An insecticide application scheme in cotton fields with bi-directional selective effects on bees and pests

In this paper, molecular dynamics, full factorial experimental design and molecular docking were used to determine the toxic effects of pesticides on pests ( Tetranychus telarius , Lygus lucorum and Helicoverpa armigera ) and bees (North Chinese bee) in a cotton field, and an insecticide collocation scheme with the bi-directional selectivity was devised. Firstly, the main insecticides for three stages of cotton growth were identified under the lateral mixing condition. Insecticides for the first phase included abamectin (avermectin B 1a and B 1b ), acetamiprid (N-(N-cyano-ethylimine)-N-methyl-2-chloropyridine-5-methylamine), dicofol (1,1-bis(p-Chlorophenyl)-2,2,2-trichloroethanol) and cypermethrin ((RS)-α-cyano-3-phenoxyebenzyl(SR)-3-(2,2-dichloroyl)-2,2-dimethyl cyclopropane carboxylic acid ester); the insecticides available in the second phase included cypermethrin ((RS)-α-cyano-3-phenoxyebenzyl(SR)-3-(2,2-dichloroyl)-2,2-dimethyl cyclopropane carboxylic acid ester), phoxim (O,O-diethyl-O-α-cyanophenylbenzylamine thiophosphate ester), deltamethrin ((R,cis)-2,2-dimethyl-3-(2,2-dibromovinylcyclopropane ester)-cyano-diphenyl ether) and abamectin (avermectin B 1a and B 1b ). In third phase, cypermethrin ((RS)-α-cyano-3-phenoxyebenzyl(SR)-3-(2,2-dichloroyl)-2,2-dimethyl cyclopropane carboxylic acid ester), and deltamethrin ((R,cis)-2,2-dimethyl-3-(2,2-dibromovinylcyclopropane ester) -cyano-diphenyl ether) were included. Different insecticide application schemes were designed according to whether the application cycle and sequence were considered. The molecular dynamics simulation method was used to determine the effects of different insecticide application schemes on pests and bees. After the simulation, the simplified mixed-weighted model carried out each application scheme. In the case of lateral mixing, the combination of avermectin + acetamiprid + trichlorobacitol + cypermethrin + phoxim + deltamethrin was selected as the optimal application program, which reduced bee toxicity by 98.77% and increased insect toxicity by 55.84%. Whereas in the case of longitudinal residue, avermectin + cypermethrin + deltamethrin was selected. This combination reduced the harm to bees by 126.55% and increased the toxicity to target pests by 34.23%. Finally, by calculating the resultant force from different types of non-bonded forces, the mechanism of the effect of the optimal application scheme on bees and pests under two scenarios was analyzed. The optimally combined schem