**2. Historical perspective**

Pesticides are used for a number of decades. People have been fighting with pests for centuries [5]. Chemical experiments during the late 19th and early 20th centuries allowed human beings to develop modern pesticides. Producing new mixtures with a right proportion made it possible to control unwanted organisms. Paris green was one of the first chemical pesticides produced, marking the beginning of chemical insecticide use in the United States in 1867 [30]. By the late 19th century, U.S. farmers were using calcium arsenate, nicotine sulfate, and sulfur to control insect pests in field crops, except Paris green [4]. Since the middle of the 20th century, these chemicals have been widely used to control pests [31,32]. Ancient Romans controlled weeds with salt and killed insect pests by burning sulfur [4]. Sulfur, also known as brimstone, was used by pagan priests 2000 years before the birth of Christ. Additionally, sulfur was used to purify a sick room and cleanse its air of what was believed to be evil. In the 1600s, ants were controlled with mixtures of honey and arsenic. Early plant-derived insecticides included nicotine to control aphids, hellebore to control body lice, and pyrethrins to control a wide variety of insects [5].

The availability of dichlorodiphenyltrichloroethane (DDT), starting in 1945 for civilian/ agricultural usage, opened a new era of pest control, leading to not only its extensive usage but also the development of numerous other synthetic organic insecticides. DDT was especially favored for its broad-spectrum activity against insect pests of agriculture [4]. Unfortunately, its properties of persistence, along with its broad-spectrum biological activity against pests and beneficial insects alike, made it a poor choice for use in agriculture after World War II [33]. Except DDT, aldrin, BHC, endrin, dieldrin, and 2,4-D began to be used after World War II. These new chemicals were effective, inexpensive, and enormously popular [34]. However, with continuous usage of pesticides, some pests developed resistance to them. As a result, nontarget plants and animals were damaged; surprisingly, pesticide residues were observed to be present in unexpected places. Rachel Carson's book, *Silent Spring* in 1962, shook public confidence in pesticide usage. Carson presented a harsh picture of environmental consequen‐ ces of careless pesticide employment. Although her report has been strictly criticized, Carson pointed out the risks of pesticides more than anyone [4].

As chemical controls became more and more common in agricultural, public health, and nuisance applications throughout the first half of the 20th century, a myriad of problems were being discovered. Chemically reliant methods had quickly resulted in pesticide resistance within the target species, harm to nontarget species, food contamination, water contamination, overall ecological degradation, and public health problems [30].
