Chlorpyrifos Treatment Research Articles

The Effect of Chlorpyrifos, an Organophosphorus Pesticide, on Glucose Uptake in Whole Blood

Background: The sub-chronic organophosphorous pesticide exposure increases insulin resistance and thereby the risk of developing Diabetes mellitus. Its acute exposure also leads to hyperglycemia. However, the mechanism is not clearly understood. Hence the present study explores the effect of low and high concentrations of chlorpyrifos, an organophosphorous pesticide on glucose uptake by whole blood and its possible mechanism. Methods: Level of hemolysis was determined at 2 and 4 hours of 1% DMSO (Dimethyl sulfoxide) and chlorpyrifos (0.3 and 10 mg/ml) exposure. The whole blood was treated in vitro with vehicle i.e., 1% DMSO or high (10 mg/mL) or low (0.3 mg/mL) concentrations of chlorpyrifos dissolved in DMSO. Then plasma glucose was assayed by glucose oxidase method at 2 and 4 hours of DMSO/chlorpyrifos exposures. Results: There was no effect of DMSO or 0.3 mg/ml chlorpyrifos treatment on hemolysis even after 4 hours. 10 mg/ml chlorpyrifos causes 2% and 14% hemolysis at 2 and 4 hours respectively. Plasma glucose level decreased in a time dependent manner after collection of blood (15.9% at 2 hours and 34.2% at 4 hour) in presence of DMSO. Chlorpyrifos did not influence glucose uptake by whole blood in low concentration but suppressed it in high concentration. Conclusion: Chlorpyrifos does not impair glucose uptake at low concentration in whole blood probably because major glucose uptake in blood is insulin independent. The impaired glucose uptake at high concentration is mostly due to toxic metabolic impairment and partly due to its hemolytic effect.

Decreased anxiety in juvenile rats following exposure to low levels of chlorpyrifos during development

Exposure to chlorpyrifos (CPF) during the late preweanling period in rats inhibits the endocannabinoid metabolizing enzymes fatty acid hydrolase (FAAH) and monoacylglycerol lipase (MAGL), resulting in accumulation of their respective substrates anandamide (AEA) and 2-arachidonylglycerol (2-AG). This occurs at 1.0mg/kg, but at a lower dosage (0.5mg/kg) only FAAH and AEA are affected with no measurable inhibition of either cholinesterase (ChE) or MAGL. The endocannabinoid system plays a vital role in nervous system development and may be an important developmental target for CPF. The endocannabinoid system plays an important role in the regulation of anxiety and, at higher dosages, developmental exposure to CPF alters anxiety-like behavior. However, it is not clear whether exposure to low dosages of CPF that do not inhibit ChE will cause any persistent effects on anxiety-like behavior. To determine if this occurs, 10-day old rat pups were exposed daily for 7 days to either corn oil or 0.5, 0.75, or 1.0mg/kg CPF by oral gavage. At 12h following the last CPF administration, 1.0mg/kg resulted in significant inhibition of FAAH, MAGL, and ChE, whereas 0.5 and 0.75mg/kg resulted in significant inhibition of only FAAH. AEA levels were significantly elevated in all three treatment groups as were palmitoylethanolamide and oleoylethanolamide, which are also substrates for FAAH. 2-AG levels were significantly elevated by 0.75 and 1.0mg/kg but not 0.5mg/kg. On day 25, the latency to emerge from a dark container into a highly illuminated novel open field was measured as an indicator of anxiety. All three CPF treatment groups spent significantly less time in the dark container prior to emerging as compared to the control group, suggesting a decreased level of anxiety. This demonstrates that repeated preweanling exposure to dosages of CPF that do not inhibit brain ChE can induce a decline in the level of anxiety that is detectable during the early postweanling period.

