| Plant-induced resistance to insects is the plant’s form of a self-defense mechanism against feeding by pests and is a long-term cooperative evolutionary process. Volatile secondary plant substances can attract or repel adult insects, influence their oviposition behavior, prevent feeding, cause poisoning of their larvae and so forth. The relevant research has increasingly drawn attention. This experiment used the adsorption method (Tenax tube) to collect tobacco volatile substances before and after damage by Myzus persicae (Sulzer) feeding, and then the samples were analyzed by gas chromatography mass spectrometry (GC-MS). Changes in volatile substances that were emitted from tobacco that was damaged by Myzus persicae (Sulzer) feeding were then studied. Based on the literature, we selected the active substances that caused a larger change and used electroantennogram (EAG) technology and the Y-shaped olfactometer to create a bioassay to identify a material that indicated unique effects on Myzus persicae (Sulzer). The results are as follows.1The total area of volatile compounds was reduced, and the hydrocarbons, aldehydes, esters, and other volatile peak areas were significantly reduced, whereas the areas of alkenes, alcohols, and phenols were significantly increased.2The study of the EAG response of Myzus persicae (Sulzer) to the various concentration gradients of the various materials shows that at the different concentrations of each material, Myzus persicae (Sulzer) produced a variety of responses to various substances; the EAG response increased gradually with an increasing volume concentration of each material. The experiment regarding the overall response of the aphids to the classified substances of various volume concentrations showed that the EAG response of Myzus persicae (Sulzer) at different concentrations was the following:aldehydes> alcohol> olefin> esters> ketones, but for the aldehydes and alcohols with the same number of carbon atoms, the reaction of the aphids to alcohol was greater than to aldehydes. In each category of material, the aphids’ responses to the six carbon substances were more robust than to the substances with other numbers of carbon atoms. The responses to saturated alcohols were more robust than the responses to unsaturated alcohols; however, at low concentrations, the aphids responded to saturated aldehydes was more mildly than to unsaturated aldehydes. From the comprehensive results of all of the substances, Myzus persicae (Sulzer) had the strongest EAG responses to hexanol, n-hexyl aldehyde, octanal, octanol, benzaldehyde, and (E)-2-hexenal, nonanal, and heptaldehyde.3The study regarding the aphids’behavioral responses using the Y-shaped olfactometer shows that at the same concentration of various substances, the attractive or repellent response of the aphids was very different; moreover, at different concentrations of the same substances, the attractive or repellent response of the aphids to changes in concentrations varied widely. Taken together, the attractiveness of a-terpene (10-1), heptaldehyde (10-1), a-phellandrene (10-1), cis-3-hexenol (10-1), methyl jasmonate (10-1), cis-3-hexenyl acetate (10-3), benzaldehyde (10-3), eucalyptol (10"3), geraniol (10-4), farnesene (10-4), octanol (10-5) were stronger, and the repelling effects of octanal (10-1), a-pinene (10-1), carvone (10-1), nonanal (10-1), eucalypt (10-4) were stronger.4Based on the integrated EAG technology and Y-shaped olfactometer bioassay results, heptaldehyde, a-phellandrene, cis-3-hexenol, methyl jasmonate, and octanol were selected as attractive components, and octanal, a-pinene, carvone, cineole, and1-hexanol were selected as repellent components. Using these as mixed substances for further experiments, the mixed ratio was divided into4groups:(1)1and A was based on the attraction ratio or repellency ratio,(2)2and B was based on the EAG ratio,(3)3and C was based on the attraction ratio or repellency ratio multiplied with the value of EAG ratio,(4)4and D was based on the ratio of1:1:1:1. The outcomes of the mixture of substances of different components of attraction ratios or repellency ratios to Myzus persicae (Sulzer) showed that the attraction ratio was1>2>3>4, and the repellency ratio was A> B> D> C. This study shows that the mixed components based on the attraction ratio or repellency ratio had the most significant effect. |
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