The discovery of thiamethoxam: a second-generation neonicotinoid

Abstract

Neonicotinoids represent a novel and distinct chemical class of insecticides with remarkable chemical and biological properties. In 1985, a research programme was started in this field, in which novel nitroimino heterocycles were designed, prepared and assayed for insecticidal activity. The methodology for the synthesis of 2-nitroimino-hexahydro-1,3,5-triazines, 4-nitroimino-1,3,5-oxadiazinanes and 4-nitroimino-1,3,5-thiadiazinanes is outlined. Bioassays demonstrated that 3-(6-chloropyridin-3-ylmethyl)-4-nitroimino-1,3,5-oxadiazinane exhibited better insecticidal activity than the corresponding 2-nitroimino-hexahydro-1,3,5-triazine and 4-nitroimino-1,3,5-thiadiazinane. In most tests, this compound was equally or only slightly less active than imidacloprid. A series of structural modifications on this lead structure revealed that replacement of the 6-chloro-3-pyridyl group by a 2-chloro-5-thiazolyl moiety resulted in a strong increase of activity against chewing insects, whereas the introduction of a methyl group as pharmacophore substituent increased activity against sucking pests. The combination of these two favourable modifications led to thiamethoxam (CGA 293 343). Thiamethoxam is the first commercially available second-generation neonicotinoid and belongs to the thianicotinyl sub-class. It is marketed under the trademarks Actara for foliar and soil treatment and Cruiser for seed treatment. The compound has broad-spectrum insecticidal activity and offers excellent control of a wide variety of commercially important pests in many crops. Low use rates, flexible application methods, excellent efficacy and the favourable safety profile make this new insecticide well-suited for modern integrated pest management programmes in many cropping systems.

Toxicity of pymetrozine and thiamethoxam to Aphelinus gossypii and Delphastus pusillus

“…Thiamethoxam is a second-generation neonicotinoid compound with stomach and contact activity. It belongs to the subclass thianicotinyl of the neonicotinoid insecticides, which interferes with the nicotinic acetylcholine receptors in the insect nervous system (Maiensfisch et al, 2001). After foliar, soil application or as seed treatment, it has systemic and long residual activity in several plants for a broad range of commercially important sucking pests and some coleopteran and lepidopteran pests as well.…”

Toxicity of thiamethoxam and imidacloprid to Podisus nigrispinus (Dallas) (Heteroptera: Pentatomidae) nymphs associated to aphid and whitefly control in cotton

“…Imidacloprid and thiamethoxam are considered first-and second-generation of neonicotinoid compounds belonging to the chloronicotinyl and thianicotinyl subclasses, respectively, with both having gut and contact activities (Mullins 1993, Maiensfisch et al 2001. After foliar or soil application or seed treatment, thiamethoxam and imidacloprid have prolonged systemic and residual activity in several crop plants against a broad range of commercially important sucking insect pests.…”

“…Thiamethoxam and imidaclorpid have been recommended mainly as an initial protection against sucking pests, but they lack efficacy against most lepidopteran larvae (Elbert et al 1991, Mullins 1993, Maiensfisch et al 2001, whih are common after the crop reaches its mid cycle. The lack of efficacy of these insecticides against lepidotperan larvae combined with the complexity and costs of establishment of a program with seasonal inoculative release of pest-specific natural enemies, in a multi-pest ecosystem such as cotton, endorse the conservation of generalist predators as an increasingly recognized strategy.…”

Simultaneous Determination of Six Insecticides in Okra (Abelmoschus esculentus L. Moench) by UHPLC-MS/MS

“…Thiacloprid, a neurotoxic insecticide, belongs to family of the neonicotinoids [4]. Thiamethoxam is a second-generation neonicotinoid; it belongs to the thianicotinyl subclass that interferes with the nicotinic acetylcholine receptors in the insect's nervous system, it has systemic and residual activity in several crop plants against broad range pests [5]. Clothianidin, the newest member of the chloronicotinyl insecticide family, it has a high activity against a broad range of insects, including sucking insects, chewing insects, and some lepidopterans [6].…”