The turnip white or turnip (Pieris rapae) is a common insect that causes great nuisance to gardeners, especially in America. Often this butterfly is not seen as a threat, allowing it to reproduce freely. But when the reptile population increases, the fight against it becomes noticeably more difficult, and the damage caused suddenly becomes serious and noticeable.
Turnip white (turnip): butterfly, appearance
Repnitsa: appearance and features
This pest is often confused with other members of its family, since they all have similar body structure and coloring. The butterfly also has a high prevalence, which is justified by its unpretentiousness to living conditions.
External characteristics
The body length of adult individuals is 2-2.6 cm. The length of the front wing is 2.2-3 cm. The wingspan is 4-5 cm. It has a developed proboscis and short club-shaped antennae. The wings are wide, with dark pollination at the base. Their color is predominantly white, but the shade may vary slightly depending on the age of the individual and living conditions. The front wings have a black or dark gray border. The body most often has a gray, less often black or slightly brownish tint.
Sexual dimorphism is manifested in the size and number of dark spots on the wings. Females are larger and have two dark gray or black spots, often with ragged edges. Males have a smaller spot with clear boundaries.
How does turnip differ from cabbage and rutabaga?
Repnitsa has similar external characteristics to other members of the family. It is often confused with cabbage and rutabaga. The first has a list of differences:
- more saturated color;
- a large area of black border on the front wings.
- slightly larger than the turnip white (approximately 0.3 cm);
Rutabaga often has a black pattern running along the vein line of the wings. It is also distinguished by a green coating, which can be seen on the underside of the hind wings.
Population and species status
Photo: Mourning Butterfly
Before the outbreak of World War II, the number of moths was quite high. Lepidoptera were distributed throughout Europe. For reasons still unknown, the population declined significantly after the war. At the moment the level is low but relatively stable.
At the end of the 1960s, there was a massive surge in the number of insects in the Moscow region, in 1970 - in Novosibirsk, in 1985 - in the Tula region, and more recently - in 2008 in the Chelyabinsk region. Over its history, the species has experienced several fluctuations in numbers, either decreasing or increasing.
The population decline trend mainly depends on the destruction of the mourning bird's natural habitats. In the 1990s, moths were found in more than 20 natural and artificially created territories of the Moscow region. During this period, individuals could be found in residential areas, the Kuzminsky forest, and on the Krylatsky hills.
In the 1990s, the number recovered and even increased slightly, but it was rare to see it within the Moscow Ring Road. Since the early 2000s, only five habitats have remained. If before that there were many individuals in Tsaritsyn, then after 2005, no matter how much the territory was surveyed, no population could be detected.
Insects are important elements in the food chain. Larvae and pupae play an important role in bird nutrition. Thanks to adult individuals, rare species of small mammals, birds, amphibians and reptiles survive. They play an important role in flower pollination.
In built-up areas, mourners lack food and wintering places. Due to the drying out of trees along the roads, lack of water and moist soil, reduction of green spaces, and regular destruction of old hollow trees, a decrease in the number of insects is observed.
Habitat of the turnip white
The original habitat is Europe. But now the pest is extremely common in many countries of the world. The reason for this expansion of the habitat was trade. At the moment, the species is most often found in the following places:
- Western Europe;
- North America;
- Central Asia (except the extreme south);
- North Africa;
- Australia;
- Caucasus and Transcaucasia;
- Kazakhstan;
- Ukraine;
- Belarus;
- Moldova.
In Russia, the reptile lives all the way to the Far East, the south of Western and Eastern Siberia. The pest is resistant to weather changes and tolerates wintering well. The insect is believed to cause the most significant damage in North America. In Europe, despite favorable conditions, the turnip whiteweed destroys noticeably fewer plants.
Features of character and lifestyle
Photo: Daytime mourning butterfly
With the onset of spring, butterflies emerge from secluded places, bask in the sun and look for food for themselves. In Russia they can be found only from July-August to October. When the nights become cool, insects begin to look for places to winter - cracks in stumps and trunks to protect themselves from the cold, basements of residential buildings.
The dark color of the wings helps insects easily hide in the grass. At the beginning of spring, only females can be found. They lay eggs and then die immediately. These individuals are capable of covering vast distances. Migration usually occurs in the fall in search of refuge.
Interesting fact: You can determine the cardinal directions by the mourning table. When a moth sits down to rest, it folds its wings and turns its back to the sun. In the morning the wings are turned to the east, at noon to the south, and in the evening they point to the west.
