The fly Drosophila suzukii (Matsumura, 1931) is a plague of Asian origin with high virulence and rapid expansion capacity.
It is currently one of the pests with the greatest impact plantations cherry tree in Spain.
The control in the crops is complex due to its rapid development cycle.
The plague mainly attacks fruits of soft skin, cherry, strawberry, lays, raspberry and other red fruits. Although it has also been detected in fruits such as kaki, plum or kiwi. It can be said that any overripe fruit is a potential guest.
Curiosities: EPPO (European Organization for the Protection of Plants) includes Drosophila Suzukii on the alert list.
Drosophila Suzukii in Spain
Although it is a native species of Asia (China, Japan, Korea and Thailand ), the world trade in fruits has helped its spread around the world.
The first detection in Spain of the Drosophila Suzukii fly occurred in the province of Tarragona during the year 2008. During this year the fly also enters the United States where it has expanded causing large losses.
During the year 2012 its presence was detected in Andalucía, specifically in the provinces of Jaén, Almería and Huelva.
It is a major threat to Spanish and European fruit producers.
The need to apply treatments for the control of Drisophila Suzukii increases the production costs of the cherry, strawberry…
Organic fruit orchards are the ones that can suffer the most.
This cherry plague is causing great concern in the sector. In addition, the authorized treatments to defend themselves are increasingly limited.
Identification of Drosophila suzukii
Drosophila suzukii is a vinegar fly that looks similar to drosophila melanogaster. It is distinguished from the vinegar mosquito by having the males at the tip of its wings a gray spot. It differs from other species of drosophilas by having a sawed oviscapto (organ used for laying eggs) that allows it to attack healthy fruits.
Fly Drosophila suzukii male (left) and female (right) [/ caption]
The adults of this insect are flies with a size of 2-3mm, light yellowish-brown thorax, red eyes and abdomen with black bands.
Larvae: at first sight they are similar to those of other drosophilas, they are whitish color and small size (only 3.5mm long at the end of their development).
Pupa: it has a 3mm length and is colored, it is distinguished from other pupae by the shape of the spiracles (breathing ducts), which has 7-8 ramifications .
Biological cycle of the suzukii fly
Although like other flies prefers cool and humid climate, Drosophila suzukii adapts well to different climatic conditions.
Adults can reproduce in a wide range of temperatures (between 10 and 32ºC), although optimal conditions are 20-25ºC.
The most limiting aspect is the relative humidity, being quite sensitive to drying.
The cycles are completed very quickly in just 1-2 weeks depending on the temperature. Under optimal conditions this fly can reach up to 15 generations per year.
During their adult stage the females of the suzukii fly can live up to 30 days. In this time they put between 7 and 13 daily, surpassing the 300 laying eggs during their life. The fly has preference for mature fruits to make the laying.
The pupa is usually done inside the fruit. In cold areas the fly hibernates in an adult state seeking refuge from the cold. When temperatures drop below 5 ° C, the female of Drosophila Suzukii enters reproductive diapause and can survive for 200 days.
Damages produced in cherry by Drosophila Suzukii
Adult females of Drosophila Suzukii damage the surface of the cherry during laying. This wound can be a point of entry for fungi such as the monilia. Although the major damages are caused by the larvae that soften the cherry by making not marketable s.
Although up to 65 adults have been found in the same cherry, only the presence of one of them causes appreciable damage to the fruit.
Control techniques of the Drosophila Suzukii
Both the cultural measures and the use of chemical treatments are necessary for proper control of Drosophila Suzukii.
As with the cherry fly, fully harvesting the trees and keeping fruit out of the field is essential.
Picking cherries on time before they overmatter is also a good form of control.
It is recommended to leave the remains of cherries inside airtight plastic bags and exposed to the sun for at least a week. The humidity and temperature conditions attained suffocate the larvae.
The massive trapping is the form of control to be applied in areas of organic farming, it is recommended to include insecticide in the bait.
Application of chemical treatments
Due to its short life cycle (barely a week under favorable conditions), control with chemical treatments is complex (few products have adequate safety deadlines).
In addition, being a new pest there are no specific products registered for control.
For this reason, the ministry has been carrying out special treatment authorizations for several years against Drosophila Suzukii.
Up to the year 2015 the use of Dimethoate 40% EC was allowed. Effective but forbidden at the moment to present residues in the cherry when it is applied in period of maturity.
In the absence of specific treatments against Drosophila Suzukii, effective products are authorized that are usually used in the control of other pests .
DuPont ™ Exirel® based on the Cyazypyr® insecticide is one of the authorized products during the 2017 cherry campaign.
Some control treatments of the cherry fly can also help in the control of the Drosophila Suzukii. Although the specific treatments are more effective.
As in the case of the cherry fly, the patching techniques reduce their populations.
A significant part of the information, comes from Spanish research organizations. When phytosanitary products are used, it is important to verify that their use is currently authorized in the country of application.