Electroantennogram and Behavioral Responses of <i>Nematus hequensis</i> Xiao Adult to Volatiles of <i>Salix alba</i> Leaves

The aim of this study was to investigate how leaf volatiles from Salix alba affect the orientation of Nematus hequensis Xiao adults towards host plants and contribute to the development of plant-based attractants for N. hequensis. Solid-phase microextraction (SPME) coupled with gas chromatograph-mass spectrometry (GC-MS) was used to extract, identify, and screen leaf volatiles from S. alba aged 10-15 years during the peak eclosion of N. hequensis. Electroantennogram (EAG) and Y-shaped olfactometry assays were utilized to identify volatiles with relative content > 1% and determine the optimal concentration for attracting, 1-day-old unmated males and females. The results showed that among the 15 volatiles with a relative content of more than 1%, (E)-2-hexenal, benzaldehyde, and 2-hydroxybenzaldehyde elicited the strongest EAG response in adult males and females at a concentration of 100 μg·μL^-1, with (E)-2-hexenal exhibiting a greater effect than 2-hydroxybenzaldehyde, which in turn was more effective than benzaldehyde. At this concentration, the attractive effects of (E)-2-Hexenal, and benzaldehyde on adult males and females were significant. These findings provide an important basis for developing attractants and repellents used in control of this insect pest.