Abstracts
Teflubenzuron
CAS No. 83121-18-0

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Advese Effects

ACTIVITY: Insecticide (benzoylurea)

CAS Name: N-[[(3,5-dichloro-2,4-difluorophenyl)amino]carbonyl]-2,6-difluorobenzamide

Structure:


http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=pubmed&cmd=Retrieve&dopt=AbstractPlus&list_uids=16786494&query_hl=1&itool=pubmed_docsum

Pest Manag Sci. 2006 Aug;62(8):752-8.

Hazards and uptake of chitin synthesis inhibitors in bumblebees Bombus terrestris.

Mommaerts V, Sterk G, Smagghe G.

Department of Biology, Faculty of Sciences, Free University of Brussels, Brussels, Belgium.

This research project examined the potential hazards of a major class of insect growth regulators (IGRs) to survival, reproduction and larval growth in bumblebees Bombus terrestris L. Eight chitin synthesis inhibitors (CSIs) were tested: buprofezin, cyromazine, diflubenzuron, flucycloxuron, flufenoxuron, lufenuron, novaluron and teflubenzuron. These different IGRs, which are important in the control of pest insects in greenhouses, were applied via three different routes of exposure under laboratory conditions: dermal contact, and orally via the drinking of sugar/water and via pollen. The compounds were tested at their respective maximum field recommended concentrations (MFRC) and also in dose-response assays to calculate LC(50) values. In general, none of the CSIs showed acute worker toxicity. However, there was a dramatic reduction in brood production, especially after oral treatment with pollen and sugar/water. Conspicuously, egg fertility was reduced in all treatments with diflubenzuron and teflubenzuron. In addition to egg mortality, the worker bumblebees removed larvae from the treated nest, and in most cases these individuals were dead first-second instars. Under a binocular microscope, such larvae showed an abnormally formed cuticle leading to mechanical weakness and death. In another series of experiments using (14)C-diflubenzuron and (14)C-flufenoxuron, cuticular penetration in workers was studied for a better understanding of the differences in toxicity. With (14)C-diflubenzuron, transovarial transport and accumulation in the deposited eggs supported the strong reproductive effects. Overall, the present results suggest that CSIs should be applied with caution in combination with bumblebees. The compatibility of each compound to be used in combination with B. terrestris is discussed in relation to calculated LC(50) values, routes of uptake and effects.

PMID: 16786494 [PubMed - indexed for MEDLINE]

NOTE from FAN: 6 of the 8 pesticides tested are fluorinated: diflubenzuron, flucycloxuron, flufenoxuron, lufenuron, novaluron and teflubenzuron

 

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Ecotoxicol Environ Saf. 2005 Aug 17; [Epub ahead of print]

Effects of insect growth regulators on the nontarget soil arthropod Folsomia candida (Collembola).

Campiche S, Becker-van Slooten K, Ridreau C, Tarradellas J.

Ecole Polytechnique Federale de Lausanne, ENAC-ISTE, Laboratory of Environmental Chemistry and Ecotoxicology, Station 2, CH-1015 Lausanne, Switzerland.

The aim of this study was to assess the effect of several insect growth regulators (IGRs) on the nontarget soil arthropod Folsomia candida (Collembola). The survival and reproduction rates of F. candida were evaluated after 28 days of exposure to six IGRs (methoprene, fenoxycarb, precocene II, tebufenozide, hexaflumuron and teflubenzuron) and to one herbicide (diuron) in artificial soil. The differences in the sensitivity of F. candida to these different substances are high. The chitin synthesis inhibitors teflubenzuron and hexaflumuron were the most toxic compounds with an EC50 of 0.05mg/kg (dry weight) for teflubenzuron and an EC50 of 0.6mg/kg for hexaflumuron. Teflubenzuron is toxic for F. candida at concentrations that are probably close to environmental levels of this insecticide. Inhibition of reproduction is strongly related to adult survival for the juvenile hormone agonist methoprene and for the antijuvenile hormone precocene II, with an EC50 of 173mg/kg and a LC50 of 178mg/kg for methoprene and an EC50 of 15mg/kg and a LC50 of 26mg/kg for precocene II. Fenoxycarb, another juvenile hormone analog, showed a dose-response curve for mortality different from that of methoprene; at concentrations such as 3052mg/kg no effect on adult survival was observed. However, the EC50 value of 113mg/kg is of the same order of magnitude as that obtained for methoprene. A test with compressed soil contaminated with fenoxycarb was conducted to observe parameters such as numbers of eggs laid and juveniles hatched. No differences were observed between these two endpoints for fenoxycarb. An EC50 of 109mg/kg was obtained for the ecdysone agonist tebufenozide. The herbicide diuron showed a relatively high toxicity for F. candida with an EC50 of 20mg/kg. Our results show that some of the tested IGRs can have effects on Collembola at environmentally relevant concentrations (toxicity/exposure ratios <5 for teflubenzuron, hexaflumuron, and diuron).

