Tomato farmers have suffered massive losses as a result of Tuta absoluta. This invasive pest can destroy an entire tomato farm, grown in an open field or in a greenhouse if no effective measures are taken.

Tuta absoluta which is also commonly known as Tomato Leaf miner also attacks potatoes. Infested tomatoes have reduced yield and fruit quality. The main damage is noticed on the leaves and fruits, but flowers and stems can also be affected. The distinctive symptoms are blotch-shaped mines in the leaves.

Inside these mines both the caterpillars and their dark remains can be found. The damage results in malformation and provides room for fungal diseases to enter which in turn causes rotting of the fruits before and after harvest.

Where pest hides

The pest hides underside the tomato leaves, bud stems and the calyx of unripe fruits. This makes the pest hard to control. The pest has a short lifecycle of 30 to 38 days and the female moth has ability to lay 260 eggs in one cycle. This means within 38 days the number of pests attacking the crop are numerous.

Why it’s difficult control

With this kind of reproduction, the pest can cause massive losses destroying the crop and increasing cost of production. The pest is devastating because it is resistant to most pesticides making chemical control ineffective.

The most destructive stage is the larval stage which lives as a miner in the fruit, stem, fruit or stem. The larva attacks by sucking sap from the leaf which results in marks on the leaf.

Active at the night

The adult pests are active during the night making it hard for the farmer to target. Infestation of the pest has been attributed to buying seedlings with traces of moth’s larva. You should therefore procure seeds/seedlings from certified sources.

Look out for abnormal signs on your crop. This should be done regularly to detect the symptoms early enough. Check out for deformation or curling leaves, silvery tunnels on the leaves, malformation or collapse of stems, presence of excrement of the larvae on the plant and wilting of the plants. Severe attack could be manifested by fruits developing an abnormal shape.

Crop rotation

Effective control of Tuta absoluta starts with identifying the leaf miner. To do this, use insect traps baited with pheromone. The baits will capture the pests and reduce their numbers. Place the traps in the crop field strategically to capture the male insects. This method can be effective in low infested field or complement other control measures.

Planting tomatoes in shade nets can reduce pest infestation. Crop rotation will also ensure crops belonging to the same family are not planted successively. Soil sterilisation/solarisation to get rid of the larva eggs in the soil will prevent the spread of the pest.

Biological control

Use of predators such as spiders, wasps and ants have been reported to be effective as biological control methods. Chemical control is difficult because the larvae live inside leaves, fruits and stems.

Finally, pests such as T. absoluta, with a high reproductive capacity and short generations, have an increased risk of developing resistance.

It is therefore crucial to avoid systematic applications, and only apply treatments according to pest population density and crop damage.