Sublethal Effects Of Chlorpyrifos Research Articles

Sub-lethal Effects of Chlorpyrifos on Glutathione S-Transferase Activity and Total Protein Contents of Fish, Labeo rohita

Sub-lethal Effects of Chlorpyrifos on Glutathione S-Transferase Activity and Total Protein Contents of Fish, Labeo rohita

Acute warming increases pesticide toxicity more than transgenerational warming by reducing the energy budget

There is increasing awareness that the toxicity of pesticides can to a large extent be modulated by warming, and that temporal exposure scenarios may strongly affect the impact of two stressors. Nevertheless, we lack information on how the exposure duration to warming may shape pesticide toxicity under warming. Furthermore, despite that bioenergetic responses have the potential to generate mechanistic insights in how toxicants interact with warming, this has been understudied in ecotoxicology. To investigate whether warming duration modifies pesticide toxicity, mosquito larvae were exposed to a control temperature at 20 °C or three warming treatments at 24 °C (acute, developmental and transgenerational warming), and to four pesticide treatments (solvent control, and three chlorpyrifos concentrations) in a full factorial design. Chlorpyrifos increased mortality, growth rate and the energy consumed, and reduced the AChE (acetylcholinesterase) activity, the energy available, and the net energy budget (estimated as cellular energy allocation). The warming treatments did not affect mortality, AChE activity, and the energy consumed. However, acute warming increased the growth rate and decreased the energy available, while both acute and developmental warming decreased the cellular energy allocation. A first key finding was that the lethal and sublethal effects of chlorpyrifos were less strong under warming because of a higher degradation in the medium under warming. A second key finding was that, among the warming treatments, the pesticide toxicity was more increased under acute warming than under transgenerational warming. This could be explained by the negative impact of acute warming but not transgenerational warming on the net energy budget. The results in this study provide mechanistic insights that the exposure duration to warming can play an important role in modulating the impact of pesticides under warming. Therefore, including ecologically relevant temporal scenarios of exposure to warming is important in ecotoxicological studies.

Lethal and Sublethal Effects of Chlorpyrifos on Biological Traits and Feeding of the Aphidophagous Predator Harmonia axyridis.

Except of pest control, insecticides have shown adverse effects on natural enemies as well. Thus, risk assessment of pesticides for biological control agents is critical for effective use in integrated pest management (IPM) schemes. In the present study, the lethal and sublethal effects of chlorpyrifos, a commonly used insecticide that may negatively affect biological control agents, were evaluated on a non-target predator, the Asian ladybeetle Harmonia axyridis. Previous studies have reported on lethal concentrations, but the effects of sublethal concentrations remain unclear. Lethal and sublethal concentrations of chlorpyrifos were applied to third instar larvae of H. axyridis, and different growth and developmental parameters were measured. Treatment with LC10 (4.62 mg a.i. L−1) significantly shortened the developmental period of third instar larvae, whereas it significantly prolonged those of fourth instar larvae and pupa. Treatment with LC30 (9.59 mg a.i. L−1) significantly increased the larval and pupal developmental period compared with that of the control, whereas feeding potential, female fecundity, and adult longevity significantly decreased after LC10 and LC30 treatment. The pre-oviposition period significantly increased compared with that of the control. Population growth parameters, the finite (λ) and intrinsic rate of increase (r) and the net reproductive rate (R0), decreased following exposure to sublethal concentrations of chlorpyrifos. According to the results, the use of chlorpyrifos in IPM schemes requires further research because even sublethal concentrations of this insecticide were harmful to H. axyridis population growth.

