Hydrolysis and photolysis of diacylhydrazines-type insect growth regulator JS-118 in aqueous solutions under abiotic conditions.

JS-118 is a diacylhydrazines-type insect growth regulator which is now used extensively in China. The hydrolysis and photolysis of the pesticide JS-118 in aqueous solutions have been assessed under natural and controlled conditions in this project. Hydrolysis experimental results show that JS-118 is quite stable in aqueous solutions in dark, with no significant variations be observed in degradation under various conditions. Abiotic hydrolysis is relatively unimportant compared to photolysis. The rate of photodecomposition of JS-118 in aqueous solutions follows first-order kinetics both in UV radiation and natural sunlight. The degradation rates are faster under UV light than sunlight, with the half-lives (t (1/2) = ln2/k) of 6.00-10.85 min and 6.63-10.16 day, respectively. Under UV light, two major photoproducts are detected, and tentatively identified according to HPLC-MS spectral information as N-t-butyl-N-(3,5-dimethylbenzoyl) and 3,7-dimethyl-benzoatedihydrofuran. The corresponding photolysis pathways of JS-118 are also proposed. The results obtained indicate that direct photoreaction is an important dissipation pathway of JS-118 in natural water systems.

Methoprene photolytic compounds disrupt zebrafish development, producing phenocopies of mutants in the sonic hedgehog signaling pathway.

Environmental chemicals have been proposed to impact endocrine or retinoid pathways, causing developmental abnormalities in humans and other vertebrates. Presented evidence shows that exposure of zebrafish embryos to sunlight-induced photolytic products of the pesticide methoprene results in developmental defects in the head, heart, pectoral fins, and somites, and in spinal motor and optic nerve axons. Exposed embryos are phenocopies of zebrafish you-type mutants and, as in the mutant sonic-you, show underexpression of the signaling protein sonic hedgehog. Reduced expression of sonic hedgehog is also displayed in embryos treated with the retinoic acid synthesis inhibitor citral. This study identifies citral-related compounds as embryonic signaling disruptors of potential environmental concern.