In recent years, crops of cherries, strawberries, blueberries, raspberries, blackberries and vines have been threatened by the fruit fly ( Drosophila suzukii ), an insect of the order Diptera and family Drosophilidae, native to Southeast Asia. This small insect has recently spread to Italy, probably brought with the goods from the Far East. Here he found a favorable environment and proliferated at the expense of growing berries.
The mosquito causes serious damage and irreversible in various species of thin-skinned fruits. Drosophila spreads without problems in the absence of effective natural antagonists. The insect has already been identified in 12 Italian regions and 13 European countries.
It is not easy to protect crops from fruit flies, because Drosophila affects the fruit during ripening , phase in which it is not possible to carry out treatments due to the imminent harvest. What makes the insect particularly dangerous for orchards and vineyards is also its rapid reproduction: the females even reach 10 generations per year.
Today, knowledge of the behavior of this oriental mosquito is insufficient: there is still very little experience, given the relatively recent spread in our territory. The first discoveries in Italy date back to 2009, in Tuscany and Trentino.
While chemical interventions are often impossible or ineffective, some biological methods have given excellent results. In particular, the combination of mass capture of adult individuals (operation which requires the use of biotraps) with correct agronomic practices Preventive in nature, it effectively defends crops against Diptera attacks.
Drosophila suzukii: characteristics of insects
How to defend the garden
Monitoring and mass capture of insects
Other biological control methods
Drosophila suzukii: characteristics of bedbugs
The Adults The mosquito fruit is about three millimeters long and can be recognized by its rather large red eyes and golden brown body, characterized by the presence of dark bands on the dorsal abdominal segments. Males have black spots on their wings, which are also found on the dentate ovipositor of females.
The insect hibernates on local wild plants. In fact, another factor that has contributed to the spread of oriental midge in Europe is the presence of many plant species that can act as intermediate hosts during the winter. Subsequently, the females lay small eggs in several fruit species, ensuring the development of 10 generations per year and showing a much higher egg-laying capacity than the native mosquito. There are 2-3 eggs laid on each fruit and 350-400 laid by a female during the entire life cycle.
The eggs take 12 to 72 hours to hatch, while the larvae they turn into pupae in 3-14 days. The pupae in turn become adults in a period of time between 3 and 15 days. The duration of each stage and therefore of the entire life cycle depends on the temperature.
Natural gas damage
Attacks by Drosophila suzukii begin at the time of egg laying. With the dentate ovipositor, the females engrave the exocarp of the ripe fruit and lay eggs in the mesocarp.
Subsequently, larvae emerge from the eggs which feed on the pulp and cause irreparable damage to the ripe fruits, also causing bacterial infections. and fungal . Already after 2-3 days, the fruits affected by the insect present sunken and soft areas, in correspondence with the incisions of the ovipositor. In a short time, the fruits fall apart.
which plants strike
In Italy, the mosquito caused serious damage to stone fruits (cherries, peaches, plums, apricots) and berries (blueberries, raspberries, blackberries, strawberries), as well as kiwis, persimmons, figs and grapes. Diptera females also affected already damaged apples and pears.
How to defend the garden
As already mentioned, the fruit midge is difficult to oppose to chemicals: even if you want to use them, the treatments must be carried out when the fruits are ripe and this would make the harvest risky due to the presence of residues in the fruit. However, for those who wish to use insecticides, it is essential to alternate the active ingredients to avoid the appearance of resistance phenomena.
In organic farming, the most effective control method against Drosophila suzukii is based on food bait traps, which allow the capture of adult specimens and prevent their reproduction. Certain agronomic practices, such as good pruning, are also very useful in preventing problems caused by Diptera.
Monitoring and mass capture of insects
To minimize the damage caused by the fruit fly, the most effective methods are monitoring and the mass capture of adult individuals through the use of food chromotropic biotraps . The traps do not contain harmful substances or pheromones, but food baits that are easy to prepare even at home. Traps designed specifically for the capture of Drosophila suzukii, Tap Trap and Glass Trap red They are made of plastic, resistant, versatile and able to attract the mosquito using the red color, preferred by the insect. Traps are applied as plugs to containers filled with food bait.
Before setting the traps, you must prepare the bait , which is nothing more than a mixture of apple cider vinegar, red wine and brown sugar. This recipe has been tested and recommended by the Edmund Mach Foundation in Trento.
Then the biotraps They cling to plants. You can use a plastic bottle with a red label in combination with the Tap Trap lid or a glass jar in combination with the Cup Trap, which you can also put in its place. Ideally, the biotraps should be at ground level and well exposed to the sun.
For an effective capture, it is best to wait until half April , when Drosophila suzukii usually begins to appear. To establish the right moment to plant the traps, it is always necessary to take into account both the growing area and the cycle of the fruit plant to be defended. In general, the best thing to do is to check for the presence of the Oriental mosquito by first setting up a few Vaso boat traps with a monitoring function, then several additional tap traps.
When a strong presence of Drosophila suzukii is observed, it is advisable to install Tap Trap for massive catches mosquito. Instead, install Tap Trap for selective capture of the insect. Vaso Trap has in fact a funnel with many holes which only lets the fruit fly into the trap and thus facilitates the detection of dangerous Diptera.