Plutella xylostella (L.) is one of the most serious pests of cruciferous vegetables. Our previous work demonstrated that the essential oil of Artemisia lavandulaefolia DC. exhibits promising insecticidal activities against P. xylostella. This study further characterizes the key components that are responsible for the insecticidal effect. In total, 47 compounds (96.52% of the total compounds) were identified from the total oil using GC-MS, and the major compounds were eucalyptol (21.57%), D(+)-camphor (17.33%), (-)-4-terpineol (9.96%) and caryophyllene oxide (10.96%). Among them, (-)-4-terpineol showed significantly larvicidal and fumigant activities against P. xylostella. The LD₅₀ of (-)-4-terpineol was 43.15 mg/mL at 12 h and 31.22 mg/mL at 24 h for 3rd instar larvae, and the LC₅₀ for adults was 8.34 mg/mL at 12 h and 7.35 mg/mL at 24 h. In addition, the adults treated with (-)-4-terpineol showed varying degrees of inhibitory activity toward glutathione S-transferase, catalase, acetylcholinesterase and Na⁺/K⁺-ATPase at different post-treatment intervals and concentrations. The results indicate that (-)-4-terpineol has promising insecticidal activities against P. xylostella, and it has good inhibitory effects on the four enzymes of P. xylostella adults.

The aphid Myzus persicae is an important agricultural pest relying on olfactory cues to find food and escape from predators. The considerable difficulty of anatomical manipulation and other related technical challenges may underlie the absence of studies systematically mapping the central projections of antennal sensory neurons in its central nervous system. We used mass stain, immunohistochemistry, laser scanning confocal microscope and three-dimensional reconstruction techniques to trace the central projections of sensory neurons from the antennae. The ipsilateral antennal nerve targets mainly the antennal lobe, the antennal mechanosensory and motor center, and most neuromeres of the ventral nerve cord. There are also several axons that project to other regions, like the contralateral antennal lobe, the contralateral antennal nerve, the ipsilateral calyx and some region of the protocerebrum. The numerous neuropils innervated by axons from the antenna indicate the multiple roles that this sensory organ serves in insect behavior, and the results which provide information about the basic anatomical arrangement of the olfactory nervous system in aphid M. persicae may provide some basic knowledge for the further investigations of the aphid.