The spider mite was first described in the writings of Carl Linnaeus in the 18th century. These insects owe their name to females that secrete cobwebs. With its help, they protect themselves and their offspring from predators, temperature fluctuations, dust, humidity, and strong winds. Thanks to webs and wind, ticks can also travel long distances.
Species origin and description
Spider mite belongs to the phylum Arthropoda, class Arachnida, subclass ticks. These are very small (0.2-1 mm) arthropods that feed on plants. Their sexual dimorphism is well expressed: females are much larger than males, have a more rounded body; males are correspondingly smaller, and with a more elongated body.
The appearance of adults is characterized by a solid body structure. Their body, in contrast to larvae and nymphs, is segmented only conditionally, and traces of dissection are visible only in the arrangement of setae (hitta). The bristles perform a tactile function and are arranged in transverse rows. They are very diverse in their form, depending on where they are located (on the crown, on the back, on the lower back, on the sacrum, on the tail).
Video: Spider mite
There are several types of spider mites:
- common – infects almost all types of plants;
- red – feeds on all nightshade crops, as well as citrus fruits;
- Turkestan – a polyphagous parasite that infects leguminous plants, stone fruits and pome fruit trees;
- cyclamen – lives only indoors or greenhouses, you will not meet him on the street; settles on cyclamens, geraniums, chrysanthemums, gloxinia, balsam;
- gallic – prefers to settle on young leaves, in the course of its life forms peculiar warts (galls) on them;
- root (bulbous ) — lives inside flower bulbs, feeding on their tissues;
- wide – prefers to settle on citrus fruits, cacti, ficuses, saintpaulias, aucuba;
- false – lives only in greenhouses, very small (0.3 mm), does not spin a web.
hawthorn – lives on fruit trees, both stone fruits and pome fruits (plum, cherry, cherry, peach, blackthorn, apple tree, pear, hawthorn);
An interesting fact: Recently, scientists have discovered several species of mites of the superfamily Tetranychoidea and among no males were found.
Appearance and Features
The entire body of the spider mite is enclosed in a structured thin or more dense cuticle with folds, dots or tubercles. Covers of a denser cuticle can form a kind of shields. The color of the body of ticks, depending on their species, can be translucent, yellow-green, orange, bright red. Regardless of the color of the body, its internal organs are always visible through the outer covering of the insect in the form of a darker spot.
Adult ticks and nymphs have four pairs of thin legs, while larvae have only three. At the ends of the paws they have complex adaptations in the form of claws. With their help, mites cling tightly to stems and leaves. The genital organs of female ticks are located on the abdomen, while in males — at the back of the body. The mouth apparatus of these insects is of the piercing-sucking type and is well suited for quickly piercing the skin of plants and absorbing the secreted juice.
The gland responsible for the production of cobwebs is located on the head (only in females and nymphs) and is located inside short segments (pedipalps), which have grown together in the process of evolution. On the second segment of the body from the head, ticks have four simple red eyes that react exclusively to short wavelengths of the light spectrum.
Now you know what measures are there to combat the spider mite. Let's see where this insect is found.
Where does the spider mite live?
Spider mites can be found everywhere except Antarctica. After all, the boundaries of their habitat are not limited by climatic zones, but by the average annual temperature, which is plus 4.5 ° C. More than a hundred species of these insects have been described in Russia alone. When periodic outbreaks of an increase in numbers occur, ticks can migrate in search of places to feed over fairly long distances. In this they are often helped by the wind. Hungry mites crawl out to the edges of the leaves and form moving live balls that are picked up by the wind.
Spider mites are most active in warm and dry weather. During rain and even with a slight increase in humidity, they become inhibited. The thing is that the excretory system of arthropods does not provide for the removal of excess fluid that enters their body with food. Because of this, they stop eating and multiplying, due to the so-called physiological starvation.
In autumn, when daylight hours decrease to 16 hours, most fertilized female spider mites burrow into the ground and fall into a special state – diapause. At this time, all their life processes slow down. Since they do not move and do not eat anything, they consume 5 times less oxygen. At this time, the mite's body becomes resistant to sudden changes in temperature, excess moisture, and insecticides.
What does the spider mite eat?
The menu of spider mites consists of the cell sap of various plants. Most often they attack young plants, although in case of their acute shortage (especially at the end of summer or early autumn), they do not disdain older ones. At the tips of the paws, ticks have special pointed claws that make many holes on the back of the leaves. Cell sap flows out of these holes, which insects suck up with their mouthparts.
The salivary glands of ticks contain a special aggressive enzyme that destroys chloroplasts (green cells) of plants and partially digests their food. Most often, these arthropods feed on the juice of various herbs and deciduous trees, but occasionally there are lovers of coniferous flora.
Some types of spider mites are polyphages, that is, they can feed on many types of plants, others are oligophages (a limited number of plant species, for example, within the same family – nightshade, legumes, melons, geraniums, etc.); still others are monophagous (they live on only one type of plant).
The following are especially susceptible to attacks by spider mites:
- melon crops;
- fruit trees;
- ornamental herbaceous plants in greenhouses, on windowsills, in open ground.
Character and Lifestyle Features
Despite their almost microscopic size, spider mites are truly dangerous pests of both wild and cultivated plants. In a short time, they can harm not only home collections of plants, but also large nurseries that are engaged in the industrial cultivation of flowers. Young ticks have three pairs of legs. After two molts, they acquire another pair and become adults – adults. Females live an average of 5 to 40 days.
