Bactrocera oleae, the Olive Fruit Fly is recognized as the most important enemy of olive trees in the areas of its cultivation.
In times of exacerbation of the attack, the damage it produces, quantitative and qualitative can amount to up to 50% of the oil and fruit production, and its treatment contributes significantly to the increase in the cost of cultivation.
Particularly intense are the insults of the Bactrocera oleae in olive groves bordering with wild olive trees or in those where the olives remain in the trees in the winter.
Species: Bactrocera oleae (Rossi, 1790), (syn. Dacus oleae Gmel)
Egg: Ellipsoid, elongated, glossy white to creamy-white in color, 0.8-1 mm long and about 0.2 mm in diameter.
Larvae: Long, white or creamy-white, headless and without legs, with the posterior part wider than the anterior, while length is of up to 7-8 mm and 1.2-1.7 mm in diameter.
Pupa: Cylindrical-ellipsoidal, initially white in color and then brown-yellow, 4-5 mm long and about 2 mm in diameter.
Adult: It is 4-5 mm long, yellowish-headed, complex green-eyed and iridescent. The chest is brownish-yellow and black its dorsal portion, which has four gray strips, while the abdomen is dark brown in color with reddish spots. The wings of 4.3-5.2 mm are transparent, at the top of which a black color spot is visible. In female, the ovary is 1 mm long and the main part is black.
Generations per year: 2-5
Biological cycle: Eggs, larvae, pupae and adult are the four stages that the Bactrocera oleae passes to complete its life cycle. Its duration depends on conditions, season and temperatures and lasts from 21 to 100 days. After mating, female using the ovipositor open small holes and insert 1 egg per position and fruit.
With the hatching of the eggs, the young larvae come out, which eat the fruit internally by opening galleries. After three larval stages, they are pupate in summer in the same fruit of the olive, while in the autumn the nymph is carried out a few centimeters from the surface of the soil.
At an average temperature of 24-26 °C (76-79 °F), the adults emerges within 20 to 34 days.
Overwintering: As a pupa in the ground and at a depth of 1-6 cm or as an adult in sheltered places and in mild winters.
General: Small triangular spots on the affected areas of the fruit, usually one per fruit in the summer, while in the autumn, and especially in periods of limited oil production or under high population densities, there may be more. Larvae galleries on unripe fruit can be externally perceived as dark oil spots. The pathogenic fungi may enter the oviposition holes, most notably Macrophoma dalmatica, which carries the Prolasioptera berlesiana fungus, causing diseases both in green and ripe olives. Lastly, larvae open a round hole in the fruit of the olive tree, which is covered only by the tegument, to facilitate the fly of the adults.
The Olive Fruit Fly is treated with the use of various methods – chemical, biological etc. But what is of great importance for the proper control of Olive Fruit Fly is the monitoring of the variation of its populations with traps, and hence the evaluation of the most appropriate time for the intervention to take place.
The application of 0,002 mm of granular zeolite powder has given encouraging results. It is used in dissolution of 1.5-2 % together with adhesive and spraying coverage. The result is the creation of a protective ‘film’ on the surface of the olive tree that works repellently for Bactrocera oleae. Sprays are repeated at least one per month.
The application of processed kaolin has given encouraging results, not only to fight the Olive Fruit Fly, but also to control the populations and other enemies of the olive, such as Rhynchites cribripennis, Prays oleae and Saissetia oleae. The repellent action of kaolin can be attributed to the tropical or visual impact caused by the fine, white-colored powdery hydrophobic membrane formed after application to the olive. Kaolin sprays start at the end of Spring and repeat at least one per month.
The insect Psytallia concolor (syn. Opius concolor) has been tested to fight the Bactrocera oleae with very good results. However, because of the high production costs it does not used.
The method consists in unleashing sterile adults of the Olive Fruit Fly with the purpose of reducing their reproductive capacity in a given area and thus controlling its population. However, due to the negative coupling behavior of steriles Bactrocera oleae, it is not applicable.
The method of mass trapping attempts to monitoring but also, to control the populations of the Bactrocera oleae using pheromone, trophic and color traps, which are used either alone or in combination. This method is used with satisfactory results.
For foliar spot sprays, an insecticidal active substance is used together with 2-4% trophic attractant (hydrolyzed protein or other trophic attractant) and and the trunk and part of the crown of each third tree are sprayed.
An insecticidal active substance is used and the entire surface of the trees is sprayed.
Some of the insecticidal active substances used to control the Bactrocera oleae in both types of spraying are:
As attractives insecticidal active substance are used:
Algeria, Angola, Egypt, Eritrea, Ethiopia, Kenya, Libya, Mauritius, Morocco, Réunion, Seychelles, South Africa, Sudan, Tunisia.
Armenia, Azerbaijan, Cyprus, Georgia, India, Iran, Israel, Jordan, Lebanon, Pakistan, Saudi Arabia, Syria, Turkey.
Albania, Canary Islands, Corsica, Croatia, France, Greece, Italy, Portugal, Serbia, Slovenia, South Russia, Sardinia, Sicily, Slovenia, Spain, Switzerland.
The Olive Fruit Fly References are presented with great pride by the excellent Mrs Enya
with the song Orinoco Flow.