Flypad

First, the gene fragments of CchlOR18 and CchlOR47 were amplified from the cDNA of male antennae by LA Taq DNA polymerase (Takara, Beijing, China) and sub-cloned into pGEM-T vectors (Promega, Madison, USA). T sequences were then amplified using specific forward primers containing T7 promoter and respective reverse primers. Using 3 µg of purified PCR products as templates, double-strand RNAs were synthesized by T7 RiboMAX Express RNAi System (Promega, Madison, WI, USA) as per the manufacturer’s protocol. In parallel, the dsRNA of GFP (green fluorescent protein, GenBank ^#AAX31732.1) was synthesized as a control. For injection, the newly emerged wasps (less than 1 day) were anesthetized with carbon dioxide on a fly pad (Genesee Scientific, CA, USA) and manually flipped with forceps to expose a soft area around the pharynx. Then, 0.1 μL of each dsRNA (2 μg/μL) was injected using a PLI-100A microinjector (Harvard Apparatus, Holliston, MA, USA) under a stereomicroscope (Olympus, Japan). Notably, for double-gene silencing, both types of dsRNAs were mixed well by pipetting on ice and a total of 0.2 μL of dsRNA mixture was injected. After 3 d, qRT-PCR was performed to check the efficiency of RNAi. The primers for cloning and qRT-PCR are provided in SI Appendix, Table S2.