Tuta absoluta (Tomato Leafminer) - Fact Sheet

---

Background

Tuta absoluta (Lepidoptera: Gelechiidae) is a highly destructive insect pest to tomato plants and fruit and is also reported to infest other plants in the Solanacaeae family (potato, eggplant, etc.).

This moth is native to the Andes region of South America but can now be found in Europe and North Africa. It is likely to continue spreading in the Mediterranean Basin. It is a tropical-to-subtropical moth, but has invaded greenhouses in Northern Europe.

Host

Tuta absoluta lives on and in the leaves, stems and flowers of plants in the Solanacaeae family and also in the fruit of tomatoes. It has also been found on bean plants (Phaseolus vulgaris).

Movement and dispersal

This insect pest travels in several ways.

• Tomato plants, tomatoes and used containers are known to be high-risk pathways for the introduction of this pest.
• Soil is a suspected pathway.
• Production greenhouses that repack and distribute tomato fruit produced in infested countries are likely pathway for the spread of this pest.
• Outdoor markets that sell tomatoes from infested countries and are located in areas with suitable summer conditions for the survival of Tuta absoluta also pose a risk.

This moth is reported to fly up to a distance of 100 kilometres. It is likely to be able to move between unscreened greenhouses and outdoor crops.

Biology

The female moth lays up to 260 eggs, mostly singly, on leaves, stems and young fruit. The larvae bore between the epidermal layers of the leaf creating mines and, when older (at the 3rd to 4th instar or later developmental stage of the larva) they leave these mines and travel to new locations to mine again.

Young larvae usually attack the leaves, but can be found in growing points and in the flower. Later stage larvae tend to attack the fruit. Pupation happens in the mine, outside the mine, or in the soil.

At 20°C, the average developmental period from egg to adult is 40 days. Tuta absoluta might form temporary outdoor populations in Canada, but it is not likely to be able to survive the winter here. However, it poses a high risk to greenhouse tomato cultivation in Canada as nine generations are possible each year within greenhouses.

Signs and symptoms

Common signs and symptoms of Tuta absoluta on fruit and stems include :

• puncture marks,
• abnormal shape,
• exit holes,
• rot due to secondary infective agents, and
• frass (fine powdery material that plant-eating insects pass as waste after they digest plant parts).

Young larvae and eggs are difficult to find. Fruits show puncture marks on the surface where the larva has entered the plant.

Attacked tomatoes are easy to spot by the exit holes and the dried frass produced by the last larvae as they pupate.

Signs of damage on the fruit are often observed under the calyx (green leaf-like organ above the fruit). Cracks and crevices on containers should be checked for the presence of pupae.

Detection and identification

Click on image for larger view

 

 

Text: Plant Health and Biosecurity Directorate
Figures: www.tutaabsoluta.com