# Permethrin Insecticide Influence on Microorganisms Present in Surface Waters
## 1 Introduction  
Pesticides, including insecticides and fungicides, are chemical compounds that are an integral part of agriculture and food production. They are used to protect plant crops from the negative effects of pests, weeds, or pathogens, mainly fungi (e.g., of the genus _Erysiphe_) and viruses (e.g., tobacco mosaic virus) but also bacteria (e.g., of the genus _Streptomyces_). These substances facilitate the control of plant growth and development, which results in increased productivity and higher quality of agricultural production [1, 2, 3]. It is worth noting that pesticides play an important role in global food security. Estimates provided by [PERSON] et al. [4] state that about 3 billion kilograms of these chemicals are used annually, generating a global market worth 40 billion US dollars. Insecticides account for a significant part of this budget [4, 5]. The literature reports a significant increase in pesticide consumption. Asia, especially China and Turkey, have reported very high levels of pesticide consumption [6]. India ranks 12 th in the world in terms of pesticide consumption, which is largely disposed of in Asia. In Chile, in the second decade of the 21 st century, pesticide consumption was 2.7 kg/ha, which is well above the average for OECD countries (0.93 kg/ha). Brazil, as one of the largest producers of pesticides, authorizes 332 active substances for use in agriculture [1, 4, 5]. Permethrin, as a representative of synthetic pyrethroids, is an important component of modern plant protection and public health. Although pyrethroids were originally derived from natural sources, their limitations, such as sensitivity to light, led scientists to develop more stable synthetic analogs [7]. Permethrin, as a chlorophyll derivative of chrysanthemum acid, has shown high efficacy against a wide range of insects, including beetles, fleas, lice, moths, mosquitoes, termites, and ants. Synthetic pyrethroids, including permethrin, deltamethrin, and cypermethrin, occupy a significant position in the global insecticide market, generating revenues estimated at $1.4 billion a year [8; 9]. Their popularity is due to both their high efficacy and relatively low toxicity to vertebrates compared to other classes of insecticides. In addition to agricultural applications, permethrin is widely used in public health [10]. The World Health Organization recommends the use of pyrethroids in the fight against vectors of diseases such as malaria and Zika fever. Preparations containing permethrin, such as shampoos, are used to treat scabies and lice [7]. The usage of pesticides in agriculture, while necessary for food security, has a significant negative impact on soil biodiversity. The widespread use of these substances leads to biodiversity depletion, especially among organisms not directly targeted by crop protection products. Among the most affected groups are primary and secondary consumers (especially when first-generation insecticides were used). The latest generations of insecticides are considered as safer for the food chain organisms [11; 12]. Unfortunately, even newly designed pesticides, which are among the most common soil pollutants, can disrupt the delicate balance of these ecosystems. Soil microorganisms, due to their large numbers and metabolic diversity, play a key role in soil-forming processes and the detoxification of contaminants. Microorganisms, in response to the presence of pesticides, can develop resistance mechanisms, but often at the expense of other important ecological functions [13]. The significant increases in pesticide use predicted for the coming years pose a serious threat to the health of soil ecosystems and, consequently, to human health. The active ingredients in pesticides, especially persistent organic compounds such as organochlorine pesticides, have high mobility in the environment. Their semi-volatility allows them to be transported over long distances, leading to the contamination of both soil and surface water.