Search Results (6)

The sublethal toxic effects of pyriproxyfen, an insect juvenile hormone analog (JHA) insecticide, on the circulating metabolite balance in the Neotropical brown stink bug, Euschistus heros, one of the main agronomic pests in South America, were investigated. Our objectives were to evaluate changes in the baseline levels of lipids and carbohydrates, along with three selected micro-elements—nickel (Ni), copper (Cu), and zinc (Zn)—in the hemolymph of adult E. heros, following the application of a predetermined LC₃₀ of pyriproxyfen (single topical application) in fourth-instar nymphs (N4). Hemolymph was sampled using glass capillaries, with the resulting concentrations of lipids and carbohydrates determined through vanillin- and anthrone-positive reactions, respectively, and micro-element analysis was performed through total reflection X-ray fluorescence (TXRF) spectrometry. Lipids are the main and more stable energy metabolites for E. heros, with a proportion of 2:1 compared to carbohydrate levels. A remarkable sensitivity of carbohydrate levels to sublethal pyriproxyfen exposure, irrespective of sex, was observed. Baseline micro-element levels based on untreated control insects indicate sex-based differences in Ni and Zn, but not in Cu, concentrations. After insecticide exposure, the levels of these micro-elements were variable, with Ni and Zn generally decreasing and Cu decreasing in females but nearly doubling in males. The observed disproportion in lipids, carbohydrates, and inorganic micro-elements suggests potential physiological shifts triggered by pyriproxyfen activity in E. heros during late juvenile stages. Full article

A reliable, simultaneous residue-analysis method for pyriproxyfen and its five metabolites in fresh tea leaves, green tea, black tea, green-tea infusion and black-tea infusion was developed and validated. The samples were extracted with acetonitrile, purified using a modified QuEChERs (quick, easy, cheap, effective, rugged and safe) method and determined using ultra-performance liquid chromatography–tandem mass spectrometry (UPLC-MS/MS). The method was successfully calibrated in the range of 0.005–2.50 mg/L with correlation coefficients (r) equal to or above 0.9957. The limits of detection (LODs) were less than 0.002 mg/L. The average spiked recoveries of pyriproxyfen and its metabolites at four levels were 71.2~102.9% with relative standard deviations (RSDs) of 0.3~14.4%. The limits of quantification (LOQs) in fresh tea leaves, tea and tea infusion were 0.002 mg/kg, 0.005 mg/kg and 0.0002 mg/L, respectively. This proposed method was feasible and was applied to analyze the residues of pyriproxyfen and its five metabolites on real fresh tea leaf samples. The results indicated that the half-life (t_1/2) of pyriproxyfen on fresh tea leaves was 2.48 d, and the five metabolites were detected on fresh tea leaves during field growth after application. Full article

Background. Poisoning from pesticides can be extremely hazardous for non-invasive species, such as bees, and humans causing nearly 300,000 deaths worldwide every year. Several pesticides are recognized as endocrine disruptors compounds that alter the production of the normal hormones mainly by acting through their interaction with nuclear receptors (NRs). Among the insecticides, one of the most used is pyriproxyfen. As analogous to the juvenile hormone, the pyriproxyfen acts in the bee’s larval growth and creates malformations at the adult organism level. Methods. This work aims to investigate the possible negative effects of pyriproxyfen and its metabolite, the 4′-OH-pyriproxyfen, on human and bee health. We particularly investigated the mechanism of binding of pyriproxyfen and its metabolite with ultraspiracle protein/ecdysone receptor (USP-EcR) dimer of A. mellifera and the relative heterodimer farnesoid X receptor/retinoid X receptor alpha (FXR-RXRα) of H. sapiens using molecular dynamic simulations. Results. The results revealed that pyriproxyfen and its metabolite, the 4′-OH- pyriproxyfen, stabilize each dimer and resulted in stronger binders than the natural ligands. Conclusion. We demonstrated the endocrine interference of two pesticides and explained their possible mechanism of action. Furthermore, in vitro studies should be carried out to evaluate the biological effects of pyriproxyfen and its metabolite. Full article

Pyriproxyfen is a juvenile hormone mimic used extensively worldwide to fight pests in agriculture and horticulture. It also has numerous applications as larvicide in vector control. The molecule disrupts metamorphosis and adult emergence in the target insects. The same types of adverse effects are expected on non-target insects. In this context, the objective of this study was to evaluate the existing information on the toxicity of pyriproxyfen on the honey bee (Apis mellifera) and non-Apis bees (bumble bees, solitary bees, and stingless bees). The goal was also to identify the gaps necessary to fill. Thus, whereas the acute and sublethal toxicity of pyriproxyfen against A. mellifera is well-documented, the information is almost lacking for the non-Apis bees. The direct and indirect routes of exposure of the non-Apis bees to pyriproxyfen also need to be identified and quantified. More generally, the impacts of pyriproxyfen on the reproductive success of the different bee species have to be evaluated as well as the potential adverse effects of its metabolites. Full article

Since the 1990s, the insect growth regulator pyriproxyfen has been widely used worldwide as a larvicide in vector control and in agriculture to fight a very large number of pests. Due to its widespread use it is of first importance to know how pyriproxyfen behaves in the terrestrial ecosystems. This was the goal of this work to establish the fate profile of pyriproxyfen in soils and plants. Thus, in soil, pyriproxyfen photodegrades slowly but its aerobic degradation is fast. The insecticide presents a high tendency to adsorb onto soils and it is not subject to leaching into groundwater. On the contrary its two main metabolites (4′-OH-Pyr and PYPAC) show a different fate in soil. When sprayed to plants, pyriproxyfen behaves as a translaminar insecticide. Its half-life in plants ranges from less than one week to about three weeks. The review ends by showing how the fate profile of pyriproxyfen in soils and plants influences the adverse effects of the molecule on non-target organisms. Full article

Based on the structural framework of a pyriproxyfen metabolite, nineteen oxime ester derivatives were synthesized via reaction of the carboxylic acids with 4-(2-(2-pyridinyloxy)ethoxy)benzaldehyde oxime. The corresponding structures were comprehensively characterized by ¹H-nuclear magnetic resonance (NMR), ¹³C-NMR, and electrospray ionization high-resolution mass spectrometry (ESI-HRMS). All of the compounds were screened for their insecticidal activities against Plutella xylostella and Myzus persicae, and for their ovicidal activities against Helicoverpa armigera eggs. The results obtained show that most of the oxime ester derivatives displayed moderate to high insecticidal activities and ovicidal activities at a concentration of 600 ug/mL. In particular, the ovicidal activity of compounds 5j, 5o, 5p, 5q, and 5s was determined to be 100%. Importantly, some of the compounds presented even higher biological activities than the reference compound pyriproxyfen. For example, compound 5j displayed an insecticidal activity value of 87.5% against Myzus persicae, whereas the activity value of pyriproxyfen was 68.3% at a concentration of 600 ug/mL. Among the synthesized compounds 5j and 5s exhibited broad biological activity spectra. Full article