Halophilic bacteria are able to decontaminate dichlorvos, a pesticide, from saline environments

Dichlorvos (DDVP) is an organophosphorous pesticide with a high degree of dangerous effect towards the environment. We have investigated the growth and susceptibility to DDVP of halophilic bacteria isolated from Romanian salt lakes. The growth of four strains was affected by DDVP, which may be correlated with the rate constant values of DDVP disappearance from the saline solutions. This is due not to a chemical degradation in solution but to the diffusion process and namely DDVP penetration into the cell cytoplasm by an “organic-osmolyte” mechanism. The permeability coefficient P was calculated.     

Evaluation of extended-life pheromone formulations used with and without dichlorvos for boll weevil (Coleoptera: Curculionidae) trapping

Boll weevil traps baited with a ComboLure (25 of mg grandlure + 30 mg of eugenol + 90 of mg dichlorvos [DDVP]), an extended-release lure (25 mg of grandlure + 30 mg of eugenol + 60 of mg DDVP kill-strip), and extended-release lure with no DDVP were evaluated for boll weevil, Anthonomus grandis grandis Boheman (Coleoptera: Curculionidae), captures in South Texas cotton, Gossypium hirsutum L., fields during February-March 2005 and March-April 2006. The traps were serviced once a week for five consecutive weeks by using the same methodology as active boll weevil eradication programs. Mean captured boll weevils from extended-release lures with no DDVP were significantly higher in five of 10 trapping weeks compared with captures of the ComboLure and extended lure. Weekly mortality of boll weevils captured was similar for the ComboLure (72.6 +/- 4.7%) and extended lure + DDVP (73.5 +/- 4.0%), and both were significantly higher than the extended lure (32.8 +/- 5.0%) with no DDVP. The presence or absence of DDVP did not significantly affect the sex ratio of field-captured boll weevils. We found no functional reasoning for using DDVP in large scale trapping of boll weevils regardless of the formulation or presentation in the trap. We conducted two additional trapping evaluations after the 2005 and 2006 studies, but the numbers of boll weevils captured were too low for statistical comparisons, indicating that boll weevil eradication is reducing populations in the Rio Grande Valley of Texas.     

Activity of some mitochondrial enzymes in the progeny of rabbits treated with dichlorvos in the gestation period.

The activities of cytochrome oxidase (CYO) and succinate dehydrogenase (SDH) in brains of progeny of rabbits treated with dichlorvos (DDVP) 6 mg/kg/day during last ten days of pregnancy were investigated. Biochemical estimation of mitochondrial fraction of the brain tissue and the histochemical studies of fresh cryostat slices were carried out in 1, 8 and 16 day old rabbits. In comparison with control animals the decrease in CYO and SDH activity and the disturbances in "enzymatic maturation" rythm were observed in progeny of rabbits submitted to treatment with DDVP. In neuropil the changes were more pronounced than in pericarium of the nerve cells. In the brain structures which are sensitive to the metabolic disturbances (Ammon horn) SDH activities decreased.     

Clastogenic and mitodepressive effects of the insecticide dichlorvos on root meristems of<Emphasis Type="Italic">Vicia faba</Emphasis>

Plant bioassays are an important and integral part of the test battery used in detecting genotoxic/carcinogenic contamination in the environment. Highly sensitive biomonitoring of plant models have been developed, which enables the detection of hazards arising from pesticides, insecticides, industrial contamination, heavy metals and radiation. Root tips of Vicia faba ssp. minor were treated with 1-60 mM of the organophosphorus insecticide dichlorvos (DDVP) for 2 h, followed by a 20-h recovery period. Maleic acid hydrazide (MH) was used as a positive control for the mitotic index, micronucleus and chromosomal aberration assays performed on the Vicia model system. All treatments with DDVP significantly decreased the mitotic activity and increased the frequency of chromosomal aberrations at the metaphase. The frequency of micronuclei was significantly increased at DDVP concentrations starting from 10 mM. The results demonstrate clastogenic and mitodepressive effects of DDVP on Vicia faba cells.     