Dynamin-related protein 1 mediates mitochondria-dependent apoptosis in chlorpyrifos-treated SH-SY5Y cells

Recent studies have demonstrated that dynamin-related protein 1 (Drp1), a mitochondrial fission protein, mediates mitochondria-dependent apoptosis through mitochondrial division. However, little is known about the mechanism by which Drp1 modulates apoptosis in response to chlorpyrifos (CPF)-induced toxicity. In this study, we determined that CPF-induced mitochondrial apoptosis is mediated by Drp1 translocation in SH-SY5Y human neuroblastoma cells. Our results showed that CPF treatment induced intrinsic apoptosis by activating caspase-9, caspase-3, and cytochrome c release in SH-SY5Y cells. Cytosolic Drp1 translocated to the mitochondria in CPF-treated cells and was phosphorylated at Ser616. Treating cells with CPF induced the generation of reactive oxygen species (ROS) and activation of mitogen-activated protein kinases (MAPKs). Inhibiting this ROS generation and MAPK activation abolished CPF-induced expression of phospho-Drp1. Furthermore, Drp1 was required for p53 to translocate to the mitochondria under CPF-induced oxidative stress. Treating cells with mitochondrial-division inhibitor-1 (mdivi-1), which blocks Drp1 translocation, increased the viability of CPF-treated cells by abrogating Drp1 translocation and caspase-3 activation. Specifically, pretreating cells with mdivi-1 inhibited Bax translocation to the mitochondria by blocking p53 signaling. Taken together, these data reveal a novel mechanism by which Drp1 activates mitochondrial-dependent apoptosis and indicate that inhibiting Dpr1 function can protect against CPF-induced cytotoxicity. We propose that inhibiting Drp1 is a possible therapeutic approach for pesticide-induced toxicity when hyperactivated Drp1 contributes to pathology.

Sublethal effects of Bt toxin and chlorpyrifos on various Spodoptera exigua populations

AbstractBt cotton (Cry1Ac) has been commercially grown in China since 1997, saving China's cotton production from attack by Bt‐target pests and also tremendously reducing pesticide usage. In recent years, however, Bt cotton, with 4.2 million ha of cultivation, has suffered from a secondary target pest, Spodoptera exigua (Hübner) (Lepidoptera: Noctuidae). In China, growers have even had to re‐adopt conventional pesticides to control the pest, and this practice has already caused serious pesticide residue. In order to clarify the sublethal effects of chemical pesticide, the responses of a Bt‐susceptible and a Bt‐tolerant (Bt10) S. exigua strain to three treatment combinations were examined, including Bt toxin, sublethal chlorpyrifos, and Bt + sublethal chlorpyrifos. The susceptible and the Bt10 strain responded differently to dual pressure. Bt toxin + sublethal chlorpyrifos treatment lowered larval mortality and stimulated population increase of the susceptible S. exigua, whereas it delayed growth and development of the Bt10 strain. Under dual pressure, although larvae of the Bt10 strain developed faster than larvae of the susceptible strain, the Bt10 population experienced higher larval mortality, prolonged pupal duration, decreased pupal weight, decreased emergence rate, and shortened adult longevity. Compared with the susceptible strain, the Bt10 strain was deleteriously affected by sublethal chlorpyrifos. The Bt‐tolerant/resistant S. exigua population was more vulnerable to chemical pesticides like chlorpyrifos regardless of whether it was exposed to Bt toxin or not. Our study provides a reference for increasing the efficacy of control of S. exigua in Bt‐cotton planting areas.

Advanced oxidation processes for the treatment of chlorpyrifos, dimethoate and phorate in aqueous solution

