Isolation and identification of the main components of garlic, Allium sativum, volatiles and their determination of repellent or toxic activities on green peach aphid, Myzus persicae

To determine the control mechanism of garlic on Myzus persicae, volatiles from garlic plants were collected, and the components were determined by GC–MS. Then, the volatile extracts and standard components were screened by electroantennogram (EAG) apparatus and Y-tube olfactometer, and the toxic effects were determined by the immersion method. The results showed the main components from garlic plant volatile were 2-methoxyphenol, 2,4-di-tert-butylphenol, diallyl disulfide, butyl phthalate esters, (1-hydroxycyclohexyl) phenyl ketone, and 2,6-di-tert-butylp-cresol. The volatile extracts and the standard components had significant repellent effects (P ≤ 0.05) on M. persicae when the volume ratio was 1:100. The relative values of EAG from volatile extracts and diallyl disulfide were significantly higher than those of the other substances (P ≤ 0.05) when the volume ratio was 1:100. The toxicity of garlic volatile extracts to M. persicae significantly (P ≤ 0.05) increased with increasing concentration. After 72 h (treated), the adjusted mortality of the extract to M. persicae was 36.99% at 90 ml/L. The standard components had the significant toxic effect on M. persicae at 30 mg/mL, and the rates of mortality were over 78.95%. Thus, the results suggested that the volatile extracts and the four standard components from garlic plants had significant repellent effects and electroantennogram responses for M. persicae, and the toxic effects were stronger than the repellent effects for M. persicae.