High-persistence mosquito-repellent biological agent and preparation method

The invention relates to the technical field of biological mosquito-killing pesticides, in particular to a high-persistence mosquito-repellent biological agent and a preparation method. Bacillus thuringiensis subsp. israelensis original bacteria are subjected to seed culture in a slant seed medium, then seeds are inoculated into a fermentation medium of a seed tank for seed culture, and the slant seed medium includes beef extract, peptone, glucose, agar and deionized water; the mass ratio of the beef extract to the peptone to the glucose to the agar to the deionized water is (0.5-1): (1-2): (0.5-1): (0.5-1): (3-4): (400-500), and the fermentation medium is prepared from the following raw materials in percentage by weight: 2-2.5% of corn starch, 0.2-0.4% of peptone, 0.1-0.2% of yeast powder, 2.2-3.0% of soybean meal, 1.0-1.5% of corn steep liquor, 0.05-0.1% of potassium dihydrogen phosphate, 0.01-0.03% of magnesium sulfate, 0.1-0.2% of calcium chloride, 0.003-0.005% of manganese sulfate and 92.065-94.337% of d