Mourning women appear in one generation. The subspecies have not been studied, but there are a lot of them. The brightness of their color depends on the time of year and habitat. When emerging from the cocoon in the spring, the insect will have a duller color. Immediately after birth they migrate. In hot weather, flights take several days. They depend on weather conditions.
Moths can live until June of next year, and in the mountains until August. In spring, butterflies live in places far from where they were born. In winter, many cannot withstand the frost and die. From the beginning of summer, the number of males predominates, then the inequality is eliminated.
Repnitsa: lifestyle
From 2 to 3 generations develop per year. In the northern regions, only 1 generation can develop, which can be seen from the end of June to the end of July. In the most comfortable conditions, the number of generations can reach 5. In this case, butterflies can be seen from April to October. The last generation is always incomplete. Different generations may have minor external differences.
Reproduction and life cycle
The insect quickly finds a partner and mates with him. The initiator can be either a male or a female. After fertilization, the female searches for the most suitable place to lay eggs. The average fecundity is 150 eggs, but it has been observed that the number can reach 500.
Eggs are laid singly. The female glues them to the leaves of plants, most often on the underside. Egg development takes 5-11 days and is highly dependent on temperature and humidity. Although the eggs are laid separately, they can be found in close proximity to each other. Thus, there can be a huge number of eggs on one leaf.
The eggs are pear-shaped with pronounced ribs. The color is always yellow. Color saturation changes over time. As the larva develops, the egg becomes more transparent and may slightly change shape.
Newborn larvae are evenly distributed over the leaves of the infected plant. Activity occurs mainly at night. The caterpillars are located on the top of the leaf. The insect at this stage is quite slow. Therefore, it relies on its color to help it blend into its surroundings. If the larva has been spotted, it raises the front of its body, exposing its underside to its attacker. There is a bright pattern typical of poisonous animals. In extreme cases, the caterpillar may squirt a repellent-type caustic liquid. Development takes from 20 to 30 days. There are 5 instars of the larval stage.
What does the turnip white caterpillar (larva) look like?
Turnip white (turnip): caterpillar
The body length of the larva varies between 3-4 cm, which depends on the number of molts. At the larval stage, the insect has 3 pairs of thoracic and 5 pairs of abdominal limbs. The turnip larva has the following distinctive features:
- main color – bright green;
- on the back there is an inconspicuous longitudinal yellow stripe, which may be interrupted and have uneven edges;
- there are short bright yellow stripes on both sides;
- the whole body is covered with long light hairs.
The segmentation of the larva is not very pronounced. Small black dots can be seen all over the body.
The pupa is attached to plant stems, bark or wood, less often on other solid objects. At this stage, some generations of reptiles overwinter. The development of a non-overwintering pupa takes 8-15 days.
The pupa is yellow-green in color. There may be a gray tint, black dots and longitudinal yellow stripes. There are large lateral and dorsal spines. The brightness of the color directly depends on the material to which the pupa is attached.
Diet
The basis of nutrition for the larvae are plants belonging to the cruciferous (cabbage) family. It should be taken into account that newborn larvae hide on the underside of the leaves. Most often, caterpillars damage young leaves: first they skeletonize them, and then gnaw through holes and gnaw off the edges.
The pest's favorite food is cabbage and cauliflower. The insect also poses a threat to the following plants:
- rapeseed;
- mustard;
- turnip;
- mignonette;
- radish;
- radishes;
- rutabaga;
- turnips;
- horseradish;
- core;
- rapeseed;
- bugs;
- shepherd's purse;
- watercress.
It is important to know that caterpillars can damage not only leaves, but also other parts of the plant. An insect, in the absence of other food, can feed on plants that do not belong to the cruciferous family, but are included in the order Brassicaceae. For example, the larvae's diet includes mignonette and capers.
Life image
Reptiles are diurnal.
Prieš 1 metus
Of all Lepidoptera, they are the most resistant to cold.
This is confirmed by the fact that even in October they are energetic and can be seen everywhere, and already in March they again bring joy to people with their flights, announcing that the frost has ended and the warmth has come again. Reproduction of reptiles is bisexual. If the male flutters, making unusual movements, this means that mating time has come, and it is time to attract a partner to reproduce offspring. After mating comes the period to lay eggs.
Females can debug them one at a time. They stay on the leaf by gluing to the leaves or stems. And although all the eggs are located one at a time from one another, there can very often be up to 200 of them, but it happens that the number reaches 500.
