Jim X. Huang

Discovery and Characterization of Sulfoxaflor, a Novel Insecticide Targeting Sap-Feeding Pests

The discovery of sulfoxaflor [N-[methyloxido[1-[6-(trifluoromethyl)-3-pyridinyl]ethyl]-λ(4)-sulfanylidene] cyanamide] resulted from an investigation of the sulfoximine functional group as a novel bioactive scaffold for insecticidal activity and a subsequent extensive structure-activity relationship study. Sulfoxaflor, the first product from this new class (the sulfoximines) of insect control agents, exhibits broad-spectrum efficacy against many sap-feeding insect pests, including aphids, whiteflies, hoppers, and Lygus, with levels of activity that are comparable to those of other classes of insecticides targeting sap-feeding insects, including the neonicotinoids. However, no cross-resistance has been observed between sulfoxaflor and neonicotinoids such as imidacloprid, apparently the result of differences in susceptibility to oxidative metabolism. Available data are consistent with sulfoxaflor acting via the insect nicotinic receptor in a complex manner. These observations reflect the unique structure of the sulfoximines compared with neonicotinoids.

Biological characterization of sulfoxaflor, a novel insecticide

BACKGROUND The commercialization of new insecticides is important for ensuring that multiple effective product choices are available. In particular, new insecticides that exhibit high potency and lack insecticidal cross-resistance are particularly useful in insecticide resistance management (IRM) programs. Sulfoxaflor possesses these characteristics and is the first compound under development from the novel sulfoxamine class of insecticides. RESULTS In the laboratory, sulfoxaflor demonstrated high levels of insecticidal potency against a broad range of sap-feeding insect species. The potency of sulfoxaflor was comparable with that of commercial products, including neonicotinoids, for the control of a wide range of aphids, whiteflies (Homoptera) and true bugs (Heteroptera). Sulfoxaflor performed equally well in the laboratory against both insecticide-susceptible and insecticide-resistant populations of sweetpotato whitefly, Bemisia tabaci Gennadius, and brown planthopper, Nilaparvata lugens (Stål), including populations resistant to the neonicotinoid insecticide imidacloprid. These laboratory efficacy trends were confirmed in field trials from multiple geographies and crops, and in populations of insects with histories of repeated exposure to insecticides. In particular, a sulfoxaflor use rate of 25 g ha(-1) against cotton aphid (Aphis gossypii Glover) outperformed acetamiprid (25 g ha(-1) ) and dicrotophos (560 g ha(-1) ). Sulfoxaflor (50 g ha(-1) ) provided a control of sweetpotato whitefly equivalent to that of acetamiprid (75 g ha(-1) ) and imidacloprid (50 g ha(-1) ) and better than that of thiamethoxam (50 g ha(-1) ). CONCLUSION The novel chemistry of sulfoxaflor, its unique biological spectrum of activity and its lack of cross-resistance highlight the potential of sulfoxaflor as an important new tool for the control of sap-feeding insect pests.

Gelatin encapsulation of chloropicrin and 1,3-dichloropropene as fumigants for soilborne diseases in the greenhouse cultivation of cucumber and tomato

Abstract Combined use of chloropicrin (Pic) and 1,3-dicloropropene (1,3-D) is as effective as methyl bromide (MB) at controlling soilborne diseases in many trials and commercial uses. However, Pic and 1,3-D are both highly volatile and may pose strong exposure risks to humans and the environment. A gelatin capsule formulation containing Pic and 1,3-D has been developed to reduce exposure risks to workers and bystanders and improved application safety. We conducted two experiments in tomato and cucumber greenhouses located in Beijing and Qingdao, China, to study the efficacy of Pic plus 1,3-D gelatin capsules applied at different dosages and soil depths. Results indicated that both injection and gelatin capsules of Pic plus 1,3-D provided good control of soil nematodes and reduced disease index of Fusarium wilt and root-knot nematode. Plant yield of tomato and cucumber treated with gelatin capsules was similar to MB treatment. Based on our results, gelatin capsules applied at a soil depth of 15 cm provided better control of soilborne diseases and led to higher fruit yield compared to an application depth of 5 cm. In conclusion, a gelatin capsule of Pic plus 1,3-D is a promising and novel formulation, which not only shows good efficacy in controlling soilborne diseases, but also reduces potential exposure risks of fumigants.