Toxicity Of Synthetic Pyrethroids Research Articles

Toxicity of synthetic pyrethroids against Spodoptera mauritia found attacking maize in the farmers’ fields

The contact toxicity of three synthetic pyrethroids viz., deltamethrin, alphamethrin and bifenthrin was investigated against third instar of swarming caterpillar, Spodoptera mauritia by dry film technique and topical application technique. The data on mortality were recorded twenty-four hours after setting the experiment. The order for toxicity of different synthetic pyrethroids, based on LC50/LD50 Value was: Deltamethrin > bifenthrin > Alphamethrin. On the basis present findings Deltamethrin was found to be most suitable synthetic pyrethroid and was more effective even at low LC50/LD50 value.

β -Cypermethrin promotes the adipogenesis of 3T3-L1 cells via inducing autophagy and shaping an adipogenesis-friendly microenvironment.

The toxicity of synthetic pyrethroids has garnered attention, and studies have revealed that pyrethroids promote fat accumulation and lead to obesity in mice. Nevertheless, the effect of β-cypermethrin (β-CYP) on adipogenesis and its underlying mechanism remains largely unknown. In this study, mouse embryo fibroblasts 3T3-L1 cells were exposed to β-CYP, and the cell viability, intracellular reactive oxygen species (ROS) level, autophagy, and adipogenesis were assessed to investigate the roles of oxidative stress and autophagy in the toxic effects of β-CYP on adipogenesis. The results demonstrated that treatment with 100μΜ β-CYP elevated the ROS level, decreased mitochondrion membrane potential, stimulated autophagy, and enhanced the adipogenesis induced by the mixture of insulin, dexamethasone, and 3-isobutyl-1-methylxanthine. However, co-treatment with N-acetyl-L-cysteine partially blocked the abovementioned effects of β-CYP in 3T3-L1 cells. In addition, co-treatment with rapamycin, an autophagy agonist, enhanced the inductive effect of β-CYP on adipogenesis, whereas co-treatment with 3-methyladenine blocked the enhancement of adipogenesis caused by β-CYP. Moreover, β-CYP also altered the microenvironment of 3T3-L1 cells to an adipogenesis-friendly one by reducing the extracellular expression of miR-34a, suggesting that the culture media of β-CYP-treated 3T3-L1 cells could shift macrophages to M2 type. Taken together, the data obtained in the present study demonstrated that β-CYP promoted adipogenesis via oxidative stress-mediated autophagy disturbance, and it caused macrophage M2 polarization via the alteration of miR-34a level in the microenvironment. The study demonstrated the adipogenesis-promoting effect of β-CYP and unveiled the potential mechanism.

Inhalation Exposure of Formulated Fenvalerate (20% EC): Toxicologic Alterations in Kidney of Rats

Synthetic pyrethroid insecticides are logically gaining ground in agriculture, veterinary and in house pest control programmes (Leahey 1985) due to severe knock down effects on insects (Casida et al. 1983) and environment compatible over organochlorine insecticides with less toxicity to mammals (Aldridge 1990). Toxicity of pyrethroids was studied in different animals and it was found that these insecticides have neurotoxic (Crafton et al. 1995) and genotoxic effects (Amer et al. 1993). He et al. (1989) reviewed 573 cases of acute pyrethroid poisoning caused by deltamethrin followed by fenvalerate. Importantly, all of the pyrethroid exposures were attributed to formulated products, specified as emulsifiable concentrates, therefore undoubtedly containing organic solvent and surfactant. Thus, the health effects reported are not due to pyrethroids alone, but also due to the formulated solvent, surfactant and other uncharacterized co-exposures (Yang et al. 2002). Xylene may also be present in the concentrates (IARC 1989). Fenvalerate is also formulated in combination with oxydemeton–methyl (Royal society of chemistry 1986). Fenvalerate [(RS)-a-cyano-3-phenoxy benzyl (RS)-2-(4chlorophenyl)] isovalerate, a photo stable pyrethroid insecticide has been used worldwide for control of wide range of pest insects of cotton and vegetables (Shiba et al. 1990). India is an agricultural country and the farmers use array of pesticides for controlling agricultural pests and disease causing vectors. Fenvalerate is one among the several pesticides used in large quantity for plant protection purpose. Pesticides may reach the water bodies through different modes like, run-off from agricultural fields along with rainwater, accidental spills, atmospheric transport and also by direct application (Mushingeri and David 2005). Reports in respect of toxicity of synthetic pyrethroids including formulated fenvalerate in experimental animals is very scarce. Earlier studies from this laboratory reported the pulmonary toxicity and steroidogenic alterations in fenvalerate inhalation exposed rats (Mani et al. 2001, 2002). However reports on nephrotoxicity of formulated fenvalerate in individuals exposed through inhalation is not available in literature. The purpose of present work was to investigate the effects of formulated fenvalerate (20% EC) in kidney of rats.

Temperature-Dependent Variation in Toxicity of Insecticides Against <I>Earias</I> v<I>itella</I> (Lepidoptera: Noctuidae)

The toxicity of synthetic pyrethroids was found to be negatively correlated with temperature, whereas contrasting correlation was observed with the toxicity of organophosphorous compounds chlorpyriphos and quinalphos, which was most toxic at higher temperature. A similar phenomenon was observed in endosulfan at higher temperature and humidity combination. The insecticide molecules indoxacarb and spinosad were effective among the insecticides tested. Indoxacarb was effective at lower temperature, and spinosad was effective at all the temperature and relative humidity combinations with minor difference in LD50 values. During both the years, however, the levels of resistance were higher in second year compared with previous year.

