Changes in the emission of volatile compounds from Hippophae rhamnoides ssp. sinensis induced by Holcocerus hippophaecolus (Lepidoptera:Cossidae)

The study explores changes in variety and content of volatile compounds in Hippophae rhamnoides ssp. sinensis damaged by Holcocerus hippophaecolus. Volatiles of healthy and artificially infested plants leaves were collected during 0–51 hours using continuous dynamic headspace-collection and analysed by using Automated Thermal Desorption-Gas Chromatography-Mass Spectrometry. Thirty-one compounds were identified, including seven alcohols, four esters, two terpenes, six aldehydes, five alkanes, two olefins, three ketones and two benzodiazepines. Compounds of (Z)-3-Hexenyl-3-methylbutanoateand 2-ethylhexyl acetate were herbivore-induced compounds. Olefins, ketones, benzodiazepines, terpenes and alkanes increased shortly after insect feeding. Aldehydes, alcohols and esters decreased in generally. Release regularity and function of compounds respectively discussed followed, especially including 2-ethylhexanol, alpha-terpineol, phytol, methyl salicylate, (Z)-3-Hexenyl-3-methylbutanoate, 2-ethylhexyl acetate, longifolene, 1,3,6-octatriene, 3,7-dimethyl-, hexanal, (Z)-3-hexen-1-ol acetate, with the purpose to approve basic date for disaster mechanisms of H. hippophaecolus.

Volatile Compounds of Healthy and Insect-Damaged Hippophae rhamnoides sinensis in Natural and Planted Forests

Volatile compounds of healthy and insect-damaged stems of Hippophae rhamnoides sinensis were analysed using dynamic headspace and thermal-desorption cold-trap injector gas chromatography/mass spectroscopy (TCT-GC/MS). Sixteen compounds, belonging to alkanes, alcohols, aldehydes, esters, ketones, and ethers, were identified in the stems of healthy H. rhamnoides sinensis; the compounds in H. rhamnoides sinensis occurring naturally or cultivated in plantations were similar, but the relative contents were significantly different. In plants damaged by Holcocerus hippophaecolus, the nature and content of the volatile compounds were greatly changed. Butanedione and butyl glyoxylate were newly generated after damage by the pest, and the relative levels of pentanal, heptanal, eucalyptol, terpineol, and camphor were sharply increased in both naturally occurring and plantation-grown plants. n-Decane, trans-2-nonen-1-ol, and n-hexadecane levels increased in plants cultivated in the plantation and decreased in natural forests, whereas the levels of other types were reduced. Thus, both the nature and the content of volatile compounds of H. rhamnoides sinensis are affected by H. hippophaecolus damage, providing a theoretical basis to identify the mechanism of pest destruction

Mechanisms Underlying Host Plant Selection by Holcocerus hippophaecolus Adults

We determined the mechanisms underlying host selection by adults of the seabuckthorn carpenterworm, Holcocerus hippophaecolus Hua, Chou, Fang et Chen. Four sea buckthorn (Hippophae rhamnoides L.) subspecies (varieties) with different degrees of resistance to H. hippophaecolus were chosen for artificial insect infection in cages. The results showed that olfactory and visual cues are very important for the selection of host plants by H. hippophaecolus, but that olfactory stimuli play a more vital role in this process. The relative abundance of branches and leaves had no effect on the likelihood that adults landed on plants from four subspecies (varieties), but did influence landing rates within the same subspecies (varieties). When considering only the most resistant sea buckthorn subspecies (varieties), the presence of luxuriant branches and leaves led to lower landing rates. These results provide a theoretical basis for the understanding of H. hippophaecolus damage to sea buckthorn and the means to implement effective measures of control