Sub-lethal toxicity of chlorpyrifos alone and in combination with polyethylene glycol to common carp (Cyprinus carpio)

In the present study, sub-lethal effects of chlorpyrifos, alone (25 and 50 μg L−1) and in combination with Polyethylene glycol (5 and 10 mg L−1), on common carp were investigated. Exposure to chlorpyrifos caused significant changes in all blood biochemical parameters compared to control groups. Total protein, triglyceride, glucose levels, as well as lactate dehydrogenase (LDH), gamma-glutamyl transferase (GGT), and creatine phosphokinase (CPK) activities in plasma changed after exposure to 10 mg L−1 polyethylene glycol (PEG), while fish exposed to PEG did not show any significant difference in aspartate aminotransferase (AST), alanine aminotransferase (ALT), alkaline phosphatase (ALP), and acetylcholinesterase (AChE) activities and albumin and globulins levels. Exposure to a combination of chlorpyrifos and PEG caused a significant change in AST, GGT, CPK, LDH and AChE activity, total protein and glucose level. The influence of chlorpyrifos and PEG combination on ALP, cholesterol, triglyceride, albumin, and globulin depends on the concentration of the insecticide and PEG. With a reduction in chlorpyrifos concentration, PEG can maintain ALP activity and albumin at a normal level. Although fish exposure to chlorpyrifos, alone or in combination with polyethylene glycol, significantly increased malondialdehyde (MDA) and catalase (CAT) level, it decreased total antioxidant level (TAN). Exposure to just polyethylene glycol had no impact on CAT activity, TAN and MDA level. According to the results, PEG can have an antagonistic effect on chlorpyrifos toxicity, depending on these two materials concentration. However, chlorpyrifos increased the toxicity of PEG.

Lethal and sublethal responses in the fish, Odontesthes bonariensis, exposed to chlorpyrifos alone or under mixtures with endosulfán and lambda-cyhalothrin.

Need for ecotoxicological information on local species has been recently highlighted as a priority issue in Latin America. In addition, little information has been found on concentration distances between lethal and sublethal effects, and the effect of mixtures at these two levels of analysis. Chlorpyrifos (CPF) is an organophosphate insecticide broadly used in soybean crops which has dramatically expanded in Latin America and other regions of the world. The aim of the present study was to evaluate lethal and sublethal effects of CPF, singly or in mixtures, on the inland "Pejerrey" (Odontesthes bonariensis) under laboratory conditions. Bioassays were performed using 15-30 d post hatch Pejerrey larvae. Six toxicity tests were run for estimating the average inter-assay dose-response curve of CPF and other six for assessing the effects of mixtures of CPF with endosulfan (EN) or lambda-cyhalothrin (LC), at three toxic units (TU) proportions (25:75, 50:50, 75:25). In addition, four assays were performed to describe the average inter-assay dose-response inhibition curve of acetylcholinesterase (AchE) for CPF alone and two for assessing the mixtures. The estimated 96 h-LC50 for CPF was 2.26 ± 1.11 µg/L and the incipiency value was 0.048 ± 0.012 µg/L, placing this Neotropical species among the 13% of worldwide fish more sensitive to CPF. In addition, the 96 h-LC50 for EN and LC were 0.30 ± 0.012 µg/L and 0.043 ± 0.031 µg/L, respectively. Therefore, relative toxicity of the three soybean insecticides for O. bonariensis was LC > EN > CPF. Effects of mixtures with EN and LC were variable, but in general fitted to both, independent action (IA) and concentration addition (CA) models. Slight antagonism was found when CPF TU proportions were above 50%. Therefore, from the regulatory point of view, the use of both mixture models, CA or IA, would be precautionary. Differential sensitivity to CPF was found for AchE inhibition at the head (96 h-IC50 = 0.065 ± 0.058 µg/L) and the body (96 h-IC50 = 0.48 ± 0.17 µg/L). In addition, whereas no significant effects induced by mixtures was observed in body AchE activity, antagonism was induced in head AchE inhibition in presence of both, EN and LC in the mixture. The lethal to sublethal ratio was close to 25.2 and 3.4 when comparing the CPF-LC50 and IC50s for head and body AchE activity, respectively. However, considerable overlapping was observed between concentration-response curves, indicating that the use of AchE as biomarker for environmental monitoring would be limited.

