Insecticidal activity and mode of action of novel nicotinoids synthesized by new acylpyridinium salt chemistry and directed lithiation |
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Authors: | Christof F Stumpf Thomas C Sparks R Michael Roe |
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Institution: | a Department of Entomology, Campus Box 7647, North Carolina State University, Raleigh, NC 27695-7647, USA b Department of Chemistry, Campus Box 8204, North Carolina State University, Raleigh, NC 27695-8204, USA c Dow AgroSciences, Insect Management Biology, 9330 Zionsville Road, Bldg. 306/G1, Indianapolis, IN 46268, USA |
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Abstract: | Novel acylpyridinium salt chemistry and directed lithiation methodology was developed to add for the first time substitutions directly to the phenylpyridine heterocyclic ring of nicotine. A variety of 3-(1-methylpyrrolidin-2-yl)-4-(alkyl, aromatic, heterocyclic and silanyl) and -N-alkyl pyridines were synthesized (compounds 1-9). In vial tests with the green peach aphid, Myzus persicae, compounds 1-4 were 1.1, 1.8, 2.3 and 1.9×, respectively, more active than nicotine and 64, 40, 31 and 38×, respectively, less active than acetamiprid. Against the western flower thrips, Frankliniella occidentalis, 1-4 were 1.4, 2.1, 2.0 and 1.6×, respectively, more active than nicotine and 9, 6, 6 and 8×, respectively, less active than acetamiprid. For the cotton aphid, Aphis gossypii, the activity of 1-9 was similar to nicotine. Compounds 7 and 9 when incorporated into artificial diet produced low mortality for larvae of the beet armyworm, Spodoptera exigua, but were not active against the corn earworm, Helicoverpa zea. When 1-4 and 6-9 were injected into larvae of the beet armyworm, a variety of symptoms similar to acetamiprid were observed which included tremors, uncoordinated movement, diuresis, paralysis and death. In addition, imidacloprid-binding to membranes from the house fly head, Musca domestica, was inhibited by compounds 1-9, when using a concentration range of 1-100 μM. These studies demonstrate that our new chemistry enhances the insecticidal activity of nicotine with an apparent mode of action as an acetylcholine agonist. |
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Keywords: | Nicotinoid Neonicotinoid Nicotine Acetamiprid Insecticidal activity Mode of action Green peach aphid Cotton aphid Western flower thrips Corn earworm Beet armyworm House fly |
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