Thiamethoxam Treatment Research Articles

Expression and Functional Analysis of Two Cytochrome P450 Monooxygenase Genes and a UDP-Glycosyltransferase Gene Linked with Thiamethoxam Resistance in the Colorado Potato Beetle.

Cytochrome P450 monooxygenases (P450s) and UDP-glycosyltransferases (UGTs) are involved in the evolution of insecticide resistance. Leptinotarsa decemlineata (Say), the Colorado potato beetle (CPB), is a notorious insect that has developed resistance to various insecticides including neonicotinoids. This study investigated whether the differentially expressed P450 genes CYP9Z140 and CYP9AY1 and UGT gene UGT321AP1, found in our transcriptome results, conferred resistance to thiamethoxam in L. decemlineata. Resistance monitoring showed that the sampled field populations of L. decemlineata adults collected from Urumqi City and Qapqal, Jimsar, and Mulei Counties of Xinjiang in 2021-2023 developed low levels of resistance to thiamethoxam with resistance ratios ranging from 6.66- to 9.52-fold. Expression analyses indicated that CYP9Z140, CYP9AY1, and UGT321AP1 were significantly upregulated in thiamethoxam-resistant populations compared with susceptible populations. The expression of all three genes also increased significantly after thiamethoxam treatment compared with the control. Spatiotemporal expression patterns showed that the highest expression of CYP9Z140 and CYP9AY1 occurred in pupae and the midgut, whereas UGT321AP1 was highly expressed in adults and Malpighian tubules. Knocking down all three genes individually or simultaneously using RNA interference increased the sensitivity of adult L. decemlineata to thiamethoxam. These results suggest that overexpression of CYP9Z140, CYP9AY1, and UGT321AP1 contributes to the development of thiamethoxam resistance in L. decemlineata and provides a scientific basis for improving new resistance management of CPB.

Wheat seed quality assessment after thiamethoxam treatment: integrating optical techniques with standard methods

Insecticide treatment of seeds protects against early field pests. Therefore, studies on the physiological and biochemical responses of crops exposed to insecticides are required. Standard (non-optical) tests are used to evaluate the physiological quality of seeds. However, some tests may need to be more sensitive to observe possible differences between the control group and the groups of interest. Optical techniques such as ultra- weak photon emission and Fourier transform infrared spectroscopy have been discovered to aid standard tests. The effects of different doses of Thiamethoxam were evaluated on wheat seeds from the cultivar FPS Certero. Samples were divided into five groups: control and treated with 75, 150, 225, and 300 mL of Thiamethoxam for each 100 kg of seeds. The ultra-weak photon emission results showed that it was possible to classify the treatment doses through the intensity of photon emissions. The Fourier transform infrared spectroscopy analyses can be used for biological analysis but are unrelated to Thiamethoxam seed treatment. Considering the findings, optical techniques can be used as an additional tool for assessing the physiological quality of seeds.

The Effect of Different Thiamethoxam Concentrations on Riptortus pedestris Development and Fecundity.

The stink bug, Riptortus pedestris (Fabricius) (Hemiptera: Alydidae), is a highly destructive pest that significantly damages legume crops in East and South Asia. Neonicotinoid insecticides containing thiamethoxam are widely used to control R. pedestris in soybean fields. However, the current knowledge on the impact of different thiamethoxam concentrations on R. pedestris growth and reproduction is lacking and insufficient. The present study investigated the effects of thiamethoxam on the biological traits of R. pedestris after treatment with LC10 (19.8 mg/L), LC20 (31.6 mg/L), LC30 (44.2 mg/L), LC40 (58.9 mg/L), and LC50 (77.0 mg/L) concentrations. These five thiamethoxam concentrations (LC10~LC50) reduced adult longevity and fecundity in the F1 generation females. Thiamethoxam treatment also significantly decreased the population trend index, intrinsic rate of increase, net reproductive rate, gross reproductive rate, and finite rate of increase and increased the mean generation time. These results show that thiamethoxam hinders and suppresses the development and growth of the F1 population of R. pedestris. Thiamethoxam is recommended for spray control during peak adult emergence, as it not only has a controlling effect on the parental generation but also a negative impact on the F1 generations.

