# In Vitro Compatibility of Three Native Isolates of _Trichoderma_ with the Insecticide Chlorpyrifos
## 1 Introduction  
Agriculture is the backbone of a nation [1]. However, the quality and productivity of cultivars are affected by different microorganisms known as phytopathogens, which lead to economic losses [2; 3; 4]. For this reason, pesticides have been used against these plagues, where the unbalanced application of pesticides leads to unwanted effects, for example, pesticide resistance in plant pathogens, environmental persistence, and the contamination of soils and groundwater [5; 6]. In addition, in recent years, it has generated various controversies due to its effects on public health, which have been well documented [7; 8]. Organophosphates are part of modern agriculture; however, their indiscriminate use has caused serious effects on the environment and public health [9]. Chlorpyrifos (C 9H11 Cl3 NO3 PS) or (O,O-diethyl) O-(3,5,6-trichloro-2-pyridyl) phosphorothioate)) is an organophosphate insecticide used against a wide spectrum of pest insects that attack crops, such as citrus fruits, bananas, vegetables, potatoes, coffee, cocoa, tea, cotton, wheat, and rice, among others [10; 11]. This insecticide is poorly soluble in water (2 mg/L) but has strong adsorption to organic matter and soil particles. This insecticide can persist in thesoil for 60-120 days or up to a year, depending on climate, dose, and other environmental conditions [11; 12]. Chlorpyrifos is known to inhibit acetylcholinesteraseokinase [13]. [PERSON] [14] mentions that there is strong evidence of fetal brain damage and cognitive and behavioral dysfunction through multiple mechanisms, including thyroid disruption. A request in order to seek bean chlorpyrifos was denied by the United States Environmental Protection Agency (EPA) in 2017 [15]. Chlorpyrifos is listed as an unauthorized pesticide in developed countries. In contrast, it is still used in countries such as Peru in spite of its negative effects on people's health [16; 17]. For this reason, there is a double need to address this issue; on the one hand, farmers need to be aware of the danger that the use of chlorpyrifos attracts. On the other hand, there is an urgency to decontaminate environments of chlorpyrifos residues [18]. An alternative strategy in the control of pests and plant disease is integrated pest management (IPM) [18]. One of the IPM strategies is biological control (BC). BC involves using microorganisms or biocontrol agents (BA), mainly bacteria and fungi, to combat phytopathogens through a series of strategies. In addition, BC does not require the use of pesticides, which makes it a green technology with low production costs [19; 20; 21; 22; 23; 24; 25]. One of the most widely applied BA is the filamentous fungi of the genus _Trichoderma_ (Ascomycota: Hypocreaceae), which are cosmopolitan and very versatile. They represent between 50 and 60% of all BA. In the global biopesticides market, a variety of commercial products based on _Trichoderma_ can be found due to their ability to produce enzymes and secondary metabolites. This fungus can behave as an antagonist against a wide range of fungal phytopathogens, such as pathogenic bacteria _Ralstonia solanacarum_, Lepidoptera insect pests, and nematodes of the genus _Meloidogyne_. On the other hand, they can be potential biofertilizers found in symbiotic associations of the plant, giving them certain nutritional advantages. Based on all these characteristics, _Trichoderma_ constitutes a promising alternative for use in sustainable agriculture [25; 26; 27; 28; 29; 30; 31; 32]. Despite the remarkable characteristics of BA, modern agriculture still needs to depend on pesticides; therefore, the compatibility of use between these two control alternatives is being investigated as part of an IPM strategy [33]. [PERSON] et al. [34] mentioned that both pesticides and biopesticides are necessary for the current scenario of agriculture. The metabolic diversity of the _Trichoderma_ species allows them to use diverse xenobotic compounds as carbon and energy sources [35].