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// // // Biological control of tomato moth

Biological control of tomato moth

Tuta absoluta

There is a limited number of chemicals effective against Tuta. The pest is able to develop resistance to existing insecticides, so sometimes treatments against tomato moth do not produce the desired result. By using predatory insects in the greenhouse, you can do without chemical treatments and control phytophagus. The application of biological control methods to Tuta has its own peculiarities, and which today we will talk about.

Biopreparations against Tuta Absoluta

Of the non-systemic biological agents used against the Tuta, one can speak of those based on Bacillus thuringiensis. The crystals of a biopreparation, when eaten by a caterpillar, cause it to rupture the intestine. According to my observations, these drugs are not sufficiently effective. Under the action of sunlight, such drugs rapidly decompose. The biopreparation acts on the surface of the leaf for 2-3 days after treatment. At the same time, other treatments, for example fungicidal, wash the crystals of the preparation from the sheet. Therefore, there are no sufficiently large periods of time so that the larvae that came out of the mines could feed on the treated leaves. It is believed that treatments once a week reduce the number of caterpillars, but the question is the cost-effectiveness of such treatments, but this is already decided by the agronomists themselves or the management of the plant.

There are preparations to fight fungus-based tomato moth. The problem with fungi is that when using them, it is necessary to keep a high humidity in the greenhouse and they must reach the pest within 4 hours to continue their development cycle. Nematodes were also tested against the Tutus Absolutes, but it was not effective. Since caterpillars are most of the time inside the leaf, neither fungi nor nematodes can affect the pest population to a sufficient degree.

Enthomophases against tomato moth

To date, two bugs have been used against tomato moths: Macrolophus caliginosus and Nesidiocoris tenuis. In due time, other predatory and parasitic species of entomophages were tried, but at the moment they stopped at these two. Each of them has its advantages and disadvantages. Both bugs feed on eggs and larvae of the pest, but they prefer eggs. There are many subtleties that should be taken into account when using biological pest control methods. When fighting the Tuta Absoluta it is important not to allow the development of its population. The use of biology against a pest with a high density of the population is not justified. It must be understood that the protection of culture takes place not by the species of entomophagus we evict, but by their 3-4 generation, which develops in the greenhouse. If you use the right amount of entomophagous at once to overcome the pest, then it will not be economically profitable. If a large population of a pest already exists in a greenhouse, it is necessary, first of all, to make chemical treatment with effective products. If drugs are used in an integrated defense system, then it is important to take into account (for example, for Avanta and Pirat) the time that must pass before the evolution of entomophagus, otherwise the bugs will not come alive.

Macroluphus caliginosus, Макролофус фото
Macroluphus caliginosus

The life cycle of predatory bugs

Predatory bugs of the Nesidiocoris and Macrolophus have a long period of build-up of their own population. Under optimal conditions, the first larvae of predatory bugs can be detected in the greenhouse only 3 weeks after eviction. However, often in greenhouses for these entomophages, far from ideal conditions develop, therefore the development of the next generation can take 5-6 weeks. Predatory bugs prefer moth eggs, so they will destroy the larvae only if there is a large population of their own. 

Norm of introduction of Macrolophus and Nesidiocoris

The rate of introduction of entomophages depends on many factors, such as: the temperature in the greenhouse, the time of year, the time of the beginning and the end of the revolution, the population density of the pest.

The non-iodicore cannot propagate at low temperatures, it requires an average temperature of about 20 ° C. Macrolophus can be introduced at low temperatures, but it should be fed. The non-iodicorus is usually introduced in a dosage of 0.5-1 individuals / m2, but this is in the general case. In a particular case, there may not be any need for the use of the Nesidiocoris, and only Macrolofus needs to be introduced or vice versa. It all depends on the conditions in each particular plant and should be taken into account.

Nesidiocoris tenuis, Незидиокорис фото
Nesidiocoris tenuis

Time of introduction of entomophages against Tuta Absoluta

The beginning of the introduction of entomophages depends on the expected time of occurrence of the pest in the greenhouse. There is always a question: to introduce early Macrolophus and to feed it or to apply at the beginning of the turn of the chemical preparations, while the population of the Nesidiocoris grows, parallel to the population of Tuta.

When using Macrolophus, it is necessary to take into account that it lays its eggs on the leaves near the streaks. Therefore, the leaves that are torn off from the plant are not thrown away, but are placed under the heating pipe in the passage between the rows - there the entomophagus will develop more rapidly. Macrolophus are introduced normally when it is still cold on biological rows, for the reason that it needs to be fed to increase the population. It is much more difficult to do Macrolophus feeding if it is spread throughout the greenhouse. Therefore, his introductions are made on biological rows. The number of biological series required for the development of the Macrolophus population is determined by each combine for itself. If you evict Macrolophus at temperatures that are used in a greenhouse when growing tomatoes, when at night the "pit" is made up to 14-16 ° C and the average temperature per day does not exceed 18-19 ° C, then the next generation of entomophagus will appear only after 5 -6 weeks Under the pipe it can be a little faster. It is still too early to introduce the non-iodicoric compound at this time; it does not come alive at low temperatures. The Nesidiocoris postpones the eggs to the top of the plant, in the axillum of the leaf, and not on the sheet itself, so you do not have to put the collected leaves under the pipe. If you evict him at the end of March - early April, when the temperatures are already high enough to develop this entomophage, then in 3 weeks it is possible to increase its sufficient population.

Articles on the fight against tomato mining moth:

Tuta absoluta - spread and harmfulness

Tomato moth control in a greenhouse

Chemical products remedies for tomato moth control

Cross-resistance of tomato moth to preparations