Plant protection consequences in Hungary of the withdrawal of systemic active substances from sugar beet seed treatment

After decades of development, neonicotinoids were widely used in Hungarian sugar beet production and seeds included thiamethoxam treatment by 2019 increasing protection against early spring pests. In Hungary, neonicotides’ influence on bee health led to their removal of emergency authorization. In the absence of thiamethoxam in 2020, experience showed that multiple treatments were needed to protect beet from pests early spring pests. Repeated applications of mostly pyrethroids have proved suitable; however, in sugar beet, this has resulted in a multiple increase in environmental stress and honey bee mortality, as well as increased input values. The aim of this work is to explore the current state of production and collect new alternative options for applying effectively in Hungarian sugar beet production technology, against early spring pests.

Neonicotinoid Sunflower Seed Treatment, While Not Detected in Pollen and Nectar, Still Impacts Wild Bees and Crop Yield

Neonicotinoid seed treatments are commonly used in agricultural production even though their benefit to crop yield and their impact on pollinators, particularly wild bees, remains unclear. Using an on-farm matched pair design in which half of each field was sown with thiamethoxam treated seed and half without, we assessed honey bee and wild bee exposure to pesticides in sunflower fields by analyzing pesticide residues in field soil, sunflower pollen and nectar, pollen-foraging and nectar-foraging honey bees, and a sunflower specialist wild bee (Melissodes agilis). We also quantified the effects of thiamethoxam-treated seed on wild bee biodiversity and crop yield. M. agilis abundance was significantly lower with thiamethoxam treatment and overall wild bee abundance trending lower but was not significantly different. Furthermore, crop yield was significantly lower in plots with thiamethoxam treatment, even though thiamethoxam was only detected at low concentrations in one soil sample (and its primary metabolite, clothianidin, was never detected). Conversely, wild bee richness was significantly higher and diversity was marginally higher with thiamethoxam treatment. Nectar volumes harvested from the nectar-foraging honey bees were also significantly higher with thiamethoxam treatment. Several pesticides that were not used in the sunflower fields were detected in our samples, some of which are known to be deleterious to bee health, highlighting the importance of the landscape scale in the assessment of pesticide exposure for bees. Overall, our results suggest that thiamethoxam seed treatments may negatively impact wild bee pollination services in sunflower. Importantly, this study highlights the advantages of the inclusion of other metrics, such as biodiversity or behavior, in pesticide risk analysis, as pesticide residue analysis, as an independent metric, may erroneously miss the impacts of field realistic pesticide exposure on bees.

Metabolic responses of tea (Camellia sinensis L.) to the insecticide thiamethoxam.

Thiamethoxam (TMX) is insecticidal, but also can trigger physiological and metabolic reactions of plant cycles. The objective of this work was to evaluate the physiological and metabolic effect of TMX on tea plants and its potential benefits. In this study, dose of TMX (0.09, 0.135 and 0.18 kg a.i./ha) were tested. Except for peroxidase (POD) and glutathione S-transferase (GST), chlorophyll, carotenoid, catalase (CAT) and malondialdehyde (MDA) were significantly affected compared with the controls. The CAT activity was increased by 3.38, 1.71, 2.91 times, respectively, under three doses of TMX treatment. The metabolic response between TMX treatment and control groups on the third day was compared using a widely targeted metabolomics. A total of 97 different metabolites were identified, including benzenoids, flavonoids, lipids and lipid-like molecules, organic acids and derivatives, organic nitrogen compounds, organic oxygen compounds, organoheterocyclic compounds, phenylpropanoids and polyketides, and others. Those metabolites were mapped on the perturbed metabolic pathways. The results demonstrated that the most perturbation occurred in flavone and flavonol biosynthesis. The beneficial secondary metabolites luteolin and kaempferol were upregulated 1.46 and 1.31 times respectively, which protect plants from biotic and abiotic stresses. Molecular docking models suggest interactions between TMX and flavonoid 3-O-glucosyltransferase. Thiamethoxam spray positively promoted the physiological and metabolic response of tea plants. And this work also provided the useful information of TMX metabolism in tea plants as well as rational application of insecticides. © 2023 Society of Chemical Industry.

Efficacy of Some Botanical Pesticides Against Mustard Aphid <i>Lipaphis erysimi</i> (Kalt.) In <i>Brassica napus</i>

Field experiment on canola type variety of gobhi sarson, GSC 7 was conducted on 20 locations in district SAS Nagar during rabi 2021 and 2022 to evaluate botanical pesticides against mustard aphis Lipaphis erysimi (Kalt.). Seven treatments viz., mixing of non-recommended insecticides (Farmer’s practice), spray thiamethoxam 25WG @ 100 g/ ha, spray homemade neem extract @ 2.5 l, 3.75 l and 5 l/ ha, spray azadirachtin 0.15 EC (1500 ppm) @ 1.25 l/ ha and untreated control were included and evaluated at farmer’s field. Highest crop yield (20.14 q/ ha) was obtained with thiamethoxam followed by azadirachtin spray (19.64 q/ ha) which was on par with homemade neem extract treatment @ 5 l/ ha. Similarly, B:C ratio was found maximum (3.45) in thiamethoxam treatment. The efficacy of all treatments was found maximum on third day after spray which later decreased with time.

