Crops
Tuta absoluta Meyrick
Tomato leafminer
General
- Microlepidopteran insect of the Gelechiidae family which is particularly prevalent in several countries of South America (Argentina, Bolivia, Brazil, Chile, Colombia, Ecuador, Paraguay, Peru, Uruguay, Venezuela).
- Emerging in Europe since 2016, then spread to many other countries of the Mediterranean Basin (Algeria, Egypt, Greece, Israel, Italy, Libya, Morocco, Syria, Tunisia, Turkey).
- Essentially stripping on Solanaceae, especially on aubergine, in the open field and in crops under cover.
- Organs attacked : leaves, fruits.
- Symptoms :
- Mines * and galleries on leaflets and leaves materializing in the long term as irregular whitish spots becoming progressively brown and necrotic. Only the tissues of the mesophyll are affected, the epidermis remains intact.
- Heavily parasitized leaves can completely necrode.
- Attacks on green and ripe fruits rather rare, galleries and exit holes are visible on the latter. Note that parasitized fruits are often unsalable.
- Galleries dug in the young stems disrupting the development of plants.
- Black feces are visible here and there on the affected organs.
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- Signs : Presence of larvae and adults on the affected organs (figures).
- Possible confusion :
* The damage of should not be confused T. absoluta with that of leafminers belonging to the Agromyzidae family.
Biology
- Development cycle : comprising 4 stages of development: egg, larva, chrysalis and adult. Its duration varies depending on the temperature in particular; for example, it would be approximately 24 days at 27 ° C. There could be up to 10 to 12 generations per year.
- Eggs tiny and invisible to the naked eye, measuring less than a millimeter. They are cylindrical in shape and are cream to yellowish in color. They hatch 4 to 6 days after laying.
- Four larval stages follow one another, with larvae measuring a few millimeters in length. First cream colored, then greenish to pinkish, they dig galleries on the aerial organs of the tomato.
- Pupa stage occurring either inside galleries, or on the host's surface, or on the ground. Pupation lasts 10 to 12 days.
- Adults, butterflies, measuring 5 to 7mm in length and about 10mm in wingspan. They have a silvery gray to brown tint with black spots on the forewings. Males are a bit darker than females. Their antennae are threadlike. The approximate lifespan of adults is 6-7 days for males and 10-15 days for females. Each female can lay 40 to 250 eggs, often located on the underside of the leaves or on the young tender stems and sepals of young fruits.
- Spends the winter in the form of eggs, pupae or adults. These are nocturnal and usually hide between the leaves during the day. The main host of T. absoluta is tomato, but it can also occasionally parasitize various other cultivated Solanaceae species (eggplant, pepino - Solanum muricatum , pepper, potato) and wild ( Datura stramonium, D. ferox , Lycium chilense, Lycopersicon hirsutum, Nicotiana glauca, Solanum lyratum, S. nigrum, S. elaeagnofolium, S. puberulum ...).
Protection
- If possible, produce the plants in an shelter insect-proof . The use of insect nets can protect the nursery, but also the crop.
- Check the sanitary quality of the plants and refuse those showing suspicious symptoms.
- Set up pheromone traps (water traps, Delta type, Mc Phail type) in order either to detect this insect pest early and to assess the potential risk for the crop, or to reduce the population present.
- Eliminate parasitized leaves, stems and fruits and burn them quickly. It will be the same for plants or plants that are too attacked.
- Regularly remove leaves from parasitized plants and remove the leaves.
- Do not leave parasitized plant debris in piles on the ground in greenhouses or tunnels, or near, which allows this pest to persist locally.
- Fruits that have fallen to the ground must be picked up and destroyed.
- Close the openings and openings of greenhouses and tunnels to prevent adults coming from outside. Install nets insect-proof .
- Several auxiliary insects have been reported as more or less effective against this lepidoptera: Nesidiocoris tenuis, Macrolophus caliginosus, Trichogramma pretosium, Trichogramma sp, Pseudoapanteles dignus, Dineulophus phthorimaeae, Cornua sp., Podisus nigrispinus, etc.
- Implement sexual confusion in addition to other means of control.
- Reason the chemical protection, in particular if you use auxiliaries or biopesticides.
- At the end of cultivation, quickly remove the crop residues and burn them; In greenhouses, disinfection of the soil can be considered in order to destroy the pupae, especially in the case of monoculture of tomatoes. In the open field, tillage will help reduce their number.
* Cases of resistance to insecticides having been reported for T. absoluta, alternate the active ingredients, and respect the doses and number of applications recommended per year.
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