The whitefly has probably become one of the most evolving and persistent pests for many crops. Its ability to fly when the treatments are carried out and the speed of reproduction makes it necessary to carry out many applications to eliminate the pest.
In this article we want to tell you everything you need to make an action plan and eliminate this pest from your main crops.
Although in order of importance, it mainly affects horticultural and ornamental plants, it can also be seen in production shrubs and trees.
The whitefly can appear under two scientific names, being different species but with practically the same infestation habits and damage to the plant.
It is known as the tobacco whitefly ( Bemisia tabaci ) and the greenhouse whitefly ( Trialeurodes vaporariorum ).
To differentiate one whitefly from another we will need a magnifying glass. The upper and lower part of the compound eyes are connected by a single ommatidium in Bemisia tabaci , while they are totally separated in Trialeurodes vaporariorum .
In any case, there are also other types of flies that affect crops:
- Aleurocanthus woglumi : citrus black fly, which, despite its color, is a white fly that attacks citrus.
- Aleyrodes proletella : cabbage whitefly, is a pest of several crops of the genus Brassica .
- Bemisia tabaci : whitefly , very common in horticultural and ornamental crops.
- Trialeurodes vaporariorum: known as greenhouse whitefly, very present in horticultural crops.
- Aleurothrixus floccosus: cottony whitefly.
They belong to the Aleyrodidae family and received the name of the tobacco whitefly since it was identified in this plantation in Greece, in 1889.
The biggest problems that we find with this pest is its ability to transmit viruses, its increasing resistance to different insecticidal active ingredients and its ability to fly, which allows it to quickly flee from treatment.
The whitefly is capable of laying up to 500 eggs at one time, being able to carry out a new laying every 30 days, with good temperatures, and a maximum of 50 days, with colder temperatures. It has a survival of up to 2 months, being located on the underside of the leaf, further complicating the treatments to combat it.
The nymphs of the first stage move through the leaves looking for an area where they can stick their stylet and feed on the cellular juice of the plant (sap), with a high sugar content.
Given that the whitefly is a very polyphagic pest and with a very dizzying population evolution, the individuals stick their stylet and suck the cell juice. When there are many, it produces general weakening of the plant and loss of turgor.
As an addition, the sugars disaggregated over the entire surface of the leaf attract fungi (the best known is called “bold” or “soot”) that make the situation even worse.
- General weakening of the plant.
- Sticky molasses on the leaves.
- Generalized yellowing of the leaves.
- Entry of fungi attracted by molasses.
- Possible virus transmission.
- All bulb, tuber, leaf and fruit horticultural crops.
- Fruit trees.
- Ornamental plants
- Industrial crops.
In total, around 500 species affected by all the whitefly species described have been counted.
HOW TO GET RID OF WHITEFLIES
There is currently a long list of authorized raw materials for whitefly control in a wide variety of crops. Among them, we have substances that can be used in organic farming, such as plant oils and extracts .
Currently, the following can be used, although for each product there is a list of authorized crops:
- ABAMECTINA + PYRETRIN
- Rapeseed oil
- ORANGE OIL
- PARAFFIN OIL
- ALPHA CYPERMETRIN
- BEAUVERIA BASSIANA
- LAMBDA CIHALOTRIN
- LECANICILLIUM MUSCARIUM
- PAECILOMYCES FUMOSOROSEUS
- POTASSIUM SALTS OF VEGETABLE FATTY ACIDS
The increasing development of biological control, with parasitoid insects and predators, makes it a much more sustainable means compared to the use of active materials such as those listed above.
Currently there are a large number of insects for whitefly control, and they are commonly used in greenhouse crops.
The most important are the following:
- Lacewing ( Chrysoperla carnea ): Lacewing larvae attack their prey and suck up their bodily fluids.
- Predatory beetle ( Delphastus catalinae ): adults and larvae eat a large number of whitefly eggs and larvae.
- Parasitic wasp ( Encarsia formosa ): the adult female wasp parasitizes the third and fourth larval instars of the whitefly.
- Parasitic wasp ( Eretmocerus eremicus ): the adult female wasp parasitizes the second and third larval instars of the whitefly.
- Predatory bug (Nesidiocoris tenuis ) – Adult predatory bugs and nymphs actively seek their prey.
- Predatory mite ( Amblyseius swirskii ): Adult predatory mites search for their prey or wait for it to pass by and feed on it.
To combat the whitefly in our garden or ornamental pots, we have several home remedies that can work well. The main issue is to be patient and perform treatments every 3-5 days until the population is eliminated.
These proposed treatments are also valid to eliminate the whitefly in tomato and other vegetables.
- Potassium soap at 10 ml / L of water.
- Hand soap 2 ml / L + vinegar 2 ml / L of water.
- Hand soap 2 ml / L + bleach 2 ml / L of water.
- Neem oil at 1.5 ml / L of water.
Read More: Neem Oil Uses
The soaps used have a double action against this pest. On the one hand, the direct application on the body causes the exoskeleton to soften and hinder its mobility, being trapped by the force of the water on the blade. On the other hand, the effect of the soap eliminates the molasses and sticky substances generated with the extraction of sap.
The main problem is that, as it is a contact action, it is necessary to spray directly on the underside of the leaf before they fly. Once they do, the effectiveness of the treatment decreases considerably.
Hence, it is necessary to make applications at least every 3 days to prevent the population from increasing. On the other hand, these treatments are not totally innocuous for the plant, since the abuse of soap-based products makes the leaf harder and somewhat more chlorotic.