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PubMed1986

Some Effects of Diflubenzuron on Growth and Sporogenesis in Streptomyces spp.

Diflubenzuron, an insect growth regulator that blocks chitin deposition in insect cuticles, was tested for its effects on morphogenesis of Streptomyces spp. Use of diflubenzuron resulted in reduced dominance of spore hairs, reduced the width of the outer wall, and prevented formation of the inner spore wall in S. bambergiensis. In S. coelicolor, diflubenzuron altered the structure of the fibrillar pattern of spore envelopes. Exposure to diflubenzuron resulted in small increases in exported protein and in a ca. 20% increase in chitinase in both Streptomyces spp.

Journal Article↗
PubMed1979

The accumulation and elimination of diflubenzuron by fish.

In summary, diflubenzuron is accumulated from water into fish tissues at levels up to 80 fold within 24 hr when fish are exposed to concentrations of 10 ppb. Within the concentration range of 1-10 ppb, the amount accumulated in a 24 hr exposure is proportional to concentration. After 24 to 48 hr exposure fish degrade and eliminate diflubenzuron and the excretory products are neither the parent compound nor p-chlorophenylurea. The amount of diflubenzuron remaining in fish tissues with time is dependent on the reduction of residue concentration in water; however, the potential for degradation and elimination is very great.

Animals↗
PubMed1993

Effect of diflubenzuron on the incorporation of UDP-N-acetyl-[3H]glucosamine (UDP-[3H]NAGA) to chitin in permeabilized, and isolated integuments from the newly molted American cockroach Periplaneta americana.

1. Diflubenzuron (DFB) was found to inhibit the incorporation of UDP-N-acetyl-[3H]glucosamine (UDP-[3H]NAGA) to chitin in permeabilized and isolated integument from newly molted American cockroach. 2. The favorable experimental conditions demonstrating the effect of diflubenzuron were: 10 mM phosphate, low calcium concentration (10(-6) M-10(-8) M), high potassium concentration (> 100 mM), and high pH (> or = 7). 3. The action of diflubenzuron was completely erased by preincubating the isolated integument with valinomycin, FCCP, or A23187. 4. By lowering the external pH to 5.2, it was also possible to reduce the rate of UDP-[3H]NAGA incorporation to the extent that DFB's effect was no longer recognizable. 5. Both Cs+ and Rb+ could replace K+ in maintaining a high level of chitin synthesis and the inhibitory action of DFB under the optimum conditions.

Animals↗
PubMed1993

Efficacy of diflubenzuron in simulated household and yard conditions against the cat flea Ctenocephalides felis (Bouché) (Siphonoptera: Pulicidae).

Diflubenzuron-treated carpet inhibited egg-to-adult development of the cat flea for up to 12 mo even with weekly vacuuming of the carpet. The efficacy of diflubenzuron was similar in treated soils over a 6-mo test period except in the case of treated soil that remained outside. Reduced efficacy is attributed to degradation of diflubenzuron by microorganisms and water.

Animals↗
PubMed2002

Effect of diflubenzuron on immature stages of Haematobia irritans (L.) (Diptera: Muscidae) in Uberlândia, State of Minas Gerais, Brazil.

Horn fly immatures were raised in media containing different concentrations of diflubenzuron in order to verify their susceptibility to this insect growth regulator (IGR). The 50% and 95% lethal concentrations of diflubenzuron for the population (LC50, LC95) were determined as well as the effect of this IGR on the different immature horn fly stages. The tests were performed using the progeny of adults collected in the field. The immatures were maintained in a growth chamber at 25.0 +/- 0.5oC and 12-12 h photoperiod. IGR concentrations of 300 ppb, 100 ppb and 50 ppb were lethal for 100% of the sample. Pupae malformation occurred in the breeding media containing different diflubenzuron concentrations. Values for LC50, LC95 (+/- 95% fiducial limits) and the slope of the regression line were respectively, 25.521 +/- 1.981 ppb, 34.650 +/- 2.001 ppb and 12.720 +/- 1.096. The third larval instar was more sensitive to the sub-lethal concentration of the product than the first and second ones were. The results indicate that this IGR can be an important tool for controlling horn fly populations as well as for managing horn fly resistance to conventional insecticides against Haematobia irritans in Uberlândia, State of Minas Gerais.

Animals↗
PubMed1993

Effects of the insect growth regulators OMS 2017 and diflubenzuron on the reproductive potential of Aedes aegypti.

