Euzophera pinguis (Haworth) is a Lepidoptera that causes the young olive trees to die and reduces the production of mature crops. It is considered the third most serious pest for Spanish olive groves.
MORPHOLOGY AND BIOLOGY
In its larval stage, the insect is found inside the trunk of the olive tree at a depth of 4 to 5 mm, making it almost impossible to reach with chemical treatments. It is only vulnerable when its biological cycle is known and the moment of egg laying, which takes place outside the gallery, is determined.
The eggs are oval, flat and have a finely reticulated structure. They are a pinkish-white colour, turning a darker colour as the incubation process advances. The female lays the eggs individually or in small groups of 4 to 5 eggs in the crossings and fissures of the branches.
The larva reaches 25 mm in length and is a light green colour. Its head and thorax are black. The pupa, which is a brown colour, grows inside a fairly dense silk structure of about 10 to 15 mm long.
The adult is a cream-coloured moth with a wingspan of 20 to 25 mm. The forewings have two pale stripes in a zigzag pattern. The hindwings are essentially white with a thin brown border.
DETECTION AND MONITORING
1 to 2 traps per hectare should be placed at the same height as the crops or on a specific support. The traps should be placed in spring.
Primarily, the males of this species are captured in order to reduce mating, meaning that the unfertilised females will lay unviable eggs. In this way, the pest population is reduced.
For mass trapping, the amount of traps per surface area must be increased, depending on the location and homogeneity of the plots. One trap controls a surface area of 1.000 m2.
This means a density of 10 traps per hectare.
PERIOD OF USE
To obtain good control of Euzophera pinguis it is advisable to combine two methods: detection and monitoring; and mass trapping.
In spring, 1 trap per hectare can be placed for the detection of the pest and the observation of its population levels. With tolerance thresholds established in each area, the moment to adopt control measures, in this case mass trapping, can later be defined.
The tolerance threshold for Euzophera pinguis is very low and varies depending on the area. In general, it is approximately 3 captures per trap and per week. For mass trapping, traps should be placed throughout the plots.
SYMPTOMS AND DAMAGES
Presence of fissures and bulges on the bark as a result of galleries that have been perforated by the larva, which block the bleeding of the sap.
The existence of accumulations of excrement and silk threads that are external and a brown colour. They are removed by the larva and accumulated at the entry of the gallery. These prevent both the sunlight and natural enemies of Euzophera pinguis larvae from entering. To recognise them, just raise the bark on the areas with presence of excrements and sawdust. Continue excavating along the gallery until the larva or pupa is found.
Discolouration of the leaves in branches attacked by the insect. This symptom is especially severe at the tip of the highest branches. However, as the attack develops, this discolouration appears on the rest of the tree.
Strong defoliation of the branches that are already infested, which usually means that the branch has dried up. In the case of young olive trees, this can be mortal. The mortality rate is very high in young olive trees between 4 and 10 years old.
Euzophera pinguis attacks mainly healthy trees. The first visible signs in a tree that has been attacked are not very obvious, so they are not noticeable at first.
In general, the only sign that the farmer notices before the first dry branches appear, is the larvae that are in the cuts of the branches, which are exposed after pruning or in the fissures caused by removing the suckers.
With the exception of the winter months, this pest can be found at any time throughout the year and in all and every one of its developmental stages: larva, butterfly, eggs and adults. This makes it very difficult to establish a plan of action against this moth. In addition, it grows depending on the temperature. That is why the olive areas of Cordoba and Malaga are infested with this Lepidoptera all year round. This is due to the extinction of its natural enemies by uncontrolled and mass use of pesticides.
If specialists or farmers use the traps and pheromones correctly, as previously described, especially during the early stages when adults of the first generation appear, then this monitoring system is very effective. A very low level of damage, mainly on organic land, has been demonstrated. A level of control of more than 95% is very common, especially in large areas of crops.
A limiting factor of this system could be when there are small plots distributed all around and the neighbours have a high level of infestation of this pest.
Despite some important basic rules for an effective monitoring of Euzophera pinguis, every farmer or specialist has to find their own system of control to achieve it. They can experiment with this system, even establishing their own tolerance thresholds.
FACTORS THAT INFLUENCE THE NUMBER OF TRAPS NEEDED
The pest population, the bordering crops, level of control required, etc….
One important factor is the size of the crops. In small and irregular crops, a greater number of traps are required than in larger and more uniform plots.
Another important factor is the distance between plots that have the same pest. In cases like this, the borders of the plots must be reinforced, so it could be necessary to place up to 20 traps per hectare or even more for mass trapping.
Corrugated cardboard box of 3.000 units (150 packs of 20 units)
Box size: 0.60×0.40×0.35 m (length x width x height)
Box weight: 9.8 kg.
No. of boxes per pallet: 20.
Pallet size: 1.20×0.80×1.90 m (length x width x height).
Pallet weight: 203 kg.