A rugged and sensitive method was developed to monitor urinary concentrations of O,S-dimethyl hydrogen phosphorothioate (O,S-DMPT), a specific biomarker of exposure to the organophosphate insecticide methamidophos. After pH adjustment and C18 solid phase extraction column cleanup, the urine was lyophilized at a low temperature to prevent loss of possibly highly volatile and unstable O,S-DMPT me...

We have in vitro tested the ability of common, commercially available, cholinesterase reactivators (pralidoxime, obidoxime, methoxime, trimedoxime and HI-6) to reactivate human acetylcholinesterase (AChE), inhibited by five structurally different organophosphate pesticides and inhibitors (paraoxon, dichlorvos, DFP, leptophos-oxon and methamidophos). We also tested reactivation of human butyrylc...

The toxicity of methamidophos on the shrimp Litopenaeus vannamei was evaluated using acetylcholinesterase (AChE) activity, behavior, and feeding rate as effect criteria. The biochemical characterization of the soluble cholunesterase (ChE) present in both muscle and eye tissues of L. vannamei was performed in a first phase of the study. In both tissues, almost full inhibition of enzyme activity ...

The performances of support vector machine (SVM) and linear discrimination analysis (LDA) for detecting pesticide on spinach leaf were investigated. Fluorescence images of spinach leaves without any treatment, treated with pure water and methamidophos solution were taken under 561 different wavelength conditions to acquire hyperspectral excitation-emission matrix (EEM) data. Then LDA and SVM we...

Methamidophos is a representative organophosphate insecticide. The knowledge of its developmental neurotoxicity is limited, especially for zebrafish in the early stages of their life. Four hour post-fertilization (hpf) zebrafish embryos were exposed to several environmentally relevant concentrations of methamidophos (0, 25, and 500 μg/L) for up to 72 hpf. Locomotor behavior was then studied in ...

The insecticides esfenvalerate, endosulfan, imidacloprid, and methamidophos were screened against 74 clonal populations of the green peach aphid, Myzus persicae (Sulzer), collected as fundatrices from peach (Prunus spp.) and as apterous virginoparae from various weeds near potato (Solanum spp.) fields in the Yakima Valley and Columbia Basin regions of Washington state. Response to diagnostic co...

We examined the cytogenetic and genotoxic effects of the neonicotinoid insecticide imidacloprid and the organophosphate insecticide methamidophos, when administered alone or in combination. These insecticides were tested with the bone marrow chromosome aberration assay and micronucleus test in rats and by the bacterial mutation assay (Salmonella/microsome mutagenicity assay). Wistar albino rats...

Arthropods are an important group of macroorganisms that work to maintain ecosystem health. Despite the agricultural benefits of chemical control against arthropod pests, insecticides can cause environmental damage. We examined the effects of one and two applications of the insecticides chlorfenapyr (0.18 liters a.i. ha-1) and methamidophos (0.45 liters a.i. ha-1), both independently and in com...

In this study ready-to-eat food samples were collected in the production line of the university restaurant of the University of Brasilia, Brazil, which serves non-vegetarian and vegetarian meals daily. Samples were analysed for the presence of ten organophosphorus insecticides (OPs) by GC/FPD, after extraction with ethyl acetate and anhydrous sodium sulfate (LOQ = 0.002 mg kg(-1)), and for dith...

Laboratory bioassays were done to determine the level of resistance to endosulfan, cypermethrin, deltamethrin, methamidophos, profenofos and chlorpyrifos in field populations of cabbage aphid, Brevicoryne brassicae (L). Comparison between Multan and Kabirwala strains revealed that the level of resistance in Multan strain was comparatively higher to methamidophos, profenofos and chlorpyrifos as ...