Tea, our national drink in China, is also one of the oldest and most widely consumed beverages in the world. The production of tea relies on the cultivation and management of tea trees. Tea gardens serve as the cultivation sites for tea trees and constitute complex ecosystems. In tea gardens, apart from tea trees, there are many other organisms that coexist and collectively contribute to the ecological diversity of tea gardens. However, this ecological diversity also brings about some challenges. In tea gardens, certain organisms can adversely affect tea trees and tea leaves, which we refer to as tea garden pests. Tea garden pests are one of the main limiting factors in tea production and pose a significant threat to the safety of tea leaves.
In this series on tea pest control, we aim to introduce you to the types, habits, modes of harm, and control methods of these tea garden pests. Through our educational efforts, we hope to provide you with a deeper understanding of tea garden pests, thereby better protecting our tea gardens and ensuring that every tea leaf can grow in the optimal environment. The third installment of this series focuses on the common tea caterpillars found in tea gardens.
Identification of Tea Caterpillars
Tea caterpillars, commonly known as Euproctis pseudoconspersa, belong to the family Lymantriidae in the order Lepidoptera. They are an important pest in Chinese tea-growing regions. The morphological characteristics, habits, and occurrence patterns of tea caterpillars are as follows:
Adult Stage: Adults measure 6-13mm in length, with a wingspan of 20-35mm, with males being smaller. The wings are sparsely covered with black-brown scales, with three wavy lines and seven small black dots on the forewings, and two transverse lines and five small black dots on the hindwings. They are strongly phototropic, active at night, and rest with their wings spread flat during the day among the tea bushes.
Egg Stage: Eggs are about 1mm long, oval-shaped, initially green, later turning gray-brown, and black before hatching. They are usually laid in clusters of tens to over a hundred, covered with white fluffy material. Eggs are laid in crevices of tea tree branches, soil cracks, fallen leaves on the soil surface, or among branches and leaves.
Larval Stage: Larvae measure 26-30mm in length, with a cylindrical body and a brown head. They are light brown or light gray-brown in color, with a diamond-shaped gray-black spot on the back of the 2nd-4th abdominal segments, and an inverted "eight" shaped spot on the back of the 8th segment with small protrusions on each side. Larvae avoid sunlight and are often found hiding on the undersides of leaves or in shaded areas of tea bushes during sunny days, and they may drop or hang down on silken threads when disturbed.
Pupal Stage: Pupae are 10-14mm long, elongated oval-shaped, with males being smaller. They are reddish-brown, with a darker head. The antennae and wing buds reach the 4th abdominal segment, each side of the 5th abdominal segment has an eye-like spot, and the hind spines are nearly triangular, with the tip of the hind spine of the male pupa having a bifurcated short spine. Pupae overwinter in the soil near the tea tree roots for more than five months.
Harmful Characteristics of Tea Caterpillars
The damage symptoms caused by tea caterpillars include leaves being chewed into arched notches, and severe infestations can result in the complete consumption of leaves and tender shoots, affecting not only the tea yield of the current year but also leading to tree vigor decline and reduced tea yield in the following year.
The harmful characteristics of tea caterpillars are as follows:
1. They occur in multiple generations, reproduce quickly, spread rapidly, and are prone to outbreaks. Serious occurrences are seen in tea-producing provinces south of the Yangtze River, especially in provinces such as Jiangsu, Zhejiang, Anhui, and Hunan.
2. Larvae gather and feed in clusters, often with tens to hundreds of individuals feeding on the undersides of leaves, and sometimes even consuming entire tea tree leaves, leading to dead branches and trees.
3. Larvae exhibit pseudo-death behavior and may drop or hang down on silken threads when disturbed, making them difficult to catch and kill.
4. Both larvae and adults possess poisonous hairs and scales. Contact with human skin can cause redness, swelling, itching, and allergic reactions, affecting agricultural operations.
Control Methods of Tea Caterpillars
Given the occurrence characteristics and degree of damage of tea caterpillars, the following control methods can be adopted:
Deep Plowing to Eliminate Pupae: Deep plowing between tea rows to expose overwintering pupae to sunlight and kill them, thereby reducing the source of pests.
Manual Trapping and Killing: Utilize the phototactic behavior of tea caterpillars to lure and kill male moths with light traps, reducing the number of mating and oviposition events.
Chemical Control: During the peak period of tea caterpillar occurrence, select low-toxic, high-efficiency, and safe pesticides for spraying, such as flubendiamide, tebufenozide, chlorfenapyr, etc., spraying once every 7-10 days for 2-3 consecutive times, paying attention to prevent pesticide damage and residues.
Biological Control: Utilize pathogens and natural enemies of tea caterpillars, such as the nuclear polyhedrosis virus of tea caterpillars, to produce viral insecticides to infect and kill tea caterpillars, achieving the purpose of control.
Yeehar Agricultural Science has been deeply engaged in the field of green prevention and control for many years and has developed a series of products including natural enemy-friendly series, insect situation monitoring and forecasting series, and trapping series, aiming to achieve the goal of "disaster prevention and reduction, quality improvement and efficiency increase, and safety guarantee." We have various methods for trapping and controlling tea tussock moths.
1. Multi-functional Flying Insect Traps: Utilize sexual lure technology to attract tea tussock moths, then use a high-voltage grid to kill them. Powered by solar energy + lithium batteries, with long battery life and easy installation, it effectively controls the population of tea tussock moths in the area.
2. Small-volume Insect Light Traps: Designed to capture small insects, it has efficient trapping capabilities and is suitable for monitoring and controlling small insects such as tea tussock moths. Widely used in agricultural research, field monitoring, and tea garden pest control to capture and monitor populations of small insects harmful to crops, achieving precise pest control.
3. Boat-shaped Sex Pheromone Traps: Sexual pheromone technology is a primary measure for green control of tea tree pests, serving as an important alternative and supplement to chemical pesticides. Among various trap types, boat-shaped traps have a good capturing effect on tea tussock moths and are ideal companions to sexual pheromone lures.
Notes on The Precautions of Tea Tussock Moth
When carrying out control measures for tea tussock moths, the following precautions should be noted:
Timing of Control: Control should be conducted based on the occurrence pattern of tea tussock moths, focusing on the initial outbreak period and peak occurrence period, especially for the overwintering generation and the first generation. Timely control measures should be implemented to prevent their spread and proliferation.
Control Methods: It is essential to comprehensively utilize various control methods, including physical, biological, and agricultural non-chemical control measures. Additionally, appropriate use of chemical pesticides should be considered, aiming to avoid the development of resistance in tea tussock moths and minimize any negative impacts on tea trees and leaves caused by a singular method.
Effectiveness of Control: Regular monitoring and evaluation of the occurrence and effectiveness of tea tussock moth control measures are necessary. Based on actual circumstances, adjustments should be made to control measures to ensure the health of tea gardens and the quality of tea leaves.
Challenges in Control: The main challenges in controlling tea tussock moths include their strong resistance to pesticides. Commonly used pesticides often result in poor control effects, necessitating the continual updating of pesticide types and quantities, thereby increasing control costs.
The toxic hairs and scales of tea tussock moths can cause irritation to the human body. Therefore, when spraying pesticides, protective measures should be taken to avoid skin contact or inhalation, which may lead to allergic reactions or respiratory diseases. Since the occurrence of tea tussock moths coincides with the harvesting period of tea leaves, attention should be paid to the safe interval after pesticide application to prevent residue on tea leaves, which could affect the quality and safety of tea.
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