United States Department of Agriculture, Center for Medical, Agricultural, and Veterinary Entomology, Gainesville, FL 32610, USA; Emerging Pathogens Institute, Department of Entomology and Nematology, University of Florida, Gainesville, FL 32610, USA.
Emerging Pathogens Institute, Department of Entomology and Nematology, University of Florida, Gainesville, FL 32610, USA.
Pestic Biochem Physiol. 2022 Aug;186:105171. doi: 10.1016/j.pestbp.2022.105171. Epub 2022 Jul 9.
We explored the potential of two sodium channel activators, veratrine and aconitine, as both insecticides and synergists of natural pyrethrins (NP) on Aedes aegypti adults and larvae. Aconitine was more toxic than veratrine, with an LD of 157 ng/mg compared to 376 ng/mg, on the pyrethroid-susceptible Orlando strain, but only aconitine showed significant resistance in the pyrethroid-resistant Puerto Rico strain (RR = 14.6 in topical application and 8.8 in larval bioassay). When applied in mixtures with piperonyl butoxide (PBO) and NP, large synergism values were obtained on the Orlando strain. Aconitine + PBO mixture synergized NP 21.8-fold via topical adult application and 10.2-fold in larval bioassays, whereas veratrine + PBO synergized NP 5.3-fold via topical application and 30.5-fold in larval bioassays. Less synergism of NP was observed on the resistant Puerto Rico strain, with acontine + PBO synergizing NP only 4.1-fold in topical application (8-fold in larval bioassays) and veratrine + PBO synergizing NP 9.5-fold in topical application (13.3-fold in larval bioassays). When alkaloids were applied directly to the mosquito larval nervous system, veratrine was nearly equipotent on both strains, while aconitine was less active on pyrethroid-resistant nerve preparations (no block at 10 μM compared to block at 1 μM on the susceptible strain). The nerve blocking effect of NP was significantly synergized by both compounds on the pyrethroid-susceptible strain by about 10-fold, however only veratrine synergized NP block on the pyrethroid-resistant strain, also showing 10-fold synergism). These results highlight the potential of site II sodium channel activators as insecticides and their ability to synergize pyrethroids, which may extend the commercial lifetime of these chemistries so essential to public health vector control.
我们探索了两种钠离子通道激活剂，藜芦碱和乌头碱，作为杀虫剂以及天然除虫菊酯（NP）增效剂对成蚊和幼虫的作用。乌头碱比藜芦碱毒性更大，对拟除虫菊酯敏感的奥兰多品系，LC 为 157ng/mg，而对拟除虫菊酯抗性的波多黎各品系，LC 为 376ng/mg，但只有乌头碱在拟除虫菊酯抗性的波多黎各品系中表现出显著的抗性（局部应用时 RR=14.6，幼虫生物测定时 RR=8.8）。当与增效醚（PBO）和 NP 混合应用时，在奥兰多品系中得到了很大的增效作用。乌头碱+PBO 混合物通过局部成年应用增效 NP 21.8 倍，幼虫生物测定增效 10.2 倍，而藜芦碱+PBO 混合物通过局部应用增效 NP 5.3 倍，幼虫生物测定增效 30.5 倍。在抗性波多黎各品系中，NP 的增效作用较小，乌头碱+PBO 仅局部应用增效 4.1 倍（幼虫生物测定增效 8 倍），藜芦碱+PBO 局部应用增效 9.5 倍（幼虫生物测定增效 13.3 倍）。当生物碱直接应用于蚊幼虫的神经系统时，藜芦碱在两种品系上的效价几乎相同，而乌头碱在拟除虫菊酯抗性神经制剂上的活性较低（在敏感品系上 1μM 时阻断，而在抗性品系上 10μM 时无阻断）。NP 的神经阻断作用在拟除虫菊酯敏感品系上被这两种化合物协同增效约 10 倍，但只有藜芦碱协同 NP 阻断了拟除虫菊酯抗性品系，也表现出 10 倍的增效作用）。这些结果突出了位点 II 钠离子通道激活剂作为杀虫剂的潜力及其与拟除虫菊酯协同增效的能力，这可能延长这些对公共卫生病媒控制至关重要的化学物质的商业寿命。
