Effect of insecticidal fusion proteins containing spider toxins targeting sodium and calcium ion channels on pyrethroid‐resistant strains of peach‐potato aphid ( Myzus persicae )

BACKGROUND The recombinant fusion proteins Pl1a/ GNA and Hv1a/ GNA contain the spider venom peptides δ ‐amaurobitoxin‐ PI1a or ω ‐hexatoxin‐Hv1a respectively, linked to snowdrop lectin ( GNA ). Pl1a targets receptor site 4 of insect voltage‐gated sodium channels ( NaCh ), while Hv1a targets voltage‐gated calcium channels. Insecticide‐resistant strains of peach‐potato aphid ( Myzus persicae ) contain mutations in NaCh . The pyrethroid‐resistant kdr ( 794J ) and super‐kdr ( UKO ) strains contain mutations at residues L1014 and M918 in the channel α ‐subunit respectively, while the kdr + super‐kdr strain ( 4824J ), insensitive to pyrethroids, contains mutations at both L1014 and M918 . RESULTS Pl1a/ GNA and Hv1a/ GNA fusion proteins have estimated LC 50 values of 0.35 and 0.19 mg mL −1 when fed to wild‐type M. persicae . For insecticide‐resistant aphids, LC 50 for the Pl1a/ GNA fusion protein increased by 2–6‐fold, correlating with pyrethroid resistance (wild type < kdr < super‐kdr < kdr + super‐kdr strains). In contrast, LC 50 for the Hv1a/ GNA fusion protein showed limited correlation with pyrethroid resistance. CONCLUSION Mutations in the sodium channel in pyrethroid‐resistant aphids also protect against a fusion protein containing a sodium‐channel‐specific toxin, in spite of differences in ligand–channel interactions, but do not confer resistance to a fusion protein targeting calcium channels. The use of fusion proteins with differing targets could play a role in managing pesticide resistance. © 2014 Society of Chemical Industry