Photo-chemical-transformations of organophosphate pesticides, chlorpyrifos, dimethoate and phorate, using advanced oxidation processes (AOPs) namely UV photolysis, UV/H2O2, UV/Fenton and Fenton systems in aqueous solution were investigated in this work. A laboratory set-up was designed to evaluate and select the optimal oxidation process. Results show that addition of hydrogen peroxide/Fenton's reagent increased the UV degradation rates of all pesticides, and data were simulated through kinetic modeling. Kinetic results evidence pseudo first-order degradation, with the rate constant of reaction as 3.3 × 10–4, 2.07 × 10–2 and 1.88 × 10–2 for chlorpyrifos, dimethoate and phorate, respectively. Furthermore treatment efficiencies obtained for the studied AOPs indicate that UV/Fenton was most efficient for chlorpyrifos (50.3% degradation) and UV/H2O2 for dimethoate (96.9%) and phorate (89.6%). Finally, the identification of degradation products indicated that the UV/H2O2 technique results in the formation of fewer end products, with low toxicity. However, UV irradiation of phorate results in information of more toxic degradation end products such as phorateoxonsulfone.

A point mutation in the acetylcholinesterase-1 gene is associated with chlorpyrifos resistance in the plant bug Apolygus lucorum

Control of Chinese Apolygus lucorum relies heavily on organophosphate insecticides. Here we describe resistance to the organophosphate chlorpyrifos in an A. lucorum strain, BZ-R, which was developed from a field-collected strain (BZ) by selection with chlorpyrifos in the laboratory. BZ-R showed 21–58 fold resistance to chlorpyrifos compared with the laboratory reference strain LSF and another susceptible strain, BZ-S, derived from BZ. BZ-R also showed several fold resistance to two other organophosphates and a carbamate. No synergism of chlorpyrifos by metabolic enzyme inhibitors nor any increase in detoxifying enzyme activities were observed in BZ-R. No sequence differences in acetylcholinesterase-2 were found to be associated with the resistance but the frequency of an alanine to serine substitution at position 216 of acetylcholinesterase-1 was 100% in BZ-R, ∼21–23% in SLF and BZ, and 0% in BZ-S. A single generation treatment of chlorpyrifos on the BZ strain also increased its frequency of the serine substitution to 64%. Recombinantly expressed acetylcholinesterase-1 carrying the serine substitution was about five fold less sensitive to inhibition by chlorpyrifos oxon than the wild-type enzyme. Quantitative real-time PCR found no differences in ace1 or ace2 expression levels among the strains tested. Thus the chlorpyrifos resistance is strongly associated with the serine substituted acetylcholinesterase-1. An equivalent substitution has been found to confer resistance to many organophosphate and carbamate insecticides in four other insect species.

Lethal and Demographic Impact of Chlorpyrifos and Spinosad on the Ectoparasitoid Habrobracon hebetor (Say) (Hymenoptera: Braconidae).

The appropriate use of biological agents and chemical compounds is necessary to establish successful integrated pest management (IPM) programs. Thus, the off-target effects of pesticides on biological control agents are essential considerations of IPM. In this study, the effects of lethal and sublethal concentrations of chlorpyrifos and spinosad on the demographic parameters of Habrobracon hebetor (Say) (Hymenoptera: Braconidae) were assessed. Bioassays were carried out on immature and adult stages by using dipping and contact exposure of dry pesticide residue on an inert material, respectively. The lethal concentration (LC)50 values of chlorpyrifos and spinosad were 3.69 and 151.37 ppm, respectively, on the larval stage and 1.75 and 117.37 ppm, respectively, on adults. Hazard quotient (HQ) values for chlorpyrifos and spinosad were 400 and 2.2, respectively, on the larval stage and 857.14 and 2.84, respectively, on adults. A low lethal concentration (LC30) was used to assess the sublethal effects of both pesticides on the surviving females. In each treatment, 25 survivors were randomly selected and transferred into 6-cm Petri dishes. Adults were provided daily with last instars of Anagasta kuehniella (Zeller) as a host until all of the females died. The number of eggs laid, percent of larvae hatched, longevity, and sex ratio were recorded. Stable population growth parameters were estimated by the Jackknife method. In control, chlorpyrifos, and spinosad treatments, the intrinsic rates of increase (r m) values were 0.23, 0.10, and 0.21, respectively. The results of this study suggest a relative compatibility between spinosad use and H. hebetor. Finally, further studies should be conducted under natural conditions to verify the compatibility of spinosad with H. hebetor in IPM programs.

