Researchers asked people if they had a rich cherry harvest last year in their gardens and if they have noticed that the berries had larvae, there were no berries or no birds or if they just fell on the ground without a clear reason. The mysterious pest is actually a quite well known insect. It is the common fruit fly, also referred to as the cherry fly. Once contaminated cherries drop to the ground the larvae follow and their cocoons should now be in the soil. The Lithuanian national research center is currently conducting research which should help protect the berries from insecticide in the future. According to a senior researcher at the Laboratory of Chemical Ecology and Behavior at the Nature Research Center, cherry flies are harming cherries, particularly in ecological farms where the flies can quickly spread and are capable of destroying the whole crop.
Since the pest can be found in the berries under attack, the berries are no longer suitable for direct consumption but only for processing. The research center is looking for materials that the cherry flies react to. Scientists hope to find pheromones that are involved in the reproduction process.
Pheromones are currently believed to be released by males, thus attracting females. So, using these materials, it should be possible to control this pest. Since pheromones are a natural material – both the pheromone material extracted from the plant and the insect itself could be used in organic farms. Common flies lay eggs on the berries and then the larvae penetrate the berry and feasts inside. When the damaged berry ripens and falls, the larvae are transported underground where they can make a cocoon to survive during winter in the depths of 3-5 cm near the tree. Researchers obtain samples out of the ground which will wake up in the lab and thus these cocoons will produce the flies for research.
Cherry flies are widespread throughout Lithuania and throughout Europe. They multiply in all kinds of cherry species and their berries without exception. Damage can therefore be very high. For example, nearly 3 hectares of organic cherry and cherry areas are registered throughout Lithuania. Just last year in one organic farm cherry flies violated all of the berries. Cherry yields also depend on the pest population. In standard farms systemic insecticides have to be used, which destroy the fly and thus protect the crop, but if chemical means are used then it is no longer an organic farm.
The research process is very complex. It is now known that pheromones are excreted by males, therefore after injecting a group of males into a flask, the scientists would then connect it to a special piece of equipment that collects odors. The absorbed sample is injected into a gas chromatograph which is synchronized with an electro-electron scan detector. This device makes it possible to determine what odors are attracting or repelling the flies. The insect's head is placed between the electrodes, and the insect’s organs - antennas - are sprayed with individual substances coming out of the chromatograph. If the insect is reacting to the substance, the device sends a response which is recorded on the computer. In this way it is possible to discover the substances that the insect is reacting to and which substances have some significance to its life. Synthetic analogues are then ordered by identifying the material that the fly responds to. The analogues are then tested in the laboratory to investigate how the substance affects insect behavior - attractive or repellent. The materials are then tested in traps outside and monitored in the natural environment. According to scientists, pheromones are used to control many pests, such as bark-types, frequent spruce pests. Similar studies are also conducted on walnut pests in Southern Europe. Pheromones and herbal scents are used to catch and control plum or apple fruit, where traps are used.