Comparative study of the volatiles' composition of healthy and larvae-infested Artemisia ordosica

Volatiles emitted by healthy Artemisia ordosica (Asteraceae) and plants infested with larvae of Sphenoptera sp. (Coleoptera: Buprestidae) or Holcocerus artemisiae (Lepidoptera: Cossidae) were obtained using a dynamic headspace method and analysed by automatic thermal desorption/gas chromatography/mass spectrometry (ATD/GC/MS). Twenty-eight major compounds were identified, and qualitative and quantitative differences were compared. The novel green leaf volatiles 2-hexenal, (Z)-3-hexen-1-ol, 2-hexen-1-ol 1-hexanol, and (Z)-3-hexen-1-ol acetate, the terpenoids alpha-copaene, beta-cedrene, and (E,E)-alpha-farnesene, and the ester methyl salicylate were present in all infested plants. Volatiles from healthy plants were dominated by D-limonene (32.14%), beta-pinene (16.63%), beta-phellandrene (16.06%), and sabinene (12.88%). Volatiles from Sphenoptera sp. larvae-infested plants were dominated by D-limonene (24.74%), beta-pinene (21.05%), alpha-pinene (19.39%), and sabinene (11.64%), whereas volatiles from H. artemisiae larvae-infested plants were dominated by D-limonene (31.76%), sabinene (18.49%), ocimene (15.93%), and beta-phellandrene (10.59%). In addition to the qualitative variation, a larvae-induced quantitative change in the proportion of terpenoids in the blends was also a noticeable feature.