In recent months, a survey conducted among technicians in Hebei Pixian County revealed that ground tigers have been significantly impacting spring corn fields. This has raised concerns among farmers, emphasizing the need for timely and effective preventive measures.
The ground tiger is particularly destructive during its larval stage, with varying levels of damage depending on the age of the larvae. The 1st and 2nd instar larvae tend to feed on heart leaves or young leaves, often staying up late at night. By the time they reach the 3rd instar, they become more active at night, hiding in the soil during the day and causing damage by biting off the stems of young seedlings, which can lead to plant loss. The 4th instar larvae are the most harmful, as their resistance to pesticides increases significantly. Therefore, it's crucial to control them before they reach the 3rd instar stage.
To effectively manage ground tigers, a combination of strategies should be implemented, including trapping adult moths, weeding, chemical treatment, and manual removal. Trapping adult insects using black light or sweet and sour liquid is an effective method to reduce the population of the first generation of larvae.
Weeding plays a vital role in controlling ground tigers, as weeds serve as breeding grounds for these pests. Removing weeds from the field, around the base of plants, and along pathways can help eliminate eggs or larvae. Proper disposal of the removed weeds, such as composting or treating them in the field, further reduces the risk of infestation.
Spraying insecticides in the evening is recommended. For instance, applying a 2.5% deltamethrin emulsifiable concentrate diluted 2000 times, or a 4.5% beta-cypermethrin EC diluted 3500–4000 times, or a 50% phoxim EC diluted 1000 times can be effective. It is essential to strictly follow the dosage instructions to ensure safety and effectiveness.
Soil treatment with toxic substances is another approach. Mixing 50% phoxim (0.5 kg) with 100 kg of fine soil and applying it to the field, or combining 20% mevinphos permethrin EC with sand in a 2000:1 ratio, can provide long-lasting protection against larvae.
Bait traps are especially effective for the 4th instar larvae. A mixture of 0.5 kg of 90% trichlorfon with approximately 5 liters of water can be sprayed onto straw or cottonseed husks, which act as bait. Applying about 4–5 kg of poisoned bait per acre in the evening helps to target the most damaging stage of the pest.
When the larvae are older, using 80% dichlorvos EC or 50% phoxim at a rate of 0.2 kg per acre mixed with 400 kg of water can be effective. Alternatively, this solution can be applied directly to the plant stems for better coverage.
Manual removal is also a practical option. When damaged seedlings are observed, farmers can carefully lift the topsoil or wheat straw near the affected area in the morning to locate and destroy the young larvae.
Zhang Mingjun, Zhaoxiang Yue, Ganyu County Agricultural Bureau, Hebei Province
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