| Popis: |
Neonicotinoids are the leading class of insecticides on the global market, accounting for nearly twenty-five percent. They are widely used in both agricultural and residential settings. Causing neuron failure and insect death by irreversibly binding to the insect nicotinic acetylcholine receptor, neonicotinoids offer broad spectrum efficacy against a variety of pests. However, because they are non-selective with regards to insect species, there has been a large amount of concern over threats to pollinators, such as honey bees, and, more recently, over potential indirect effects to migratory waterfowl as a result in invertebrate prey population depletion due to neonicotinoid exposure. In order to study occurrence and fate of neonicotinoids, we analyzed cotton leaves grown from neonicotinoid-treated seeds and corresponding soil samples to quantify field concentrations, as well as playa wetland water samples, to quantify potential for exposure to aquatic invertebrates. It was found that neonicotinoids remained present in the soil for months post planting, and that nearly 50% of playa samples had detectable levels of neonicotinoids. We also determined the toxicity of three neonicotinoids, clothianidin, imidacloprid, and thiamethoxam, to a model invertebrate species, Aedes aegypti. Clothianidin was found to be the most acutely toxic to the test species, followed by thiamethoxam and imidacloprid. |
