Persistence and transformation of thiamethoxam, a neonicotinoid insecticide, in soil of different agroclimatic zones of India.

Division of Agricultural Chemicals, Indian Agricultural Research Institute, New Delhi 110012, India.
Bulletin of Environmental Contamination and Toxicology (Impact Factor: 1.22). 04/2006; 76(3):400-6. DOI: 10.1007/s00128-006-0935-9
Source: PubMed

ABSTRACT No abstract available.

1 Bookmark
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Dinotefuran (DNT), imidacloprid (IMD), and thiamethoxam (THM) are commonly used neonicotinoid insecticides in a variety of agriculture operations. Although these insecticides help growers control pest infestation, the residual environmental occurrence of insecticides may cause unintended adverse ecological consequences to non-target species. In this study, the leaching behavior of DNT, IMD, and THM was investigated in soils collected from an active AgriLife Research Extension Center (AREC) vineyard. A series of column experiments were conducted to evaluate the leaching potential of insecticides under two experimental scenarios: a) individual pulse mode, and b) mixed pulse mode. In both scenarios, the breakthrough pattern of the insecticides in the mostly acidic to neutral vineyard soil clearly demonstrates medium to high leachability. Of the three insecticides studied for leaching, DNT has exhibited high leaching potential and exited the column with fewer pore volumes, whereas IMD was retained for longer, indicating lower leachability. Relative differences in leaching behavior of neonicotinoids could be attributed to their solubility with the leaching pattern IMD < THM < DNT showing strong correlation with increasing aqueous solubility 610 mg/L < 4100 mg/L < 39,830 mg/L. Triplicate column study experiments were conducted to evaluate the consistency of the breakthrough pattern of these insecticides. The repeatability of the breakthrough curves shows that both DNT and IMD are reproducible between runs, whereas, THM shows some inconsistency. Leaching behavior of neonicotinoid insecticides based on the leachability indices such as groundwater ubiquity score, relative leaching potential, and partitioning between different environmental matrices through a fugacity-based equilibrium criterion model clearly indicates that DNT may pose a greater threat to aquatic resources compared to IMD and THM.
    Journal of Contaminant Hydrology 10/2014; 170. DOI:10.1016/j.jconhyd.2014.09.009 · 2.70 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Imidacloprid, clothianidin, and thiamethoxam are under re-evaluation by PMRA.•Some fate monitoring of imidacloprid in Canada but not clothianidin or thiamethoxam•Fish, algae, amphibians, and molluscs are relatively insensitive to neonicotinoids.•Interim guideline might not be sufficiently protective of aquatic invertebrates.•Concentrations measured in Canadian waters could have impacts on aquatic organisms.
    Science of The Total Environment 02/2015; 505. DOI:10.1016/j.scitotenv.2014.09.090 · 3.16 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: A soil enrichment culture (SEC) rapidly degraded 96% of 200 mg L(-1) neonicotinoid insecticide thiamethoxam (TMX) in MSM broth within 30 d; therefore, its metabolic pathway of TMX, bacterial diversity and plant growth-promoting rhizobacteria (PGPR) activities of the cultured isolates were studied. The SEC transformed TMX via the nitro reduction pathway to form nitrso, urea metabolites and via cleavage of the oxadiazine cycle to form a new metabolite, hydroxyl CLO-tri. In addition, 16S rRNA gene-denaturing gradient gel electrophoresis analysis revealed that uncultured rhizobacteria are predominant in the SEC broth and that 77.8% of the identified bacteria belonged to uncultured bacteria. A total of 31 cultured bacterial strains including six genera (Achromobacter, Agromyces, Ensifer, Mesorhizobium, Microbacterium and Pseudoxanthomonas) were isolated from the SEC broth. The 12 strains of Ensifer adhaerens have the ability to degrade TMX. All six selected bacteria showed PGPR activities. E. adhaerens TMX-23 and Agromyces mediolanus TMX-25 produced indole-3-acetic acid, whereas E. adhaerens TMX-23 and Mesorhizobium alhagi TMX-36 are N2-fixing bacteria. The six-isolated microbes were tolerant to 200 mg L(-1) TMX, and the growth of E. adhaerens was significantly enhanced by TMX, whereas that of Achromobacter sp. TMX-5 and Microbacterium sp.TMX-6 were enhanced slightly. The present study will help to explain the fate of TMX in the environment and its microbial degradation mechanism, as well as to facilitate future investigations of the mechanism through which TMX enhances plant vigor.
    Journal of Environmental Science and Health Part B Pesticides Food Contaminants and Agricultural Wastes 06/2014; 49(6):381-90. DOI:10.1080/03601234.2014.894761 · 1.10 Impact Factor