Sublethal Effects of Neonicotinoid Insecticides on the Development, Body Weight and Economic Characteristics of Silkworm.

Silkworm Bombyx mori (L.) (Lepidoptera: Bombycidae) is a critical insect for silk producers, but the inappropriate application of insecticides negatively affects the physiology and behavior of silkworms. This study found that the effects of neonicotinoid insecticides applied using two spraying methods on the growth and development of silkworms were different: the median lethal concentration (LC50) values of two pesticides applied using the leaf-dipping method were 0.33 and 0.83 mg L-1 and those of two pesticides applied using the quantitative spraying method were 0.91 and 1.23 mg kg-1. The concentration of pesticides on the mulberry leaves did not decrease after their application using the quantitative spraying method, and a uniform spraying density was observed after the mulberry leaves were air-dried (no liquid) under realistic conditions. We then treated silkworms with the quantitative spraying method and leaf-dipping method. The treatment of silkworm larvae with imidacloprid and thiamethoxam at sublethal concentrations significantly prolonged the development time and significantly decreased the weight and pupation rate, as well as economic indicators of enamel layers and sputum production. Thiamethoxam treatment significantly increased the activities of carboxylesterase (CarE) and glutathione-S-transferase (GST). The activity of CarE and GST increased, decreased, and then increased, and the highest activity was detected on the 10th and 12th days. Thiamethoxam exposure significantly elevated the transcription levels of CarE-11, GSTe3 and GSTz2 and induced DNA damage in hemocytes. This study confirmed that the quantitative spray method is more stable than the leaf-dipping method. Moreover, imidacloprid and thiamethoxam treatment affected the economy and indexes of silkworms and induced changes in detoxification enzymes and DNA damage in silkworms. These results provide a basis for understanding the mechanism of the sublethal effects of insecticides on silkworms.

Effect of thiamethoxam on the behavioral profile alteration and toxicity of adult zebrafish at environmentally relevant concentrations

Thiamethoxam (THM) is a commercial neonicotinoid insecticide with broad-spectrum insecticidal activity. It has been widely detected in the aquatic environment, but its behavioral toxicity on aquatic organisms received limited attention. In this study, adult zebrafish were exposed to THM at three levels (0.1, 10, and 1000 μg/L) for 45 days to investigate its effect on their ecological behavior, histopathology, bioaccumulation, and stress response. The bioconcentration factor in zebrafish brain was significantly higher (p < 0.05) at low concentration of THM (0.1 μg/L) than in other treatment groups. In terms of individual behavior, the locomotor activity, aggregation, and social activity of fish were enhanced after THM exposure, but the memory of the food zone was disturbed and abnormal swimming behavior was observed. THM exposure caused brain tissue necrosis, erythrocyte infiltration, cloudy swelling, and other pathological changes in brain tissue and affected the concentrations of acetylcholinesterase and cortisol related to neurotoxicity. The condition factor and organ coefficients (brain, heart, and intestine) of zebrafish were markedly impacted by THM treatment at 0.1 and 1000 μg/L, respectively. This finding showed that THM was more harmful to fish behavior than lethality, reproduction, and growth, and a behavioral study can be a useful tool for ecological risk assessment.

Comparison of the effectiveness of thiamethoxam and its main metabolite clothianidin after foliar spraying and root irrigation to control Myzus persicae on peach

The green peach aphid, Myzus persicae, is one of the most economically important pests in peach-growing areas around the world. In many countries, the application of insecticides is the main method to control and reduce the population of M. persicae. In this study, we investigated the effects and persistence of thiamethoxam against M. persicae by foliar spraying and root irrigation. The residues of thiamethoxam and clothianidin in peach were determined to assess food safety. The results showed that thiamethoxam treatment significantly reduced the population of M. persicae through foliar spraying and root irrigation. And the persistence of root irrigation on M. persicae was significantly longer than that of spraying. Thiamethoxam and clothianidin were absorbed by the roots, transported to other parts of the plant, and concentrated in the leaves, especially new leaves. The final residues of thiamethoxam and clothianidin in peaches were below the maximum residue limit (MRLs). These results suggested that thiamethoxam is more effective in M. persicae control through root irrigation than foliar spraying. The persistence of root irrigation on M. persicae was significantly longer than that of spraying. These results shed some light upon the control of M. persicae by root irrigation of thiamethoxam.

