It is a species of dipterous of the family Tephritidae. Its larvae feed on the pulp of the olive fruit, the olives, hence its vulgar name. Its distribution coincides with that of the olive tree, it is found in the north, south and east of Africa, the Canary Islands, India, Western Asia and Mediterranean Europe. In the Western Hemisphere, it is currently only found in California.
It is considered as the most problematic plague that olive cultivation has
Diffusion and importance
This species is associated to the plants of the Olea genus and in particular to the olive tree. It is present throughout the Mediterranean area and in South Africa. It is considered as the most important pest of olive cultivation in the regions in which it is present, reaching to condition the quantity and quality of most of the cultivated areas.
The incidence of their attacks tend to accentuate in the wetter and fresher areas, with a great variability depending on the cultivated variety, it is less pronounced in areas with hot and dry summers.
Larva in its third stage in an olive.
The egg has a length of between 0.7 and 1.2 mm, is elongated, slightly flattened at the base, with a small whitish tuber, important for embryo respiration.
The larva is a conical-cylindrical shape. In its development it passes through three stages. The mature larva measures between 6 and 7 mm, is yellowish white, elongated.
The pupal stage is developed inside the puparium which is an elliptical capsule formed by the transformation of the exuvium from the last larval molt. The puparium has an elliptical shape and a length of 3.5 to 4.5 mm, its color varies from cream white to reddish yellow.
Adults measure between 4 and 5 mm in length. In Spain they are easily distinguished from other tephritids by the characteristic black spot at the apex of the wing and the extension of the anal cell, narrow and elongated.
The adult insect presents a reddish brown or orange coloration on which a series of black plates stand out.
Its wings are transparent and iridescent, and the posterior border of the thorax is yellow.
The females lay their eggs after the olive has a diameter of 7-8 mm. The oviposition is done by piercing the skin of the olive with its oviscapto, placing a single egg under it in each olive. The incision he makes has a characteristic triangular shape due to an optical effect. The new bites have a dark green coloration, while the older bites have a yellowish-brown color, as a result of wound healing.
The hatching of the egg takes place in a period that varies between 2 or 3 days in summer and up to 10 in autumn. The neonatal larva initially excavates a superficial gallery, but soon deepens the pulp until it reaches the bone, which it can not damage. During the larval development, two molts are produced with the consequent increase in the size of the larva.
When the larva approaches the third molt, it approaches the surface of the olive and prepares the area where it will emerge and will fall to the ground. To do this, it gnaws the pulp through the area where it will leave leaving only the thin layer of the epidermis. In this stage, the olive clearly shows the damage since the area that has gnawed below the surface is darker and stands out from the rest of the olive that is still green. The pupa remains at rest below the epidermis, in the area where it has prepared its exit, protected by the puparium formed by the exuvia of the mature larva.
When the pupa becomes an adult, it breaks the pupario by coming out of it. Pressing breaks the thin layer of epidermis that left and leaves the fruit. At the end of autumn and in winter, the behavior changes: the mature larva leaves the olive and is dropped into the ground where it will transform into a pupa, and the cold season will pass through until the following spring.
Adults eat mainly sugary substances such as natural molasses and other substances. As this diet is poor in protein, they are also attracted to protein materials and emit volatile nitrogenous substances as they complete their diet with them. An example is the excrement of birds and other animals. This habit is important because it can be used in control and surveillance programs using attractants based on hydrolyzed proteins and ammonium salts.