The use of sex pheromone traps for Bactrocera oleae (Rossi) and Pray oleae (Bernard) monitoring

The Directive 2009/128/EC, which aims to achieve a sustainable use of pesticides in the EU, underlines the need to develop and implement effective strategies of crop protection to contribute to a sustainable production. In this regard, a suitable use of pest population monitoring tools is essential, and its implementation should be mandatory in farms.

The olive fruit fly, or Bactrocera oleae (Rossi), is a major pest of olives worldwide. When feeding, larvae create galleries throughout the fruit, destroying and consuming the pulp, and allowing the access and development of secondary organisms such as fungi that depreciate the quality of olive oil.

It is recommended to use pheromone traps for monitoring olive fruit fly adults. These are normally yellow sticky traps with a capsule impregnated with a synthetic chemical compound, 1,7-dioxaspiro [5.5] undecane, similar to the sex pheromone released by females.

Traps should be installed before the fruit hardening (between the end of June and mid-July), which is the phenological stage considered receptive to the oviposition of the olive fruit fly and inspected weekly. The image acquisition of captured adults using a camera and the remote monitoring is already possible for some species and will be soon a reality for the olive fruit fly.

Traps are fundamental tools for adults monitoring and allow to analyse spatial and temporal distribution of the pest, determine the periods of risk (when visual observation should be done), and help in the decision regarding timing and necessity of phytosanitary treatments.

The reference values for economic thresholds levels differ between countries so farms should follow guidelines of their country’s agriculture services.

The olive moth, or Pray oleae (Bernard), is another serious pest in the Mediterranean region. It develops three generations per year that damage different organs of the plant: (1) the phyllophagous generation feeds on leaves and buds; (2) the anthophagous generation feeds on the flowers and; (3) the carpophagous generation feeds on the fruit seeds causing fruit premature fall.

For monitoring olive moth adults, it is recommended to use Delta traps with a capsule impregnated with a synthetic chemical compound, (Z)-7-tetradecenal, similar to the sex pheromone released by females. They should be installed before the flight of phyllophagous generation starts and inspected weekly.

The overall purpose of pheromone trapping is to obtain monitoring data that provide information about the spatio-temporal dynamics of the pest population. Data, which allow to identify the main pest hotspots, can be used in decision support systems as a way to forecast the pest activity and determine its risk periods, thus helping in making decision about necessity and timing of phytosanitary.