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Synthetic cis-jasmone exposure induces wheat and barley volatiles that repel the pest cereal leaf beetle, Oulema melanopus L.

Delaney, Kevin J., Wawrzyniak, Maria, Lemańczyk, Grzegorz, Wrzesińska, Danuta, Piesik, Dariusz
Journal of chemical ecology 2013 v.39 no.5 pp. 620
Hordeum vulgare, Oulema melanopus, Triticum aestivum, acetates, beta-caryophyllene, beta-ocimene, emissions, exposure duration, farnesene, females, field crops, herbivores, indoles, induced resistance, insect behavior, insect pests, insect repellents, leaves, linalool, males, natural enemies, olfactometers, semiochemicals, spring barley, spring wheat, volatile organic compounds, winter wheat
The plant semiochemical cis-jasmone primes/induces plant resistance to deter herbivores and attract natural enemies. We studied the induction of volatile organic compounds (VOCs) in winter wheat and spring barley after exposure of plants to three synthetic cis-jasmone doses (50 ml containing 1, 100, and 10000 ng cis-jasmone per ml) and durations of exposure (1, 3, and 6 hr). Cereal leaf beetle, Oulema melanopus, adult behavioral responses were examined in a Y-tube olfactometer to cis-jasmone induced plant VOC bouquets and to two synthetic blends of VOCs (3 green leaf volatiles (GLVs); 4 terpenes + indole). In both cereals, eight VOCs ((Z)-3-hexanal, (Z)-3-hexanol, (Z)-3-hexanyl acetate, (Z)-ß-ocimene, linalool, ß-caryophyllene, (E)-ß–farnesene and indole) were usually induced 100- to 1000-fold after cis-jasmone exposure. The degree of VOC induction in both cereals was usually positively and linearly associated with increasing exposure dose and duration. However, the VOC emission rate was only ~ 2-fold greater from plants exposed to the highest vs. lowest cis-jasmone exposure doses (10000-fold difference) or durations (6-fold difference). Male and female O. melanopus were deterred by both cereal VOC bouquets after plant exposure to the high cis-jasmone dose (10000 ng per ml), while females were also deterred after plant exposure to the low dose (1 ng per ml) but attracted to unexposed plant VOC bouquets. Both O. melanopus sexes were repelled by terpene/indole and GLV blends at two concentrations (25 ng per min; 125 ng per min), but attracted to the lowest dose (1 ng per min) of a GLV blend. It is possible that the biologically relevant low cis-jasmone dose has ecological activity and potential for inducing field crop VOCs to deter O. melanopus.