PMID: 16112194 [PubMed - as supplied by publisher]


http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=pubmed&dopt=Abstract&list_uids=16084001&query_hl=6

Environ Pollut. 2005 Aug 2; [Epub ahead of print]
 
Effects of teflubenzuron on sediment processing by members of the Capitella species-complex.

Mendez N.

Laboratorio de Invertebrados Bentonicos, Unidad Academica Mazatlan, Instituto de Ciencias del Mar y Limnologia, UNAM, Apdo. Postal 811, Mazatlan, Sinaloa 82000, Mexico.

The cosmopolitan deposit-feeding polychaete Capitella is widely used as an indicator of organic pollution and plays an important role in waste recycling at aquaculture sites. Teflubenzuron is currently employed by salmon farms as an in-feed compound to control ectoparasite infestations. Its occurrence in sediments could pose a hazard to local sediment infauna. A bioassay to investigate the effects of exposing Capitella sp I and Capitella sp B to sediment spiked with environmentally relevant concentrations of teflubenzuron (8.4, 25 and 41.8 mug/g dry wt. sediment) is described. No mortality was recorded for Capitella sp I, but increasing teflubenzuron concentrations significantly reduced egestion rates. Capitella sp B exhibited mortality, although egestion was not affected. These results using Capitella spp. indicated that teflubenzuron could affect the rate of sediment processing by polychaetes close to fish farms treated with this compound. Further studies are recommended to assess the potential of contaminants in aquaculture wastes.

PMID: 16084001 [PubMed - as supplied by publisher]


http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=pubmed&dopt=Abstract&list_uids=12152902

Dis Aquat Organ. 2002 Jun 21;50(1):29-33.

Field trials in Norway with SLICE (0.2% emamectin benzoate) for the oral treatment of sea lice infestation in farmed Atlantic salmon Salmo salar.

Ramstad A, Colquhoun DJ, Nordmo R, Sutherland IH, Simmons R.

VESO Vikan AkvaVet, Namsos, Norway.

Four commercial salmon farms on the West coast of Norway were recruited to a programme of field trials in which the efficacy of SLICE (0.2% emamectin benzoate; Schering-Plough Animal Health) was compared with a commercially available product, EKTOBANN (teflubenzuron 2 g kg(-1); Skretting A/S) in treating natural sea lice Lepeophtheirus salmonis infections in Atlantic salmon Salmo salmar L. At each test site, 3 fish pens were treated with each product. In total, nearly 1.2 million first-year-class fish were included in the trial, of which approximately 561,000 received emamectin benzoate at a dosage of 50 microg kg(-1) body wt d(-1), while approximately 610,000 received teflubenzuron at a dosage of 10 mg kg(-1) body wt d(-1). Medicated feed was provided at 0.5% body wt d(-1) over 7 consecutive days. Feed containing emamectin benzoate was generally well accepted by the fish and no problems were encountered in feeding the medicated diet at the desired dose. Lice numbers were counted 2 d before and 1, 7, 14 and 21 d after commencement of treatment. While treatment with both substances rapidly reduced lice numbers, pens treated with emamectin benzoate were found to harbour significantly fewer lice 14 and 21 d post-treatment. Twenty-one days following treatment with emamectin benzoate the lice abundance was reduced on average by 94%. Limited sampling outside the main study period indicated that emamectin benzoate protects against sea-lice infestation over longer periods.

PMID: 12152902 [PubMed - indexed for MEDLINE]


http://www.ncbi.nlm.nih.gov:80/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=11599720&dopt=Abstract

J Environ Sci Health B. 2001 Sep;36(5):559-67.

Transformation of the insecticide teflubenzuron by microorganisms.

Finkelstein ZI, Baskunov BP, Rietjens IM, Boersma MG, Vervoort J, Golovleva LA. G.K.

Skryabin Institute of Biochemistry and Physiology of Microorganisms, RAS, Pushchino, Moscow.