Carbon dioxide enrichment and brassinosteroid pretreatment alleviate chlorpyrifos phytotoxicity under suboptimal light and temperature conditions in tomato

Phytotoxicity is a daunting challenge for facility agriculture, and a crop is more susceptible to phytotoxicity under sub-optimum growth conditions. Although the practical values of brassinosteroid (BR) treatment or CO2 enrichment in promoting crop yield have been confirmed, few studies have focused on the regulation of pesticide phytotoxicity, especially under sub-optimum growth conditions. In this study, the phytotoxicity of chlorpyrifos was evaluated mainly by monitoring the transcriptional responses of genes involved in various physiological processes in tomato leaves under chilling temperature and low light, which occur frequently during the cool season in China. Additionally, we investigated whether 24-epibrassinolide (EBR) pretreatment (0.1μmol/L) or CO2 enrichment (1000μmol/mol) could mitigate this phytotoxicity. The treatment of chlorpyrifos decreased the transcriptions of photosynthetic and defense genes and increased those of antioxidant and detoxification genes. EBR pretreatment significantly increased the transcription of antioxidant, detoxification and defense genes, which could enhance the tolerance of the plants to pesticides and mitigate the phytotoxicity, as indicated by the increased mRNA level for photosynthetic genes. Similar observations were found with CO2 enrichment, and the effects of CO2 enrichment were even more pronounced than the effects of EBR pretreatment for the photosynthetic genes. Moreover, the changes of antioxidant enzymes activity and lipid peroxidation further confirmed that the chlorpyrifos exposure induced the oxidative stress, which could be ameliorated by either EBR pretreatment or CO2 enrichment. These results strongly suggest a promising prospect for the practical application of BRs or CO2 enrichment to alleviate the phytotoxicity of pesticides in facility agriculture.

PINK1/Parkin-mediated mitophagy alleviates chlorpyrifos-induced apoptosis in SH-SY5Y cells.

Chlorpyrifos (CPF) is one of the most widely used organophosphorous insecticides. There are links between CPF exposure and neurological disorders. Mitochondrial damage has been implicated to play a key role in CPF-induced neurotoxicity. Mitophagy, the selective autophagic elimination of mitochondria, is an important mitochondrial quality control mechanism. However, the role of mitophagy in CPF-induced neurotoxicity remains unclear. In this study, CPF-caused mitochondrial damage, role and mechanism of mitophagy on CPF-induced neuroapoptosis were extensively studied by using SH-SY5Y cells. We showed that CPF treatment caused mitochondrial fragmentation, excessive ROS generation and mitochondrial depolarization, thus led to cell apoptosis. Moreover, CPF treatment also resulted in increased colocalizaton of mitochondria with LC3, decreased levels of mitochondrial proteins, PINK1 stabilization and mitochondrial accumulation of Parkin. These data suggested that CPF treatment induced PINK1/Parkin-mediated mitophagy in SH-SY5Y cells. Furthermore, knockdown of Parkin dramatically increased CPF-induced neuroapoptosis. On the other hand, overexpression of Parkin markedly alleviated CPF-induced SH-SY5Y cell apoptosis. Together, these findings implicate a protective role of PINK1/Parkin-mediated mitophagy against neuroapoptosis and that enhancing mitophagy provides a potential therapeutic strategy for CPF-induced neurological disorders.

Insecticidal efficacy and persistence of a co-occluded binary mixture of Helicoverpa armigera nucleopolyhedrovirus (HearNPV) variants in protected and field-grown tomato crops on the Iberian Peninsula.

