Tree showing relationships of D. melanogaster, A. gambiae, and A. mellifera nAChR subunit protein sequences. Numbers at each node signify bootstrap values with 1000 replicates and the scale bar represents substitutions per site. The D. melanogaster GABA_A subunit (GenBank accession no. AAA28556) was used as an outgroup. The nAChR subunits shown in the tree (as well as GenBank accession nos.) are as follows: Dα1 (CAA30172), Dα2 (CAA36517), Dα3 (CAA75688), Dα4 (CAB77445), Dα5 (AAM13390), Dα6 (AAM13392), Dα7 (AAK67257), Dβ1 (CAA27641), Dβ2 (CAA39211), Dβ3 (CAC48166), Agamα1 (AY705394), Agamα2 (AY705395), Agamα3 (AY705396), Agamα4 (AY705397), Agamα5 (AY705399), Agamα6 (AY705400), Agamα7 (AY705402), Agamα8 (AY705403), Agamα9 (AY705404), and Agamβ1 (AY705405). A. mellifera nAChR subunits are shown in boldface type.