An ungrateful guest wanders through the Chilean fruit orchards from 2017 and last February, for the first time, detected in the central zone. It is the Drosophila suzukii, better known as the spotted wings fly, an insect that due to its feeding habits could be a great threat to Chilean fruit production, especially in species of great economic relevance, such as cherries, blueberries, Raspberries and other berries.
“Unlike other flies, such as vinegar, which feed on the over-ripe, fallen or fermented fruit, Drosophila damages the fruit that begins to ripen on the tree, since it changes color. It punches it, lays its eggs and then the larvae feed on the fruit, which causes very high productive damage, ”explains Paula Irles, a researcher at the Institute of Agronomic and Veterinary Sciences of the University of O'Higgins. The researcher leads a project to train producers in the containment of the pest, and its financing was obtained through the Innovation Fund for Competitiveness (FIC) of the Regional Government of O'Higgins, with the support of its Regional Council and framed in the Regional Innovation Strategy.
The variety of threatened fruits is wide, of course with some specific characteristics. “It is very polyphagous, it likes many types of fruit, especially berries, soft, tender and thin skinned pulp fruit, such as cherry, blueberries, plums. With the arrival of this plague, Chilean fruit growing could be exposed to very large damages, ”says Irles.
Last season the cherry became the second most exported fruit, behind the table grape, with shipments in volume of 184.873 tons and returns for US $ 1.028.579, according to Odepa data. The item has had an explosive expansion in the last 15 years, considering that in 2003 the cherry was in fifth place in exports, with US $ 50 million.
The fly, which appeared two years ago, was approaching the central area and last February was detected in the O'Higgins Region, an area where cherry is of great importance. “We had different detections in the areas of Chimbarongo, Rengo, Placilla and San Fernando,” says Isidora Meléndez, a researcher at SAG.
Currently Drosophila suzukii is a pest present with restricted distribution, so there is no mandatory control. “We notify the producer or packing, deliver data and posters. We explain how it behaves and we propose mitigation measures, but as a proposal, ”adds Meléndez.
This fly is native to Asia and in the 2008 it expanded to California and Europe.
The productive losses caused without any type of management can reach 80% and even 100% In Holland, losses of 100% were reported for the harvest of cherries of late varieties in 2014, because the pest was not identified in time. In the south of Spain that figure, also for cherries, has reached 50%.
To solve it, the O'Higgins U. project seeks to create a comprehensive system of autonomous pest management by the producer, for which dissemination and training sessions have been carried out, in addition to transfer of integrated management tools pests "The information obtained in the project is unique and original, given the lack of knowledge about the behavior of the pest in the country, and especially in the central area, due to its recent arrival," says the project coordinator.
“The idea is to mitigate the impact based on the knowledge of what happened in other places, for which we have worked with the SAG; with the Center for Advanced Studies of Fruit Growing, the Rosario Evaluation Center; and with Dutch researcher Herman Helsen, fruit entomologist at Wageningen Plant Research, ”explains Irles.
“What was seen in countries where there was havoc is that now they know how to handle it without major problems. That is why we seek to inform, train and prepare the region to face it when the plague is established and with a density that can be of concern, ”he adds.
The training sessions are theoretical practices, since the producer is taught the available knowledge about the pest, but at the same time he is trained to detect the flies on his land and act to contain them.
“We are interested that the producer can identify the plague with a kit that has a magnifying glass and a trap, so that they themselves make the self-diagnosis, since the SAG declared that it is a pest that is going to be established, that is not going to eradicate, and whose control will not be mandatory, that is to say that the producer has to take charge of its management ”, adds Irles.