These small eggs can be recognized by their shade of the palest yellow, fawn or shade of white. They are oval in shape, and more oblong at the edges. The development period is no more than a few days.
In May days, less often in June, caterpillars appear. Their body has no hairs, their body has a smooth structure. This stage lasts about a month. After this time, the caterpillar’s diet is not excessive: they eat only the leafy part of the plants, the most appetizing.
The development of the caterpillar takes about a month, and after this time it changes through five instars. Currently lives on the outer part of the leaves. If at this stage he senses any danger, he raises the front part of his body, but at the same time retracts his head. The threatening pose is complemented by a change in the color of the torso. A bright red color appears, plus the caterpillar can release a caustic liquid.
Large individuals feed by collecting nectar from a wide variety of plants.
Why are turnip white caterpillars dangerous? Why is the reptile considered a pest of agricultural crops?
Turnip white caterpillars not only damage plants, but also contaminate food with their excrement, causing the process of rotting. The insect at this stage of development gnaws off the edges of the leaves and skeletonizes them. Caterpillars often get inside the cabbage head and contaminate it with excrement, which leads to rotting, which is why the cabbage heads cannot be stored for long and quickly become unsuitable for food.
Thus, reptiles impede the growth and development of plants, weaken them, promoting the appearance of diseases and fungi. The pest has an extremely negative effect on the reproduction of cruciferous plants, both wild and cultivated.
The larvae, despite the presence of a caustic liquid, do not pose a threat to humans and animals. Their jaws are too weak to bite through the skin of mammals. In addition, they are not poisonous. But it should be noted that their excrement and protective fluid can cause an allergic reaction.
Damage to cultivated plants
Reptile caterpillars can cause great harm to cultivated plants if they have settled in the garden. They are especially attracted to cabbage - both cauliflower and white cabbage, as well as radishes and turnips, rutabaga and horseradish. But wild herbs also become the objects of their countless feasts. These are mignonette, shepherd's purse and other plants.
First, the caterpillars eat the very edges of the leaves, leaving an adhesive sclera that extends to every centimeter of the surface. Then it gets to the head of cabbage, gnawing a hole in it and leaving secretions. Thanks to this, the vegetable begins to rot. Therefore, people come up with different ways to deal with such a pest.
Turnip white (turnip): how to get rid of it?
Turnip white is sensitive to insecticides and many folk methods. However, pest control can become noticeably more complicated if there are many wild plants near the garden plot that are part of the insect’s diet.
If the number of caterpillars is insignificant, then it is permissible to use the mechanical method, that is, catching the larvae manually. If necessary, plants can be covered with mosquito netting to prevent egg laying.
Chemicals against turnips
It is important to consider that pupae and adults are practically insensitive to insecticides. Therefore, it is necessary to focus on eliminating the caterpillars. Newborn larvae are most sensitive to such drugs. Several remedies are considered the most effective against turnips, which we will discuss later.
Aktellik
Organophosphorus insecticide has an intestinal-contact mode of action. The active ingredient is pirimiphos-methyl. Actellik is considered an extremely popular and effective acaricide. It is distinguished by its high speed and duration of action, and a wide spectrum of action.
However, it has a hazard class 1 for beneficial insects, as well as a hazard class 2 for humans. Therefore, if safety rules are not followed, it can pose a serious threat to bees, children, people prone to allergies and pets. Has an unpleasant pungent odor.
Sumi alpha
The active substance is esfenvalirate. The main advantage is cost-effectiveness. At the same time, the product is highly effective. The insecticide is resistant to changes in weather conditions. The product has a hazard class 1 for bees and a hazard class 3 for mammals (moderately dangerous).
Baciturin
It has slightly less efficiency when compared with previous options. However, it is completely safe for plants, and also has a hazard class 4 for people and animals (low-hazard). If the established processing rules are followed, it does not harm beneficial insects. The drug is not addictive.
Lepidocide
The biological insecticide is not addictive and also has a high speed of action. Completely safe for fruit plants. Has a hazard class 4 for humans. Also, this biological product has a hazard class 3 for bees. Does not accumulate in plants and fruits, can be used at any phase of plant development. Not addictive.
The main disadvantage is the exclusively intestinal type of exposure. In addition, the product has a strong pungent odor and cannot boast of a long-term preventive effect.
Inta-vir
The active ingredient is cypermethrin. Hazard class for humans – 3. The pesticide has hazard class 2 for bees. It is highly effective and resistant to sunlight. It is odorless and does not pose a threat to plants.
Inta-vir is easily washed off by rain and can also have a negative effect on the composition of the soil. It quickly becomes addictive to pests.
