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You can recognize an adult Tuta absoluta by its gray-brown color, elongated body and wingspan of about 10 mm. The antennae of this miner moth are long and wire-shaped. In total, the females lay about 260 eggs on young leaves. These can be recognized by their round shape and a white to yellow color. The eggs are always dark in color and will be almost black just before hatching.

As soon as the eggs hatch, the caterpillars can be recognized by their yellow color. Caterpillars, like the eggs, discolor over time to a yellow-green color. One characteristic is a dark band that later becomes visible behind the head of the caterpillar.

Once the caterpillars grow larger, they leave the leaf to pupate. In doing so, they fall off the leaf and onto the ground, where they often hide between the leaves. After pupation, the moths spread into the crop where they lay eggs again.

​​​​Tuta absoluta caterpillar​​​​

​​​​Tuta absoluta adult leafminer​​​​

Most of the damage is caused by the caterpillars of the miner moth. In particular, they damage the leaves and stems of the plant. This does not mean that they do not affect the fruit. You can recognize the damage done by Tuta absoluta by noting translucent areas, also called blister-shaped mines, on the leaf. Because the caterpillar eats everything but the outer leaf layer, you can see through the leaf. In cases of severe damage, this can lead to leaf mortality. When the fruit is affected, the risk of fungal diseases is high and causes fruit rot.

Sometimes, damage symptoms of Tuta absoluta are confused with damage symptoms of the leaf miner. The damage done by Tuta absoluta forms blistery mazes; leaf miners leave standard tunnels in the leaves.  

​​​​Damage by leafminer​​​​

To combat Tuta absoluta, you can use the biological agents Macrolophus and Trichogramma. The parasitic wasp Trichogramma aecheae needs to be introduce for prevention from the start of cultivation. This helps you to control Tuta absoluta load until the Macrolophus population is sufficiently large. 

If infestation levels become too high – seen especially towards the final stage of cultivation – then you can choose to use a chemical treatment such as Altacor. This insecticide has no negative side effects on biological control agents in the crop. Tracer and NeemAzal work well against Tuta absoluta, but they have a negative effect on the development of the Macrolophus population.

Please note: keep in mind that dripper application has little effect from the moment the tips are out of the plants. At that stage the product is no longer transported via the sap circulation to the very top of the plant.

Crop rotation time is the time to tackle Tuta absoluta. Below you will find a step-by-step plan for combating Tuta absoluta during crop rotations. 

1. Completely empty out the greenhouse
   It is important that the greenhouse is completely emptied during a crop change and that all of the leaf litter is removed from the greenhouse. The leaves may contain older caterpillars that can pass into the pupa stage, allowing them to survive the crop rotation and infest the new crops.
   
   
2. Disinfection during crop rotations
   After cleaning out the old crop, disinfect the greenhouse according to the disinfection protocol for your crop. This kills the present Tuta absoluta (and also other pests such as caterpillars and white fly) and you will start a clean new crop. 
   
   
3. Immediate start with biologic treatment
   Once the new plants are in, make sure to start applying biologic agents immediately so that the population can build up quickly. As mentioned earlier, you can choose Macrolophus and Trichogramma in this step. Release 25-40 parasitic wasps per m2 every week and a total of 2 to 3 Macrolophus. The minimum population you need in the crop to counteract Tuta absoluta is 5 – 10 Macrolophus per stem or 80-90% parasitisation with Trichogramma. Monitor the population development of the biologic control agents carefully so that you can use any additional material if necessary.
   
   
4. Monitoring of Tuta absoluta with delta traps or signaling rolls
   It is also recommended at the start of cultivation, to hang up delta capsules with pheromones to check infestation levels. Hang at least four delta capsules per hectare along the concrete path at a maximum height of 100cm and check every week to what degree there has been an increase or decrease of infestation. In addition to delta capsules, signalling rolls with a special bait substance for the Tuta absoluta moth can also be suspended near the crops. This signaling roll is a remedy against Tuta absoluta. This helps to check the effectiveness of the biological control method - and chemical method if relevant - and to adjust it if necessary. 
   
   
5. Using Isonet-T or Tutatec 
   Isonet-T is a product that spreads a large amount of female Tuta pheromone in the greenhouse, causing the male specimens to become confused and no longer able to find the females. This thus inhibits mating, which makes the population less likely to increase or even makes it decrease. This product needs to be used from the beginning of a new cultivation to limit population growth as much as possible, because at this stage infestation burden is still low. In severe infestations, Isonet-T has virtually no effect. The pheromone works for about 150 days in the autumn-winter period and 110 days in the summer. The use of Isonet-T requires 1000 dispensers per hectare.
   
   It is very important to state that Isonet-T is no stand-alone strategy or an alternative for chemical crop protection or biological control agents. However, it is a very good aid that can be used as a combat strategy against Tuta absoluta to limit its presence from the start of crop cultivation.
   
   Tutatec is a similar pheromone. Because Tutatec releases a large amount of the female Tuta pheromone, the males become confused and are unable to find the females. As a result, no mating occurs and no offspring is produced. Under normal conditions, they last for 180 days. High temperatures and strong winds can shorten duration of action. Using Tutatec requires only 300 dispensers per hectare.

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