Tomato Leafminer (Tuta absoluta): Effective Control
Tomato Leafminer (Tuta absoluta)
Introduction
The tomato leafminer (Tuta absoluta), also known as the tomato moth, moth borer, or South American tomato pinworm, is a small moth in the Gelechiidae family. This pest, originally from Latin America, is present in various countries, including Argentina, Bolivia, Brazil, Chile, Colombia, Ecuador, Paraguay, Peru, Uruguay, Venezuela. It typically doesn’t thrive above 1,000 meters or in low-temperature areas. Introduced in Spain (Levante) in 2006, it quickly spread, severely impacting tomato crops in southern Spain. Subsequently, it appeared in Morocco, Algeria, southern France, Italy, and Tunisia.
It primarily affects Solanaceae plants, particularly tomatoes, but also impacts potatoes, eggplants, and, to a lesser extent, peppers.
Life Cycle
Tuta absoluta has a high reproductive potential, with up to 12 generations per year. Adults are nocturnal, hiding in the foliage during the day. Females lay 40-50 eggs (sometimes up to 260) on the underside of leaves, stems, or near leaf veins. The female lifespan is about two weeks, while males live for approximately one week. The minimum temperature for activity is 9°C.
Egg
The eggs are cylindrical, creamy white to yellow, about 0.4 mm long and 0.2 mm in diameter. They turn black before hatching.
Tuta absoluta egg
Larva
The eggs hatch into larvae (caterpillars) that create galleries within leaves, stems, or fruits. They emerge to pupate, usually in the soil. This larval stage causes the most damage and is difficult to control with standard treatments. The larvae go through four stages, growing from 1 mm to 8 mm long. They have a dark brown head, and their body changes from creamy green to pinkish with black spots on the back and a black line behind the head from the second larval stage.
Tuta absoluta larvae
Pupa
After the larval stage, pupation occurs in the soil, on leaves, or within galleries, depending on environmental conditions. The pupa is usually covered in a silky white cocoon.
Tuta absoluta pupa
Adult
Adult moths have threadlike antennae, and their head, thorax, palps, and wings are gray with black spots on the forewings. Females have a wider, brown thorax. They reach 10 mm in size. The life cycle takes 29-38 days, depending on temperature, with 10-12 generations per year. Low temperatures limit their survival.
Adult Tuta absoluta
Crop Damage
Larvae create holes and galleries in tomatoes, leaves, and stems. Fruit can be attacked from its formation, leading to rot. The larvae move from one fruit to another. In leaves, they feed on mesophyll tissue, leaving the epidermis intact, causing irregular mines that become necrotic. Damage can be significant without timely detection and control.
Damage to tomato by Tuta absoluta
Pest Control
Tuta absoluta can reduce tomato and other Solanaceae yields by 50-100%. Prevention and management are crucial.
- Remove old plants, fruits, and weeds around greenhouses.
- Use insect screens on ventilation openings.
- Repair greenhouse plastic holes and install double doors.
Chemical control is often ineffective due to Tuta absoluta‘s resistance to many pesticides and its development within the plant. Integrated pest management strategies are recommended.