Transformation of teflubenzuron, the active component in the insecticide commercialized as Nomolt, by soil microorganisms was studied. It was shown that microorganisms, belonging to Bacillus, Alcaligenes, Pseudomonas and Acinetobacter genera are capable to perform the hydrolytic cleavage of the phenylurea bridge of teflubenzuron in different positions, especially active was Bacillus brevis 625. The structure of the intermediates formed was established using TLC, HPLC, mass-spectrometry and 19F NMR techniques. It was shown that for a dose range of 53-132 microM and upon 12 days of fermentation about 30% of the teflubenzuron was modified. About 10-15% was transformed into 2,6-difluorobenzamide, 3-5% into 2,6-difluorobenzoic acid, 10-12% into 2,4-difluoro-3,5-dichloro-aniline. The late compound gave rise to formation of a condensed compound, identified as 1,2-bis(2,4-difluoro-3,5-dichlorophenyl)urea with molecular mass of 420. The results obtained indicate degradation of teflubenzuron by soil microorganisms to be a process to be mediated by microbial consortia, and starting with hydrolysis of the phenylurea bridge by several bacterial species. Subsequent further degradation of the aromatic degradation products has to be mediated by other strains known to be capable of degradation of halogenated aromatics.

PMID: 11599720 [PubMed - indexed for MEDLINE]


http://www.ncbi.nlm.nih.gov:80/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=10552854&dopt=Abstract

J Agric Food Chem. 1999 Nov;47(11):4583-6.

Evaluation of teflubenzuron residue levels in grapes exposed to field treatments and in the must and wine produced from them.

Tsiropoulos NG, Aplada-Sarlis PG, Miliadis GE.

Benaki Phytopathological Institute, 7 Ekalis Street, Kifissia 14561, Greece. ntsirop@uth.gr

Dissipation of benzoylurea insecticide teflubenzuron in grapes exposed to field treatments was evaluated. Vines of a white grape vineyard located in central Greece were sprayed twice, at a 28-day interval, with a commercial formulation of the insecticide at 12 g of active ingredient/100 L. Residues were determined by HPLC diode array detection, after ethyl acetate extraction and cleanup on silica phase cartridges, with a detection limit of 0.005 mg/kg. Under field conditions teflubenzuron residues in grapes were found to be very stable with no significant reduction for the whole experimental period of 49 days. However, residues were slightly lower than the maximum residue limits set by individual countries. The fate of teflubenzuron during the vinification process was also studied. Residues were found to be transferred completely into the must but, due to their high affinity for the suspended matter, were removed by approximately 98%; thus, very low concentrations were detected in the produced wine. Among various clarifying agents studied, charcoal was the only one found to be effective for removing teflubenzuron residues from wine.

PMID: 10552854 [PubMed - indexed for MEDLINE]


http://www.ncbi.nlm.nih.gov:80/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=10552588&dopt=Abstract

J Agric Food Chem. 1999 Jul;47(7):2926-9.

Dissipation of teflubenzuron and triflumuron residues in field-sprayed and cold-stored pears.

Aplada-Sarlis PG, Miliadis GE, Tsiropoulos NG.

Department of Theoretical and Applied Sciences, University of Thessaly, Pedion Areos, Volos 38334, Greece.

Dissipation of residues of benzoylurea insecticides teflubenzuron (TFB) and triflumuron (TFM) under field conditions was evaluated on a pear orchard in Greece. Residues were determined by UV-HPLC analysis, with a detection limit of 0.030 mg/kg for both pesticides. TFB residues in pears were found to persist for 2 weeks and decline thereafter with 48% of the initial deposit remaining 42 days after the last application. TFM residues were found to decline following first-order kinetics and with a half-life of 39(+/-7) days. Residues of both pesticides found in pears collected at harvest maturity were lower than the maximum residue limits (MRLs) set by individual countries. Dissipation of TFB and TFM in cold-stored pears was also evaluated. TFB residues were very persistent for the whole storage period, whereas TFM residues did not dissipate for 6 weeks and then showed a constant decline; 7% of the initial concentration remained at the end of the storage period of 29 weeks.

PMID: 10552588 [PubMed - indexed for MEDLINE]


http://www.ncbi.nlm.nih.gov:80/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=9293617&dopt=Abstract

Xenobiotica. 1997 Aug;27(8):801-17.

Metabolism of the insecticide teflubenzuron in rats.

Koerts J, Soffers AE, De Kraker JW, Cnubben NH, Rietjens IM.

Department of Biochemistry, Agricultural University Wageningen, The Netherlands.

