Get rid of agricultural residues and improve the efficacy of biological pesticides from the source
August 22 09:07:00, 2025
With the growing awareness of environmental protection and health, the issue of pesticide residues has become a major concern. To address this problem at its source, the development of green agriculture is essential. In recent years, biological pesticides have gained increasing popularity due to their eco-friendly nature. But how can we enhance the effectiveness of these biological pesticides? Here's an in-depth analysis from **Chinese Pesticide Net**:
First, understanding the mechanisms of biological pesticides is crucial. There are three main types:
1. **Bt (Bacillus thuringiensis)**: This microbial insecticide works by producing parasporal crystals and spore toxins that are toxic when ingested. Once consumed by pests, the toxins cause them to stop feeding, and the spores then multiply inside the insect’s body, leading to death.
2. **Yanshen**: A plant-based insecticide containing nicotine and oxymatrine, it exerts multiple effects—stomach poisoning, contact, and fumigation. It disrupts the nervous system of pests, making it highly effective when sprayed as a vapor or mist.
3. **Avermectin**: A newer type of antibiotic insecticide and acaricide, it primarily acts through stomach and contact toxicity. It enters the pest through its mouthparts and pads, affecting the nervous system and causing paralysis. Affected pests gradually lose mobility and eventually die.
Second, timing is key when applying biological pesticides. Unlike chemical pesticides, they often take longer to show results. For example, avermectin is most effective during the hatching stage of pests like *Plutella xylostella*, particularly on second-instar larvae. Bt and Yanshen are more effective on younger larvae than older ones.
Third, choosing the right product for the target pest is important. Different pests respond differently to biological pesticides, so selecting the appropriate concentration and type based on the pest’s sensitivity is critical. For instance, *Pieris rapae* is highly sensitive to both avermectin and Bt, and can be controlled using a 3500–4500 times dilution of avermectin or a 500–1000 times dilution of Bt.
Fourth, weather conditions play a significant role in the effectiveness of biological pesticides. Avermectin performs best in high temperatures, making it ideal for summer and autumn applications. Bt, on the other hand, is most active between 20°C and 25°C with high humidity. It is less effective in strong sunlight or extreme heat, so it’s best applied in the early morning or late afternoon, especially on cloudy days.
Finally, proper spraying techniques are essential. Ensure even coverage, paying special attention to both sides of the leaves. Bt powders and granules should be applied after dew or light rain to help the formulation adhere better to the crop. To improve the adhesion of avermectin, adding a small amount of vegetable oil to the solution can be beneficial.
By following these guidelines, farmers can maximize the benefits of biological pesticides while minimizing environmental impact.