A binary co-occluded mixture (HearSP1B:LB6) of Helicoverpa armigera single nucleopolyhedrovirus (HearNPV) variants was previously found to be highly pathogenic under laboratory conditions. The insecticidal efficacy and persistence of this mixture were determined in greenhouse and field-grown tomato crops in Spain and Portugal. Concentrations of 10(9) -10(11) occlusion bodies (OBs) L(-1) of HearSP1B:LB6 resulted in 89-100% mortality of larvae on treated tomato plants in growth chambers. In protected tomato crops, application of 10(10) OBs L(-1) of HearSP1B:LB6 was as effective as Bacillus thuringiensis (Bt) and spinosad in reducing the percentage of damaged fruits, and resulted in higher larval mortality than the Bt treatment. In open-field tomato crops, virus treatments were as effective in reducing the percentage of damaged fruit as spinosad, Bt and chlorpyrifos treatments. The persistence of the insecticides on tomato plants was negatively correlated with solar radiation in both field and greenhouse settings. Residual insecticidal activity of OBs on protected tomato crops at 6 days post-application was 55 and 35% higher than that of Bt and spinosad respectively. On field-grown tomato, OB persistence was significantly lower than with spinosad or chlorpyrifos. The efficacy and persistence of HearSP1B:LB6 OBs were comparable with those of commercial insecticides in both field and greenhouse tomato crops. Future studies should focus on reducing application rates to determine insecticidal efficacy at lower OB concentrations. © 2015 Society of Chemical Industry.

Study of the chlorpyrifos neurotoxicity using neural differentiation of adipose tissue-derived stem cells.

Chlorpyrifos (CPF) is the most commonly used organophosphorus insecticide which causes neurodevelopmental toxicity. So far, animals have been used as ideal models for neurotoxicity studies, but working with animals is very expensive, laborious, and ethically challenging. This has encouraged researchers to seek alternatives. During recent years, several studies have reported successful differentiation of embryonic and adult stem cells to neurons. This has provided an excellent model for neurotoxicologic studies. In this study, neural differentiation of mouse adipose tissue-derived stem cells (ADSCs) was used as an in vitro model for investigation of CPF neurotoxicity. For this purpose, mouse ADSCs were cultured in a medium containing knockout serum replacement and were treated with different concentrations of CPF at several stages of differentiation. Cytotoxic effect of CPF and the expression of neuron-specific genes and proteins were studied in the differentiating ADSCs. Furthermore, the activity of acetylcholinesterase was assessed by Ellman assay at different stages of differentiation. This study showed that up to 500 μM CPF did not alter viability of the undifferentiated ADSCs, whereas viability of the differentiating cells decreased with 500 μM CPF. CPF upregulated the expression of some neuron-specific genes and seemed to decrease the number of β-tubulin III and MAP2 proteins-expressing cells. There was no detectable acetylcholine esterase activity in differentiated ADSCs. In summary, it was shown that CPF treatment can decrease the viability of ADSC-derived neurons and dysregulate the expression of some neuronal markers through acetylcholinesterase-independent mechanisms. © 2015 Wiley Periodicals, Inc. Environ Toxicol 31: 1510-1519, 2016.

Honey has a protective effect against chlorpyrifos-induced toxicity on lipid peroxidation, diagnostic markers and hepatic histoarchitecture

IntroductionCurrently, there is increasing interest in the identification of natural sources of antioxidants that have minimal side effects and can be used as preventive medicine. In this study, the protective role of honey against oxidative damage and hepatotoxicity induced by sub-chronic exposure to chlorpyrifos (CPF) was investigated. MethodsFemale Wistar rats (n=24) were randomly divided into the following four groups: (1) control, (2) honey-treated (3.0g/kg), (3) CPF-treated (5.4mg/kg) and (4) honey (3.0g/kg)+CPF (5.4mg/kg) treatments. All of the doses were administered daily via oral gavage for 4 weeks. ResultsOral exposure to CPF caused hepato- and nephrotoxicity as indicated by the marked elevation in the serum hepatic marker enzymes (the transaminases and alkaline phosphatase activities), the total bilirubin, total cholesterol, triglycerides, urea, creatinine and hepatic lipid peroxidation levels, whereas the serum total protein level was significantly lower compared with the control. A significant decrease in the body weight gain and an increase in the absolute and relative liver weights were observed in the CPF-treated animals compared with the control. The biochemical alterations observed were accompanied by histopathological changes marked by the appearance of degenerative necrosis, congestion, inflammation and edema in the liver section. However, co-treatment with honey ameliorated the changes in the investigated biochemical parameters and the changes in the body and liver weights as revealed by the inhibition of lipid peroxidation and the improvement observed histopathologically. ConclusionsThe present study suggests that honey has a protective potential for the alleviation of hepatic and renal toxicities induced by CPF.

