Pest Management in Tea Plantation: Major Insect Pest of Tea, Control and Prevention Methods

Pest management in tea gardens is crucial for maintaining healthy tea plants. One significant challenge tea growers face is dealing with insect pests that can harm tea crops. Controlling these pests is essential to ensure a successful tea harvest. In this, we will delve into the major insect pests affecting tea and explore effective methods for their control and prevention.

Pest Management in Tea Plantation

What is a Tea Garden?

Scientifically known as Camellia sinensis, tea is a member of the Theaceae family, prized for its leaves used in beverage production. This botanical gem exhibits a branching structure with elliptical leaves, possessing a leathery texture, matte green hue, and serrated edges. While it can grow into a tree with a canopy resembling a bowl, cultivation usually involves careful pruning to maintain a smaller, shrub-like form. This tea plant occasionally graces us with fragrant white blossoms, individually or in small clusters. These remarkable trees can attain heights of up to 15 meters (49 feet) and have lifespans ranging from 30 to 50 years.

Tea Plant Propagation

Tea plants thrive in warm, humid climates, favoring temperatures between 14°C and 27°C, with 18-20°C ideal. They cannot endure frost and require temperatures above 13°C but below 29°C. The soil should be deep, well-draining, and slightly acidic (pH 4.5 to 6.0). An annual rainfall of 1600 mm, distributed evenly, is necessary. In dry regions, shading is crucial to maintain humidity.

Propagation methods include seeds or rooted leaf cuttings. Quality seeds are chosen by those sinking in the water. These seeds are germinated using wet cloths before being transferred to a nursery for 2-3 years. Single node cuttings are rooted in polyethylene bags with regular watering for leaf cuttings. New tea plants from cuttings can be planted out after 6-9 months. Tea can be planted in various arrangements.

Care and Maintenance

Newly planted tea gardens should be weeded by hand until the canopy shades out weeds. Pruning is essential to encourage lateral branches and maintain the desired shape. It should be done during dormancy or in winter. Tea plantations require regular fertilization, customized based on soil testing results. Harvesting involves plucking the youngest leaves every 7-14 days, with variations in leaf count affecting quality and yield.

Insect Pests Management in Tea Garden

Insect Pest	Damage in Tea Gardens
Red Spider Mite (RSM)	17-46% crop loss, reduced leaf quality, and decreased productivity.
Aphids	Sucking sap, leading to wilting, deformities, and reduced growth.
Tea Mosquito Bug	Feeding on leaves, causing leaf curling and stunted growth.
Tea Tortrix Caterpillar	Defoliation, resulting in reduced photosynthesis and yield.

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Tea Aphid (Toxoptera Aurantii)

Symptoms

Tea Aphids are small, soft-bodied insects found on the underside of tea leaves and stems. They come in various colors, often green, yellow, pink, brown, red, or black.
Heavy infestations can cause yellowing and distortion of leaves, necrotic spots, and stunted shoots.
Aphids excrete honeydew, a sugary substance that promotes the growth of sooty mold on plants.

Cause

These pests are insects with distinguishing features, including tubular structures called cornicles extending backward from their bodies.
They tend to move slowly when disturbed.

Management

For minor infestations, prune affected leaves or shoots to control aphids.
Inspect transplants for aphids before planting.
If available, use tea plant varieties that are tolerant to aphids.
Infected plants can be sprayed with a strong jet of water to dislodge aphids from leaves.
Insecticides are usually only necessary for severe infestations, as tea plants can tolerate low to moderate aphid levels. Insecticidal soaps or oils like neem or canola oil are effective for control but always follow product labels for specific usage guidelines.

Tea Scale (Fiorinia Theae)

Symptoms

Look for pale yellow spots on leaves, entire leaves turning yellow, browning, and premature leaf drop.
Adult tea scale insects are oblong with a ridge along their centers. They start as bright yellow but darken to a deep brown.
These scales are typically found on the undersides of leaves.

Cause

Tea scale is an insect pest.

Management

Light infestations can be scraped off and destroyed, or you can handpick infested leaves.
For heavier infestations, consider using horticultural oil after the bloom.
Appropriate insecticides can be applied but are effective only against actively crawling scales.

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Two-Spotted Spider Mite (Tetranychus urticae)

Symptoms

Spider mites cause stippling and bronzing of tea leaves.
You may notice webbing covering leaves, with tiny moving dots (mites) visible on webs or the underside of leaves.
Often, these symptoms become visible only after significant damage has occurred.