Integration analysis of PacBio SMRT- and Illumina RNA-seq reveals P450 genes involved in thiamethoxam detoxification in Bradysia odoriphaga

The sciarid fly Bradysia odoriphaga is a serious pest of Chinese chive (Liliaceae). Neonicotinoid insecticides including thiamethoxam have been used for B. odoriphaga control. However, thiamethoxam resistance in B. odoriphaga has developed in recent years. To identify potential genes involved in detoxification metabolism of thiamethoxam in B. odoriphaga, a PacBio single-molecule real-time (SMRT) transcriptome sequencing and Illumina RNA-seq analysis on thiamethoxam treated B. odoriphaga were performed to explore differentially expressed genes in B. odoriphaga. After SMRT sequencing, analysis of Illumina RNA-Seq data showed a total of 172 differentially expressed genes (DEGs) after thiamethoxam treatment, among which eight upregulated DEGs were P450 genes that may be related to thiamethoxam metabolism. The qRT-PCR results of the eight up-regulated P450 unigenes after thiamethoxam treatment were consistent with RNA-Seq data. Furthermore, oral delivery mediated RNA interference of the eight upregulated P450 transcripts followed by insecticide bioassay was conducted, and three P450 unigenes were verified to be related to thiamethoxam detoxification in B. odoriphaga. This study provides new information about the P450 genes involved in thiamethoxam detoxification in B. odoriphaga.

Transcriptional analysis of Bemisia tabaci MEAM1 cryptic species under the selection pressure of neonicotinoids imidacloprid, acetamiprid and thiamethoxam

BackgroundNeonicotinoids are widely applied in the control of the destructive agricultural pest Bemisia tabaci, and resistance against these chemicals has become a common, severe problem in the control of whiteflies. To investigate the molecular mechanism underlying resistance against nenonicotinoids in whiteflies, RNA-seq technology was applied, and the variation in the transcriptomic profiles of susceptible whiteflies and whiteflies selected by imidacloprid, acetamiprid and thiamethoxam treatment was characterized.ResultsA total of 90.86 GB of clean sequence data were obtained from the 4 transcriptomes. Among the 16,069 assembled genes, 584, 110 and 147 genes were upregulated in the imidacloprid-selected strain (IMI), acetamiprid-selected strain (ACE), and thiamethoxam (THI)-selected strain, respectively, relative to the susceptible strain. Detoxification-related genes including P450s, cuticle protein genes, GSTs, UGTs and molecular chaperone HSP70s were overexpressed in the selected resistant strains, especially in the IMI strain. Five genes were downregulated in all three selected resistant strains, including 2 UDP-glucuronosyltransferase 2B18-like genes (LOC 109030370 and LOC 109032577).ConclusionsTen generations of selection with the three neonicotinoids induced different resistance levels and gene expression profiles, mainly involving cuticle protein and P450 genes, in the three selected resistant whitefly strains. The results provide a reference for research on resistance and cross-resistance against neonicotinoids in B. tabaci.

Insecticides action of neonicotinoids group in fall armyworm (Spodoptera frugiperda) control on bean leaves (Phaseolus vulgaris)

Among several factors that impact the bean culture productivity there are pest insects, which affect the plant since seeding until postharvest, causing loss in the culture yield. The fall armyworm (Spodoptera frugiperda) stands out among the main pests of common bean (Phaseolus vulgaris). The aim of this work was to evaluate the effectiveness of insecticides of the neonicotinoid group in the control of the fall armyworm in the bean crop, comparing dinotefuran, acetamiprid, thiamethoxam and imidacloprid performance. Experimental design was composed of blocks entirely randomized, with 9 treatments and 10 replicates. Three caterpillars, at the stage of second instar, were used in each experiment, focusing on the ingestion of leaves containing the treatments. Evaluations were realized in the intervals of 1, 3, 6 and 8 days after every application, counting the number of caterpillars alive in the Petri’s dish, attributing visual notes on bean leaves, according to the foliar area affected (consumed). The dinotefuran treatment with the highest dose presented superior efficiency at 80% in the first evaluation. The thiamethoxam treatment with the lowest dose, in the latest analyses, showed efficient superior at 90%. The major doses of all treatments presented efficiency higher than 80% in the last evaluations, being efficient in the S. frugiperda control.

