Get rid of agricultural residues and improve the efficacy of biological pesticides from the source
August 22 10:01:01, 2025
With growing awareness of environmental protection and health, the issue of pesticide residues has become a major concern. To address this, it's essential to promote green agriculture, and one effective approach is the use of biological pesticides. In recent years, these eco-friendly alternatives have gained popularity. But how can we enhance their effectiveness? Let’s take a closer look at the mechanisms and best practices for using biological pesticides.
First, understanding the mechanism of biological pesticides is key. There are three main types:
1. **Bt (Bacillus thuringiensis)**: This microbial insecticide works by producing parasporal crystals and spore toxins. When pests ingest Bt, they stop feeding due to the toxins, and the spores multiply inside the insect, eventually causing death.
2. **Yanshen**: A plant-based insecticide containing nicotine and oxymatrine, it acts through contact, stomach poisoning, and fumigation. It disrupts the nervous system of pests, making it highly effective against a range of insects.
3. **Avermectin**: A newer type of antibiotic insecticide and acaricide, it primarily affects pests through ingestion and contact. It enters the insect through its mouthparts and pads, disrupting the nervous system and leading to paralysis and death.
Second, timing is crucial when applying biological pesticides. Unlike chemical pesticides, they often take longer to work, so applying them at the right time is important. For example, avermectin works best during the hatching stage of pests like the diamondback moth, targeting second-instar larvae for optimal control. Similarly, Bt and Yanshen are most effective on young larvae rather than older ones.
Third, choosing the right product based on the pest species is essential. Different pests respond differently to various biological pesticides. For instance, *Pieris rapae* (cabbage white butterfly) is highly sensitive to both avermectin and Bt. A 3500–4500 times dilution of avermectin or a 500–1000 times dilution of Bt can effectively control these pests.
Fourth, environmental conditions play a significant role in the performance of biological pesticides. Avermectin is more active at higher temperatures, making it ideal for summer and autumn applications. Bt, on the other hand, performs best at 20–25°C with high humidity. If the temperature exceeds 25°C or sunlight is strong, it's better to apply Bt in the late afternoon to avoid UV damage to the spores.
Lastly, proper application techniques are vital. Ensure even coverage, especially on both sides of the leaves. Bt powders and granules should be applied after dew or light rain in the early morning or evening to help the product stick to the crop. For avermectin, adding a small amount of vegetable oil when diluting can improve adhesion and effectiveness.
By following these guidelines, farmers and gardeners can maximize the benefits of biological pesticides while minimizing environmental impact.