Also known as olive moth, prays is a plague synchronized to perfection with the biological cycle of the olive.
It has three annual generations, the Phyllophagous (feeds on leaves and buds), Antophagous (prays larvae feed on the flowers of the olive tree) and Carpophagous (feed on the seed or almond of the olive).
The prays is one of the most relevant and harmful olive groves . During the Carpophagous generation, can cause significant crop damage.
Phases of development of the olive moth (Prays oleae)
Egg: the egg has a diameter of 0.5mm, is lenticular and crushed. Its color is whitish during laying, but it changes to yellow as hatching approaches.
Larvae: light color, green or brown and with a length of 8 mm at the end of its development phase.
Chrysalis: they are protected by silk and plant debris when chrysalis in the olive and use silk and debris from the soil when chrysalis in this. Depending on the generation choose one site or another.
Adult: In the adult state, the prays is a moth with only 6-7 mm in length and about 14 mm wingspan.
Generations of prays oleae
The biological cycle of the olive prays takes place in three phases or generations (Phyllophagous, Antophagous, Carpophagous).
1st Generation: Phyllophagous
During the autumn (October and November) the adults of the olive moth put their eggs on the leaf. The larvae are kept in inner leaf galleries for most of the winter. During the month of February, the larvae increase their activity and have to change leaves to feed. Finally, is fed externally of leaves and buds. Most of the chrysalis larvae forming a silk cocoon on the underside of the leaf, few being protected in the trunk of the olive tree or the ground.
Damages produced: During this generation the damage hardly affects the adult olive grove. You can see some galleries in the olive leaves, but with damage of difficult appreciation. In the olive nurseries, the damage is greater, since the prays can destroy buds necessary in the formation of the plant.
2nd Generation: Antophagous
The egg laying is done on the floral buttons of the olive tree. The larvae feed mainly from anthers and stigmas. During this phase the Prays can feed on between 20 and 30 olive flowers. When you complete your diet, forms a chrysalis and is protected with dried flowers that binds with silk.
This generation is very fast developing (just a month and a half).
Damages: difficult to quantify, if we consider that the olive tree itself discards more than 95% of its flowers, these damages should not have a great incidence. Although, in cases of olive blooms scarce, affected by the regularity of bearing. An important infestation of prays can cause damage to the crop. However, the plague itself is interested in the presence of olives to accommodate the next generation
3rd Generation: Carpophagous
The adults of the second generation of prays appear in May-June and perform the putting in the small olives, just freshly curdled. The larvae at birth pierce the olive and enter the almond before the bone hardening phase. They remain in the olive until the end of summer-beginning of autumn, when leaving pierce the peduncle and cause the olive to fall to the ground. This chrysalis generation on the ground. Prays adults lay their eggs on the olive leaves during the month of October, giving way again to the phyllophagous generation.
Damages: This generation is the one that greatest loss of production produces to the farmer. The olives already practically finished form irremediably fall to the ground next to the exit of the Prays. Although depending on the year it may increase more or less, the sensitive olive varieties can lose around 15% of the olives
In favorable years the olive moth can cause damage and high crop losses.
Prays oleae treatment
The olive prays (Prays oleae), is affected by the climatic conditions, the defense mechanisms of the olive and other insects that parasitize or prey.
Prays parasitic insects
Although they do not involve a sufficiently effective control of the pest, help limit its incidence. The larvae of Chrysoperla carnea (commonly known as Crisopa ), feed on the eggs laid by the olive moth. Also the parasitoid hymenoptera of the species Ageniaspis fuscicollis, Angitia armillatan, Chelonus rimatus and Diadegma semiclausum.
Death of Prays larvae by temperature
The winter cold affects the larvae of the Phyllophagous generation.
The high temperatures of summer, affect the Carpophagous generation, when the prays larvae are feeding on the almond of the olive. Without a doubt, the episodes of high temperatures during the summer, are the best ally of the olive grower in the fight against prays.
Olive loading regulation
During the hardening phase of the olive bone, the olive tree discards an important number of fruits. This natural fall, depending on the olive variety, can kill between 30 and 80% of Prays larvae.
Phytosanitary treatments against the Prays oleae
The treatment is complex and the level of success is usually not total. Treatments carried out with control trees show a reduction in olives falling by 30-40% after dealing with the anti-phage generation.
The authorized insecticide treatments are used. Well during the Antophagous generation, when the open flower is only 5%.
Or in the Carpophagous generation, it is profitable when there are more than 20% olives with eggs present, the application is done when half of the laying has already hatched.
Prays resistance of olive varieties
For various reasons, some olive varieties are more sensitive than others to the attack of the Prays.
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We have translated the information on our website from Spanish to English. Note that some words may have seen their meaning altered during their translation.