The chemical basis of oviposition elicitation in a generalist herbivore was determined by examination of oviposition responses in Ostrinia nubilalis to corn (Zea mays) chemicals in two-choice laboratory bioassays. A pentane extract of corn leaves stimulated oviposition and the activity persisted for three days, indicating that oviposition in O. nubilalis is elicited by low-volatility chemicals. Chemicals in the extract were fractionated by column chromatography on Florisil, using a sequence of solvents of increasing polarity. Bioassays of Florisil fractions indicated that the stimulants were eluted with nonpolar solvents. Positive bioassay results with an extract prepared by dipping corn leaves in pentane for 20 see for extraction of leaf surface chemicals suggested that some of the active material was present in the leaf epicuticle. Gas chromatographic analyses and comparisons with retention times of standards suggested the presence of several n-alkanes in the dip extract. Five n-alkanes-hexacosane, heptacosane, octacosane, nonacosane, and tritriacontane-known to be present in the epicuticle of corn leaves were bioassayed, and all five elicited oviposition responses. These results suggest that oviposition elicitation in O. nubilalis is influenced by the presence of n-alkanes in the host plant epicuticle.
|Original language||English (US)|
|Number of pages||13|
|Journal||Journal of Chemical Ecology|
|State||Published - 1997|
Bibliographical noteFunding Information:
Acknowledgments—We are grateful to John D. Pesek, Jr., for assistance with statistical analyses; Laura Iraki, Eva Santana, and Nate Ehresman for assistance in conducting the experiments; and Sulekha Rao for reviewing the manuscript. This research was part of the North Central Regional Research Project NC-205, Integrated Crop Management Effects on Stalk-Boring Lepidoptera. It was supported by funds to C.E.M. from the State of Delaware and from the E. I. DuPont Inc. De Nemours and Company under the auspices of the Delaware Research Partnership Program. Published as Paper No. 1590 in the Journal Series of the Delaware Agricultural Experiment Station, Contribution No. 689 of the Department of Entomology & Applied Ecology, University of Delaware, Newark, Delaware.
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- Epicuticular chemicals
- Ostrinia nubilalis
- Oviposition stimulants
- Phytochemical cues