Mealybug (Planococcus)
Mealybugs are insects in the family Pseudococcidae of Hemiptera order. There are more than 2 thousand species, since only about 300 species can be found in Europe. It is an extremely dangerous pest of plants. It has a piercing-sucking oral apparatus and feeds on plant juices. By nature, it is omnivorous — polyphagous. It is dangerous for indoor and outdoor plants, as well as indoor plants. The popular name is “hairy lice”
Mealybug is an insect of medium size, ranging from 3-10 mm, quite sufficient to detect it with the naked eye. Sexual dimorphism is clearly expressed in individuals. The female’s body is ellipsoid and covered with a white wax powder resembling flour, which explains the name of the species. Larvae differ from females in smaller sizes. Males are winged individuals and outwardly resemble midges and gnats. The males of the mealybug do not have an oral apparatus, and therefore they do not pose a direct danger to plants.
Stages of development
In the closed ground, parthenogenesis prevails as a method of reproduction. This is due to the fact that males are less common in greenhouses than females. The fecundity of the female is 200-500 eggs, depending on the species and conditions.
The insect has 5 stages of development from an egg to an adult: an egg, three stages of a nymph, among which the first is the larvae of a “vagrant”. After this stage, two moults later, the individual becomes a male, and after three — a female, followed by the stage of a false pupa and an adult.
At the vagrant stage, the insect does not have a wax coating, has a greenish colour, has 3 pairs of legs and is able to move around the plant. At this stage, the wind is one of the carriers of the worm.
It is the “vagrants” and females that cause harm to the plant. Piercing the leaf of the worm, I suck out the juices, thereby slowing down the growth process. Getting carbohydrates in the process of nutrition, they get rid of excess sugar in the body by releasing honeydew. The consequence of the formation of honeydew on the plant is the formation of fungal diseases, which leads to phytopathologies, as well as the attraction of ants that eat this molasses liquid.
There are also types of worms used by humans for industrial purposes. One of them is cochineal, from which carmine, a red food dye, is obtained. Gaspare Campari used carmine in the manufacture of Campari vermouth of the same name, and it is still used in its production.
Signs of mealybug
To detect a mealybug, it is enough just to carefully examine the plant. If it was not detected at an early stage, then it can be determined by the symptoms of the plant. Pieces similar to cotton wool or felt appear on the damaged plant (which corresponds to one of its names). Sticky pad accumulates on the surface. The shoots and leaves of the plant are deformed.
There are three main types of mealybugs
- Citrus mealybug (Pseudococcus citri)
- Obscure mealybug (Pseudococcus affinis)
- Long-tailed mealybug (Pseudococcus longispinus)
In general, the species are similar to each other, the main differences are that the females of the Long-tailed mealybug are viviparous, and the Obscure mealybug is the most common species.
How to deal with the pest?
Among the methods of combating the mealybug, according to tradition, three directions can be distinguished
- The folk way
- Chemical preparations
- Biological means of protection
Folk methods include spraying with soap solution, various herbal infusions, oil emulsions and can be quite effective when used on indoor plants in the fight against a small pest population.
Chemical preparations cope well with young individuals. But given that the worm has several stages of development, it will be necessary to repeat this process to destroy only the hatched offspring. It may have to be repeated numerous times, while means should be alternated in order to avoid resistance of the species to one drug.
Biological means imply the use of entomophages. The natural enemy of the mealybug is Cryptolaemus montrouzieri, also named Mealybug ladybird. The beetle of the Coccinellidae family feeds on eggs, larvae and imago of the mealybug.
The safest ways for the plant to combat the mealybug can be noted folk and biological. It should be noted that in the conditions of greenhouse farms, folk methods will be useless. If you love your plants and do not want to over-treat them with chemistry, then you definitely need to get to know entomophages, in particular Cryptolaemus montrouzieri.