Dichlorvos toxicity in the white-footed mouse (Peromyscus leucopus)

The organophosphate pesticide, dichlorvos (DDVP), is used commonly to control ectoparasites in laboratory rodents colonies. This compound is relatively nontoxic to Mus musculus at dosages several times the therapeutic level. However, usage of a similar therapeutic level in the white-footed mouse (Peromyscus leucopus) resulted in substantial mortality. To determine whether P. leucopus is more susceptible than M. musculus to the toxic effects of DDVP, both species were exposed to 0, 3 and 6 g of pelleted DDVP per cage. In a subsequent experiment, P. leucopus were exposed to 0 and 1 g of DDVP per cage. Mortality was not observed in M. musculus at any dosage level. P. leucopus exposed to 1, 3 and 6 g of DDVP exhibited mortalities of 3%, 20% and 53%, respectively. Mean serum cholinesterase in P. leucopus exposed to 3 and 6 g of DDVP was 0.35 and 0.21 U/ml as compared to 3.13 U/ml in unexposed mice. The analogous values for M. musculus were 1.60 and 0.79 U/ml while the level in unexposed mice was 6.79 U/ml. In the second experiment, mean serum cholinesterase in P. leucopus exposed to 1 g of DDVP was 0.32 U/ml as compared to 2.33 U/ml in unexposed mice. Histopathology revealed no lesions in the brain, liver or kidneys. The increased susceptibility of P. leucopus to the toxic effects of DDVP was related to the lowered serum cholinesterase. This indicates that DDVP should not be used for control of ectoparasites in P. leucopus.     

Studies on the Mode of Action of Dipterex

To elucidate the reason of low mammalian toxicity of Dipterex, decomposition of this compound by rabbit tissue was investigated. Though splitting of P-C linkage was not confirmed, two glucuronides, presumably derived from the metabolite (s) of Dipterex, were isolated from the urine. Molar ratio of phosphorus and glucuronic acid in them are both estimated as 1 : 1, and they are observed to differ from trichloroethyl glucuronide. The rapid detoxification might be ascribed to the capacity of glucuronide formation as well as the enzymatic hydrolysis of DDVP, the active ingredient of Dipterex.     

Organophosphorus Compound O,O-Dimethyl-O-(2,2-dichlorovynyl)-Phosphate as Selective Inhibitor for Separate Determination of Acetylcholinesterase and Butyrylcholinesterase Activities in the Roach Rutilus rutilus

A comparative study is carried out on dependence of degree of activity inhibition of acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) of a freshwater bony fish, the roach Rutilus rutilus L., on concentration of organophosphates: O,O-dimethyl-O-(2,2-dichlorovynyl)phosphate (DDVP) and tetraisopropylamidopyrophosphate (iso-OMPA). It has been shown that both in roach and in horse the both inhibitors are selective for BChE in comparison with AChE. Their selectivity degree was 2000-fold and 80-fold, respectively. The ranges of effective DDVP concentrations are overlapped for horse AChE and BChE, while they do not for the roach enzymes. A similar regularity is revealed at action of iso-OMPA. It is established that DDVP has a higher inhibitory potency and selectivity in relation to roach BChE, than iso-OMPA. It is suggested to use DDVP as a new selective inhibitor for separate evaluation of AChE and BChE activities in fish tissues.     

Enantioseparation and enantioselective behavior of trichlorfon enantiomers in sediments

Trichlorfon (TF), an organophosphorus insecticide, has been widely used in seawater aquaculture; it is easily degraded to the highly toxic insecticide, dichlorvos (DDVP). In this study, the enantioseparation of TF enantiomers, as well as their degradation behavior and product (DDVP) formation in mariculture pond sediments, was investigated. The results show that both TF enantiomers degrade into DDVP, which is the main degradation product. Furthermore, S ‐(+)‐TF is preferentially degraded under natural conditions, suggesting that TF enantiomers degrade enantioselectively. Nevertheless, the degradation behavior of TF enantiomers is not enantiospecific under sterile conditions. The formation of DDVP and the enantiospecific degradation of TF enantiomers are attributed to the activities of microbes present in the sediments.     

