|BERNKLAU, ELISA - Colorado State University|
|NORTON, A.P. - Colorado State University|
|BJOSTAD, LOUIS - Colorado State University|
Submitted to: Journal of Economic Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/1/2016
Publication Date: 8/1/2016
Publication URL: https://handle.nal.usda.gov/10113/5454519
Citation: Bernklau, E.J., Hibbard, B.E., Norton, A., Bjostad, L.J. 2016. Methyl anthranilate as a repellent for western corn rootworm larvae (Coleoptera: Chrysomelidae). Journal of Economic Entomology. 109(4):1683-1690. doi: 10.1093/jee/tow090.
Interpretive Summary: Insects typically utilize various chemical and/or physical factors to accept or reject potential hosts. These cues may also be of use in pest management. A compound (methyl anthranilate) with strong repellent properties to western corn rootworm larvae was isolated from germinating corn seeds and identified using the behavior of the insect larvae as a guide in a series of chemical separation techniques. In a verification study, a synthetic version of methyl anthranilate prevented larvae from locating carbon dioxide doses which are normally highly attractive to western corn rootworm larvae. Knowledge of rootworm chemical ecology, including this primary repellent, may lead to additional management options for this major pest of corn.
Technical Abstract: Methyl anthranilate was identified as the active compound in extracts of maize roots that were shown to be repellent to neonate western corn rootworm (Diabrotica virgifera virgifera LeConte) larvae. A bioassay-driven approach was used to isolate the active material from diethyl ether extracts of roots from germinating maize seeds. Separation of the extract on a Florisil column yielded an active fraction of 90:10 hexane:diethyl ether (F2). GC-MS analysis identified two compounds in the active fraction: indole (2,3-benzopyrrole) and methyl anthranilate (methyl 2-aminobenzoate). When tested in behavioral bioassays, methyl anthranilate elicited a significant (P < 0.5) repellent response at doses of 1, 10 and 100 micrograms. In subsequent single-choice bioassays, 1, 10 and 100 mg of methyl anthranilate prevented larvae from approaching 10 mmol per mol concentrations of carbon dioxide, which is normally highly attractive to the larvae. Indole, the other compound identified from the active fraction, did not elicit a behavioral response by the larvae.