1. The metabolic fate of the insecticide teflubenzuron, orally dosed to the male Wistar rat, was investigated. Particular attention was paid to the metabolic fate of the benzoyl and aniline moiety after hydrolysis of the urea bridge.
2. The 0-48-h urinary and faecal metabolic patterns and recoveries showed that for a dose range of 4-53 mumol (1.5-20 mg) teflubenzuron, 90% of the dose was excreted in the faeces mainly in unmodified form, approximately 4.6% was absorbed from the lumen and excreted in the urine, and 5.4% was retained in the body. Metabolites excreted in the urine could be identified as benzoate and aniline derivatives originating from the two aromatic rings of teflubenzuron liberated from the parent molecule by hydrolysis of the urea bridge.
3. The amount of urinary benzoate-type metabolites was about eight times the amount of aniline-type metabolites, indicating significant differences in efficiency of urinary excretion of the benzoate moiety as compared with the aniline ring.
4. To investigate further the possible reason underlying this difference in urinary excretion efficiency between the two aromatic derivatives formed from teflubenzuron, dose-recovery studies of these aniline- and benzoate-type metabolites were performed. These studies confirmed the discrepancy observed between the urinary recovery of the benzoyl and the aniline moiety of teflubenzuron.
5. Additional results of the present study indicate that the above discrepancy can be explained by the fact that the benzoate derivative is excreted mainly in its unmetabolized form, whereas the aniline derivative needs additional phase I and II modifications before it can be excreted from the body, the former being a relatively slow reaction. Furthermore, conversion of the halogenated aniline derivative in phase I metabolism might result in a reactive benzoquinone-type or N-oxidized primary metabolite, which can be retained in the body due to reaction with cellular macromolecules.

PMID: 9293617 [PubMed - indexed for MEDLINE]


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Eisei Shikenjo Hokoku. 1996;(114):95-8.

[First drafts of the Environmental Health Criteria (EHC) circulated for comments by IPCS in 1995-1996]

[Article in Japanese]

Ohtake C.

Summaries of first draft of Environmental Health Criteria (EHC), which were circulated for comments by IPCS in the period of 1995-1996, are presented. EHC drafts on 9 compounds were received in this period.

PMID: 9037873 [PubMed - indexed for MEDLINE]


From Toxline at Toxnet

Pesticide residues in food - 1993. Toxicology evaluations Vol:Part II (1995) pp 171-88

Teflubenzuron

FAO and WHO working groups

Levels that cause no toxic effect.
Mouse: 100 ppm, equal to 11.9 mg/kg bw per day (13-week study of toxicity)
Rat: 100 ppm, equal to 4.8 mg/kg bw per day (120-week study of toxicity and carcinogenicity) 500 ppm, equal to 40 mg/kg bw per day (two-generation study of reproductive toxicity) 1000 mg/kg bw per day (study of teratogenicity, maternal and fetal toxicity)
Rabbit: 1000 mg/kg bw per day (fetal toxicity in a study of teratogenicity) 250 mg/kg bw per day (maternal toxicity in a study of teratogenicity)
Dog: 100 ppm, equal to 3.2 mg/kg per day (one-year study of toxicity) Lowest-observed-adverse-effect level.
Mouse: 15 ppm, equal to 2.1 mg/kg bw per day (18-month study of carcinogenicity)
Humans: Estimate of acceptable daily intake for humans. 0-0.01 mg/kg bw.
Studies that would provide information useful for continued evaluation of the compound. Further observations in humans.


From Toxline at Toxnet

Journal of Applied Toxicology, Vol. 13, No. 1, pages 67-68, 7 references, 1993

Comparative Study on the Effects of Five Benzoylphenylurea Insecticides on Haematological Parameters in Rats

Tasheva M, Hristeva V


The effects of five benzoylphenylurea insecticides, diflubenzuron (35367-38-5), flufenoxuron (101463-69-8), hexaflumuron (86479-06-3), teflubenzuron (83121-18-0), and triflumuron (64628-44-0) were comparatively evaluated on hematological parameters in rats. Sixty adult Wistar-rats were divided into five dose groups and a control group. Daily doses of 100mg/kg of each tested insecticide were administered by gavage for 28 days, after which rats were sacrificed and blood was taken for examination. Parameters measured were red blood cell count, hemoglobin (Hb), hematocrit, mean corpuscular volume, mean corpuscular Hb concentration, methemoglobin (metHb), and reticulocyte counts. Results showed that treatment with insecticides at the dose given did not produce any overt signs of toxicity. However, with regard to hematological parameters, both diflubenzuron and triflumuron induced elevated metHb levels. The no observed effect level for metHb was 45mg/kg. The reticulocyte level was increased in all treated groups, even at dose levels of 50mg/kg. The authors conclude that the metHb level increase and reticulocyte increase are the most sensitive parameters, but that one might be independent of the other.

Note: All the pesticides cited are fluorinated


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