On isolated neurons, clothianidin (30 nM) shows significant action [2]. Larvae of monarch butterflies exposed to milkweed (1 µg/L; 36 h) exhibit sublethal effects from clothianidin [3]. In corn and soybean growing fields, clothianidin (0.25 mg/capsule and 0.50 mg/capsule) is present in low amounts in the soil and water [4].

Absorption, Distribution and Excretion
Background: Neonicotinic insecticides are a new type of insecticide widely used worldwide due to their selective toxicity to arthropods and relatively low toxicity to vertebrates. Studies have shown that several neonicotinic insecticides can cause neurodevelopmental toxicity in mammals. This study aimed to establish the relationship between oral intake of neonicotinic insecticides and urinary excretion in humans to facilitate biosurveillance and estimate dietary intake of neonicotinic insecticides in Japanese adults. Methods/Main Findings: Nine healthy adults were given oral microdose of deuterium-labeled neonicotinic insecticides (acetamiprid, thiamethoxam, dinotefuran, and imidacloprid), and 24-hour mixed urine samples were collected for four consecutive days after administration. Excretion kinetics were modeled using one-compartment and two-compartment models, and these models were validated in a microdose study of non-deuterium-labeled neonicotinic insecticides involving 12 healthy adults. Increased concentrations of labeled neonicotinic insecticides in urine were observed after administration. Thiamethoxam was excreted unchanged within 3 days, while most of dinotefuran was excreted unchanged within 1 day. Approximately 10% of the dose of imidacloprid was excreted unchanged. Most acetamiprid was metabolized to desmethylacetamiprid. Neonicotinic insecticides were analyzed in random urine samples from 373 Japanese adults, and daily intakes were estimated. The estimated mean daily intake of these neonicotinic insecticides ranged from 0.53 to 3.66 μg/day. Dinotefuran had the highest neonicotinic insecticide intake in the study population, at 64.5 μg/day, less than 1% of the acceptable daily intake. The recovery rate of radioactive substances after administration to mice was 98.7–99.2%. Following a single oral dose of 5 mg/kg body weight, the drug was readily absorbed and excreted within 168 hours. The overall recovery rate in rats was 95–100%. Following a single oral dose of 2.5 mg/kg body weight or repeated oral doses of 25 mg/kg body weight, the drug was readily absorbed and excreted within 96 hours; however, at doses up to 250 mg/kg, absorption exhibited a biphasic pattern and reached saturation. In a standard metabolic study, CD rats were administered an aqueous suspension via gavage. 0.5% tragali gum, ... Most studies used nitromino-(14)C-labeled or thiazolyl-2-14C-labeled thiamethoxam (active ingredient purity 99.8%; radioactivity purity of both labels >99%). ... Based on the results showing 89% to 95% radioactivity in urine 72 hours after oral administration, nitromino-(14)C-labeled thiamethoxam (2.5 mg/kg) was well absorbed, while the radioactivity in male feces was 6% to 9% and in female feces was 3%. This is consistent with the results of autoradiography studies, which showed that the drug rapidly entered the body and was subsequently rapidly eliminated. The highest residual drug concentration in the liver was observed 72 hours later, but it was less than 1% of the drug concentration in the liver during the first few hours. There was no conclusive evidence of a sex effect, high-dose effect, or repeated-dose effect regarding the observed rapid excretion. This study investigated the absorption, distribution, excretion, and metabolism of [nitroimino-(14)C]- or [thiazolyl-2-(14)C]thiamethoxam [(E)-1-(2-chloro-1,3-thiazolyl-5-ylmethyl)-3-methyl-2-nitroguanidine] in male and female rats following a single oral administration. The doses administered were 5 mg/kg body weight (low dose) and 250 mg/kg body weight (high dose), respectively. In both labeled thiamethoxams, peak carbon-14 concentrations in the blood were reached 2 hours after low-dose oral administration, followed by a decrease in blood carbon-14 concentrations over a half-life of 2.9–4.0 hours. Orally administered carbon-14 is rapidly and extensively distributed to all tissues and organs within 2 hours of administration, particularly concentrated in the kidneys and liver, but is subsequently rapidly and almost completely cleared from all tissues and organs without accumulation. Orally administered carbon-14 is almost completely excreted in urine and feces within 2 days of administration, with approximately 90% of the administered dose excreted in the urine. The main compound in the excrement is thiamethoxam, accounting for more than 60% of the administered dose. The main metabolic reactions of thiamethoxam in rats involve oxidative demethylation to N-(2-chlorothiazol-5-ylmethyl)-N'-nitroguanidine, and the cleavage of the carbon-nitrogen bond between the thiazolium methyl moiety and the nitroguanidine moiety. The portion of the molecule containing the nitroguanidine moiety is primarily converted to N-methyl-N'-nitroguanidine, while the thiazolium moiety is further metabolized to 2-(methylthio)thiazol-5-carboxylic acid. …The biokinetics, excretion, distribution, and metabolic rate of thiamethoxam are not significantly affected by dose level or sex.

