The problem is, 'designer' insecticides are more robust than spontaneous molecular experiments by nature. Nature tries things slowly, in small local trials and quantities. What fails, gets washed away in the ocean of alternatives that succeed and blend in. What succeeds, gains footholds, and becomes more prominent by continued integrations. Human techniques throw massive quantities of substances into the world and reaps no in-between.
Successes are extraordinary.
Problems tend to become disasters. Only it never disintegrates or decomposes, it stays to poison the tissue of life that ingests it. The Belugas, hundred and thousand of miles from the toxic dumping grounds were taking the poison and concentrating it in mother's milk. Downstream from where Myrex was cast out of the human food chain and food-dependent chain years earlier, it remains to brutalize our world today. Passing into the 'life giving' waters in the heart of a major global continent.