The effects of 2 benzoylphenylurea insect growth regulators, OMS 2017 and diflubenzuron, on 4th instar larvae of Aedes aegypti were investigated in the laboratory. Apart from delayed lethal action, possible effects on the reproductive potential were also studied. A baseline concentration of each compound causing 30% emergence inhibition was determined. At this concentration, OMS 2017 affected fecundity of the mosquito but diflubenzuron did not. The fertility of females that survived OMS 2017 exposure also was decreased; 23% of the eggs reached the 4th larval instar. Diflubenzuron did not cause any reduction in fertility. The basal follicle number showed great variability after both treatments as it was alternatively equal, lower, or higher than in the control.

Aedes↗
PubMed1993

In vitro cytotoxic and cell transforming activities exerted by the pesticides cyanazine, dithianon, diflubenzuron, procymidone, and vinclozolin on BALB/c 3T3 cells.

Cytotoxic and cell transforming activities of the pesticides cyanazine, diflubenzuron, dithianon, procymidone, and vinclozolin were investigated in vitro by utilizing the BALB/c 3T3 cell transformation test performed in the presence or in the absence of S-9 mix as an exogenous bioactivation system for the chemicals. All the assayed pesticides were cytotoxic in the absence of S-9 mix, whereas only dithianon exerted cytotoxic effects in the presence of metabolic activation. All the chemicals tested did induce BALB/c 3T3 cell transformation, to a various extent, in the absence of S-9 mix. Cell transforming ability of cyanazine and diflubenzuron was not detectable in the presence of S-9.

3T3 Cells↗
PubMed1995

Determination of the pesticides diflubenzuron and clofentezine in plums, strawberries and blackcurrant-based fruit drinks by high performance liquid chromatographic/atmospheric pressure chemical ionization-mass spectrometry.

A high performance liquid chromatographic/atmospheric pressure chemical ionization-mass spectrometric (HPLC/APCI-MS) method has been developed for the determination of the pesticides diflubenzuron (1-(4-chlorophenyl)-3-(2,6-difluorobenzoyl)urea) and clofentezine (3,6-bis(2-chlorophenyl)-1,2,4,5-tetrazine) in plums, strawberries and blackcurrant-based fruit drinks. Samples were homogenized with acetone, extracted into dichloromethane + cyclohexane and cleaned-up by high performance gel permeation chromatography. HPLC was performed on an ODS column with methanol + water at 1 mL/min. Detection was by negative-ion selected-ion monitoring APCI-MS. Comparison of response with solvent and matrix-matched standards showed some enhancement of response for the latter, and these standards were consequently used for quantification. The calibration was linear over the range 0.05-0.50 ng/microL in all three matrices. The mean overall recovery of diflubenzuron and clofentezine from spiked extracts (0.086 mg/kg) in all three matrices was 76% and 70% respectively with relative standard deviations of 15% and 12% respectively (n = 12). The limit of detection was both compound and commodity dependent and ranged from 0.01-0.05 ng/microL, equivalent to 0.003-0.014 mg/kg in the crop.

Basidiomycota↗
PubMed1982

The effects of diflubenzuron on a complex laboratory stream community.

Effects were assessed on the total biological community in complex laboratory streams caused by continuous exposure to diflubenzuron (1-(4-chlorophenyl)-3-(2,6-difluorobenzoyl) urea). The insect fauna suffered direct toxic effects at concentrations of 1.0 microgram/L and greater. The algal and fungal floras were mildly affected at the same concentrations; apparently indirect effects in response to the reduced herbivore and shredder components of the insect fauna. No effects were observed on the bacteria, oligochaetes or gastropods, at any of the test concentrations. Within the insect fauna, differences in sensitivities were observed: mayflies and stoneflies were affected at 1.0 microgram/L, dipterans were affected at 10.0 microgram/L, and coleopterans were apparently unaffected at any of the test concentrations. Effects on caddisflies could not be determined due to their failure to become established in the stream systems. These differences between insect orders in sensitivity, coupled with differences in generation time, may reduce the overall benefits of the insecticide. For example, if diflubenzuron is used for chironomid control, the result may be more severe and longer lasting effects on nontarget mayfly and stonefly populations.

Animals↗
PubMed1982

Histopathological effects of diflubenzuron on the cirripede crustacean, Balanus eburneus.

Histopathological studies on the cirripede crustacean, Balanus eburneus, at light and electron microscopic levels indicated that the chitin-inhibiting insecticide, diflubenzuron, caused similar disruption of the exoskeleton as observed in insects. Under the light microscope, globular particles were present within the chitinous layers of the cuticle, and these particles appeared electron dense and pleomorphic at the ultrastructural level. The cytoplasm of the cuticle-secreting epidermal cells appeared more dense and showed at least a five-fold increase in multivesicular bodies, which possessed electron dense cores. Barnacles exposed to diflubenzuron for 10 days or longer at 750 and 1,000 ppb were delayed in the premolt phase of cuticle secretion.

