A phylogenetic tree based on protein sequences of candidate ORs from Yemma signatus (Ysig). Included are ORs from Apolygus lucorum (Aluc), Halyomorpha halys (Hhal), Acyrthosiphon pisum (Apis), Nilaparvata lugens (Nlug), and Cimex lectularius (Clec). The branch containing Orco is marked with a brace. This tree was constructed using PhyML based on the alignment results of MAFFT.