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Early twenty-first century pesticide research has focused on developing molecules that combine low use rates and that are more selective, safer, resistance-breaking and cost-effective. Obstacles include increasing pesticide resistance and an increasingly stringent regulatory environment. The sources of new molecules employ natural products, competitors, universities, chemical vendors, combinatorial chemistry libraries, intermediates from projects in other indications and compound collections from pharmaceutical and animal health companies.〔 == History == Along with improved agrochemicals, seeds, fertilizers, mechanization, and precision farming, improved protection of crops from weeds, insects and other threats is highly sought. Developments over the past 1960-2013 period enabled reduced use rates, in the cases of the sulfonylurea herbicides (5), the piperidinylthiazole fungicides, and the mectin insecticides and acaricides, reaching 99%, with concomitant environmental improvements.〔 The rate of new molecule introductions has declined. The costs to bring a new molecule to market have risen from U.S. $152 million in 1995 to $256 million in 2005, as the number of compounds synthesized to deliver one new market introduction rose from 52,500 in 1995 to 140,000 in 2005.〔 New active ingredient registrations with the US Environmental Protection Agency (EPA) over the 1997–2010 period included biological (B), natural product (NP), synthetic (S) and synthetic natural derived (SND) substances. Combining conventional pesticides and biopesticides, NPs accounted for the majority of registrations, with 35.7%, followed by S with 30.7%, B with 27.4% and SND with 6.1%. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Pesticide research」の詳細全文を読む スポンサード リンク
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