Integrative analysis of transcriptomics and metabolomics reveals the hepatotoxic mechanism of thiamethoxam on male Coturnix japonica

Thiamethoxam (TMX), a representative neonicotinoids, is widely used for seed coating. The consumption of TMX-coated seeds posed threat to birds during crop sowing. The hepatotoxicity of TMX has been reported in mammals, however, no clear evidence showed TMX-induced toxic effects on bird liver. In this study, male Japanese quails (Coturnix japonica) were exposed to 20 or 200 mg/kg TMX-treated bird feed for 28 days. Results showed that Clothianidin (CLO), a TMX metabolite preferred to accumulate in quail plasma and liver, and inflammatory cell infiltration was found in quail livers. Oxidative stress-related biological processes were significantly enriched in both TMX treatment groups through transcriptomics analysis. Moreover, integrative analysis of transcriptomics and metabolomics indicated ferroptosis and DNA damage was implicated in hepatotoxicity caused by high- and low-concentration of TMX exposure, respectively. High-dose TMX treatment decreased CAT activity and GSH concentration and increased expression of the ferroptosis-related gene. In addition, the up-regulation of 8-OHdG concentration and DNA repair-related genes expression demonstrated low-dose TMX triggered oxidative DNA damage. The present results highlight the toxicity of TMX to bird livers and contribute to a better understanding of the TMX toxic mechanism in birds.

Insecticide resistance trait may contribute to genetic cluster change in Bemisia tabaci MED (Hemiptera: Aleyrodidae) as a potential driving force.

Previously, we reported that the majority of the Bemisia tabaci Mediterranean (MED) populations converged from two dominant genetic clusters (cluster 1 and 2) to one (cluster 2) during 1 year in greenhouse tomatoes in Korea. To find possible mechanisms for this phenomenon, we investigated the concurrent changes in resistance traits of the two clusters for three insecticide classes (organophosphate, pyrethroid, and neonicotinoid). Since the resistance mutation frequencies in regional samples were either high (i.e. the voltage-sensitive sodium channel L925I/T929V mutations and the F392 acetylcholinesterase 1 mutation) or zero (the nicotinic acetylcholine receptor R81T mutation), no meaningful correlation between the resistance allele frequency and genetic cluster was deduced. However, the actual resistance levels to all three insecticide classes were significantly higher in cluster 2 than in cluster 1, suggesting that cluster 2 has a higher resistance potential. Furthermore, thiamethoxam treatment to the mixed population of clusters 1 and 2 over three generations exhibited a strong tendency of population change from cluster 1 to cluster 2. Our results demonstrated that the insecticide resistance trait is one of the driving forces for rapid genetic cluster change in B. tabaci MED populations. © 2021 Society of Chemical Industry.

Reduced bacterial network complexity in agricultural soils after application of the neonicotinoid insecticide thiamethoxam.

Pesticides may alter soil microbial community structure or diversity, but their impact on microbial co-occurrence patterns remains unclear. Here, the effect of the widely used neonicotinoid insecticide thiamethoxam on the bacterial community in five arable soils was deciphered using the 16S rRNA gene amplicon sequencing technique. The degradation half-life of thiamethoxam in nonsterilized soils was significantly lower than that in sterilized soils, suggesting a considerable contribution from biodegradation. Soil bacterial community diversity diminished in high concentration thiamethoxam treatment and its impact varied with treatment concentration and soil type. Bacterial co-occurrence network complexity significantly decreased after exposure to thiamethoxam. Under thiamethoxam stress, the relative changes in bacterial co-occurrence networks were closely related (the majority of p-values<0.05) to the soil physicochemical properties, yet the diversity and dominant phyla were slightly related (the majority of p-values>0.05). Additionally, three bacterial genera, Sphingomonas, Streptomyces, and Catenulispora, were identified to be relevant to the degradation of thiamethoxam in soils. This finding deciphers the succession of the bacterial community under thiamethoxam stress across multiple soils, and emphasizes the potential role of physicochemical properties in regulating the ecotoxicological effect of pesticides on the soil microbiome.

Effect of thiamethoxam on photosynthetic pigments and primary photosynthetic reactions in two maize genotypes (Zea mays).

