Tuta absoluta

Bioaggressor - (Tuta absoluta) - Insect - Insect (pest)

South American tomato leafminer

Insect (pest) Insect

Ravageur

The South American tomato leafminer (Tuta absoluta) is a species ofinsect in the order Lepidoptera (butterflies), in the family Gelechiidae.

Its tiny larvae (less than 8 mm long) attack in particular the leaves and fruit of tomatoes under cover or in the field, as well as other solanaceous plants such asaubergines, tobacco, peppers, potatoes and wild species(datura, nightshade). This pest, which originated in South America, appeared in the Mediterranean basin in 2006 and in France in 2008. In addition to prophylactic measures, this new pest can be combated by using pheromone traps and parasitoids to kill eggs and larvae.

This larval stage insect makes galleries in leaves, stems, flowers and fruit, often leaving the fruit unmarketable and altering the growth structure of plants, destroying the apical buds of the stem or flower buds. Crop losses can be in the region of 80-100% in areas where it occurs. This insect has spread via the plant and fruit trade. Adult moths can fly several kilometres and are carried by the wind.

Details

• Common name : South American tomato leaf miner
• Scientific name : Tuta absoluta
• Affected plants : All Solanaceae, increased palatability for tomatoes
• Symptoms : Whitish galleries in leaves, damage to fruit and stems
• Activity : All year round if greenhouses or tunnels are heated
• Cycle : 10 to 12 generations per year
• Control : March to October using Macrolophus pygmaeus, nematodes such as Steinernema feltiae or Delta-type pheromone traps.
• Dose :
  • 2 to 4 per m² for Macrolophus
  • 1 to 2 Delta traps with pheromones
  • 166,000 per m² for Steinernema feltiae

Find out more about the South American tomato leafminer (Tuta Absoluta)

This insect can overwinter as eggs, pupae or adults, and all stages can be identified at the same time in sheltered, heated conditions. Adults are nocturnal and hide between leaves during the day.

Its life cycle comprises 4 stages :

• Egg,
• Four larval stages,
• A chrysalis stage,
• An adult stage.

Adults are butterflies 5 to 7 mm long that hide during the day.

They are most active at the end of the day and at sunrise, affecting the lower parts of plants. They reproduce rapidly, with up to 12 generations per year depending on climatic conditions. A female can lay up to 250 eggs during her life span of 10 to 15 days for females and 6 to 7 days for males.

Males and females mate and egg-laying begins 3 to 4 days later. Eggs are often isolated on leaves but also on young fruit, not easily identifiable in cultivation.

Tuta does not go into diapause as long as food is available. Fruits are likely to be attacked as soon as they are formed and until they reach maturity. One larva can cause damage to several fruits in a single cluster.

Recognising Tuta absoluta

Being a leafminer, its damage can sometimes be confused with other pests, including Liriomyzas.

The galleries of Liriomyzas resemble those of Tutas, but the latter form beaches, whereas those of Liriomyzas are in the form of tunnels that gradually enlarge. The excrement of Tutas is more dispersed, whereas that of Liriomyzas forms a narrow net inside the gallery.

Tuta larvae have clearly visible heads and legs, whereas Liriomyza larvae have no distinct head or legs.

Control methods

Prophylaxis

Prophylactic techniques can be used to partially control Tuta :

• Remove contaminated plant parts such as leaves and fruit
• Then dispose of or burn this waste, and do not leave it in the glasshouses to prevent the bioaggressors from maintaining their presence.
• At the end of the crop, remove crop residues by burning them.
• Anti-insect netting around greenhouse openings

Biological control

Natural enemies partially or completely control the proliferation of Tuta absoluta, when they are not disturbed by ants, dust, insecticide treatments or bad weather.

• Macrolophus pygmaeus is a generalist predator; all stages are predators and attack Tuta eggs and small larvae. Feeding on the eggs ofEphestia or Sitotroga can help it to establish itself in unfavourable climatic conditions.

• An effective method against the larval and adult stages is the application of Steinernema feltiae nematodes. Once inside the host, the nematode releases symbiont bacteria that multiply and cause the insect to die within 24 to 72 hours. As the nematodes are sensitive to UV rays, we recommend applying a natural adjuvant such as Chitosan, which protects the nematodes and makes them effective for longer. Conditions : air temperature must be above 8°C

• Deltatraps with pheromones should beinstalled outdoors to prevent the pest from entering the crop.

• Dose :
  • 2 to 4 per m² for Macrolophus
  • 1 to 2 Delta traps (Capta) with pheromone
  • 166,000 per m² of Steinernema feltiae nematodes

• Application of Bacillus thuringiensis approximately every 15 days

Treatments

• Approval of Spinosad on phytophagous caterpillars in tomatoes at 0.015L/hl with a maximum of 2 applications (caution, risk of toxicity for beneficial insects).

All authorised treatments against Tuta Absoluta can be found here.

Appendices and Sources

• Protection strategies for protected tomato crops against Tuta absoluta http://itab.asso.fr/downloads/tutapi/cahier_technique_tutapi.pdf (published by CTIFL)
• https://www.interbio-occitanie.com/content/uploads/2019/12/mag-de-la-conversion12_maraichage.pdf
• List of MA against Tuta Absoluta http://e-phy.agriculture.gouv.fr/usa/16953113.htm
• https://www.insectesutiles.fr/33-tuta-absoluta
• BioPlanet : https://www.insectesutiles.fr/33-tuta-absoluta

S'attaque aux cultures

• Tomato