Voltage-gated sodium channels are the primary target of pyrethroid insecti-cides.Mutations in sodium channel confer knockdown resistance(kdr)to pyrethroids in various arthropod pests.Haedoxan A(HA)is the major insecticidal component from Phryma leptostachya.It has been shown that HA alters electrical responses at the Drosophila neuromuscular junction and modifies the gating properties of cockroach sodium channels expressed in Xenopus oocytes.However,whether sodium channel mu-tations that confer pyrethroid resistance also affect the action of HA is unknown.In this study,we conducted bioassays using HA and permethrin in two Drosophila melanogaster strains:w1118,an insecticide-susceptible strain,and parats1,a pyrethroid-resistant strain due to a I265N mutation in the sodium channel,and identified a new case of negative cross-resistance(NCR)between permethrin and HA.Both parats1 larvae and adults were more resistant to permethrin,as expected.However,both parats1 larvae and adults were more sensitive to HA compared to w1118.We confirmed that the I265N mutation reduced the sensitivity to permethrin of a Drosophila sodium channel variant,DmNav22,expressed in Xenopus oocytes.Interestingly,the I265N mutation also abolished the effect of HA on sodium channels.Further characterization showed that I265 on the sodium channels is critical for the action of both pyrethroids and HA on sodium channels,pointing to an over-lapping mode of action between pyrethroids and HA on the sodium channel.Overall,our results suggest an I265N-independnt mechanism(s)in parats1 flies that is responsible for the NCR between permethrin and HA at the whole insect level.

Xingtao Qie;Yuzhe Du;Ahmed A.A.Aioub;Ke Dong;Zhaonong Hu

Institution of Pesticide Science,College of Plant Protection,Northwest A&F University,Yangling,Shaanxi 712100,China;Key Labora-tory of Botanical Pesticide R&D in Shaanxi Province,Yangling,Shaanxi 712100,China;Southern Insect Management Research Unit,Agriculture Research Service,United States Department of Agriculture,141 Experiment Station Road,Stoneville,MS 38776,USA;Plant Protection Department,Faculty of Agriculture,Zagazig University,Zagazig,44511 Egypt;Department of Biology,Duke University,Durham,NC 27708,USA

中国昆虫科学（英文版）

[1]Xingtao Qie;Yuzhe Du;Ahmed A.A.Aioub;Ke Dong;Zhaonong Hu-.Negative cross-resistance of a pyrethroid-resistant Drosophila mutant to Phryma leptostachya-derived haedoxan A)[J].中国昆虫科学（英文版）,2022(03):817-826

Phryma,leptostachya,haedoxan,insecti,cides,Haedoxan,cockroach,permethrin,w1118,parats1,I265N,DmNav22,I265,independnt

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