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Metabolites/Metabolites
Known neonicotinoid insecticides have substituents of chloropyridinyl methyl (imidacloprid, thiamethoxam, acetamiprid, and nitenpyram), chlorothiazolyl methyl (thiamethoxam or TMX and thiamethoxam or CLO), or tetrahydrofuran methyl (dinotefuran or DIN). We recently reported the metabolism of chloropyridinyl methyl neonicotinoid insecticides in mice, the first part of a comparative study that now includes chlorothiazolyl methyl and tetrahydrofuran methyl analogs. We administered TMX, CLO, two demethylated derivatives (TMX-dm and CLO-dm), and DIN to mice intraperitoneally at a dose of 20 mg/kg for metabolite characterization and pharmacokinetic analysis of brain, liver, plasma, and urine by HPLC/DAD and LC/MSD. 19-55% of each compound was excreted unmetabolized in the urine within 24 hours, and tissue residues were substantially eliminated within 4 hours. Thirty-seven metabolites of TMX, TMX-dm, CLO, and CLO-dm were identified by comparison with synthetic standards; or their structures were inferred based on molecular weight and the 35Cl:37Cl ratio, usually with reference to previous reports or sequence studies of repeated dosings of intermediates. A simple reaction sequence is TMX → TMX-dm or CLO → CLO-dm. CLO-dm has been reported as one of the factors inducing liver cancer in mice by TMX, but unexpectedly, it was partially remethylated to CLO in brain tissue. Nitroguanidine, aminoguanidine, and urea derivatives of the parent compound were detected in tissues, and methylnitroguanidine, methylguanidine, and nitroguanidine were detected in urine. Chlorothiazol formaldehyde (an oxidative cleavage product of TMX and CLO) exhibits considerably higher persistence in the brain, liver, and especially plasma compared to chloropyridinaldehyde and tetrahydrofuran formaldehyde produced by other neonicotinoid insecticides. Chlorothiazol carboxylic acid can be conjugated with glycine or glucuronic acid, or converted to S-methyl and mercaptouric acid derivatives. The metabolism of DIN involves nitro reduction, N-demethylation, N-methylene hydroxylation and amino cleavage, as well as tetrahydrofuran methyl hydroxylation at positions 2, 4 and 5, resulting in 29 preliminarily identified metabolites. The diversity of biodegradation sites and multiple metabolic pathways ensure the accumulation of the parent compound, while providing reportedly active intermediates that can act as nicotine agonists and inducible nitric oxide synthase inhibitors. In a standard metabolic study of CD rats administered via gavage using an aqueous suspension, 0.5% tragali gum, ... most tests used thiamethoxam labeled with nitroimino-14C or thiazolyl-2-(14)C (active ingredient purity 99.8%; radioactivity purity of both labels >99%). ... Unaltered thiamethoxam in urine accounted for 55-73% of the administered label. The main urinary metabolites and their percentages of the administered dose were as follows: (1) N-demethylated product (labeled "TZNG", 7-12%); (2) cleavage product, which separates the methylene carbon on the thiazole group from the adjacent nitrogen atom of the nitroguanidine group (labeled "MNG", 8-13%); and (3) the product of the above two reactions, namely the demethylated product of MNG (labeled "NTG", 1-4%). The methylene carbon on the thiazole ring is part of the complementary cleavage product of MNG (metabolite #2 above), which is rapidly oxidized to a carboxylic acid (named CTCA, 1%). Subsequently, the carboxylic acid combines with a chlorine atom, the chlorine atom is substituted, and then the combination is cleaved to generate a metabolite with a higher content than the initial CTCA—a methyl sulfide analogue (named MTCA, 10%). Besides the approximately 10% to 11% of the parent compound being metabolized between the methylene carbons on the thiazolium ring, primarily producing MNG, CTCA, and MTCA, another notable metabolite is the product of the cleavage between the nitroimino-labeled carbon and the secondary amino group attached to the methylene carbon. This product, named ACT, accounted for 1% of the administered marker. No other identified urinary excretion products reached 1% of the marker. In these studies, only approximately 2–7% of urinary metabolic residues were not identified. Fecal residues contained approximately equal amounts of (1) parent thiamethoxam and (2) denitrated parent thiamethoxam (TMG): each accounting for approximately 1% to 2%. No other compounds extracted from feces exceeded 1% of the administered dose. The main metabolic reactions of thiamethoxam in rats were oxidative demethylation to N-(2-chlorothiazol-5-ylmethyl)-N'-nitroguanidine and the cleavage of the carbon-nitrogen bond between the thiazolium methyl moiety and the nitroguanidine moiety. The nitroguanidine moiety is primarily converted to N-methyl-N'-nitroguanidine, while the thiazolium moiety is further metabolized to 2-(methylthio)thiazol-5-carboxylic acid. The biokinetics, excretion, distribution, and metabolic rate of thiamethoxam are not significantly affected by dose level or sex.