Temperature-Dependent Variation in Toxicity of Insecticides Against Earias vitella (Lepidoptera: Noctuidae)

The toxicity of synthetic pyrethroids was found to be negatively correlated with temperature, whereas contrasting correlation was observed with the toxicity of organophosphorous compounds chlorpyriphos and quinalphos, which was most toxic at higher temperature. A similar phenomenon was observed in endosulfan at higher temperature and humidity combination. The insecticide molecules indoxacarb and spinosad were effective among the insecticides tested. Indoxacarb was effective at lower temperature, and spinosad was effective at all the temperature and relative humidity combinations with minor difference in LD50 values. During both the years, however, the levels of resistance were higher in second year compared with previous year.

Phase distribution of synthetic pyrethroids in runoff and stream water.

Synthetic pyrethroids (SPs) are a group of hydrophobic compounds with significant aquatic toxicity. Their strong affinity to suspended solids and humic materials suggests that SPs in natural surface water are distributed in solid-adsorbed, dissolved organic matter (DOM)-adsorbed, and freely dissolved phases. The freely dissolved phase is of particular importance because of its mobility and bioavailability. In the present study, we used solid-phase microextraction to detect the freely dissolved phase, and we evaluated the phase distribution of bifenthrin and permethrin in stream and runoff waters. In stream water, most SPs were associated with the suspended solids and, to a lesser extent, with DOM. The freely dissolved phase contributed only 0.4% to 1.0%. In runoff effluents, the freely dissolved concentration was 10% to 27% of the overall concentration. The predominant partitioning into the adsorbed phases implies that the toxicity of SPs in surface water is reduced because of decreased bioavailability. This also suggests that monitoring protocols that do not selectively define the freely dissolved phase can lead to significant overestimation of toxicity or water-quality impacts by SPs.

Relative Toxicity of Different Pesticides to Campoletis chlorideae Uchida (Hym., Ichneumonidae)

The ichneumonid Campoletis cholrideae Uchida is a common parasitoid of Helicoverpa armigera (Hubn.) and Spodoptera litura (Fab.) on many crops in India. The toxicity of 30 pesticides (19 insecticides, 9 fungicides, neem seed kernel extract (NSKE) and nuclear polyhedrosis virus (NPV) to the adults of C.chlorideae was studied. The data on the initial toxicity revealed that acephate, NSKE, NPV and the fungicides appeared to be safe to the parasitoids. The insecticides found to be toxic were tested furthur for their residual toxicity to C. chlorideae , Endosulfan, carbaryl, dichlorvos, phosalone and methyl demeton were less persistent than the other insecticides. Residual toxicity of synthetic pyrethroids especially cypermethrin persisted for a longer time (42 days) against C. chlorideae.

カンザワハダニに対する合成ピレスロイド系殺虫剤の影響

カンザワハダニに対する合成ピレスロイド系殺虫剤の影響

ミカンハダニ卵及びふ化幼虫に対する合成ピレスロイド系殺虫剤の影響

ミカンハダニ卵及びふ化幼虫に対する合成ピレスロイド系殺虫剤の影響

Comparison between the toxicity of synthetic pyrethroids and other compounds to the predacious miteAmblyseius gossipi (Mesostigmata: Phytoseiidae)

This work involves a comparison between the toxicity of four synthetic pyrethroids (cypermethrin, flucythrinate, fenvalerate and cyfluthrin), two organophosphorus compounds (pyridaphenthion and methamidophos) and a chlorinated hydrocarbon (dicofol) to the predacious miteAmblyseius gossipi El-Badry. Direct application of cypermethrin, flucythrinate and fenvalerate was moderately toxic to the adult females, while cyfluthrin was highly toxic. The most toxic compounds were pyridaphenthion and methamidophos, while the least toxic was dicofol. Residues of the synthetic pyrethroids, even at a non-toxic level, interrupted oviposition and decreased reproduction dramatically. Ingestion of cypermethrin, cyfluthrin and pyridaphenthion did not significantly increase mortality but significantly decreased the daily average egg production. In the case of cypermethrin and cyfluthrin, an increase in consumption of treated prey per day increased mortality at the higher density while egg production progressively decreased with cypermethrin, cyfluthrin and pyridaphenthion respectively.

Toxicity of Synthetic Pyrethroids to Laboratory and Field Populations of the Tobacco Budworm in Central Texas1

Populations of Heliothis virescens (F.) collected in cotton fields in Central Texas in 1978 and 1979 showed ca. 6-fold tolerance to permethrin and 2-fold tolerance to fenvalerate in comparison with a previously tested laboratory strain of this species. Similar levels of tolerance occurred to pyrethroid:chlordimeform combinations. The tolerance present in the 1978 field-collected insects disappeared within 10 generations in the laboratory. Thus, the apparent “tolerance” of the field collected insects to pyrethroids may only reflect differences associated with laboratory rearing of the budworm and not acquired resistance.