Ecotoxicological strategies employing biochemical markers and organisms to monitor the efficacy of malathion photolysis treatment.

The objective of this study was to assess the photolysis-mediated degradation of malathion in standard and commercial formulations, and to determine the toxicity of these degraded formulations. Degradation tests were carried out with 500 µg L-1 of malathion and repeated three times. The initial and residual toxicity was assessed by using Lactuca sativa seeds for phytotoxicity, Stegomyia aegypti larvae for acute toxicity, and Stegomyia aegypti mosquitoes (cultivated from the larval stage until emergence as mosquitoes) to evaluate the biochemical markers of sublethal concentrations. For the standard formulations the photolytic process efficiently reduced the initial concentration of malathion to levels below the regulatory limits however, the formation of byproducts was revealed by chromatography, which allowed for a more complete proposal of photolytic-mediated malathion degradation route. The degraded formulations inhibited the growth of L. sativa seeds, while only the untreated formulations showed larvicidal activity and mortality. Both formulations slightly inhibited acetylcholinesterase activity in S. aegypti mosquitoes, while the standard formulation decreased and the commercial formulation increased glutathione S-transferase activity. However, there were no significant differences for superoxide dismutase, esterase-α, esterase-ß and lipid peroxidation. These findings indicate that in the absence of the target compound, the presence of byproducts can alter the enzymatic activity. In general, photolysis effectively degrade malathion lower than the legislation values; however, longer treatment times must be evaluated for the commercial formulation.

Nuclear magnetic resonance chiral discrimination of fipronil and malathion agrochemicals: A case study.

The aim of the present study was to optimize a protocol for nuclear magnetic resonance (NMR) chiral discrimination to be used to determine the enantiomers ratio of agrochemicals. For this goal, the commercial agrochemicals fipronil and malathion were employed as active targets due the distinct physicochemical properties. We used the cyclodextrins to evaluate the chiral discrimination in aqueous media and chiral solvent agents to check in organic media. The fipronil chiral discrimination was accessed by ß-CD in aqueous solution, although this procedure was ineffective for malathion due the low solubility. In organic media, the NMR chiral discrimination was successful for both agrochemicals and sensitive to dilution process. The NMR experiments explore very sensitive nuclei, for instance 1 H, 19 F, and 31 P, in a simple, practical and low residue experimental protocol.

Evaluating Hemolytic and Photo Hemolytic Potential of Organophosphorus by In Vitro Method as an Alternative Tool Using Human Erythrocytes.

AIMS: The present study aims to determine the phototoxic and haemolytic activity of organophosphorus. The use of alternative in vitro assays with human erythrocytes is suggested to predict the polluting effect of these products on health. METHODOLOGY: Human erythrocytes from Toluca Blood Bank were used. Sodium dodecyl sulfate was employed as a positive control. Additionally, the haemolysis percentage of three organophosphate (Acetate, Chlorpyrifos, Malathion, Methamidophos, Methyl Parathion) induced photo haemolysis formulated with surfactants on a concentration of 2 x 109 erythrocytes were evaluated. Finally, the products were classified as irritant or phototoxic. RESULTS: Results showed that the HC50 red blood cells were similar for each organophosphate (Malathion and Methamidophos) indicating very irritant action with ratio classification (L/D) of 0.041 and 0.053, respectively. On the other hand, Chlorpyrifos was classified as an irritant with L/D= 0.14. On the other hand, the HC50 obtained photo hemolysis assays irradiated red blood cells was similar for each organophosphate (Acetate, Chlorpyrifos, Malathion, Methamidophos, Methyl Parathion) indicating no phototoxic action. CONCLUSION: As a conclusion, it can be said that the parameters of haemolysis and denaturation of proteins are good indicators to classify organophosphorus formulated with surfactants as irritating or phototoxic.

Toxicity, attraction, and repellency of toxic baits to stingless bees Plebeia emerina (Friese) and Tetragonisca fiebrigi (Schwarz) (Hymenoptera: Apidae: Meliponini).

Toxic bait formulations have been one of the main strategies used in apple orchards in southern Brazil for the control of South American fruit fly. However, its effects on the stingless bees Plebeia emerina (Friese) and Tetragonisca fiebrigi (Schwarz) are unknown. This study aimed to assess the toxicity, attraction and repellency of food lures and toxic baits on P. emerina and T. fiebrigi. We evaluated the food lures Anamed® (pure), Biofruit® (3%), Flyral® (1.25%), Sugarcane molasses (7%) and Samaritá Tradicional® (3%), in toxic baits formulations associated with spinosad (Tracer® 480SC) and malathion (Malathion® 1000EC), and the ready-to-use toxic baits Success® 0.02CB and Gelsura®. We obtained the mean lethal concentration (LC50) and the mean survival of workers after exposure to toxic bait formulations. In the field, we carried out attraction and repellency tests of toxic baits to foraging. The food lures associated with malathion and spinosad showed different levels of toxicity to P. emerina and T. fiebrigi. Sugarcane molasses and Samaritá Tradicional® associated with spinosad showed high toxicity, with LC50 values of 6.92 and 10.61 ng/µL diet to P. emerina, and of 4.37 and 15.48 ng/µL diet to T. fiebrigi, respectively. Gelsura® and food lures with malathion caused rapid workers mortality, with mean survival less than 3 h after exposure. No toxic bait formulation was attractive to P. emerina foragers in the field. Anamed®, Gelsura®, and Success® were repellent to P. emerina foragers.