Phthorimaea absoluta (formerly Tuta absoluta)
Common names: Tuta, Tomato leaf miner, Tuta absoluta
Tuta is a small moth belonging to the Gelechiidae family. It originated in South America but has since spread across Europe, the Middle East, Africa, and parts of Asia, becoming one of the most damaging pests of tomato crops worldwide. The pest was first detected in South Africa in 2016, and within a short time it had established itself in all of the country's major tomato-growing regions. Today, it ranks as the single most destructive insect pest affecting tomato production.
Beyond tomatoes, Tuta is also a serious threat to other Solanaceous crops such as potatoes, eggplant (brinjal), peppers, and tobacco, and it can survive on related weed species as well.
Tuta develops through four life stages, and the speed of development depends heavily on temperature: warmer conditions shorten the cycle, while cooler conditions slow it down. Activity halts entirely below 4°C, and populations tend to explode during hot, dry summer weather.
Egg: Tiny, pale yellow-white eggs are laid one at a time on the host plant. A single female can produce up to 300 eggs. Under conditions of roughly 23–24°C and moderate humidity, eggs hatch within about four days.
Larva: The caterpillar stage is cream-coloured with a dark head capsule. This is the most destructive phase as the larvae tunnel into leaves, stems, buds, and fruit, feeding on the soft internal tissue between the leaf's upper and lower surfaces. They pass through four growth stages (instars) before the final stage leaves the feeding site to pupate. Larval development takes roughly 10–12 days under the conditions noted above.
Pupa: Pupation typically occurs in the soil, though it can also happen on the leaf surface or inside old mines. This stage lasts about a week.
Adult: The adult moth is small (5–7 mm), with thread-like antennae and grey, black-spotted forewings. Adults live for around 12 days.
From egg to emerging adult, the full life cycle takes approximately 22 days under favourable conditions, allowing populations to build up rapidly.
Larval feeding creates irregular tunnels, or "mines," within the leaf tissue. These often start small but can expand into large, blister-like blotches, sometimes with narrow finger-like extensions. Because mines vary so much in shape, they can be confused with damage caused by the potato tuber moth, and not every mine shows the typical finger-like pattern. Occasionally, larvae mine between two overlapping leaves or within a folded leaf. Many mines appear empty simply because the larva has already left to pupate elsewhere.
When infestations are heavy, individual mines merge, causing whole leaves (and sometimes entire stems) to die back. In severe cases, most of the plant's foliage can be lost, and young, establishing plants are particularly vulnerable to destruction. Established crops can suffer yield losses of 80–100% where control measures are inadequate.
While leaf damage causes most of the economic loss, larvae will also attack fruit when populations are high, either by migrating from infested leaves or from eggs laid directly on the fruit or calyx. Entry points are most common near the calyx, often marked by visible frass (excrement). Larvae can burrow up to 1.5 cm into the fruit, and these wounds frequently open the door to secondary rot caused by opportunistic pathogens.
Characteristic mines created by feeding Tuta larvae.
The mines created by Liriomyza species are smaller, longer, and narrower than those created by Tuta larvae.
A range of naturally occurring organisms help suppress Tuta populations, including predatory insects, parasitic wasps, and disease-causing microorganisms. Mirid bugs, for instance, prey on Tuta eggs and exposed larvae in addition to other pests like aphids. Small parasitic wasps that already attack the potato tuber moth in South Africa are also known to parasitise Tuta under field conditions. Two biological agents, namely the fungus Beauveria bassiana and the bacterium Bacillus thuringiensis, are commercially available locally and can be incorporated into control programmes.
Effective Tuta control relies on integrating monitoring tools with targeted product use. Pheromone-based monitoring and mass-trapping are central to good industry practice: yellow delta traps fitted with sticky liners and pheromone lures are used to detect early moth activity and reduce adult populations before they can lay eggs, helping growers time other interventions correctly and limit reliance on chemical sprays alone.
Insect Science solution: For potato and tomato crops, Tuta can be monitored using T.A. PheroLure® with a yellow Delta Trap® and sticky liner to detect activity and track pest populations. Once Tuta activity is detected, control options include Last Call™ T.A. (attract-and-kill method) and TrapAll™ T.A. (mass trapping) used with the red water trap.