Neonicotinoid insecticides are used against the wide range of pests to protect plants. The influence of neonicotinoids on target and non-target insects is well understood. Hence, there are controversial opinions about the effect of neonicotinoids on the plants. We investigated pigments and photosynthetic primary reactions in two maize genotypes (the inbred line zppl 225 and hybrid zp 341) under thiamethoxam (TMX) treatment by root irrigation. It was found that the effect of TMX depended on pesticide application techniques and selection of maize genotype. TMX was added to the soil by root irrigation on the 4th and 8th days after planting, and photosynthetic characteristics monitored on the 10th and 12th days after planting. The primary photochemical reactions in PSII (Fv/Fm) of both maize genotypes were not affected under two variants of TMX treatment during all growing period. The hybrid zp341 was shown to be more susceptible to both TMX treatments, demonstrating a decrease in photosynthetic characteristics (JIP-test parameters) as well as changes in the content of pigments and in the conformation of the carotenoid molecule. Our findings suggest that the combination of fluorescence method and Raman spectroscopy is a perspective tool for monitoring plant state under pesticide application.

Изменение гистологических структур семенников у кроликов под влиянием тиаметоксама

Thiamethoxam (TMX) is one of new class neonicotinoid insecticides currently available in the Egyptian pesticide markets. The current study was designed to investigate the toxic effect of TMX on reproductive system in adult male rabbits. For this purpose, sixteen adult male Chinchilla rabbits were divided into two equal groups. Animals in the first group were treated orally with TMX at dose of 250 mg/kg b.wt for 90 days. The second group was served as control. Obtained results also showed that TMX treatment did not cause significant sperm DNA fragmentation, but caused marked alteration in sperm parameters (e.g. concentration, motility and morphology). In conclusion, administration of TMX for 90 days in male rabbits induced a noticeable adverse effect on the testicular function and structure. Degeneration and necrosis of the spermatogenic cells in addition to intertubular edema and vacuolations were the major observed histopathological lesions in the testis of intoxicated animals.

The neonicotinoid insecticide thiamethoxam enhances expression of stress-response genes in Zea mays in an environmentally specific pattern.

Recent studies indicate that thiamethoxam (TMX), a neonicotinoid insecticide, can affect plant responses to environmental stressors, such as neighboring weeds. The molecular mechanisms behind both stable and environmentally specific responses to TMX likely involve genes related to defense and stress responses. We investigated the effect of a TMX seed treatment on global gene expression in maize coleoptiles both under normal conditions and under low ratio red to far-red (R:FR) light stress induced by the presence of neighboring plants. The neighboring plant treatment upregulated genes involved in biotic and abiotic stress responses and affected specific photosynthesis and cell-growth related genes. Low R:FR light may enhance maize resistance to herbivores and pathogens. TMX appears to compromise resistance. The TMX treatment stably repressed many genes that encode proteins involved in biotic stress responses, as well as cell-growth genes. Notably, TMX effects on many genes' expression were conditional on the environment. In response to low R:FR, plants treated with TMX engage genes in the JA pathway, as well as other stress-related response pathways. Neighboring weeds may condition TMX-treated plants to become more stress tolerant.

Influence of the neonicotinoid insecticide thiamethoxam on soil bacterial community composition and metabolic function

Understanding of neonicotinoid insecticides toxicity on non-target organisms, such as bees, has indirectly promoted their soil treatment use. However, their effect on soil ecosystems haven’t fully understood. Here, based on 16S rRNA high-throughput sequencing and metagenomics, the effects of neonicotinoid insecticide thiamethoxam on bacterial communities and metabolic functions in two types of soils were studied. Thiamethoxam treatment significantly affected soil bacterial abundance, reduced microbial diversity, and changed the bacterial community structure in the short term, and the structure soon returned to a stable state. Soil type and time were important factors affecting bacterial community structure. Some plant growth-promoting rhizosphere bacteria (PGPR) including Actinobacteria were found, and their populations were reduced, while pollutant-degrading bacteria including Firmicutes were also found, and their populations were increased. Based on metagenomics analysis, thiamethoxam treatment insignificantly promoted or inhibited multiple metabolic processes, but gene abundance of some key processes significantly changed. Subtypes of 18 biodegradation genes (BDGs) and 5 pesticide degradation genes (PDGs) were identified. Thiamethoxam treatment significantly increased the abundance of BDGs and PDGs, including cytochrome P450. Potential hosts of P450 degradation genes, including the genus Rhodococcus, were discovered. Conclusions of this study will promote safety evaluation and degradation-related research on neonicotinoid insecticides in soil.