Cause

Spider mites are arachnids, not insects.
They thrive in dusty conditions, and water-stressed plants are more susceptible.

Management

In-home gardens reduce spider mite populations by spraying plants with strong water jets.
For problematic infestations, apply insecticidal soap.
Be cautious with chemical insecticides, which can harm mites’ natural predators and encourage mite reproduction.

Major Insect and Mite Pests in Tea Plantations

Helopeltis Mirids: Among the mirid bugs, there are about 41 species in the Helopeltis genus in Asia, Australia, and Africa. Helopeltis schoutedeni and H. theivora have become major adversaries of tea planters in Africa and Asia, causing substantial crop losses. H. theivora, in particular, is a prolific pest, laying 4 to 10 eggs daily and causing damage during its multivoltine life cycle, with peaks in population during the rainy season.

These mirids feed on tender stems, young leaves, and buds, leaving behind feeding punctures. Severe infestations can result in leaf damage, dieback, and stem canker, leading to crop loss. Their feeding punctures turn brown to black due to the action of their salivary enzymes.

Tea Tortricids: The tea tortricids, specifically Adoxophyes honmai and Homona magnanima, are leaf-feeding pests in Japan. These pests lay oval-shaped egg masses on tea leaves, from which neonates emerge and construct leaf webs for feeding. They pupate inside these webs, and understanding their developmental requirements is crucial for pest management.

Shot Hole Borer: Shot hole borers, particularly Xyleborus fornicatus, are significant pests in Sri Lanka, causing substantial infestations. These beetles construct galleries inside tea plant stems and cultivate ambrosia fungus, which may contribute to stem damage or blockage of the plant’s vascular system. The beetle’s development is temperature-dependent.

Mites in Tea: Mites are persistent and serious pests in tea production. Various mites, such as Tetranychus kanzawai, Brevipalpus phoenicis, and Oligonychus coffeae, are responsible for crop damage in different regions. They cause characteristic marks and scars on tea leaves, reducing yield. Temperature, humidity, and shading within tea plants influence mite distribution.

The red spider mite (Oligonychus coffeae) is one of the most important mites, causing crop losses in multiple countries. This mite thrives in high temperatures and dry conditions. Scarlet mite (B. phoenicis) is another widespread pest, causing scurf and defoliation. The Kanzawa spider mite is polyphagous and has a broad habitat range. It’s temperature-dependent and can migrate between tea plants and other hosts.

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Effect of Major Insect Pests and Mites on Tea Gardens

Tea Mosquito Bug: The tea mosquito bug, known scientifically as Helopeltis theivora, is a major pest in tea plantations. This tiny bug causes significant damage, with crop losses of about 55% in Africa and 11-100% in Asia. The most voracious feeder is the 5th instar nymph. It leaves behind characteristic circular rings (0.29 to 2.51 mm in size) around feeding spots on the leaves and new flushes.

These rings progressively turn dark brown, leading to upward curling and desiccated dieback of leaves, causing poor yields. Female lay up to 500 eggs in soft plant tissues, completing their life cycle in about a month. They are active from January to September and hibernate during the winter, causing the most damage in moist and shaded areas.

Termites: In Bangladesh, termites are responsible for approximately 22.56% of crop losses in tea plantations. They feed on the internal plant tissues, creating hollow trenches inside the stem, which they fill with soil. Termites are often referred to as the “cancer of tea plants.” The worker termites are the most destructive. A single termite queen can lay a staggering 84,000 eggs per day. Termites are classified into two categories: live wood termites, which feed on living plant tissues, and scavenging termites, which feed on dead plant tissues.

Thrips: Tea thrips are now a major concern for tea plantations. Both nymphs and adults are destructive, with nymphs causing more harm. They complete their life cycle in 14-20 days and suck the cell sap, leaving two longitudinal sandpaper-like lines on the leaves. Severe thrips feeding results in leaf curling and damage that resembles a burnt appearance.

Looper Caterpillar: The Hyposidra talaca looper caterpillar is a significant defoliator of tea plants. These caterpillars voraciously feed on tea leaves, leaving cut marks on leaf edges and pinholes. In severe cases, the entire bush can become stripped. Female moths lay eggs on shade tree trunks, and after hatching, the larvae start feeding on shade tree leaves before moving to tea bushes to continue feeding.

