Tomato pests: Identification, damage, and control methods

Overview:

• What pests affect tomato crops?
• Western flower thrips
• Tomato spotted wilt virus
• Two-spotted spider mite
• Green peach aphid
• Stink bugs
• Colorado potato beetle
• Silverleaf whitefly
• Tobacco hornworm
• Flea beetles
• Tomato fruitworm
• Tomato yellow leaf curl virus
• Tomato leafminer
• Septoria leaf spot
• Bacterial spot
• How do I manage tomato pests?
• Summary

Tomatoes are a vital crop worldwide and added about 235 billion rupees ($2.7 billion) to India’s economy in 2021. However, they are attacked by many pests, including insects and microorganisms. A survey of farmers in India and Bangladesh shows that pests can destroy up to 11 tonnes of tomatoes per hectare each year, highlighting the importance of controlling these pests. This article explains the main tomato insect and spider mite pests, the most critical disease-associated microbes, and how to manage them effectively, including how to use biological control agents.

What pests affect tomato crops?

Tomato plants are attacked by various pests, including insects and microorganisms like bacteria, fungi, and viruses. These pests damage different parts of the plant, which ultimately reduces the overall harvest.

Western flower thrips (Frankliniella occidentalis)

Western flower thrips are small, slender insects about 1.5 mm long. They are usually light brown or yellow, with two pairs of wings covered in long hairs. Their life cycle lasts 30 to 45 days, and they can spread to new areas through strong winds. Thrips damage tomato plants by feeding on them, but most harm comes from spreading the Tomato spotted wilt virus. Infected plants may have stunted growth and white or silvery patches on their leaves. Western flower thrips reproduce rapidly in glasshouses where 12–15 generations occur year-round.

Tomato spotted wilt orthotospovirus

Various insects, including western flower thrips, spread this virus to plants. Insects pick up the virus by feeding on infected plants. The virus affects many plants, including tomatoes. Infected plants may show bronzing on young leaves, white patches, or downward-curving leaves. Ripe tomatoes can develop whitish or discoloured circular spots when infected.

Two-spotted spider mite (Tetranychus urticae)

The two-spotted spider mite damages many plants, including tomatoes, by feeding on plant tissue, including tomato leaf cells. Adults are about 0.5 mm wide with oval-shaped bodies. Early damage appears as small white specks on leaves, while severe infestations cause yellowing, browning, and leaf dropoff. The two-spotted spider mite can slow growth and kill plants early in the growing season if infestations are severe.

Green peach aphid (Myzus persicae)

The green peach aphid is a small, soft-bodied insect that damages many types of plants. It is usually green, black, or grey and harms plants by sucking sap from leaves and stems. Green peach aphids can also spread diseases like Potato Virus Y, which damages tomato plants. Their damage often causes leaf wilting, and heavy infestations early in the season can significantly reduce tomato plant growth and yield.

Stink bugs

Several species of stink bugs damage tomato plants. Although they come in different colours, these pests are usually brown or green and have a distinct shield shape. On green fruits like unripened tomatoes, stink bug damage shows as small black spots surrounded by whitish discoloured areas. As they feed, stink bugs can spread harmful microorganisms, such as fungi, which can infect plants and cause them to rot.

Colorado potato beetle (Leptinotarsa decemlineata)

This beetle feeds on many plants, including tomatoes. Adults are about 9.5 mm long and have black and cream stripes running along their backs. They feed directly on plant leaves, with most damage caused during their early developmental stages (instars). Large infestations can lead to significant leaf loss, slowing plant growth and reducing yield, which can seriously impact overall plant health and productivity.

Silverleaf whitefly (Bemisia tabaci)

This insect is 1.5–3 mm long and damages plants by feeding on their sap. It can spread hundreds of plant diseases, including the tomato infectious chlorosis virus, which affects plant growth. Whiteflies are active during the day and appear as small yellow-white insects on the undersides of leaves. Large infestations may cause honeydew buildup, which attracts black sooty mold. Damage includes yellowing leaves, stunted growth, and early leaf drop during heavy infestations.

Tobacco hornworm (Manduca sexta)

Larvae of this moth species have a distinctive “horn” at the end of their bodies, which is where the name comes from. Adult moths can have a wingspan of up to 12 cm and lay eggs directly on plant leaves. Larvae feed on leaves, flowers, and fruits as soon as they hatch. This pest mainly targets the leaves, usually feeding from the top of the plant downward. Severe infestations can cause complete defoliation and reduce yield, with plants also at risk of sun damage due to leaf loss.