Metabolomics analysis and biomarker identification for brains of rats exposed subchronically to the mixtures of low-dose cadmium and chlorpyrifos.

Cadmium (Cd) and chlorpyrifos (CPF) are widespread harmful environmental pollutants with neurotoxicity to mammals. Although the exposure to Cd and CPF at the same time may pose a significant risk to human health, the subchronic combined neurotoxicity of these two chemicals at low levels in the brain is poorly understood. In this study, we treated rats with three doses (low, middle, and high) of Cd, CPF, or their mixture for 90 days. No obvious symptom was observed in the treated animals except those treated with high-dose CPF. Histological results showed that middle and high doses of the chemicals caused neuronal cell damage in brains. GC-MS-based metabonomics analysis revealed that energy and amino acid metabolism were disturbed in the brains of rats exposed to the two chemicals and their combinations even at low doses. We further identified the unique brain metabolite biomarkers for rats treated with Cd, CPF, or both. Two amino acids, tyrosine and l-leucine, were identified as the biomarkers for Cd and CPF treatment, respectively. In addition, a set of five unique biomarkers (1,2-propanediol-1-phosphate, d-gluconic acid, 9H-purine, serine, and 2-ketoisovaleric acid) was identified for the mixtures of Cd and CPF. Therefore, the metabolomics analysis is more sensitive than regular clinical observation and pathological examination for detecting the neurotoxicity of the individual and combined Cd and CPF at low levels. Overall, these results identified the unique biomarkers for Cd and CPF exposure, which provide new insights into the mechanism of their joint toxicity.

Effects of chlorpyrifos on in vitro sex steroid production and thyroid follicular development in adult and larval Lake Sturgeon, Acipenser fulvescens

Chlorpyrifos is a widely used organophosphate pesticide that has previously been shown to enter waterways in biologically relevant concentrations and has the potential to disrupt both thyroid hormone and sex steroid biosynthesis in vertebrates. Because gonadal maturation and larval development in Lake Sturgeon, Acipenser fulvescens, potentially coincide with the application of chlorpyrifos we examined the effects of chlorpyrifos on both thyroid follicular development in larval Lake Sturgeon, and sex hormone synthesis in adult Lake Sturgeon. For the first time, the present study reports steroidogenesis from testicular and ovarian tissue in Lake Sturgeon using an established in vitro bioassay. Furthermore, incubating gonad tissue with 5, 500 or 2000ngmL−1 chlorpyrifos revealed an inhibitory effect on testosterone synthesis in both testicular (control, 40.29pgmg−1 tissue wet weight−1h−1 compared to experimental, 21.84pgmg−1 tissue wet weight−1h−1) and ovarian (control, 33.83pgmg−1 tissue wet weight−1h−1 compared to experimental, 15.19pgmg−1 tissue wet weight−1h−1) tissue. In a second series of experiments, larval Lake Sturgeon were exposed to equivalent concentrations of chlorpyrifos as above for 10days (d) between hatch and the onset of exogenous feeding. Larvae from each treatment group were raised until 67days post hatch (dph) and growth rates were compared alongside key indicators of thyroid follicle growth. Chlorpyrifos treatment had no effect on the measured indicators of thyroid follicular development.

Modifying effects of vitamin E on chlorpyrifos toxicity in atlantic salmon.