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Biological Half-Life
This study investigated the absorption, distribution, excretion, and metabolism of thiamethoxam [(E)-1-(2-chloro-1,3-thiazol-5-ylmethyl)-3-methyl-2-nitroguanidine] after a single oral administration of [nitroimino-(14)C]- or [thiazolyl-2-(14)C]thiamethoxam to male and female rats. Following low-dose oral administration, peak plasma concentrations of both labeled thiamethoxams were reached at 2 hours, followed by a decrease in plasma concentration, with a half-life of 2.9–4.0 hours.

Toxicity Summary
Identification and Uses: Thiamethoxam is a colorless powder. Thiamethoxam is a neonicotinoid insecticide that can be used as a seed treatment/protectant. Human Studies: Thiamethoxam treatment affects the activation of human mononuclear cell lines in vitro. Animal Studies: Primary eye irritation studies in rabbits showed that mild conjunctivitis resolved within 24 hours. In mice, after treatment for 28 days at dose levels of 0 (feed only), 500, 1000, 2000, or 4000 ppm, body tremors were observed in both male and female mice at a dose of 4000 ppm. At doses of 2000 and 4000 ppm, treatment-related arched posture and lethargy were observed in both male and female mice. At doses of 1000, 2000, and 4000 ppm, a decrease in mean weight gain was observed in both male and female mice. At concentrations of 2000 and 4000 ppm, the mean relative brain weight increased in male rats; at a concentration of 2000 ppm, the mean relative brain weight increased in female rats. No tumors were observed in rats after 2 years of dietary supplementation with 0, 150, 500, 1500, or 3000 ppm thiamethoxam. Significant changes were observed in the kidneys and proventriculus at a concentration of 3000 ppm. Thiamethoxam had few detectable harmful effects on the reproductive system of male rats. Thiamethoxam adversely affected neurobehavioral parameters in mice. In rabbits administered thiamethoxam at doses of 0, 10, 25, 75, and 100 mg/kg/day, developmental toxicity was observed at doses of 75 and 100 mg/kg/day. At a dose of 100 mg/kg/day, absorption increased, and the mean weight of young rabbits decreased significantly. Thiamethoxam was tested in Salmonella typhimurium strains TA1535, TA1537, TA98, and TA100, and Escherichia coli strain WP2uvrA. Based on the response in strain TA1535, the test result was positive for mutagenicity. The response after metabolic activation was generally slightly stronger than the response without activation. Ecotoxicity studies: Thiamethoxam was found to affect the reproduction of male quail by damaging reproductive cells and inhibiting or delaying embryonic development. Non-target aquatic insects are vulnerable to chronic exposure to neonicotinoid insecticides in early developmental stages due to repeated runoff events and long-term residues of these chemicals. Thiamethoxam is extremely toxic to overwintering worker bees before spring egg-laying, making it the most susceptible bee stage discovered to date. Feeding bumblebee (Bombus impatiens Cresson) colonies with thiamethoxam resulted in behavioral changes (reduced worker bee activity, decreased feed intake, reduced wax production, and reduced nectar storage), adversely affecting the colony (reduced queen survival and increased colony weight). Wild bumblebees that rely on worker bees foraging are negatively affected by prolonged exposure to neonicotinoid insecticides at a concentration of 20 ppb. Thiamethoxam impairs the visual guidance and navigation memory of solitary bees (Osmia cornuta). Bees treated with 1 ng of thiamethoxam showed a significant increase in total distance traveled during the experiment. Furthermore, this dose also led to reduced rest time and increased duration and frequency of upside-down lying positions. Additionally, compared to untreated bees, bees in the 0.5 ng/bee dose group showed significant changes in all tested parameters at 60 minutes post-treatment. Prolonged exposure to a concentration of 15 μg/kg in winter affects the specificity of early long-term memory (24 hours) in bees. The lowest dose (0.1 ng/bee) had no significant effect on the locomotion activity of bees during the experiment compared to untreated bees. A sublethal effect was observed in monarch butterflies (larvae) at a concentration of 1 ppb.

