The olive grove is a small dipteran insect that is the most important enemy of the olive in our country.
Insect description
It is a small insect with a yellowish-red head with complex iridescent cyan-green eyes, auburn chest and a brown belly with red spots. The characteristic of the dako is the existence of a black spot on the edge of each wing.
It has 3-5 generations per year, which are overlapping and overwinters mainly as a nymph on the ground or as an adult in sheltered places.
- Adults are usually observed in February. Spawning usually begins in June-July, when the fruits are ripe enough (stone hardening stage).
- In each wrist, the female creates a hole (triangular opening) and places a single egg. Each female lays 12 eggs a day, while laying a total of 150-400 eggs. Spawning continues for weeks or months and stops in late autumn or winter when temperatures are lower.
- The young larva hatches 3-7 days later, digs a port in the mesocarp and feeds on the flesh of the fruit.
- In summer, when it completes its development, the larva nymphs near the skin of the fruit after having opened a circular outlet hole eating the flesh below the surface of the fruit, while leaving the skin intact.
- After the completion of the nymph, the adults of the next generation appear, which come out of the nymph's shell, opening a circular hole at one end. 2-4 more generations follow depending on the climatic conditions.
Conditions that favor its development
Growth is favored when the average daily temperature is below 25 ° C and above 10 ° C. Also, when the temperatures exceed 35 ° C for several days, the population of dako, its activity and its fertility decrease. In conditions of high atmospheric humidity, the growth and activity of the oak is favored, which is why the olives that are watered are more sensitive to the attraction of the oak than the dried olives.
What damage does dakos cause to olive cultivation?
The damage caused by dakos is quantitative, because the production is reduced since the dakos destroys part of the flesh of the olive, but also quality, as the produced olive oil is degraded due to increased acidity. The size of the financial loss due to the dako can exceed 50% of the value of the product produced.
Tackle
The ideal method of control is for years chemical. Biological control methods have also been tried, such as the unleashing of natural enemies of the dako and the mass launches of sterilized dakos, but with not so good results.
Chemical control
In the fight against dako, it is recommended to monitor the course of the adult population with dako traps. There it is placed as an attractive, aqueous solution of 2% ammonium phosphate or sulfate and in some cases a 4% hydrolyzed protein solution. They are usually placed around 50 traps per 1000 trees. This is where the trapped females and males are counted. If the number of adults ranges from 5 to 20 people per trap and for a period of 5 days, it is recommended to spray. However, in addition to counting the adults in the traps, it is recommended to estimate the percentage of olive infestation. This is done by sampling fruits that are collected peripherally from random trees and finding fertile nymphs. When the fertility rate is 5% for oily varieties or 2-4% for table varieties, we recommend spraying.
The medicines used for the sprays are mainly organophosphates and are carried out by each oil producer separately, especially in areas where no homicide program is applied.
The active substance spinosad, which has already been approved for spraying against dacos from the first period of development of the infestations, has given very satisfactory results. Great care should be taken to keep the last spray before harvest.
Finally, in terms of control, we should mention the preventive bait sprays that aim to attract and kill adults before they can lay eggs in the olive. The spray material consists of the appropriate organophosphate insecticide at a concentration of 0,3% and hydrolyzed protein or other product with a similar attractive action at a content of 3%.
To determine the time of the 1st bait spray, it is carried out in early June to early July and should be general, ie to be completed in a short time (7 to 10 days) throughout the area.
The ratio of males to females, the susceptibility of the olive fruit to spawning as well as the favorable conditions for the spawning of the owl, are factors that influence the decision to carry out spraying.