The aim of this study was to elucidate how vitamin E (alpha tocopherol) may ameliorate the toxicity of the pesticide chlorpyrifos in Atlantic salmon. Freshly isolated hepatocytes were exposed to vitamin E, chlorpyrifos or a combination of vitamin E and chlorpyrifos (all 100 μM). Transcriptomics (RNA-seq) and metabolomics were used to screen for effects of vitamin E and chlorpyrifos. By introducing vitamin E, the number of upregulated transcripts induced by chlorpyrifos exposure was reduced from 941 to 626, while the number of downregulated transcripts was reduced from 901 to 742 compared to the control. Adding only vitamin E had no effect on the transcriptome. Jak-STAT signaling was the most significantly affected pathway by chlorpyrifos treatment according to the transcriptomics data. The metabolomics data showed that accumulation of multiple long chain fatty acids and dipeptides and amino acids in chlorpyrifos treated cells was partially alleviated by vitamin E treatment. Significant interaction effects between chlorpyrifos and vitamin E were seen for 15 metabolites, including 12 dipeptides. The antioxidant had relatively modest effects on chlorpyrifos-induced oxidative stress. By combining the two data sets, the study suggests that vitamin E supplementation prevents uptake and accumulation of fatty acids, and counteracts inhibited carbohydrate metabolism. Overall, this study shows that vitamin E only to a moderate degree modifies chlorpyrifos toxicity in Atlantic salmon liver cells.

Chlorpyrifos induces reticulum endoplasmic stress in JEG-3 cells

Chlorpyrifos induces reticulum endoplasmic stress in JEG-3 cells

Identification of heat shock cognate protein 70 gene (Alhsc70) of Apolygus lucorum and its expression in response to different temperature and pesticide stresses.

Heat shock cognate protein 70 (Hsc70) is a very important stress-resistance protein of insects against environmental stresses. We employed fluorescent real-time quantitative polymerase chain reaction and Western-blot techniques to analyze the transcriptional and translational expression profiles of AlHSC70 under extreme temperature (4°C and 40°C) or 4 pesticide stresses in Apolygus lucorum. The results showed that the expression of AlHSC70 were significantly induced by cyhalothrin or extremely high temperature (40°C) in both transcriptional and translational levels (P < 0.05), while the transcriptional and translational level of AlHSC70 decreased significantly in treatments of chlorpyrifos or extreme cold temperature (4°C) (P < 0.05). Moreover, after Apolygus lucorum treated by imidacloprid or emamectin benzoate, the expression of AlHSC70 was only up-regulated significantly at the transcriptional level (P < 0.05), although obviously up-regulated at the translational level of AlHSC70. Therefore, this study confirmed that the Alhsc70 gene played important roles in response to both temperature and pesticide stresses, especially for cyhalothrin or extremely high temperature (40°C). In addition, the significant polynomial regression correlations between temperature and the Alhsc70 expression level were shown in all the nymph and adult stages (P < 0.01), indicating temperature was an important factor to affect the relative expression of Alhsc70.

Chlorpyrifos Induces the Expression of the Epstein-Barr Virus Lytic Cycle Activator BZLF-1 via Reactive Oxygen Species

Organophosphate pesticides (OPs) are among the most widely used synthetic chemicals for the control of a wide variety of pests, and reactive oxygen species (ROS) caused by OPs may be involved in the toxicity of various pesticides. Previous studies have demonstrated that a reactivation of latent Epstein-Barr virus (EBV) could be induced by oxidative stress. In this study, we investigated whether OPs could reactivate EBV through ROS accumulation. The Raji cells were treated with chlorpyrifos (CPF), one of the most commonly used OPs. Oxidative stress indicators and the expression of the EBV immediate-early gene BZLF-1 were determined after CPF treatment. Our results show that CPF induces oxidative stress as evidenced by decreased malondialdehyde (MDA) level, accompanied by an increase in ROS production, DNA damage, glutathione (GSH) level, and superoxide dismutase (SOD) and catalase (CAT) activity. Moreover, CPF treatment significantly enhances the expression of BZLF-1, and the increased BZLF-1 expression was ameliorated by N-acetylcysteine (NAC) incubation. These results suggest that OPs could contribute to the reactivation of the EBV lytic cycle through ROS induction, a process that may play an important role in the development of EBV-associated diseases.