Animals↗
PubMed1997

Virulence of the entomopathogenic fungus Metarhizium flavoviride Gams and Rozsypal and toxicity of diflubenzuron, fenitrothion-esfenvalerate and profenofos-cypermethrin to nontarget arthropods in Mauritania.

Within the framework of the GTZ project, Biological and Integrated Control of Locusts and Grasshoppers, a laboratory screening fo rMetarhizium flavoviride (strain Mfl 5) blastospore pathogenicity to the nontarget arthropods Pharoscymnus anchorago F. (Coleoptera:Coccinellidae), Trachyderma hispida (Forskâl) (Coleoptera:Tenebrionidae), Palpares cf. tesselatus Rambur (Neuroptera:Myrmeleontidae) and Thanatus sp. (Araneae: Philodromidae) was conducted in Akjoujt research station, Mauritania. Various larval stages of desert locust, Schistocerca gregaria Forskâl (Orthoptera:Acrididae), were tested as positive controls. The insect growth regulator diflubenzuron was used as a reference in the bioassay with P.anchorago. In addition, two organophosphate-pyrethroid insecticide swidely used in locust control, fenitrothion-esfenvalerate (P.anchorago, T. hispida) and profenofos-cypermethrin (Thanatussp.) were tested as toxic standards. M. flavoviride was not pathogenic to nontargets, but very virulent to S. gregaria. The results provided further evidence that the host range of M.flavoviride (Mfl5), a strain isolated from migratory locust in Madagascar, is very narrow. Diflubenzuron was toxic to P. anchorago and to S. gregaria. The LD50s of both chemical insecticides tested were considerably lower than the expected initial environmental concentration. The beneficial P. anchorago, a natural enemy of scale insects in date palms, was considered most at risk in the course of chemical locust control. The use of mycopesticides to control desert locust in date palm plantations offers an environmentally safe and economically viable alternative to chemical control.

Animals↗
PubMed1995

Determination of the pesticide diflubenzuron in mushrooms by high-performance liquid chromatography-atmospheric pressure chemical ionisation mass spectrometry.

A method using high-performance liquid chromatography-atmospheric pressure chemical ionisation mass spectrometry (HPLC-APCI-MS) has been developed and validated for the determination of the insecticide diflubenzuron [1-(4-chlorophenyl)-3-(2,6-difluorobenzoyl)urea] in mushrooms. Samples were homogenised with acetone, extracted into dichloromethane-cyclohexane and further cleaned-up by size-exclusion chromatography (SEC). HPLC was performed on an ODS column with methanol-water at 1 ml/min. The limit of detection was 0.02 ng/microl (equivalent to 0.017 mg/kg in the crop). The calibration was linear over the range 0.025-1.0 ng/microl. Recovery of diflubenzuron from spiked mushrooms (0.06-0.58 mg/kg) was 85.5% with a relative standard deviation of 14.5% (n = 56).

Atmospheric Pressure↗
PubMed1995

The efficacy of Diflubenzuron against the body louse (Damalinia limbata) of Angora goats.

The efficacy of an insect growth regulator, Diflubenzuron, to control biting lice (Damalinia limbata) on Angora goats was investigated. Lice on goats which were dipped in a concentration of 625 g Diflubenzuron to 1,000 1 water and then kept in quarantine was eradicated after a single treatment. Nymphs remained present on these goats up to 4 weeks and adult lice up to 8 weeks post-treatment. A single treatment provided greater than 90% reduction in nymphal stages from Week 6 to Week 16 post-treatment in treated goats continuously exposed to reinfestation. The treatment reduced adult louse infestations on these goats by 78-94% through Weeks 6-16 post-treatment. At the end of the trial (24 weeks post-treatment), these goats had 88% fewer nymphs and 84% fewer adult lice compared with untreated control goats.

Animals↗
PubMed1993

Effect of diflubenzuron on incorporation of [3H]-N-acetylglucosamine ([3H]NAGA) into chitin in the intact integument from the newly molted American cockroach Periplaneta americana.