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Toxicity Data
LC50 (Rat) >6140 mg/m3;

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Interactions
As commonly used insecticides, chlorpyrifos (CPF), tranexamic acid (FEN), thiamethoxam (CLO), and acetochlor (ACE) are widely used on crops worldwide. This study used Eisenia fetida as the test organism to evaluate the combined toxicity of binary, ternary, and quaternary mixtures of these insecticides. The combined toxicity was studied using the combination index (CI) method and visualized using equivalence line plots. The data were then compared with traditional concentration-additive (CA) and independent-action (IA) models. The two binary mixtures of CPF+FEN and FEN+ACE, the two ternary mixtures of CPF+CLO+FEN and CPF+FEN+ACE, and the quaternary mixture of CPF+FEN+ACE+CLO all showed significant synergistic effects.
The CI method was compared with the classic CA and IA models, and the results showed that the CI method can accurately predict the synergistic toxicity of these chemicals. The results indicate that due to the complex synergistic and antagonistic effects, the synergistic effects of these pesticides cannot be predicted solely based on the mechanism of action. Greater attention should be paid to the potential synergistic effects of chemical interactions, as this could cause serious ecological problems.
Background: Neonicotinic insecticides have been identified as a significant factor contributing to the decline in bee diversity. However, the effects of these compounds under field conditions remain uncertain. Most studies have focused on the Western honeybee (Apis mellifera) and tested single compounds. However, in agricultural environments, bees are frequently exposed to multiple insecticides. We investigated the synergistic lethal effects between a neonicotinic insecticide (thiamethoxam) and an ergosterol biosynthesis inhibitor (propiconazole) after oral exposure in three bee species (Western honeybee, bumblebees, and horned bees) under laboratory conditions. Results: We developed a novel method based on a binomial proportionality test to analyze synergistic effects. We estimated the amount of thiamethoxam ingested by bees per feeding session while foraging in coated rapeseed fields. We found that all three bee species exhibited significant synergistic lethal effects after exposure to non-lethal doses of propiconazole and their respective median lethal doses (LD10) of thiamethoxam. In honeybees (A. mellifera) (4 h and 24 h) and bumblebees (B. terrestris) (4 h), significant synergism was observed only at the initial assessment time point, but in bicornis (O. bicornis), this synergism persisted throughout the experiment (96 h). Bicornis was also the species most susceptible to thiamethoxam. Conclusion: Our results highlight the importance of testing pesticide combinations that may occur in agricultural settings and the importance of including multiple bee species in environmental risk assessment schemes. Revealing the interactions between pesticides and bee infections is crucial for understanding the challenges faced by pollinating insects and the extent of bee health impairment. This paper investigates the individual and combined effects of three different pesticides (dimethoate, thiamethoxam, and flufenoxuron) and American larval rot (AFB) infection on bee larval mortality and cellular immune responses. We demonstrated a synergistic effect when larvae are exposed to sublethal doses of dimethyl sulfide or thiamethoxam in combination with the powdery mildew pathogen, Paenibacillus larvae. In larvae with this combined exposure, the observed mortality rate was significantly higher than the sum of the expected individual stressors, accompanied by a sharp decline in both total and differential hemocyte counts. Our findings highlight the potential to reveal previously undiscovered sublethal effects of pesticides on bee colony health by characterizing larval cellular responses to single and combined stressors.

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Non-human toxicity values
Rats oral LD50 >5000 mg/kg /thiamethoxam technical grade/ /from table/
Mice oral LD50 425 mg/kg /thiamethoxam technical grade/ /from table/
Rats dermal LD50 >2000 mg/kg /thiamethoxam technical grade/ /from table/
Rats dermal LD50 >4000 mg/kg /Poncho 600/ /from table/
Rats oral LD50 2000 mg/kg /Poncho 600/ /from table/

[1]. Uneme H. Chemistry of clothianidin and related compounds. J Agric Food Chem. 2011 Apr 13;59(7):2932-7.

[2]. Thiamethoxam is a neonicotinoid precursor converted to clothianidin in insects and plants. Pesticide biochemistry and physiology, 2003, 76(2): 55-69.

[3]. Non-target effects of clothianidin on monarch butterflies. Naturwissenschaften. 2015 Apr;102(3-4):19.

[4]. Fate and effects of clothianidin in fields using conservation practices. Environ Toxicol Chem. 2015 Feb;34(2):258-65.

(E)-Thiamethoxam is a thiamethoxam insecticide with an E configuration at the C=N bond of its nitroguanidine moiety. It is a neonicotinoid insecticide.