Toxicological and biochemical characterizations of GSTs in Liposcelis bostrychophila Badonnel (Psocop., Liposcelididae)

Abstract: The toxicological and biochemical characteristics of glutathione S‐transferases (GSTs) in the resistant and susceptible strains of Liposcelis bostrychophila were investigated. The two resistant strains were the dichlorvos‐resistant strain (DDVP‐R) and PH₃‐resistant strain (PH₃‐R), and the resistance factors were 22.36 and 4.51, respectively. Compared with their susceptible counterparts, the activities per insect and specific activities of GSTs in DDVP‐R and PH₃‐R were significantly higher. The apparent Michaelis–Menten constant values (K_m) for 1‐chloro‐2,4‐dinitrobenzene (CDNB) were obviously lower in DDVP‐R and PH₃‐R (i.e. lower K_m values, 1.5625 mm for DDVP‐R and 0.6230 mm for PH₃‐R) when compared with their susceptible counterpart (K_m = 3.5520), indicating a higher affinity to the substrate CDNB in resistant strains. In contrast, the catalytic activity of GSTs towards CDNB in the susceptible strain was significantly higher than those in resistant strains. It was noticeable that when reduced glutathione (GSH) was used as substrate, GSTs from resistant strains both indicated a significantly declined affinity. For the catalytic activity of GSTs towards GSH, only the V_max value in DDVP‐R increased significantly compared with that from the susceptible strain, suggesting an overexpression of GST in this resistant strain. The inhibition kinetics of insecticides to GSTs in vitro revealed that dichlorvos and paraoxon possessed excellent inhibition effects on GSTs. The susceptible strain showed higher sensitivity (I₅₀ = 0.9004 mm ) to dichlorvos than DDVP‐R and PH₃‐R (higher I₅₀s, 8.0955 mm for DDVP‐R and 9.3346 mm for PH₃‐R). As for paraoxon, there was a similar situation. The resistant strains both suggested a higher I₅₀ (1.8735 mm for DDVP‐R, and 0.4291 mm for PH₃‐R) compared with the susceptible strain (0.2943 mm ). These suggested that an elevated detoxification ability of GSTs developed in the resistant strains.     

Serotonin and benzylamine oxidation by type A and type B MAO of rat brain in presence of organophosphate pesticides

Organophosphate (OP) pesticides, monocrotophos (MCP), dichlorvos (DDVP) and phosphamidon significantly inhibit both MAO-A and MAO-B activities in rat brain mitochondria. The inhibition of MAO-A by MCP is reversible whereas the inhibition by DDVP and phosphamidon is irreversible. MAO-B is inhibited irreversibly by all these organophosphates suggesting that the mechanism of action of OP pesticides is through phosphorylation of serine residue present in active centre of MAO.     

储藏物害虫嗜卷书虱对DDVP熏蒸的行为反应与致死剂量

1 引言 嗜卷书虱(Liposcelis bostrychophila)属啮虫目虱啮科。其体形微小,食性复杂,栖息场地多在粮食仓库及食品加工厂、图书馆、标本馆等地。大量发生时可造成严重损失,传播微生物,并以其尸体、排泄物等污染储藏的粮食和其它储藏物品。王进军等调查发现,在我国“双低”和“三低”贮粮的粮仓中,书虱已成为优势种群,对贮粮安全构成了威胁。使用病原真菌和细菌来防治嗜卷书虱,很难达到理想效果,即使采用菊酯类杀虫剂也难以奏效,贮粮熏蒸中普遍使用的溴甲烷(CH_3Br)和磷化氢(PH_3)对嗜卷书虱的防治效果也不很理想。利用昆虫生长调节剂防治嗜卷书虱的研究已有一些报道,但在具体应用上还存在着一些问题。气调措施可应用于控制书虱种群的增长,但书虱的抗气性发展很快,     

Toxicological effects of biocides on symbiotic and aposymbiotic juveniles of the hermatypic coral Acropora tenuis