Kinmiks
The active substance is beta-cypermethrin. Hazard class for mammals – 3. The product poses a threat to bees and other beneficial insects (hazard class 1). It has a long shelf life and low cost.
However, the insecticide is easily washed off with water, is addictive, and can also have a negative effect on weakened plants. It should be taken into account that, despite its high efficiency, the chemical preparation has a short duration of protective effect - no more than 12 days.
Bitoxibacillin
Because it is a biological agent, it does not accumulate in fruits and does not harm the plant. Can be used at any phase of plant development, harvesting can be done 5 days after treatment. The drug is aimed at combating young larvae, so it does not have a significant effect on adult individuals, but it prevents their reproduction. The insecticide has a short shelf life and is not effective at temperatures below +14 °C. It is not addictive, so the number of treatments is not limited.
Karate Zeon
The active ingredient is lambda-cyhalothrin. The product has a huge spectrum of action and does not accumulate in fruits, soil or plants themselves. Effective against pests at all stages of the life cycle. In addition, it is resistant to light and moisture. The insecticide is economical in consumption.
Hazard class for humans is 3. But the drug poses a serious threat to all beneficial insects, and has no effect on earthworms. The insecticide also causes significant damage to any inhabitants of water bodies.
It is important to understand that treating with insecticides in most cases requires special equipment, such as a respirator, goggles and gloves. Excessive or incorrect use of drugs will not only lead to the death of plants, but will also cause serious harm to the ecosystem.
Traditional methods against turnips
Folk methods are also effective against turnip whites. The main advantage of traditional methods of struggle is low financial costs. It should be borne in mind that most folk remedies produce a repellent effect, which is why such methods are useless against a large population of insects. The most popular methods of combating turnip whiteweed are:
Tobacco dust
There are 2 options for use. The first method is extremely simple and involves sprinkling the infected plants with tobacco dust. However, this method quickly loses its effectiveness due to sunlight and rain.
Another option is to make a decoction. In this case, you need to mix tobacco with water in a ratio of 1:10. To increase efficiency, you should add onion peels. The resulting liquid should be simmered over low heat for 30 minutes, after which the broth should be infused for a day. The resulting mixture should be filtered and diluted with water (the ratio of decoction to water is 1:3) so that it is completely safe for plants.
Wood ash
Although effective, it may negatively affect the growth of plants such as lingonberries, cranberries, azaleas or blueberries. At the same time, such an infusion will have an extremely positive effect on the development of cabbage.
To get rid of the pest and not harm the plantings, you should take no more than 30 g of ash per 1 liter of water. It is also permissible to add 50 g of soap. The mixture should be infused for 2 days. Be sure to filter the infusion before use.
Delphinium
For 100 g of dry leaves you need to take about 1 liter of water. It is unacceptable to use fresh leaves, because the sap of the plant is poisonous and can have a negative effect on plantings. The infusion must be left for 2 days. After this, add up to 50 g of soap to it and filter.
White mustard
For 1 liter of water, 10 g of mustard is required. It is recommended to use powder. The resulting liquid must be infused for 2 days. Next, add a little water and filter.
Vinegar essence (70%)
For 1 liter of water you need to add no more than 10 ml of vinegar essence and 20 g of mustard powder. It is acceptable to use apple or table cider vinegar. You can also add 30 g of laundry or tar soap to the product. The solution does not need to be boiled or infused. It is important to monitor the condition of the plants, as this method can lead to burns.
Fresh wormwood leaves are often placed next to infected plants. Its smell repels not only reptiles, but also many other pests. Also, sometimes cotton wool or fabric is soaked in kerosene, and then placed next to a cluster of insects.
Its natural enemies – riders – will also help in the fight against the turnip whitefish. To attract them, you need to plant Iberis and marigolds in the rows and between cruciferous plants.
Prevention
The main element of preventive measures against any pests is deep digging of the soil in late autumn. This allows you to get rid of many overwintering pupae. In spring it is recommended to carry out harrowing. You should also follow a few more rules of prevention:
- every spring you need to change the planting location;
- dry leaves and shoots should be destroyed immediately after harvesting;
- constantly get rid of weeds and wild cruciferous plants in and around the site;
- Parsley, lemon balm, thyme and peppermint should be planted between the rows; they repel insects with their scent.
The turnip moth most often settles on young plants. Therefore, such plantings require special attention and care. You can also plant tomato bushes next to cabbage plants: their smell also repels the pest.
