## 4 Materials and Methods
### Electroantenograms  
The antennal sensitivity of _F. occidentalis_ females (2-3 days old) to increasing concentrations of the five test compounds was evaluated using electroantennography (EAG) with a technique described by [PERSON] et al. (2005) and detailed in our previous study [PERSON] et al. (2005). The antennae of _F. occidentalis_ females were excised at the groove between antennal segments 7 and 8 (most distal to the head) to achieve better contact with electrodes. The antenna was placed between the head end of a reference electrode and the top of a recording electrode, with the aid of a micromanipulator. The EAG equipment (IDAC-2; Syntech GmbH, Kirchzarten, Germany) consisted of a data acquisition collector, an AC/DC amplifier, a stimulus flow controller, a single-ended probe, and a micromanipulator. To ensure electrical continuity between the antennal preparation and the EAG apparatus, the recording and reference electrodes were silver-coated wires in pulled glass micropipettes containing 0.5 M KCl conductive saline solution. For each test compound, 10 \(\upmu\)L of different mineral oil solutions, providing doses of 0.01, 0.1, 1, 10, and 100 \(\upmu\)g, was adsorbed onto a piece of filter paper (1 cm\({}^{2}\), Whatman No. 1) inserted into a Pasteur pipette, which was used as an odor cartridge [PERSON] et al. (2005). Mineral oil was used as the control in each experiment. Each dose of the four compounds was tested on five different antennae from different female thrips; each antenna sample was stimulated by each dose of each compound in the following order: control, sample, control. The average of the two controls was used for analysis. The EAG responses of thrips to the compounds were calculated as  
Relative EAG value = T - CK,  
where T is the absolute EAG value for the antennae samples and CK is the absolute EAG value for the control. For the five tested compounds, decanal (chemical purity \(\geq\) 97%), dodecanal (chemical purity \(\geq\) 95%), and \(\beta\)-myrrene (chemical purity \(\geq\) 90%) were purchased from Shanghai Macklin Biochemical Co., Ltd., Shanghai, China; 1-decanol (chemical purity \(\geq\) 97%) was purchased from Dr. A. Maisch GmbH (Baden-Wurttemberg, Germany); decanoyl acetaldehyde (chemical purity \(\geq\) 95%) was purchased from National Institutes for Food and Drug Control, Beijing, China.  
Behavioral Responses of Franklin incidentalis to Houttuynia cordata Volatiles in a Six-Arm Olfactometer  
As decanal, 1-decanol, dodecanal, \(\beta\)-myrrene, and decanoyl acetaldehyde were the five compounds with the highest relative abundances in the volatile profile of _H. cordata_, behavioral responses of _F. occidentalis_ to different doses of each of these compounds were further assessed in a six-arm olfactometer [PERSON] et al. (2005); [PERSON] et al. (2005). The six-arm olfactometer consisted of a central chamber (12 cm internal diameter) with six arms, each of which was connected to a glass tube (angles between pairs of tubes were 60\({}^{\circ}\)) that projected outwards at an equal distance. Each arm was connected with Teflon tubing to a glass vessel, which was used as the odor chamber that contained a test (10 \(\upmu\)L of each compound solution at 0.1, 1, 5, 25, and 50 \(\upmu\)g/\(\upmu\)L) or control stimulus (10 \(\upmu\)L mineral oil). The airflow was set at 200 mL/min to drive the odor towards the thrips. Female _F. occidentalis_ (2-3 days old, starved for 6 h) were introduced into the olfactometer in groups of 200 individuals. The thrips were counted and considered as having made a choice for a particular odor source within 30 min, any thrips that entered into one of these arms were considered to make a choice [PERSON] et al. (2005); [PERSON] al. (2005); [PERSON] et al. (2005).  
The bioassays were replicated five times and carried out between 09:00 and 17:00 at room temperature (\(25\pm 2\)\({}^{\circ}\)C).