FARMS: The beetle

in #farms6 years ago

About 3/4 of the beetle species are phytophagous, both larvae and adult stages, that live in or from vegetables, wood, mushrooms, and a variety of stored products, including cereals, tobacco and dried fruits. Because many of these plants are important for agriculture, forestry and houses, beetles can be considered a pest.


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Some of these species cause significant damage, such as the cotton boll weevil (picudo), which feeds on buds and cotton flowers.
Many other species have also done great damage to plant populations, such as the bark beetle and the elm leaf beetle. The bark beetle and the elm leaf, among other species, are known to nest in elm trees. Bark beetles, in particular, carry the Dutch elm disease. The spread of Dutch elm disease by the beetle has led to the devastation of elms in many parts of the northern hemisphere, especially in Europe and North America.

There are situations in which a species has developed immunity to pesticides, as in the case of the Colorado potato beetle, Leptinotarsa ​​decemlineata, which is a notorious pest of potato plants. The crops are destroyed and the beetle can only be treated through the use of expensive pesticides, many of which have begun to develop resistance. In addition to potatoes, guests can be a number of plants of the potato family (Solanaceae), such as solanaceous, tomato, eggplant and pepper. The Colorado potato beetle has developed resistance to all major classes of insecticides, although not all populations are resistant to all chemicals.

Some beetles can be harmful to horticulture, agriculture and public green spaces.

An important species in horticulture is the vine weevil, Otiorhynchus sulcatus, and on the lawns, the white worm (Phyllopertha horticol), which can cause a lot of damage. Asparagus growers fight against the asparagus beetle (Crioceris asparagi).

Capnodis tenebrionis is one of the most important pests of fruit crops of bone (eg cherry, apricot and pear). Beetles have been a serious threat for the Mediterranean area and the Middle East for decades.

biology

The beetles perform a complete metamorphosis through the states of egg, larva, nymph and adult. The larvae have mordant jaws and usually eat the same as adult beetles. Some larvae do not have legs, resembling caterpillars.

Symptoms and damages

The adult vine weevil is active only at night. They take semicircular snacks from the edge of the leaves. These cuts reduce the ornamental value of the plant. The larva sometimes damages shrubs and young trees feeding on the yolks and soft bark.
The larva causes most of the damage. The smaller larvae feed mainly on the root hairs, but the larger larvae of the roots and the base of the stem. This prevents growth and eventually causes the plant to turn yellow and whiter.
The pink beetle larva Phyllopertha horticola causes severe damage to the grass by feeding on the root hairs of the grass. This reduces the absorption of water and nutrients. In addition animals like birds, foxes and hedgehogs looking for larvae, damage the lawn seriously.
The larvae of the asparagus beetle feed on the aerial parts of the asparagus plant. The larva descends from the plant to hide in the ground and become a nymph. Adults only eat the leaves of the asparagus.

Adults of Capnodis tenebrionis feed on young stems and branches, causing problems in the nurseries of trees and young trees. However, the greatest damage is caused by the larvae when they penetrate the roots of the trees and feed on the bark causing the death of young trees. Adult trees are severely weakened or may even die within one or two years.


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Colorado beetle (Leptinotarsa ​​decemlineata)
Description

They have between 11 and 10 black bands that go through the body that is yellow.

It is a clear example of how man is the cause of the problem of pests.

Its natural distribution area is restricted: the mountains of Colorado. It was a relatively rare species that fed on wild Solanaceae (Solanium rostratum) and had never been in contact with the potato. This beetle was adapted to the potato (Solanum tuberosum) that was nutritiously more efficient generating a great expansion of its species.

The damage caused is great because it destroys almost the entire plant. As the potato is cosmopolitan, this beetle has spread throughout the world. Since the United States had caused serious damage, measures were taken in Europe. The first foci appeared in 1920 in France and in 1930 in Spain, expanding the following year throughout the peninsula. With the appearance of both civil and world wars there was a logical unconcern for pests


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Currently it is all over the world, the only free country is Great Britain. You can be an island controlled all exits and entrances. Some focus may occur but it never constitutes a plague. It is considered to expand 60 kilometers per year and may affect eggplant and tomato.

Damage

  • Both larvae and adults feed on the leaves.
  • It has a high capacity to eat, 200 larvae can eat a kilo of leaves and a female with their offspring can affect a year to half a hectare.
  • It feeds on the leaf epidermis and leaves only the central and petioles so the plant dries.
  • Since it is an exotic species, it does not have natural enemies, and since it was rare in its zone of origin, it did not possess specific predators either.

Means of pest control of potato beetle
Natural enemies are not specific, so their action is not very specific.

As it has always been treated with chemical products, there are strains resistant to most insecticides due to the large amount of insecticides used and their high reproduction rate. High doses can be used but they are phytotoxic (toxic to the plant) and also toxic to humans.

For this it is about using other means of control:

Cultural means: the potato is sown early so that it can be harvested beforehand, this can be done in certain varieties.
Use transgenic potatoes resistant to beetles that are not currently commercialized.
Use insecticides of biological origin such as Bacillus turiciensis that has a specific strain of coleoptera effective against the potato beetle. The insecticide used is called Novodor. It is applied before the third and fourth larval stages develop. It is an insecticide that the animal tends to swallow, so the insecticide is applied mainly in the lower part. It does not kill the plague instantaneously, it can last from 2 to 4 days but without feeding.


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