1. Diflubenzuron and polyoxin D clearly inhibited the incorporation of [3H]-N-acetylglucosamine ([3H]NAGA) into chitin in the isolated integument from newly molted American cockroaches under the experimental condition. 2. Upon homogenization, or tissue slicing, such an inhibitory effect of diflubenzuron on chitin synthesis totally disappeared, while that of polyoxin D did not. 3. Mitochondrial poisons (oligomycin and FCCP), protein phosphorylation modulations (8-Br-cAMP, Na3VO4 and MnCl2), potassium ionophores (valinomycin), and calmodulin inhibitor (trifluoperazine) clearly inhibited [3H]NAGA incorporation. 4. Phospholipase A2 and calcium ion significantly enhanced the [3H]NAGA incorporation.

Animals↗
PubMed2005

CYP superfamily perturbation by diflubenzuron or acephate in different tissues of CD1 mice.

This work aimed to investigate whether the insecticide acephate (125 or 250 mg/kg b.w.) or diflubenzuron (752 or 1075 mg/kg b.w.), two of the most widely used pesticides worldwide, impairs CYP-linked murine metabolism in liver, kidney and lung microsomes after repeated (daily, for three consecutive days) i.p. administration. The regio- and stereo-selective hydroxylation of testosterone was used as multibiomarker of different CYP isoforms. Both gender and tissue specific effects were observed. Lung was the most responsive tissue to induction by lower diflubenzuron dose, as exemplified by the marked increase of testosterone 7alpha-hydroxylation (CYP2A) (up to 13-fold) in males. Higher dose produced a generalized inactivation. At the lower dose acephate induced 6beta- (CYP3A1/2, liver) as well as 2beta- (CYP2B1/2, kidney) hydroxylase activities ( approximately 5 and approximately 4-fold increase, respectively) in males. In females, a marked suppression of the various hydroxylations was observed. At 250 mg/kg of acephate, animals did not survive. Induction of the most affected isoforms was sustained by immunoblotting analysis. Corresponding human CYP modulations might disrupt normal physiological functions related to these enzymes. Furthermore, the co-mutagenic and promoting potential of these pesticides, phenomena linked to CYP upregulation (e.g. increased bioactivation of ubiquitous pollutants and generation of oxygen free radicals) are of concern for a more complete definition of their overall toxicological potential.

Animals↗
PubMed1981

Effect of diflubenzuron and its major degradation products on the growth of Euglena gracilis Z. and incorporation of glycine-U-14C in protein.

Diflubenzuron (I) and its major degradation products 4-chlorophenyl urea (II), 2,6-difluorobenzoic acid (III) and 4-chloroaniline (IV) were tested for their activity on Euglena gracilis Z. The inhibition on the growth and on the incorporation of glycine-U-14C in the protein of Euglena was measured in the presence of I-IV ranging 10 to 200 ppm. 4-chloroaniline caused a considerable inhibition at every tested level whereas I-III slightly affected only the incorporation. Therefore, it must be inferred that diflubenzuron shows no effect on growth and protein biosynthesis for this nontarget organism.

Carbon Radioisotopes↗
PubMed1992

Effect of methoprene and diflubenzuron on larval development of the cat flea (Siphonaptera: Pulicidae).

Cat flea larvae, Ctenocephalides felis Bouche, exposed to glass surfaces treated with methoprene concentrations from 0.127 to 1,270 ng/cm2 did not emerge as adults. Most larvae died in the third instar, but those exposed to the 0.127 ng/cm2 concentration formed larval-pupal intermediates. Larvae exposed to glass surface treated with diflubenzuron concentrations from 12.7 to 1,270 ng/cm2 died during the process of molting in all three instars. Exposure of larvae to 12.7 and 127 ng/cm2 diflubenzuron resulted in 15 and 5.2% adult emergence, respectively.

Animals↗
PubMed2003

Effects of boric acid, fipronil, hydramethylnon, and diflubenzuron baits on colonies of ghost ants (Hymenoptera: Formicidae).

Laboratory colonies of the ghost ant, Tapinoma melanocephalum (F.) were administered sugar solution (10%) baits containing the insecticides boric acid, fipronil (REGENT), hydramethylnon (SIEGE), or diflubenzuron (DIMILN). Colonies were exposed to the baits for 21 d, and development of workers, queens, and brood (larvae and pupae) was observed for 4 wk. Fipronil (0.05%) caused 100% mortality in all colonies the first week. With boric acid (0.5%), 100% mortality of workers, queens, and brood was reached at the end of the third week. With hydramethylnon (2%), 83% of the colonies disappeared at the end of the fourth week, but some queens were still alive 9 wk after the trial started. Diflubenzuron (1%) behaved similarly to the control, although in some colonies, the brood production increased, whereas in other colonies, the queens disappeared. In the control colonies, workers, queens, and brood were always observed even up to 9 wk.

Animals↗