Microbial insecticides are made using living organisms of microorganisms. In nature, there are many microorganisms that have pathogenic effects on pests. Using this pathogenicity to control pests is an effective biological control method. From these pathogenic microorganisms, strains which are convenient to apply, stable in efficacy, safe for humans and animals and the environment are screened for industrial scale production and development, thereby preparing microbial insecticides. There are about 750 entomopathogenic fungi discovered by fungal insecticides. The parasitic range is very wide, but there are not many insecticides. It has been tested successfully and has a certain scale of application: using Beauveria bassiana to control potato beetles and soybean borers. , Dendrolimus punctatus and corn borer; use of Metarhizium to control chafers and cockroaches; use Thompson polychaete to control citrus rust; use scutellaria to control greenhouse mites; use crustacea to control whitefly and scale insects. Bacterial insecticides The most successful research and development of microbial insecticides is the use of Bacillus as an insecticide. The main species is Bacillus thuringiensis, which has been widely used in the control of crops, forests, granaries and mosquitoes. Bacillus thuringiensis was discovered in the early 20th century and became practical in the 1930s. It was industrialized in the 1950s and developed rapidly since the 1970s. In the 1980s, annual sales exceeded $20 million. China has been mass-produced in the 1970s, and has many trade names such as green worms and bacillus. There are many varieties of Bacillus thuringiensis, and its spore contains toxic protein crystals, commonly known as δ-endotoxin, which is the main component of insecticide. When the spores enter the digestive tract of the pest, the toxin is activated, causing the pest to paralyze and die. Due to the different structure of the protein crystals contained in each variant, the virulence and the applicable pest objects are also different. For example, the widely used Variety of the genus is used to control Lepidoptera larvae; the Israeli variant is used to control cockroaches. Other bacterial insecticides that have been developed and utilized include Japanese Bacillus cerevisiae, which is effective for controlling the larvae of the scarab. Viral insecticides About 200 species of viruses have been found to be parasitic on agricultural pests, and some have been developed as viral insecticides. Most of them are nuclear polyhedrosis viruses belonging to the baculovirus, and a few are granuloviruses. Insect viruses have a high degree of specific parasitism. Usually, a virus infects only one insect, but it is harmless to other insects and humans, so it does not interfere with the ecological environment. However, since the virus can only be cultured and propagated by pests, large-scale industrial production is limited. Most of the virus insecticides that have been commercialized on a small scale are used for controlling lepidopteran pests such as cotton bollworm, gypsy moth, Spodoptera litura, canopy caterpillar, and cabbage butterfly. China has extensively tested and promoted viral pesticides in the 1980s. PVC Steel Wire Hose,PVC Reinforce Steel Wire Hose,PVC Hose Fenghua Jade Motor Co., Ltd. , http://www.composite-hose-supplier.com
Microbial pesticides can be mainly classified into fungi, bacteria and viruses. Among other microorganisms, actinomycetes generally use their metabolite antibiotics instead of directly using them as insecticides. The use of microorganisms such as protozoa, nematodes and rickettsia has been studied very little and has not yet been put into practical use.