Sap-feeding insects have developed resistance to nearly all other kinds of insecticides[6] but flupyradifurone is effective at controlling aphids and whitefly, thereby maintaining yields of crops such as vegetables, fruits, cotton, and coffee.[7] It also demonstrated positive toxicological and ecotoxicological safety.[2]
According to a study by Bayer, who developed the compound, flupyradifurone has a high rate of uptake by plants and crops. The authors used phosphor imaging analysis to monitor the uptake and translocation of [pyridinylmethyl-14C]-labeled flupyradifurone by tomato plants.[2] The result revealed fast root uptake and the even distribution of labeled flupyradifurone in the entire plant. Flupyradifurone is delivered via xylem translocation in the plants. The concentration in the plants reached the highest point in 7 and 14 days. After 24 days of the application, a significant decline is observed.[2] Flupyradifurone also featured excellent speed of action. The speed of action can be observed by the prohibition of honeydew excretion. After applying the flupyradifurone to the plant by spraying, the honeydew excretion is inhibited within 2 hours and all the aphids die after 48 hours. The result demonstrated that flupyradifurone has an exceptional speed of action compared to other insecticides.[2]
Flupyradifurone presented potent efficacy in controlling aphids and whiteflies. According to bioassays research, the flupyradifurone has lower LC50 numbers of aphid and whitefly compared to imidacloprid.[2] In the field trial, flupyradifurone controlled the lettuce aphid at a favorable rate via foliar applying. It had the highest efficiency (96%) of controlling lettuce aphid after 6–10 days of the application.[2]
Flupyradifurone is structurally related to the natural insecticide, stemofoline which occurs in the plant species Stemonajaponica.[9][2] Stemofoline has some advantageous features, such as being fast-acting and an effective antifeedant, but does not efficiently bind to insect nicotinic acetylcholine receptors.[10][11]
There are two ways to synthesis flupyradifurone. First, flupyradifurone can be synthesized from reacting tetronic acid with 2,2-difluoroethylamine to produce the intermediate, 4-[(2-fluoroethyl)amino]furane-2(5H)-one. Heating the reaction intermediate with 2-chloro-5-(chloromethyl)pyridine in THF under reflux yields flupyradifurone.[2] In the second method, tetronic acid, 4-touluenesulfonic acid, and N-[(6-chloropyridin-3-yl)methyl]-2,2-difluoroethane-1-amine in toluene are heated under reflux for 2 hours to produce flupyradifurone.[2]
For the non-target species, flupyradifurone also presents toxicological safety at low concentration.[12][disputed (for: ref states "Aquatic Life Exposure – Flupyradifurone is very highly toxic to aquatic and benthic invertebrates." and that it is mobile from treated fields into groundwater) – discuss] Flupyradifurone will still bind to the nicotinic acetylcholine receptors of honey bees, however, it will only affect the taste and appetitive learning performance at the highest labeled concentration.[13] The LD50 of honey bee acute contact is >100 μg/bee and acute oral is 1200 ng/bee. For bumblebee, the acute contact LD50 is >100 μg/bee.
References
^Jeschke, Peter; Nauen, Ralf; Beck, Michael Edmund (2013). "Nicotinic Acetylcholine Receptor Agonists: A Milestone for Modern Crop Protection". Angewandte Chemie International Edition. 52 (36): 9464–9485. doi:10.1002/anie.201302550. ISSN1521-3773. PMID23934864.
^Bass, Chris; Puinean, Alin M.; Zimmer, Christoph T.; Denholm, Ian; Field, Linda M.; Foster, Stephen P.; Gutbrod, Oliver; Nauen, Ralf; Slater, Russell; Williamson, Martin S. (2014-08-01). "The evolution of insecticide resistance in the peach potato aphid, Myzus persicae". Insect Biochemistry and Molecular Biology. 51: 41–51. doi:10.1016/j.ibmb.2014.05.003. hdl:2299/19394. ISSN0965-1748. PMID24855024.
^Kaltenegger, Elisabeth; Brem, Brigitte; Mereiter, Kurt; Kalchhauser, Hermann; Kählig, Hanspeter; Hofer, Otmar; Vajrodaya, Srumya; Greger, Harald (August 2003). "Insecticidal pyrido[1,2-a]azepine alkaloids and related derivatives from Stemona species". Phytochemistry. 63 (7): 803–816. doi:10.1016/s0031-9422(03)00332-7. ISSN0031-9422. PMID12877922.
^Mungkornasawakul, Pitchaya; Pyne, Stephen G.; Jatisatienr, Araya; Supyen, Damrat; Jatisatienr, Chaiwat; Lie, Wilford; Ung, Alison T.; Skelton, Brian W.; White, Allan H. (2004-03-02). "Phytochemical and Larvicidal Studies on Stemona curtisii: Structure of a New Pyrido[1,2-a]azepine Stemona Alkaloid". Journal of Natural Products. 67 (4): 675–677. doi:10.1021/np034066u. ISSN0163-3864. PMID15104502.