Tea, a cherished beverage in China and one of the world's oldest and most widely consumed drinks, thrives through the cultivation and meticulous management of tea trees. Tea gardens, where these trees are nurtured, form intricate ecosystems teeming with various organisms. While this biodiversity supports the ecosystem, it also introduces challenges, as certain organisms can negatively impact tea trees and leaves. These pests and diseases are significant constraints to tea production and pose major threats to tea safety.
In this series on tea garden pest control, we delve into the different types of pests, their habits, damage mechanisms, and control methods. Our goal is to enhance your understanding of these pests, enabling better protection of tea gardens and ensuring that every tea leaf grows in the best possible environment. This sixth installment focuses on the common pest in tea gardens: the Black Scale Whitefly.
Identification of Black Scale Whitefly
The Black Scale Whitefly (Aleurocanthus spiniferus), also known as the citrus blackfly, belongs to the Aleyrodidae family of insects in the order Hemiptera. It is prevalent in the tea-producing regions of central and southern China, extending north to the Qinling Mountains and Huai River, west to Yunnan, Guizhou, Sichuan, and parts of Tibet, and south to the southern tip of Hainan Province, as well as Taiwan. The whitefly primarily infests new shoots of spring, summer, and early autumn growth.
Morphological Characteristics and Life Cycle
Adult Stage: Adults are 0.85–1.42 mm long, with orange-yellow bodies and wings covered in white, powdery wax. They have kidney-shaped, rose-red compound eyes. The forewings are dark brown with seven white spots, and the hindwings are smaller and light purple. Their legs are yellow, with the base of the tibiae slightly blackened. Male adults are typically smaller than females.
Egg Stage: Eggs are approximately 0.25 mm long and 0.12 mm wide, resembling miniature bananas, and are attached to the underside of leaves via a short stalk. They are milky white with a surface covered in a hexagonal mesh pattern.
Larval Stage: Larvae are black, flat, and oval, measuring about 0.65 mm long and 0.55 mm wide. Their bodies are fringed with saw-toothed white waxy substances and have 14 pairs of spines on the dorsal side. Pupae are also oval and black.
Pupal Stage: Pupal cases are glossy black, oval, and measure 0.7–1.2 mm long and 0.6–0.8 mm wide. The edges of the pupal case are serrated, and the dorsal surface is distinctly raised. There are nine pairs of spines on the thoracic dorsal plate and ten pairs on the abdominal plate. Female pupae have eleven pairs of spines along the sides, while males have ten pairs.
Damage Characteristics
Black Scale Whitefly larvae aggregate on the underside of leaves and feed on sap, causing yellow spots at feeding sites. They secrete honeydew, which leads to the growth of sooty mold, turning branches and leaves black, potentially killing them and causing defoliation. This damage affects plant growth and fruiting.
Control Methods for Black Scale Whitefly
Given the infestation characteristics and damage caused by Black Scale Whitefly, the following control methods are recommended:
1. Agricultural Control:
Frequent Harvesting: Especially during the spring, remove eggs from new shoots through regular harvesting.
Pruning and Cultivation: Remove infested branches during pruning and cultivation to improve air circulation and light penetration in the tea garden.
Fertilization: Apply organic fertilizers appropriately to enhance plant vigor and resilience against pests.
2. Biological Control:
Parasitoid Wasps: Transplant leaves with high parasitism rates by wasps to areas with dense whitefly populations to enhance biological control.
Fungal Pathogens: Introduce and establish entomopathogenic fungi in whitefly populations. Under suitable conditions, such as high humidity and dense host populations, these fungi can cause widespread disease and control whitefly populations. Pathogenic fungi like Verticillium lecanii and Beauveria bassiana can be formulated into insecticides for application.
Protect Natural Enemies: Maintain and introduce natural enemies such as ladybugs and lacewings, which prey on whiteflies, to balance the ecosystem.
3. Chemical Control:
Targeted Insecticide Use: Apply insecticides during the early nymph stages of each generation, focusing on the first generation. Ensure coordinated control measures in heavily infested tea gardens to avoid leaving untreated areas.
Broad-Spectrum Coverage: When spraying insecticides, also treat surrounding weeds to improve overall control efficacy.
4. Trapping and Monitoring:
Color Traps: Utilize color traps to monitor and reduce adult whitefly populations, exploiting their strong attraction to certain colors. Hang traps above tea plants during the adult stage (mid to late April), spacing them adequately (25-35 traps per acre).
Light Traps: Employ light traps to capture adult whiteflies, reducing their numbers and preventing further reproduction.
Advanced Control Technologies by Yeehar Agriculture
Yeehar Agriculture has been at the forefront of developing environmentally friendly pest control methods. Our goal is to achieve "disaster prevention and reduction, quality improvement, efficiency enhancement, and safety assurance." We offer several innovative products for managing Black Scale Whitefly:
- Designed with red and yellow blocks to attract and kill Black Scale Whiteflies while minimizing the accidental capture of beneficial insects.
- Uses high-viscosity, water-resistant adhesive that remains effective under high temperatures and rain. The material is biodegradable within six months.
- These devices are optimized for capturing small insects like Black Scale Whiteflies, making them ideal for agricultural research, field monitoring, and tea garden pest control.
- They are used to capture and monitor harmful insect populations, enabling precise pest management.
3. Color-Attraction Insect Monitoring Instruments:
- These smart devices automatically attract and capture Black Scale Whiteflies, using high-accuracy image recognition to identify and analyze pest types and quantities.
- They provide real-time monitoring and early warning of pest outbreaks through 4G network communication with a cloud platform.
Precautions for Controlling Black Scale Whitefly
When implementing control measures for Black Scale Whitefly, consider the following precautions:
Timing: Apply control measures during the peak hatching period and early nymph stages for optimal effectiveness. Continuously monitor and trap adults.
Protecting Natural Enemies: Use pesticides judiciously to preserve beneficial insects like ladybugs and lacewings, which naturally prey on whiteflies.
Effectiveness Evaluation: Regularly assess the effectiveness of control measures and adjust strategies as needed to ensure good results. Learn from experiences to improve control methods continually.
By understanding and applying these control methods, tea growers can effectively manage Black Scale Whitefly infestations, protecting both the quality and yield of their tea crops.
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