Tuta Absoluta: The Devastating Pest Threatening Tomato Crops Worldwide

Tuta absoluta or tomato miner moth is one of the most dangerous pests for tomatoes. This pest is found in both greenhouses and open fields. In addition to tomatoes, it can damage plants such as eggplants, peppers, potatoes, tobacco, etc. Tuta could cause great damage to plants at absolutely all stages of life. It could destroy 60-100 percent of the product.

What Is Tuta Absoluta And A Brief History

The pest expands its area by transporting tools and materials used in plant and fruit planting to other places. The pest, which evolved in South America, spread rapidly to Southern Europe and North Africa after its first detection in Spain in 2006. After that, tuta absoluta, which was found in Turkey (2009), spread to the Middle East and became one of the main threats to world tomato production. The spread to African countries began in Egypt, which covered a vast area. South and Southeast Asia are already fighting the pest.

The spread of tuta absoluta in Europe, Africa, and Asia caused extensive economic losses. The possible loss of 100 percent of the crop, rising tomato prices, bans on the sale of tomatoes and their seedlings, increasing the use of synthetic pesticides, and increasing plant protection costs are just some of the damages caused by this pest. One of the biggest examples of economic damage is that the pest causes an amount of 13 billion in annual crop loss in Africa (sub-Saharan Africa).

Biological Description

 

The life cycle of a pest consists of four stages; eggs, larvae, pups, and mature form.

Eggs: The eggs are 0.3-0.5 mm in size, cream-yellow, and cylindrical. The adult tota lays its eggs mainly on the underside of the leaves. However, this does not mean that the eggs of tomato mine remain only in the leaves. It is estimated that 73 percent of the pest's eggs are on leaves, 21 percent on shoots, 5 percent on shoots, and 1 percent on green fruit. The duration of the egg stage lasts 7 days.

 

 

 

Larvae: Young larvae hatched from eggs laid on plant leaves, shoots, or fruits and feed and grow there. Larvae, initially 0.9 mm, can grow up to 7.5 mm at the end of the stage. The caterpillar, which has just hatched from an egg, has a dark brown head and a green body. The green color turns light pink as the larvae develop. The duration of the larval stage lasts 11-15 days.

 

 

Pup:  Although the larvae pup is initially green, they turn light chestnut when they reach adulthood and are 6-8 mm long. Pups are found mainly on the growing surface (soil or substrate), leaves, and pests caused by pests. In rare cases, pups live on the flowers, fruits, and shoots of the plant. The duration of the pup stage lasts 9-11 days.

 

 

Insect (adult form): The adult form of the pest is silvery-yellow and has black dots on its wings. The main distinguishing feature is the presence of a bearded antenna. The length of the body is 6-7 mm, and the length of the wings in the open position is 10-12 mm. Although it looks like a potato moth, it is smaller than a potato moth. Besides, the appearance makes it difficult to detect the pests between fruits and plants.

 

 

Tuta absolute butterfly begins to fly in early spring. It usually appears in the morning at dusk and after sunset, and in the afternoon it hides among the leaves. The pest lays eggs 3-4 days after it starts to fly. It can lay 250-300 eggs throughout its life. Female insects are wider and larger than males. While the lifespan of females is 10-15 days, this figure is 6-7 in males.

Various factors can affect the presence of an insect pest. The temperature factor is considered to be the most important factor as it affects the development, survival, and reproduction of trust. The lifespan of Tuta at different temperatures:

14°C - 76 days

20°C - 24 days

27°C - 24 days

DAMAGES

 

Tomatoes can be attacked by this pest at all stages of development. These situations can result in the loss of the entire product if not managed properly. Tuta absolute damages the leaves, stems, flowers, hill shoots, green, and ripe fruits of the plant. The larvae open crooked paths in the mentioned parts. Initially, the larvae that feed between the leaf epidermis have necrotic spots. Then it enters the fruit and begins to feed on it, starting to damage the fruit.

The larvae of the pest create spots by mining the leaves. One and two-year-old larvae feed on leaf mesophylls and open spot-like sewers on the leaves. This causes the leaf to dry out. Various infections weaken the photosynthetic activity of the plant, which weakens the plant.