Rearing tomato whitefly and field evaluation of modified and unmodified conidia of Beauveria bassiana, Isaria farinosa, Metarhizium anisopliae and low rates of chlorpyrifos under tropical conditions.

The whitefly ( Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae) is a serious pest of a wide range of economically important agricultural and ornamental crops in all agro-ecological regions in the world. This study evaluated the efficacy of conidia of entomopathogenic Beauveria bassiana (BB 315), Isaria farinosa (ARSEF 5081) and Metarhizium anisopliae (Ma 275.86DC), against whitefly ( Bemisia tabaci ) under tropical climate. Two forms of conidia: (a) modified conidia (conidia with improved ecological competence), and (b) unmodified conidia of the three isolates were subjected to heat treatment (45°C) for 5 days. Germination rates of these conidia before and after their exposure to heat were compared at 25 °C on Sabouraud Dextrose Agar (SDA, aw= 0.995) to assess resilience to heat stress. Further, assessment of germination potentials of conidia was conducted at three aw levels (0.995, 0.98 and 0.96: corresponding to different levels of water availability). Thereafter, they were tested against B. tabaci infestation on tomato plants and insect densities after the treatments were compared with the effect of low rate chlorpyrifos. The conidia germinated differently on SDA at the three a w levels and the rate of germination of modified conidia of each isolate was significantly higher at 0.98 a w (F 2, 16 =0.31, P=0.001). Modified conidia of B. bassiana appeared more tolerant to temperature stress. All the isolates significantly reduced pest incidencerelative to control after 14 days and there was no significant difference (P>0.05) between the effect of modified and unmodified conidia against B. tabaci in the field. The level of control achieved using the conidia of the three fungal isolates was comparable with the chlorpyrifos treatment. Key Words : Bemisia tabaci, entomopathogen, water activity

Sex-dimorphic effects of gestational exposure to the organophosphate insecticide chlorpyrifos on social investigation in mice

Several pieces of evidence from animal and human studies indicate that the organophosphate insecticide chlorpyrifos (CPF) acts as a developmental neurotoxicant at environmentally relevant doses, and it is possibly endowed with endocrine-disrupting activity. Data collected in rodent models show that developmental exposure to CPF at sub-toxic doses induces long-lasting and sex-dimorphic changes in social and investigative responses in exposed offspring. The aim of this study was to evaluate the effects of gestational CPF treatment on social and olfactory discrimination in adult mice of both sexes. Pregnant CD1 out-bred mice were exposed to CPF per os on gestational days (GD) 14–17 at the sub-toxic dose of 6mg/kg/bw. At adulthood, male and female offspring underwent the same experimental paradigms, namely i) a social discrimination test where mice were presented with a simultaneous binary choice between a novel conspecific and a familiar one, and ii) an olfactory habituation/dishabituation test to evaluate their capability to discriminate between odors with different eco-ethological salience (non-social vs. social odors).Results showed that in the social discrimination test prenatal CPF primarily affected the female sex by raising the investigation time in females to the same levels as found in vehicle- and CPF-exposed males. The ability to discriminate between a familiar and a novel social mate was not affected by CPF in either sex. In the olfactory habituation/dishabituation test, mice of both sexes successfully discriminated non-social from social odors regardless of the prenatal treatment received.These results confirm previous evidence indicating that developmental exposure to CPF causes long-lasting and sex-dimorphic changes in responsiveness to social cues, in the absence of significant impairment of social and olfactory discrimination capacity. These findings are discussed within the framework of recent data pointing to the limbic/hypothalamic circuitry and steroid hormonal regulations as possible targets for CPF neurotoxicity.