White Spider on plants: What it is, damage it causes and how to eliminate this pest

Today I come to tell you a little about a mite that we may find in some of our crops this season. I am talking about Polyphagotarsonemus latus, better known as white spider or white spider. Throughout this article I will introduce you to this bug that can damage some of our plants.

What are white spiders like?

Actually, precisely speaking, it is not a spider. We are talking about a species of mite that belongs to the Acarina order and the Tarsonemidae family. That is why it is more correct to use the term «white mite» or white spider mite.

In Latin America it is also known as chili mite, broad mite, tropical mite or yellow mite.

In the life cycle of this mite four stages are distinguished: egg, larva, pupa and adult.

The females lay their eggs in inconspicuous holes on the surface of the leaf or fruit. The eggs are firmly attached to these surfaces. The white spider prefers for its development to be located on the underside of the leaves, where it finds the optimal climatic conditions of humidity and shade, and necessary food.

Larvae have 6 legs (3 pairs) and adults 8 legs (4 pairs). In adults, there are important differences between males and females.

how are the females

The female mites are about 0.2 mm long and oval in shape. Their bodies are swollen in profile and transparent, light yellow to pale brown or green, and waxy with a faint median stripe that forks near the rear end of the body.

The female’s fourth pair of legs is reduced to a long, thin hair that extends from the tip.

how are the males

Males are small (0.11 mm) and have relatively long legs. They are similar in color and lack the median stripe found in
females.

The male’s fourth pair of legs ends in strong claws that are used to pick up the female nymph and place it at right angles to the male’s for transport and subsequent mating.

how are the eggs

Broad mite eggs are elliptical, shiny, and colorless, about 0.08 mm long, covered by 30-40 scattered white eggs on the upper surface of each egg.

The distinctive egg is a key identifying feature that should be used to confirm that plant damage is being caused by this type of mite. When the eggs hatch, larvae emerge that are about 0.05-0.1mm long and due to the tiny ridges found on their skin they appear white, but later turn transparent.

How are the larvae?

The larvae have three pairs of legs. After 2-3 days, the larva develops into a quiescent «pupa» that appears as a clear, motionless swollen body that is pointed at both ends.

how are the pupae

The «pupa» is about 0.08 mm long. Once they molt from this stage they become adults, which have four pairs of legs.

multiplication and longevity

In conditions of high temperatures, humidity and shaded environment, it multiplies very quickly. At 25º C the development of one generation of these mites (from egg to egg) lasts between four and five days.

The longevity of a female is about ten days under normal conditions. During this period she lays about 50 eggs. Unfertilized females produce only male offspring, while females are produced from fertilized eggs.

In winter, the rate of reproduction and the activity of the mites decrease. For its survival, this mite depends on living plant material, so it cannot hibernate in parts of the greenhouse structure, as spider mites do.

What are the symptoms and damage of the white spider plague?

It is a species that especially affects crops grown in greenhouses, but it can also attack crops grown outdoors or indoors. This spider or white mite attacks both ornamental and horticultural crops.

The white spider or spider mite polyphagously affects different species in our garden. Around the world, Polyphagotarsonemus latus develops preferably in humid areas and with warm temperatures.

This mite is a major pest in tropical areas throughout the year. In subtropical areas it is a major pest during
summer and fall if weather conditions are hot and humid.

And in temperate zones it is a pest during the summer months, but under the right environmental conditions of heat and humidity it can cause severe damage.

About 50 plants that it attacks (host plants) are recognized, among others are pepper, raspberry, tea plant, citrus, tobacco and potato. In the greenhouse, they mainly cause damage to peppers, aubergines, tomatoes, cucumbers and ornamental crops such as azaleas or begonia.

It also causes very significant damage to Cannabis.

Damage caused byPolyphagotarsonemus latus consists mainly of deformed leaves and stems.

Mites prefer young, developing tissues, such as young leaves and flowers. The white mite sucks the sap and produces deformities and corky scars.

In leaves, sucking occurs on the petiole part, causing the leaf to curl. The apical part of the plant is deformed, and brown discolorations appear locally. If left unchecked, it can lead to plant death.

In the case of tomato, a bronze discoloration occurs on the stem, terminal shoots, and undersides of young leaves. The leaves of the shoots dry, so that the upper parts of the plant have a burned appearance, with the stems wrinkled and discolored. The leaves are convex and have protruding nerves.

In potatoes, it forms blackish spots with an oily appearance on the underside of the young leaves, which acquires a reddish coloration, and the leaf bends irregularly at the edges.