 

 

In plants, holes are formed where larvae enter and exit. Also, there are abnormal fruit forms. These holes and dried pest secretion (a fine powdery material that plant-eating insects pass as waste after digesting plant parts) are the main characteristics of moths. Finally, the crooked pathways opened by tuta absoluta  in the fruit result in pathogens entering and rotting the fruit.

 

 

Recommendations For Control

 

As the weather warms, there is an increase in the number of all pests. Farmers could face huge financial losses if they do not take precautionary measures. Holds at a temperature of 25-30 degrees, gives an absolute 10-12 generations per year. This fact is enough to understand how fast the pest spreads. Therefore, the fight against it must be very fast and effective. If 3 out of 100 plants have eggs or tablecloths, immediate countermeasures should be taken. Tuta can be fought with absolute, environmental, mechanical, biological, and chemical control methods.

Environmental Control. Plowing, adequate irrigation and fertilization, crop rotation (crop rotation), proper sunbathing, removal of symptomatic leaves, and destruction of infected plants are some of the environmental control methods used against moths. During planting, the soil should be plowed, sunbathed, and covered with plastic nylon. Plants and fruits should be inspected regularly to detect the first signs of damage. It is necessary to clean the damaged plants and destroy the plant residues and fruits after harvesting. In greenhouses, one of the management methods used to reduce the initial level of tuta absoluta population is to keep the greenhouses closed after harvest to prevent the migration of adult pests to open field crops.

In addition to the above, one of the important factors is the correct construction of the greenhouse structure. The presence of two entrances to the greenhouse and an infection room, the use of quality ground cover and insect wool to prevent the growth of weeds and other weeds is a must. Growing stems and seeds in specially protected areas are important to obtain pest-free plants.

Mechanical Control. The main method of mechanical control is the use of insect sex enzymes. Sex pheromones are chemical signals released by an organism to attract the opposite sex to the same species. Pheromone traps (1 - 4 / ha) should be placed two weeks before planting. 2-3 traps per hectare are recommended in open fields and 1-4 traps per hectare in greenhouses. The effect of the gravitational septum lasts 4 weeks. The height of the trap should be determined according to the growing season of the plant. After harvesting, the use of the trap should continue for 3 weeks. This is done to destroy the remaining male moths in the area.

 

 

If there are 3-4 moths in each trap every week, a mass trap should be carried out. For mass trapping, 20-40 pheromone traps can be set per hectare or 100 drops (one every 10 meters) of phenom gel can be poured per hectare. If the cultivator's goal is to find out from which direction the pests are spreading or coming, then two additional traps can be placed along the four edges of the field.

Biological Control. Biological control is carried out by pest predators. That is, insects that feed on tuta absoluta are released into the field, and these predators destroy the tomato moth. Tuta absoluta predators, which are commercially available and widely used, are the leaf parasites Nesidiocoris tenuis, Pseudo Apanteles, Podisus, and Macrolophus pygmaeus. In addition, Trichogramma and Bacillus thuringiensis (Bt) bacteria can be used to destroy older plants.

Microorganisms such as yeast and mold such as Metarhizium anisopliae, Beauveria bassiana, and Steinernema feltiae are used to control the eggs, larvae, and insects of the tomato miner. The limitation of biological control is that it is slow and inefficient when populations are large.

When dealing with chemicals, not only plants but also the environment must be treated. Many insecticides are used against the absolut, for example, spinosin, indoxacarb, abamectin, kiromazine, emamectin benzoate, etc. The following pesticides are used when larvae are found in plants:

* PHI is the minimum time between the date of application of the pesticide and the date of harvest.

 

 

Besides, each plant can be sprayed with a mixture of chemicals Dipel DF, Turex, and Costar. It is enough to mix 2 grams of this chemical mixture in one liter of water and sprinkle 20 ml on each plant. A minimum of 50 and a maximum of 200 grams of this chemical mixture can be added to 100 liters of water.

Although there are many pesticides against pests, many pesticides are more or less beneficial due to the mysterious nature of the larvae. Also, because of their high reproductive potential, moths mutate rapidly, leading to the development of pesticide-resistant populations. In some countries, the pest may be resistant to pesticides such as organophosphate, pyrethroids, cardamom, permethrin, and spinosad.

Therefore, it is important to conduct a local assessment of the effectiveness of pesticides by the relevant government agency or agency.