Reef-building (or hermatypic) corals harbor the symbiotic dinoflagellates Symbiodinium spp. (Alveolata, Dinophyceae, Gymnodiniales), and contribute to the accretion of coral reefs in tropical and sub-tropical zones. In this study, toxicological effects of three commonly used biocides (dichlorvos (DDVP), a commonly used insecticide; diuron (DCMU), a herbicide; and tributyltin chloride (TBT-Cl), an anti-fouling agent) on the hermatypic coral Acropora tenuis (Anthozoa, Hexacorallia, Scleractinia) were studied using juveniles in both aposymbiotic (symbiont-free) and symbiotic conditions. After exposure to the chemicals, abnormalities such as detachment of soft tissues from the skeleton and/or death were observed, as well as lowered uptake of symbiotic algae (in aposymbiotic juveniles) or reduction of the symbiont population in tentacles (in symbiotic juveniles). Significant reduction of the symbiont population in tentacles of symbiotic juveniles exposed to DDVP, DCMU and TBT-Cl was observed at the concentrations of 100, 10, and 1 μg/l, respectively. Results of this study suggested that symbiotic juveniles of A. tenuis are more sensitive than in the aposymbiotic condition to DDVP and DCMU, but not to TBT-Cl.     

Development, validation and application of assays to quantify metrifonate and 2,2-dichlorovinyl dimethylphosphate in human body fluids

Gas chromatographic procedures [GC with electron-capture detection (ECD) and GC–MS] for the quantitative analysis of metrifonate and its active metabolite 2,2-dichlorovinyl dimethylphosphate (DDVP) in human blood and urine were developed, validated, and applied to the analysis of clinical study samples. Analysis of metrifonate involved extraction of acidified blood with ethyl acetate followed by solid-phase clean-up of the organic extract. Acidified urine was extracted with dichloromethane and the residue of evaporated organic phase was reconstituted in toluene. ECD and diethyl analogue of metrifonate internal standard (I.S.) were used for quantitation of metrifonate. The metrifonate lower limit of quantitation (LOQ) was 10.0 μg/l. The DDVP metabolite was chromatographed separately after cyclohexane extraction of acidified blood and urine using d₆-DDVP I.S. and MS detection. The LOQ of DDVP was 1 μg/l. Stability studies have confirmed that the matrix should be acidified prior to storage at −20°C or −80°C to inhibit chemical and enzymatic degradation of the analytes and to avoid overestimation of DDVP concentrations. Metrifonate was found to be stable in acidified human blood after 20 months of storage at −20°C and after 23 months of storage at −80°C. Under these conditions DDVP was found to be stable after 12 months of storage. Both assay procedures were cross-validated by different world-wide laboratories and found to be accurate and robust during analyses of clinical study samples.     

Investigation of insecticidal properties of aerosols of mixtures of pyrethroids and DDVP.

Systematic studies of the effectivity of aerosols of the mixtures of DDVP and pyrethroids tested on house flies revealed synergism among the mentioned substances the degree of which was determined by the composition of the mixtures. Among the formulae under study, the mixture of DDVP and neopynamin in a ratio 9 : 1 is of greatest interest.     

Efficacy of methuselah gene mutation toward tolerance of dichlorvos exposure in Drosophila melanogaster

Adverse reports on the exposure of organisms to dichlorvos (DDVP; an organophosphate insecticide) necessitate studies of organismal resistance/tolerance by way of pharmacological or genetic means. In the context of genetic modulation, a mutation in methuselah (mth; encodes a class II G-protein-coupled receptor (GPCR)) is reported to extend (~35%) the life span of Drosophila melanogaster and enhance their resistance to oxidative stress induced by paraquat exposure (short term, high level). A lack of studies on organismal tolerance of DDVP by genetic modulation prompted us to examine the protective efficacy of mth mutation in exposed Drosophila. Flies were exposed to 1.5 and 15.0 ng/ml DDVP for 12–48 h to examine oxidative stress endpoints and chemical resistance. After prolonged exposure of flies to DDVP, antioxidant enzyme activities, oxidative stress, glutathione content, and locomotor performance were assayed at various days (0, 10, 20, 30, 40, 50) of age. Flies with the mth mutation (mth¹) showed improved chemical resistance and rescued redox impairment after acute DDVP exposure. Exposed mth¹ flies exhibited improved life span along with enhanced antioxidant enzyme activities and rescued oxidative perturbations and locomotor insufficiency up to middle age (~20 days) over similarly exposed w¹¹¹⁸ flies. However, at late (≥30 days) age, these benefits were undermined. Further, similarly exposed mth-knockdown flies showed effects similar to those observed in mth¹ flies. This study provides evidence of tolerance in organisms carrying a mth mutation against prolonged DDVP exposure and further warrants examination of similar class II GPCR signaling facets toward better organismal health.     