The same thing happens in the pepper plant, where it also prevents flowering, or causes the flowers to fall.

How to control the white spider?

Preventive cultural measures

To control the plague of the white spider it is important to use cultural measures such as eliminating the remains affected by the mite.

Keeping crops in a good sanitary state helps to control all species of mites. It is recommended to keep the area around the crop free of weeds or wild plants that can act as hosts, which will reduce the sources of infestation.

In seasonal crops, such as tomatoes or peppers, once the harvest is over, the crop residues must be destroyed to prevent them from becoming a breeding ground for mites.

It is also recommended to prune the affected plants, eliminating the leaves and stems that are attacked.

Other advice to follow is to prevent dust from being deposited on the leaves. The fact that there is dust deposited on the leaves facilitates the attack by mites.

In the tomato it has been seen that it is important that the plants are well watered and nourished. It is recommended to use organic fertilizers such as mulch. Water stress (lack of water) favors the appearance of mites.

It is also not advisable to go overboard with the subscriber, because an excess of fertilizer also favors the development of this pest.

Control methods in organic farming

In organic farming, to combat this pest, it is recommended to use sulfur and neem oil. Both give good results. There are commercial products available in both cases.

If you want to make a homemade miticide, you can use hot chili peppers, garlic, and liquid dishwashing soap. There are scientific studies where it has been tested and it has been seen that this mixture gives good results to control this white mite (5).

Chili contains capsaicin, which is an irritating substance for insects and mites, causing them to flee from the area, stop feeding and die (5).

Garlic contains certain sulfur compounds that affect the nervous system of insects and mites, acting as an irritant and repellent (5).

The soap serves so that the product adheres better to the stems and leaves of the plants. And furthermore, when it comes into contact with the fatty tissues of the mites, it causes them to die from dehydration (5).

How to make a homemade acaricide

Ingredients

• 100 grams of chili
• 28 grams of dish soap
• a whole head of garlic (10 or 12 cloves)
• 1 liter of water

Preparation

Grind it all together and let it rest for 24 hours. Once it has settled, filter it and dissolve it in a container with 20 liters of water.

If you want to make less, reduce the proportions.

chemical control

If conventional agriculture is carried out, acaricidal active ingredients such as Abamectin, Tau-Fluvalinate or Cypermethrin can be used.

These active ingredients are the ones that the acaricides that are sold in stores usually have.

Biologic control

Biological control is allowed in both organic and conventional agriculture.

In this case, the white spider has natural predators, that is, there are other animals that eat them. In this case, they are insects and other mites, which can be used to combat this pest.

They are sold in sachets, which are placed on the plants. The effects are greater in closed environments such as greenhouses, although they can also be released outdoors.

The main species used are:

• Amblyseius swirskii
• Eretmocerus mundus
• Eretmocerus eremicus
• Encarsia Formosa

I leave you here the link to an article about white bugs and white bugs on earth in case it helps you too.

References

1. Brust, G., Gotoh, T. (2018). Chapter 5 – Mites: Biology, Ecology, and Management. Editor(s): Waqas Wakil, Gerald E. Brust, Thomas M. Perring,
   Sustainable Management of Arthropod Pests of Tomato. Academic Press, 111-130.
2. Fathipur, Y., Maleknia, B. (2016). Chapter 11 – Mite Predators. Publisher(s): Omkar. Ecofriendly Pest Management for Food Security. Academic Press. 329-366.
3. Abrol, D., Shankar, U. (2016). Chapter 20 – Integrated Pest Management. Editor(s): Surinder Kumar Gupta. Breeding Oilseed Crops for Sustainable Production,
   Academic Press. 523-549
4. Breda MO, Oliveira JV, Esteves Filho AB, Barbosa DR, Santos AA. Lethal and sublethal effects of pesticides in the management of Polyphagotarsonemus latus (Banks) (Acari: Tarsonemidae) on Capsicum annuum L.Pest Management Sci. 2017;73(10):2054-2062. doi:10.1002/ps.4571
5. Mena-Garcia, Ariel & Rayo-Cruz, Ilda. (2016). Botanical products for the management of the white mite (Polyphagotarsonemus latus, Banks.) (Acarina; Tarsonemidae), in chiltoma (Capsicum annuum L.), in Masaya, Nicaragua. The Calera. 15. 13. 10.5377/calera.v15i24.2933.

I hope you find this article useful and that it helps you solve the problem of the white spider.