What are Bio-pesticides? Bio-pesticides are Safe Pesticides?
Bio-pesticides are made by living organisms (mostly microorganism) and their metabolites. And bio-pesticides contain both biochemical pesticides and microbial pesticides. Biochemical pesticides must meet two conditions: first, they are not direct toxicity on control objects, and only regulate growth, interfere with mating or lure and other special effects; second, they must be natural compounds, if they are synthetic, their structures must be identical to the structure of natural compounds (differences in proportions of isomers are allowed). These pesticides contain pheromones, hormones, natural plant growth regulators, insect growth regulators and enzymes. A number of botanical pesticides like toosedarin, rotenone, nicotine, natural pyrethrum and Chinese herbal medicine should be used as bio-pesticides. Microbial pesticides include formulations naturally generated by bacteria, fungi, viruses and protists or genetically modified micro-organisms for the control of diseases, insects and weeds, rodents and other harmful organisms, such as bacillus thuringiensis, nuclear polyhedrosis virus, validamycin and so on.
However, bio-pesticides are not safe pesticides, reasons are as follow:
Although bio-pesticides are less toxic to people, they are harmful to the environment, which should not be overlooked. Generally, it is widely believed that bio-pesticides are safe for the ecology and environment, actually not, bio-pesticides are just little safer than other types of pesticides.
Human beings use farming pesticides by a transition from bio-pesticides to chemical pesticides. People directly use natural products with a long history. And three botanical pesticides (pyrethrum, rotenone and nicotine) have been applied over hundreds of years. In the 1940’s, since chemical pesticides had obvious effects, this advantage makes the development and utilization of natural substances at a low ebb. However, due to the high toxicity of chemical pesticides as well as people’s growing environmental awareness, people took an interest in bio-pesticides once again in the 1970’s so as to make bio-pesticides spring to life. Although bio-pesticides are characteristics of better environmental compatibility and lower toxicity for human beings, it should not overlook their harm to environment and living beings. For example, bio-pesticides made by tripterygium and nicotine have higher toxicity on birds, bee and silkworm. Some bio-pesticides have toxicity even higher than chemical pesticides. To comprehensively evaluate environmental security should pay attention to the use of bio-pesticides, otherwise, it finally leads to harm to human beings. Therefore, bio-pesticides don’t mean safe pesticides.
The development of bio-pesticides requires high-effective, safety and low price in the production. In addition, it is necessary to strengthen pesticides management and improve farmers’ cultural quality, especially to make farmers understand unsafe aspects of bio-pesticides. In a word, there is still a lot of work to make bio-pesticides more safe and reliable.
Currently, bio-pesticides are internationally applied in a small quantity, in China as well. Chemical pesticides are in a dominant position over a long historical period. But, since bio-pesticides are little toxicity on crops so as to reduce direct harm to people, bio-pesticides have an optimistic development prospect.