Sublethal effects of four insecticides on folding and spinning behavior in the rice leaffolder, Cnaphalocrocis medinalis (Guenée) (Lepidoptera: Pyralidae).

The rice leaffolder, Cnaphalocrocis medinalis, is an important rice pest. The sublethal effects of chlorpyrifos, chlorantraniliprole, emamectin benzoate and spinosad were investigated on the folding and spinning behaviors of third- to fifth-instar C. medinalis larvae (L3 - L5) after insecticidal exposure of the second instar. A 25% lethal concentration (LC25 ) of chlorpyrifos prolonged the leaf selection time of L5, and reduced the number of binds per primary fold for L4 and L5. An LC10 of chlorantraniliprole reduced the number of binds per primary fold for L4 and increased the number of head swings per bind for L5. An LC10 of emamectin benzoate shortened the primary fold length for L5 and decreased the number of head swings per primary fold for L3 and L4 and the number of head swings per bind for L3, while an LC25 of emamectin benzoate shortened the fold length per 24 h for L5 and folding time for L3. An LC10 of spinosad lowered the fold length per 24 h and the number of head swings for L5. An LC25 of spinosad prolonged leaf selection time, and decreased primary fold length, binds per primary fold, binds per fold and fold length per 24 h in L5. Emamectin benzoate and spinosad exerted stronger sublethal effects on the folding and spinning behavior of C. medinalis than chlorpyrifos and chlorantraniliprole. These results provide better understanding of the sublethal effects of interactions of insecticides on C. medinalis. © 2017 Society of Chemical Industry.

Does pollen availability mitigate the impact of pesticides on generalist predatory mites?

The effect of the provision of pollen on the impact of pesticides on the predatory mite Kampimodromus aberrans was assessed at individual and population levels. In the laboratory we evaluated the influence of pollen amount and pollen application frequency on lethal and sub-lethal effects of chlorpyrifos and spinosad. In a potted plant experiment, the effects of pesticides and pollen were assessed on predatory mite population abundance. In the laboratory, survival and fecundity of predatory mites were reduced by insecticides, and spinosad was more toxic than chlorpyrifos. In the same experiment, high pollen application frequency alleviated the sub-lethal effect induced by chlorpyrifos. On potted plants, pollen applications reduced the impact of chlorpyrifos on K. aberrans, whereas without pollen applications the impact of spinosad and chlorpyrifos on the predatory mite population was similar. Results obtained here highlight that the provision of fresh pollen is of particular importance for predatory mites when pesticides are applied.

Toxic impact of two organophosphate insecticides on biochemical parameters of a food fish and assessment of recovery response

Sublethal effects of chlorpyrifos (CPF) and monocrotophos (MCP) on fish biochemical constituents were investigated along with the assessment of recovery response after cessation of intoxication. The fish, Clarias batrachus were exposed to 1.656 mg(-l) and 2.114 mg(-l) of CPF and MCP for 28 days. After 28 days, they were released in freshwater and allowed to recover for 21 days. The CPF exposure resulted in the decrease of carbohydrate and glycogen content, whereas MCP intoxication caused mixed response. Pyruvate and lactate contents were altered under the stress of CPF and MCP. Recovery of these alterations was observed after the cessation of toxicity. Exposure of C. batrachus to CPF and MCP resulted in decreased activity of lactate dehydrogenase in the kidney, liver and muscle but its activity increased in the gills. The CPF caused inhibition of succinate dehydrogenase enzyme in all tissues. Induction in the activity of malate dehydrogenase was caused by both insecticides. Glycogen phosphorylase a was induced in all tissues, whereas glycogen phosphorylase ab showed both induction and inhibition. Of the two insecticides, CPF was more toxic and the recovery response was less. These results are important in the assessment of the risk caused by organophosphate insecticides on nontarget organisms, especially the food fish.