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Mechanism of Action
Thiamethoxam is a neonicotinoid insecticide developed in the early 21st century. We recently demonstrated that it is a complete agonist of both α-cladosporin-sensitive and α-cladosporin-insensitive nicotinic acetylcholine receptors expressed in unpaired midline neurons on the dorsal side of cockroaches. Thiamethoxam can act as an agonist of imidacloprid-insensitive nAChR2 receptors, and the internal regulation of cAMP concentration affects the sensitivity of nAChR2 to thiamethoxam. In this study, we demonstrate that cAMP regulates the agonist effect of thiamethoxam through α-cladosporin-sensitive and α-cladosporin-insensitive receptors. The thiamethoxam-induced current-voltage curves are correlated with thiamethoxam concentration. At a 10 μM thiamethoxam concentration, the current-voltage curves show a linear change with increasing cAMP concentration. 0.5 μM α-Bungarus venom blocked the action of thiamethoxam, indicating that cAMP regulation is mediated through α-Bungarus venom-sensitive receptors. At 1 mM thiamethoxam concentration, the effect of cAMP was associated with α-Bungarus venom-insensitive receptors, as both 5 μM mecaramine and 20 μM d-tubocurarine blocked the thiamethoxam-induced current. Furthermore, we found that 1 mM thiamethoxam significantly increased intracellular calcium ion concentration. These data further confirm that calcium signaling pathways, including cAMP, regulate the effect of thiamethoxam on insect nicotinic acetylcholine receptors. We propose that intracellular calcium pathways (such as cAMP) may be targets for regulating the action of neonicotinoid insecticides.

C6H8CLN5O2S

249.67

249.008

210880-92-5

Clothianidin-d3;1262776-24-8

86287519

Off-white to light yellow solid powder

1.7±0.1 g/cm3

435.2±55.0 °C at 760 mmHg

178.8 °C

217.0±31.5 °C

0.0±1.0 mmHg at 25°C

1.709

0.4

2

5

4

15

258

0

CN/C(=N\[N+](=O)[O-])/NCC1=CN=C(S1)Cl

PGOOBECODWQEAB-UHFFFAOYSA-N

InChI=1S/C6H8ClN5O2S/c1-8-6(11-12(13)14)10-3-4-2-9-5(7)15-4/h2H,3H2,1H3,(H2,8,10,11)

1-[(2-chloro-1,3-thiazol-5-yl)methyl]-3-methyl-2-nitroguanidine

TI-435; TI435; TI 435

2934.99.9001

Powder      -20°C    3 years

                     4°C     2 years

In solvent   -80°C    6 months

                  -20°C    1 month

Room temperature (This product is stable at ambient temperature for a few days during ordinary shipping and time spent in Customs)

DMSO : ~100 mg/mL (~400.51 mM)

Solubility in Formulation 1: ≥ 2.5 mg/mL (10.01 mM) (saturation unknown) in 10% DMSO + 40% PEG300 + 5% Tween80 + 45% Saline (add these co-solvents sequentially from left to right, and one by one), clear solution.
For example, if 1 mL of working solution is to be prepared, you can add 100 μL of 25.0 mg/mL clear DMSO stock solution to 400 μL PEG300 and mix evenly; then add 50 μL Tween-80 to the above solution and mix evenly; then add 450 μL normal saline to adjust the volume to 1 mL.
Preparation of saline: Dissolve 0.9 g of sodium chloride in 100 mL ddH₂ O to obtain a clear solution.

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Solubility in Formulation 2: ≥ 2.5 mg/mL (10.01 mM) (saturation unknown) in 10% DMSO + 90% (20% SBE-β-CD in Saline) (add these co-solvents sequentially from left to right, and one by one), clear solution.
For example, if 1 mL of working solution is to be prepared, you can add 100 μL of 25.0 mg/mL clear DMSO stock solution to 900 μL of 20% SBE-β-CD physiological saline solution and mix evenly.
Preparation of 20% SBE-β-CD in Saline (4°C，1 week): Dissolve 2 g SBE-β-CD in 10 mL saline to obtain a clear solution.

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Solubility in Formulation 3: ≥ 2.5 mg/mL (10.01 mM) (saturation unknown) in 10% DMSO + 90% Corn Oil (add these co-solvents sequentially from left to right, and one by one), clear solution.
For example, if 1 mL of working solution is to be prepared, you can add 100 μL of 25.0 mg/mL clear DMSO stock solution to 900 μL of corn oil and mix evenly.

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 (Please use freshly prepared in vivo formulations for optimal results.)