The first fruits affected by the Olive Fly in Spain

The first fruits affected by the Olive Fly (Bactrocera oleae) were detected in isolated areas of the provinces of Cadiz and Seville, south of Spain. In this situation the first recommendation is to monitor the crop with entrapment (i.e. Macphail and Chromotropic) to determine the quantity of the adult population of this agent.

The adult stage of the Olive Fly has predilection for those fruits that have reached the phenological stage "H" (hardening of bone) and whose diameter has one centimeter approximately.

Another factor to the population control is the environmental conditions of temperature and relative humidity:
• Temperatures exceeding 30° C leads to a reduction of fertility in females.
• Constant temperatures above 32 ° C for several hours a day cause higher mortality rate to 80% of eggs and larva in their first stage of development.
• Below 10° C egg-laying stops.
• At temperatures below 0° C, the viability of this insect is hindered.

There is a thermal band of viability for several evolutionary stages of this agent. With this in mind evolution of the Olive Fly is hindered as we approach these limits:

• Egg stage: between 6° C and 35° C.
• Larva stage: between 8° C and 30° C.
• Pupa stage: between 7° C and 36° C.
• Adult stage: between 0° C and 40° C.

Therefore, this species can comfortably develop between 20 and 30° C, with a humid environment.

For the above, it is advisable to know that geographically, there is higher incidence in the South than in the North and in the coastal regions than in the interior of the country. 

In reference to relative humidity, it also has a major influence in the development of this pest, as it is the high humidity and mild temperatures which delimit the endemic areas.