Effects of mechanical injury and insect feeding on volatiles emitted by wheat plants

We report on changes in the volatiles emitted by wheat plants of the cultivar ‘Tonacja’ after the plants were scraped, pierced or damaged by adults of Oulema melanopus (Linnaeus). The blend of volatiles was dominated by typical green leaf volatiles and in addition contained linalool and B-caryophyllene, but the latter two were released in large amounts only after more than one day of insect feeding. Overall, the plants that had been damaged by the insect released more odors than the plants that were subjected to mechanical damage. Moreover, control plants released significantly lower amounts of volatiles. Scraping of leaves induced higher volatile emission than puncturing the leaves. A Y-tube bioassay was used to evaluate upwind orientation ofadult cereal leafbeetles. Greater number of female 0. melanopus was attracted to (Z)-3-hexenal and (Z)-3 -hexenyl acetate at low concentrations. Higher concentration of these compounds and linalool significantly repelled both females and males.