Insecticidal Activity of Eupatorium fortunei Essential Oil Against Schizaphis graminum and Its Effects on Detoxification Enzymes

<i>Schizaphis graminum</i> is the most important pest of wheat, and its feeding harm not only affects photosynthesis but also causes diseases, posing a serious threat to wheat production. We measured the contact killing and fumigation activities, population changes, enzyme activities, and nanoemulsion physicochemical property of <i>Eupatorium fortune</i> essential oil (EFEO) and pyrethrin against <i>S. graminum</i> and its natural enemy (<i>Harmonia axyridis</i>). Toxic effects of EFEO and pyrethrin increased with increasing concentration. After 24 h of contact killing, the LD₅₀ of <i>S. graminum</i> were 9.23 and 0.02 μg/head, respectively. <i>Harmonia axyridis</i> were 36.71 and 0.07 μg/head. The fumigation of EFEO LD₅₀ on <i>S. graminum</i> was 9.779 mg/L (y = 2.88x - 2.852). EFEO contains 28 chemical components, including l-Caryophyllene, Lily aldehyde, α-Terpineol, and Cineole. EFEO LD₅₀ significantly reduced the adult longevity, nymph production, and nymph production duration of the F0 <i>S. graminum</i>, while there were no significant differences in various parameters of offspring. The activity of acetylcholinesterase, glutathione-S-transferase, and carboxylesterase is significantly affected. The population decline rate of EFEO nanoemulsion is significantly higher than that of EFEO. This research aims to clarify the toxic effect of EFEO on <i>S. graminum</i>, providing a scientific basis for developing new plant essential oil preparations and nano preparations.