4/3/2018
Citation: Block, A.K., Hunter III, C.T., Rering, C.C., Christensen, S.A., Meagher Jr, R.L. 2018. Contrasting insect attraction and herbivore-induced plant volatile production in maize. Planta. doi:10.1007/s00425-018-2886-x.
DOI: https://doi.org/10.1007/s00425-018-2886-x

Interpretive Summary: Corn is one of the major agricultural crops grown in the United States, yet this crop is continually at risk from attack by insect pests such as fall armyworm, which can reduce yield and marketability as well as increase the risk of infection by toxin producing fungal diseases. One approach to combat this insect pest is to exploit its natural enemies such as the parasitic wasp Cotesia. In order to do this effectively Gainesville, FL, ARS scientists first needed to understand how corn attracts these parasitoids when under attack from fall armyworm. In this study we compared two varieties of corn to assess their ability to attract the wasps and measure some of the corn-derived chemicals that may be involved in this attraction. We showed that the two corn varieties differed both in the amount of the chemicals they produce and in their attractiveness to the wasps. Our data revealed that while both varieties could potentially be used to study how corn recruits wasps, one of the varieties (W22) is likely to be a better model for such studies. Positive results from this study help researchers understand this important plant-insect-insect interaction and apply these results toward future control of the insect pest, fall armyworm.

Technical Abstract: Maize inbred line W22 is an important resource for genetic studies due to the availability of the UniformMu mutant population and a complete genome sequence. In this study, we assessed the suitability of W22 as a model for tritrophic interactions between maize, Spodoptera frugiperda (fall armyworm) and the parasitoid wasp Cotesia marginiventris. W22 was found to be a good model for studying the interaction as S. frugiperda prefers W22 over B73 and a higher parasitism rate by C. marginiventris was observed on W22 compared to the inbred line B73. W22 also produced lower amounts of many herbivore-induced volatile terpenes and indole emission upon treatment with S. frugiperda oral secretions. We propose that some of the major herbivore-induced terpene volatiles are perhaps impeding S. frugiperda and C. marginiventris preference and that as yet unidentified compounds are produced at low abundance may be positively impacting these interactions.