Tea Red Spider Mite: The tea red spider mite, scientifically known as Oligonychus coffeae, is a major mite pest of tea. It was first discovered in 1861 and has since threatened tea production in various countries. It causes significant crop losses, ranging from 17% to 46%. This mite feeds on chlorophyll by piercing and sucking it from the upper surface of the leaves, leaving reddish-brown marks. Severe infestations can lead to defoliation, bush death, and crop loss. Outbreaks of the red spider mite typically occur during hot and dry weather conditions.

Integrated Pest Management (IPM) for Insect Pests of Tea

Cultural Control

Plucking: Proper plucking cycles are vital for controlling pests like the Tea Mosquito Bug. Removing infested shoots during plucking reduces pest populations.
Pruning: Pruning helps control pests like the Tea Mosquito Bug and thrips, as it removes their breeding sites.
Pest Collection and Destruction: Simple methods, like collecting and crushing pests upon sight, work effectively against certain pests.
Field Cleaning: Removing pruning litters and maintaining field cleanliness minimizes pest shelters.
Shade Regulation: Proper shading reduces the risk of infestations, with different pests thriving under varying light conditions.

Biological Control

Predators: Insects like praying mantids, lacewings, and spiders prey on pests like the Tea Mosquito Bug, thrips, and looper caterpillars.
Parasitoids: These insects lay their eggs inside host pests, eventually killing them. They are highly host-specific.
Microbials: Certain fungi, bacteria, and nematodes are used to control tea pests, particularly the Tea Mosquito Bug.

Botanical Control: Plant-derived products can act as antifeedants, repellants, or toxic agents against pests. Neem and extracts from various plants are known to be effective.
Chemical Control: While chemical pesticides are used as a last resort, they are still a part of IPM. Choosing the right pesticide, application method, timing, and dosage is crucial for successful pest control.
Resistant Varieties: Some tea clones have shown resistance to specific pests, such as the Tea Mosquito Bug and termites, reducing the need for chemical control.

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Integrated Pest Management for Tea Red Spider Mite

Cultural Practices: These primary control measures include traditional methods to regulate pest populations. They encompass:

Pruning: Trimming tea bushes rejuvenate vegetative growth and reduce RSM presence. The more leaves you remove, the lower the risk of RSM attacks.
Water Management & Drainage: Ensuring adequate irrigation and proper drainage is vital. RSM is less likely to infest water-stressed plants, and midseason tree washing helps prevent late-season infestations.
Shade Trees: The right number and spacing of shade trees can significantly reduce leaf temperatures, making it less favorable for RSM.

Influence of Fertilizer: The fertilizer used impacts RSM infestation. Heavier nitrogen doses increase RSM populations, while more balanced nitrogen and phosphorus fertilizer is recommended for RSM control.

Biological Control: Using natural predators, parasitoids, and pathogens can effectively combat RSM. Predatory insects like ladybird beetles and new mite species are known to prey on RSM. Proper pest management practices can enhance these predators’ presence.

Microbial Control: Certain microbes, such as Metarhizium anisopliae and Paecilomyces fumosoroseus, have proven effective in RSM control. These microbes can be applied in tea plantations to manage RSM.

Botanical Control: Plant extracts, like those from Clerodendrum viscosum, Melia azedarach, Polygonum hydropiper, and others, have shown efficacy against RSM. These natural extracts can be used as alternatives to chemical pesticides.

Chemical Control: While considered a last resort, chemical pesticides can be used for RSM management. However, they should only be employed when other methods prove ineffective.

How Can Cultural Practices Help Control Tea Pests?

Cultural practices like pruning and field sanitation can reduce pest populations.

What are Some Common Insect Pests in Tea Gardens?

Common pests include Tea Mosquito Bugs, Tea Aphids, Tea Scale, and Two-Spotted Spider Mites.

What are the Key Symptoms of Tea Mosquito Bug Infestation?

Circular rings on leaves, leaf desiccation, and upward curling are typical symptoms.

What is the Primary Damage Caused by the Tea Red Spider Mite?

The Red Spider Mite leads to crop losses, defoliation, and reduced leaf quality.

How Can Biological Control Be Employed in Tea Pest Management?

Natural predators, parasitoids, and pathogens can be used to combat tea pests.

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Conclusion

In tea gardens, effective pest management is crucial to safeguard crop yield. Employing integrated strategies, including cultural practices, biological controls, and judicious use of chemicals, ensures protection against major insect pests, enhancing tea production sustainability.

Pest Management in Tea Plantation: Major Insect Pest of Tea, Control and Prevention Methods

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