Feeding behavior and brain acetylcholinesterase activity in bream (Abramis brama L.) as affected by DDVP,an organophosphorus insecticide

1. Bream (Abramis brama) were exposed to sublethal concentration of organophosphorus insecticide DDVP and the amount of food consumed and brain acetylcholinesterase (AChE) examined in exposed fish.2. Exposure to DDVP resulted in decreased amount of food consumed and inhibited brain AChE activity.3. Intraperitoneal injection of the fish with cholinergic drugs, atropine and TMB-4 recovered the feecling efficiency in exposed fish. TMB-4 recovered brain AChE activity as well.4. The results revealed that cholinergic system in fish brain constitutes biochemical mechanism controlling feecling behavior in fish.     

Effect of DDVP (insecticide) on citric acid fermentation in Aspergillus niger

The effect of the insecticide 2,2-dichlorovinyldimethylphosphate (DDVP) on citric acid fermentation in Aspergillus niger was studied. The appearance of citric acid in the culture medium was increasingly delayed with increasing concentration of the insecticide, and at concentrations at or above 80 μg/ml medium, citric acid production was first observed after 192 h incubation, compared with 96 h in the control flasks. The timing of the maximum rate of citric acid formation was also similarly delayed. DDVP also resulted in a delay in the utilization of inorganic phosphate by the cultures.     

Changes in DNA properties due to treatment with the pesticides malathion and DDVP

Summary Properties of calf thymus DNA were investigated after treatment with the pesticides malathion (0,0-dimethyl-S-(1,2-bis ethoxycarbonyl ethyl)dithiophosphate) and DDVP (0,0-dimethyl-0-(2,2 dichlorovinyl)phosphate) in vitro by means of derivative (differential) pulse polarography (DPP), thermal denaturation curves recorded spectrophotometrically (T_m), viscometric measurements, and chromatography on the hydroxyapatite column. Changes in the properties of DNA were observed by means of DPP after only a few hours incubation with the pesticides, whereas the other methods did not detect any changes even after 48 h. The results obtained by DPP indicate that single-stranded segments and thermolabile regions are formed in DNA due to the action of the pesticides. This behaviour could perhaps be a consequence of guanine alkylation followed by depurination and chain scission at elevated temperatures. Malathion and DDVP differ in the kinetics of reaction with double-helical DNA. DDVP is more reactive and its action is also manifested after 72 h in changes in viscosity, T_m, and chromatographic behaviour on the hydroxyapatite column. The changes induced by malathion were, under identical conditions, not detectable by these methods.     

Growth of mozambique tilapia (Oreochromis mossambicus Peters) chronically exposed to cadmium,naphthalene, and DDVP

The chronic effects of cadmium, naphthalene, and DDVP on the growth of Mozambique tilapia (Oreochromis mossambicus Peters) exposed to concentrations corresponding to 1/30 LC₅₀ for 24 h (cadmium and DDVP) and 1/15 LC₅₀ for 24 h (naphthalene) have been studied. The fish are kept in toxicant solutions for 60 days and then for 60 more days in clean water. It is found that the studied toxicants affect fish-growth indices to varying extents. Organic compounds have no significant effect on the linear and mass growth of tilapia. Cadmium most strongly suppresses tilapia growth, and the toxic effect of this metal is irreversible: all fish die after being transferred to clean water.     

有机磷对抗拟除虫菊酯家蝇的毒力

测定敏感、抗溴氰菊酯(Del-R)、抗氯菊酯(2Cl-R)的家蝇品系对有机磷杀虫剂敌敌畏、辛硫磷及马拉硫磷的LD₅₀,α-乙酸萘酯（α-NA）酯酶动力学,酯酶的活性和酯酶的抑制作用。Del-R和2Cl-R的家蝇品系对三种有机磷杀虫剂的抗性倍数为0.966～7.190倍,均为低抗水平。三个家蝇品系的羧酸酯酶活性水平与抑制中浓度存在正相关性,说明羧酸酯酶在抗拟除虫菊酯家蝇对有机磷杀虫剂的抗性中起一定的作用。