Electroantennogram and olfactory behavioral responses of adult Nematus hequensis Xiao to volatiles from Salix alba leaves

To investigate how leaf volatiles from Salix alba affect the orientation of Nematus hequensis Xiao adults towards host plant in the China, and to contribute to the development of plant-based attractants for N. hequensis , solid-phase microextraction (SPME) coupled with gas chromatograph-mass spectrometer (GC-MS) was employed. This method was used to extract, identify, and screen leaf volatiles of S.alba aged 10–15 years during the peak eclosion period 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 female and male healthy adults.As a result,The findings revealed that 15 types of volatiles with relative content exceeding 1% included aldehydes, benzenes, esters, olefins, ethers, alcohols, and alkanes. Among these, three aldehydes ( (E) -2-hexenal2, benzaldehyde, and benzaldehyde,2-hydroxy) elicited the strongest EAG response in both adults at a concentration of 100ug/µL, with (E) -2-hexenal2 exhibiting a greater effect than benzaldehyde,2-hydroxy, which in turn was more effective than benzaldehyde. At this concentration, the attractive effects of (E) -2-hexenal2 and benzaldehyde on both adults were also significant. Furthermore, cis-3-hexenyl isovalerate demonstrated a significant repellent effect on female adults at 10µg/µL. Notably, Butanoic acid,3-hexenyl ester, (Z) ,cis-3-hexenyl isovalerate, and benzaldehyde,2-hydroxy at concentrations of 1µg/µL, 10µg/µL, and 100µg/µL exhibited significant repellent effects on male adults.Unmated adults of N. hequensis exhibited varying degrees of EAG response to 15 volatiles. Remarkably, (E) -2-hexenal2 and benzaldehyde elicited significant EAG responses and attracted behavioral responses both male and female adult Nematus hequensis Xiao at 100 µg/µL.