Electroantennogram-Active Components in Buffalo Gourd Root Powder for Western Corn Rootworm Adults (Coleoptera: Chrysomelidae)

Abstract

Buffalo gourd, Cucurbita foetidissima Kunth, root powder contains potent, non-volatile arrestant and feeding stimulants for adults of Diabrotica virgifera virgifera LeConte, the western corn rootworm, and baits containing this powder mixed with insecticide have become a viable alternative to granular insecticide. Anecdotal evidence has indicated that these baits may also contain volatile attractants. Solvent extracts of buffalo gourd root powder were evaluated for electroantennogram activity to western corn rootworm adults, and a sequential fractionation scheme was conducted to isolate and identify the primary EAG-active components in the extract. A probability-based computer mass spectral library search indicated that the best matches for compounds in the most EAG-active fractions to be ( E,E )-3,5-octadien-2-one, ( E,Z )-2,6-nonadienal, ( E )-2-nonenal, 2-phenylethanol, benzyl alcohol, ( E,E )-2,4-decadienal, and 6,10-dimethyl-5,9-undecadien-2-one. Retention time, mass spectrum, and EAG activity of the synthetic compounds were consistent with those of compounds in the purified EAG-active fractions (synthetic material was unavailable for 6,10-dimethyl-5,9-undecadien-2-one). Previous work indicated that several of these same compounds were in the most EAG-active fractions from corn, Zea mays L., silk. EAG data are discussed in terms of possible evolutionary considerations.