Biological cycle
Mediterranean fruit fly (Ceratits capitata) is a diptera from the Tephritidae family. The adult is smaller than the housefly. It has transparent wings decorated with eye-catching drawings. The female has an abdomen which finishes in a conical shape and it also has a long ovipositor which is used to penetrate the fruit skin and leave the eggs inside.
The eggs are long and smooth. The larva is apodous and whitish. The head stands out because of the presence of two little black dots which are the eyes. The pupae is dark brown, about 5 mm long.
This fly, which comes from the western coast of Africa, has spread out in the majority of warm areas worldwide. In Catalonia, it can be found on the coast, mainly in the Tarragona region. In the rest of the Peninsula, it spreads out in a large part of the territory, especially in Valencian Community, Murcia and Andalusia.
By the end of the spring, adults emergence begins. A few days later, the female can start laying eggs. They leave the eggs under the fruit epidermis. It is particularly interesting to know that the ones that have already been stung are not visited by other females. The laying period is between 30 to 60 days but it depends a lot on the area.
Larvae complete their development inside the fruit in one week and then jump to the ground to pupate. In 10 more days, they become new adults. The biological cycle can be completed in 20 days and annual generations may vary a lot according to the climate conditions and the food they have.
Mediterranean fruit fly is a really polyphagous species which affects mainly peach trees, orange trees and mandarin trees although damage is also detected in apple trees, pear trees, fig trees, persimmon trees, apricot trees… In the case of peach trees, the most affected varieties are the late ones (end of August). However, with citrus it is just the opposite; the earliest varieties (beginning of September) are the most sensitive to attacks.
DAMAGE
The first damage that affects fruit is due to the stings the female makes in order to leave the eggs. The sting, in the first place, opens the way for a fungal infection which favours fruit deterioration.
The second symptom is produced by larvae which feed themselves on the fruit flesh and destroy the pulp completely.
Because this damage can go unnoticed during the harvest and handling process, there can be marketing losses.
In order to control this pest, very frequent pesticide applications are carried out in order to counteract the danger that represents the constant presence of adults on the field due to the overlapping of generations. This fact entails an added risk, which is the presence of waste on the fruit, since harvest is very close. The only resources left to the farmer are using low persistence products (pyrethroids) or going for new control techniques like the mass trapping strategy suggested by PROBODELT.
In this sense, PROBODELT has started a study for fruit fly control with mass trapping. It is a good alternative to reduce insecticide treatments, reduce the fly population and avoid waste on the fruit.
CONTROL
Chemical
It can face in two ways:
- Bait treatment against adults, treating 1m2 in south part of every tree using a combination of attractant and authorized insecticide. Bait treatments are used when the level of pest is low or there aren’t recently bites in the fruitss.
- Total treatment, to eliminate larvae, spraying the entire cultivated field with an authorized insecticide. These treatments are essential in some cases, but it’s necessary to remember that carrying out these treatments it is removing beneficial fauna which control this and other pests.
Mass trapping:
The mass trapping has less drastic effects than the insecticides at the moment of its application, but its effect is continuous: the traps, along the entire live of the attractant go capturing continuously adults emerging from the same control area or border areas. Therefore, as mass trapping reduces the population continuously is a guarantee to avoid damage from sharp increase in unexpected population.
The main factors to bear in mind when applying the mass trapping technique are:
- The trap. Must be designed to catch the maximum number of adults possible, facilitating the entrance of the flies and prevent the exit. We have two designs of fruit fly traps for solid attractants (Conetrap and Maxitrap UV).
- The attractant. For a good efficiency of the technique it must be used food attractants, which capture mostly females that are the responsible for damage to the fruit. PROBODELT has the Ammonium attractant Ceratitis with exceptional performance both in terms of ability to capture females of Ceratitis as persistence. The solid attractants require to locate inside the trap a small amount of insecticide to produce death of adults captured. A proper trap reduces the risk of the fly resistance to the insecticides used because it prevents escape individuals with sub lethal doses.
- Date of traps placement. This date depends on the particular crop cycle (variety, geographical location, weather conditions of the season …). For optimal result of mass trapping, traps should be placed sooner the better, but at least 15 days before the beginning of fruit ripening. Since the effective duration of Ammonium attractant Ceratitis is 4 months, if it anticipated that will be a excess persistence due to have fully collected the harvest before the end of the effectiveness of the attractant, it can anticipate the placement of traps or also use these for other late varieties.
Cultural measures:
- Consider host trees (fig, medlar tress, peach trees, prickly pears, etc.) that may be on the inside or vicinity of the plot.
- Pick up and destroy damaged fruit, mainly which are on the ground.
