Plant diseases

Zeuzera pyrina

One of the pests that affect fruit and ornamental trees, especially apple trees and pears, is Zeuzera pyrina. It is a very polyphagous type of insect that feeds mainly on the bones and seeds of some fruit and forest species. It is especially xylophagous, which will mean that it was galleries in the trunks and branches to feed itself. This causes the destruction of the vascular system of the trees and its degradation.

Therefore, in this article we are going to tell you all the characteristics, cycle but logical and the control of the Zeuzera pyrina plague.

Main features

When a tree is attacked by Zeuzera pyrina we have the main symptom of the presence of galleries in branches and trunk. You can see how the tree begins to have some sawdust and excrement at the entrance of the galleries that weaken the tree. Generally, the appearance of Zeuzera pyrina leads to the appearance of scolithids in trees that are more weakened. The flight period of this species is very long and involves a large number of larval births. This causes their populations to grow rapidly. The monitoring of this plague is carried out by means of pheromones, being key to their control.

Adult individuals are shaped like a small butterfly. They are usually about 70 mm long. The thorax and forewings are white with some metallic blue spots. Its abdomen is elongated and darker in color with white stripes. The time of appearance is in spring and they are usually flying until September. A single female can lay up to 1000 eggs. The eggs are golden yellow in color and measure just 1 millimeter in size. This makes it difficult to find many times.

The doors of the galleries are made in a grouped way and in areas where the tree may have some wound or other entries from previous years. The larvae are recognized as they are yellow in color with various black spots and a black head. The smallest individuals hatch from the eggs and enter through the axils of the youngest branches. This is where the galleries begin to build upward.

Phenological cycle of Zeuzera pyrina

Once the hatchlings have hatched, they begin to make the galleries in an upward direction. This is where they feed in order to grow and develop. When the larvae are even more developed, they leave the same place and go towards the larger branches that already have a specialized trunk. The galleries, in this case, are being built in a descending direction. During the winter season they reduce their activity due to low temperatures and increase it again in spring. It is in the spring time when they make the chrysalis inside the gallery from which a new adult will emerge.

In cold climates, flights start later. This is because the larvae need more time to reach full development. With what it takes to complete the complete cycle, it usually takes about two years. However, the damage they cause is quite large in the trees it affects.

Pest damage and monitoring

Among the damages that it causes we see the drying of the branches and trunks with a subsequent breakage. By weakening the branches and trunks, it remains more vulnerable to the action of the wind or other causes. This reduction in the hardness of the trunks and branches is due to their xylophagous feeding. The larvae feed on the wood of the trunks and the branches become thinner as the larvae build the galleries. The galleries destroy the vascular system and cause the death of the oldest specimens.

The trees preferred by these insects are those that have been previously attacked as being more vulnerable. It can be quantified that the damage to young trees is more severe than those that are already older. This is because when they are young it directly affects their development and they can be totally destroyed. Many of the specimens that are young and are attacked by Zeuzera pyrina are left without the possibility of recovering.

In order to monitor the plague , traps with sex pheromones are used to establish the start of flights. This is where you can control and monitor to schedule a massive trapping of the pest. Phytosanitary reinforcement treatments should also be carried out with some authorized products. These treatments are normally directed at the newly hatched larvae just after the eggs hatch.

The treatment of this pest by using only chemicals is more complicated because the adult activity is very prolonged. It is also due to the fact that the application of the chemical treatment may fail to come into contact with the insect. It should be done at a very specific time or just after the eggs hatch and repeat it every two weeks.

Massive captures of Zeuzera pyrina

In order to reduce Zeuzera pyrina populations, delta traps are used that must be placed at the opening of the entrance to the galleries. They should also be positioned towards the prevailing winds in the region. In crops larger than 4 hectares, a trap must be placed for each hectare. At least two traps will be placed per plot. Another trap should be placed near the border of the plot to know if the pest is migrating to another point in the area.

Mass capture programs usually have very good effects to control and reduce the populations of this pest. They help keep populations below tolerance levels. Follow the monitoring instructions and increase the density of the traps to 10 traps per hectare.

I hope that with this information you can learn more about the Zeuzera pyrina plague.

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