## 2 Materials and Methods
### Electroantemogram Responses  
The antennal response of both sexes of adult _E. scrobiculatus_ and _E. brandti_ to the synthetic olfactory stimuli were quantified by electroantennogram (EAG) using the most abundant compounds identified in the previous study. For this experiment we evaluated1-hexanol (98%; Tianjin Guangfu Fine Chemical Research Institute, Tianjin, China), (15)-(--)-\(\beta\)-pinene (98%; Shanghai Macklin Biochemical Co., Ltd., Shanghai, China), (16)-(+)-\(\alpha\)-pinene (99%; Shanghai Aladdin Bio-Chem Technology Co., Ltd., Shanghai, China), isooctyl alcohol (99%) and liquid paraffin (both were purchased from Tianjin Yongda Chemical Reagent Co., Ltd., Tianjin, China), _cis_-3-hexen-1-ol (98%, Shanghai Yuanye Biotechnology Co., Ltd., Shanghai, China). Each compound was tested singly at five concentrations (100, 10, 1, 0.1, 0.01 \(\upmu\)g/\(\upmu\)L) using liquid paraffin as solvent. The material was applied (10 \(\upmu\)L) to a filter paper strip (5 \(\times\) 25 mm\({}^{2}\)). Because the weevils showed steady peaks in response to _cis_-3-hexen-1-ol through preliminary test, _cis_-3-hexen-1-ol (30 \(\upmu\)g/\(\upmu\)L) was selected as a reference compound. The control stimulus was liquid paraffin.  
The experiment was carried out as described by [PERSON] (2018). Briefly, weevil antennae were cut off as close as possible to the base of the clavola and took 0.5 mm off the terminal. Then, the antenna was positioned in parallel across a forked metal electrode using Spectra 360 electrode gel (Parker Laboratories Inc., Orange, NJ, USA). The electrode was connected via an interface box (INR-II, Syntech, Hilve resum, The Netherlands) to a signal acquisition system (IDAC-4, Syntech, Hilve resum, The Netherlands) connected to a computer using AutoSpike software (Syntech, Hilve resum, The Netherlands). Both constant airflow and air puffs were generated with a stimulus flow controller (CS-55; Syntech, Hilve resum, The Netherlands). The controller including a glass tube (2 cm diameter), with an outlet facing towards the antenna at a distance of 1 cm, provided airflow at 30 mL/s. The glass tube presented one lateral hole that permitted the delivery of the stimulus puff inside the tube with the aim of a glass Pasteur pipette attached to Tygon tubes leading to an air source programmed to deliver a 0.5 s pulse at 30 mL/s. The tested odor was carried out by continuous flow of clean air through a Pasteur pipette containing the filter paper strip soaked in the compound. The chemical stimuli were tested randomly from low concentration to high concentration for each compound, with a stimulus duration time of 0.5 s, followed by a 1 min purge with purified air. Liquid paraffin and _cis_-3-hexen-1-ol (30 \(\upmu\)g/\(\upmu\)L) were successively applied at the beginning and at the end of each compound. EAG responses were measured as the maximum amplitude of depolarization (mV). The response to the solvent control was subtracted from all of the initial responses, and the normalized EAG responses were presented as the ratio of the EAG responses of tested compound to the EAG responses of the standard compound. Each compound was tested on 5 individual male and female antennae.