The most comfortable temperature for life and development of spider mites is from plus 25-30°C. At this time, their full development (from egg to adult) takes 7-8 days. When the temperature drops, the development process takes 28-32 days. The spider mite usually lives on the underside of the leaves. There he makes many small holes and sucks out the juice.
Leaves damaged in this way become dehydrated, wither and dry out. Even a slight infection with these pests can significantly affect the development of the plant. After all, with a prolonged attack of ticks, the ability to photosynthesis in a plant decreases significantly. And without this important process, plants weaken and may even die.
When daylight hours decrease to 14 hours, only wintering female pests can develop. Due to diapause, they can easily endure a temperature drop to minus 28°C.
In spring, when the air temperature rises to plus 12-14°C, female mites wake up, crawl out of the soil and settle on the reverse side of plant leaves, abundantly braiding them cobwebs.
Here they also lay their eggs, because in the winter they left already fertilized. The very first — spring offspring of spider mites develop on swan, nettle, plantain. By mid-July, arthropods gradually move to cultivated plants.
Social structure and reproduction
Spider mites breed only under favorable conditions – the air temperature is above plus 25 ° C and low humidity (not more than 40%). With a decrease in temperature and an increase in humidity, mites tend (although not always) to fall into a short-term diapause or become very lethargic and inhibited. In the tropics and greenhouses, their reproduction can take place continuously throughout the year.
An interesting fact: In 12 months, spider mites are able to breed up to 20 times.
Fertilization in spider mites occurs without laying capsules with seminal fluid, but by penetrating the genital organ of the male into a special hole on the abdomen of the female. Occasionally, fertilization occurs without the participation of male germ cells (virgin).
A fertilized female tick lays her eggs in small groups (1-2-3 pieces), braiding them with cobwebs. The eggs of the mite are round in shape, somewhat flattened from below and above, with a smooth, shiny surface of a light beige color. At the top of each egg there is a thin tail. The female can lay her eggs in a variety of places: on the roots of plants, under fallen leaves, in the ground, on the inside of young leaves, and even on the walls of flower pots.
Interesting fact: Under adverse under conditions, eggs can freeze for 3-5 years, and then resume their development again.
After 3 days, the eggs hatch into larvae, which in a day become nymphs. It takes 3-4 days for nymphs to molt and 1-2 stages of development. After a week, the nymphs finally molt and turn into fully adult and sexually mature individuals.
An interesting fact: It has been proven that in most species, female ticks hatch from fertilized eggs, and males from unfertilized eggs.
The duration of the life cycle of spider mites directly depends on the ambient temperature. For example, at plus 20°C, all their stages of development pass in 20 days, at plus 25°C – in 10-14 days, at 30-33°C – in just 5-8 days. At the same time, the life span of spider mites can last 16-30 days.
When the daytime temperature drops below plus 18°C, spider mites look for a secluded place and hibernate (diapause).
Natural enemies of spider mites
Since the spider mite itself is a malicious pest, talking about its natural enemies may seem somewhat inappropriate. However, this parasite also has many natural enemies. In nature, the most important enemy of the spider mite is the predatory mite Phytoseiulus persimilis, belonging to a special family of parasitic mites Phytoseiidae.
Its homeland is the tropics, from where it was brought to more northern countries quite a long time ago (in 1963). It is very actively used for pest control in large industrial greenhouses and greenhouses. The predatory mite parasitizes the body of the spider mite, actually eating it alive.
Two more types of mites also feed on spider mites — Amblyseius and Metaseiulus occidentalis. In the northern latitudes, the well-known ladybug beetles are not averse to hunting for pests. Not so long ago, only 10-15 years ago, special soil bacteria Bacillus thuringiensis were discovered that can kill spider mites.
Under natural conditions, they usually do not reach the desired concentration that can affect mites, however, in the laboratory — very much. Based on the spores of this bacterium, today special biological products are produced that help get rid of spider mites, both on a small and larger scale.
Population and species status
The distribution area of spider mites covers a very vast territory: all continents except Antarctica. In total, this insect lives in nature wherever the temperature does not fall below plus 4.5 ° C. Moreover, in protected ground (greenhouses, greenhouses, on window sills), ticks can be found in the Arctic, Alaska and even in the Far North.
The spider mite is an arthropod arachnid of very small, almost microscopic size. It is a dangerous pest, because in its «menu» there are more than 200 species of cultivated plants. From fruit and berry crops, it can affect almost all stone and pome species, as well as legumes and melons. The tick is especially partial to cotton and at the peak of reproduction (in heat and drought) it can destroy entire fields of hundreds of hectares.
Reproduction in ticks is predominantly bisexual, occasionally parthenogenetic. Only fertilized females go to wintering, which fall into diapause, all the rest of the adults, including males, die. Development in arthropods is incomplete and, under favorable conditions, takes a very short period – up to 8 days. In different climatic zones, the spider mite is able to give from eight to twenty generations in one year.
One of the most dangerous pests of cultivated plants is the spider mite. They are very small, multiply rapidly and can cause considerable damage to plants in a short time. Among all pests in crop production, mites are the most dangerous and difficult to control, so natural methods of control have practically no effect on them, and fungicides often have to be used.