Flea beetles

Adult flea beetles are about 1.5–3 mm long and have strong hind legs that let them jump like fleas when disturbed. They chew holes in tomato plant leaves, causing a “sieve-like” appearance when damage is severe. These pests are especially harmful to young plants early in the growing season and can also feed on tomato fruits, reducing their quality. A well-known flea beetle species that attacks tomato plants is the potato flea beetle (Epitrix cucumeris).

Tomato fruitworm (Helicoverpa zea)

Adult tomato fruitworm moths have a wingspan of about 25–35 mm, but most damage occurs during the larval stage. Young larvae are white with black heads, while older ones can be yellow or green. The larvae feed inside tomato fruits, causing significant damage like watery, messy cavities and early ripening. This damage can lower the quality and market value of the tomatoes.

Tomato yellow leaf curl virus

This virus affects many plants but can be especially harmful to tomatoes, sometimes causing 100% yield loss. Pests like the silverleaf whitefly spread the virus to other plants. As the name suggests, symptoms include yellowing leaves and tomato leaf curl upwards toward the centre of the leaf. This can lead to significant reductions in fruit production, although the fruits themselves are generally unaffected in terms of shape, appearance, and overall quality.

Tomato leafminer (Tuta absoluta)

This pest feeds on various plants, including tomatoes, during its larval stage. The larvae tunnel into leaves and change colour as they mature. Early stages are white or yellow after hatching, while older larvae are usually green with a black stripe behind the head. Leafminers damage tomatoes by creating leaf mines, which can cause leaves to fall off if the infestation is severe. The larvae can also feed on green fruits, making them more susceptible to microbial contamination.

Septoria leaf spot (Septoria lycopersici)

This plant disease is caused by the fungus Septoria lycopersici, which significantly affects tomato plants in damp or humid conditions. It causes dark spots on leaves, measuring about 1.5–6.5 mm in diameter, with brown edges and lighter tan or grey centres. Lower leaf surfaces and fruits are usually affected first, turning completely brown and shriveling as the infection worsens. In severe cases, the disease can kill the entire plant.

Bacterial spot (Xanthomonas spp.)

Several closely related bacterial species from the genus Xanthomonas cause bacterial spot on tomatoes. The bacteria can spread from plant to plant through farmers’ handling or by splashing caused by rain or watering. As the name suggests, the damage appears as dark brown spots, typically around 6.5 mm (¼ inch long) in diameter, which can worsen if the infection spreads across the plant.

How do I manage tomato pests?

As shown above, tomatoes are affected by many different pests, each requiring specific management methods. These control strategies fall into several key categories:

Monitoring

Check for pest damage early in the season, as early infestations can have a bigger impact on plant growth and yield later on. While each pest has unique symptoms, common signs include slower plant growth, leaf discolouration, or visible feeding damage on tomato leaves or fruits.

Cultural control

Preventing pest outbreaks is a key way to protect crops. Some microbial pests thrive in humid conditions, so avoid overwatering. Many pests survive in leftover plant debris, so keep growing areas clean. Also, transplants should always be inspected before planting to prevent pests from being introduced.

Biological control

Biological control involves using naturally derived products to tackle specific pest problems. These include:

• Natural substances: These are typically derived from plants and can be used in sprays to repel or kill pests. Neem oil can be an effective solution against many pests, including whiteflies.
• Semiochemicals: These are messaging compounds that can be used to disrupt pest behaviour.
• Microbials: These are microorganisms like bacteria, fungi, and viruses that harm pests but not crops. Beauveria bassiana is a fungal species that causes lethal infections in different pests, including thrips.
• Macrobials: These are larger animals, like certain insects, that feed on or parasitise pests. For example, BioOrius is a predatory minute pirate bug that can be effective in managing aphids, whiteflies, and mites.

Chemical pesticides

Before considering the use of chemical pesticides, farmers should explore all available non-chemical control solutions. These might include cultural practices like handpicking pests such as caterpillars, removing diseased plants, using resistant crop varieties, applying crop rotation and consulting the CABI BioProtection Portal for identifying and applying suitable biological control products (microbials, macrobials, natural substances and semiochemicals). 

Summary

Tomato crops face major threats from pests like insects, viruses, fungi, and bacteria, causing yield losses and severe economic damage. Effective solutions include monitoring, cultural practices, biological controls, and chemical treatments. Sustainable options, like beneficial microbes and natural substances, offer eco-friendly alternatives for protecting this vital crop. Institutions like the North Carolina Agricultural Research Service (NCARS) are helping to curb the pests affecting tomato plants through research and education.

For tailored pest management advice, visit the CABI BioProtection Portal, where you can enter your location and pest problem to explore customized solutions.
We have also prepared extensive guides on dealing with pests of specific crops. Read our article on protecting your coffee crops here.