Will this large 7 to 8 mm fly with a striped abdomen be the future bane of French arborists? ANSES (National Health Security Agency) is calling this Thursday for strengthening surveillance of Bactrocera dorsalis, the oriental fruit fly, whose risks of entry into French territory are increasing. This is not the first time that the health agency has taken an interest in this exotic fly, specimens of which were captured in 2019, near the Rungis Parisian market in Paris. Insights with Christine Tayeh, scientific coordinator at Anses.
Is Bactrocera dorsalis, a fly native to Asia, present in Europe?
The oriental fruit fly is now present in a large part of sub-Saharan Africa, in India, in China, throughout southeast Asia as well as in several Pacific islands. “At the European level, Italy is the only country to have declared the presence of Bactrocera dorsalis, says Christine Tayeh. It is said that its installation there is transitional, in the sense that management measures are still being considered with the aim of eradication.” Clearly, the authorities have not given up and hope that its installation is not sustainable.
Currently, no outbreak has been declared in mainland France but ANSES considers the risk of entry into the territory to be increased. “Despite European regulations which should prevent its entry, we see that it is very probable because we find more and more of them captured around points of entry (airports, ports, wholesale markets, etc.) in France , Christine Tayeh further advances. At the same time, the probability of lasting establishment, which implies that it survives the winter until the next season, is moderate and reduced to the low-altitude Mediterranean zone (which includes Corsica). »
What dangers do oriental fruit flies pose?
There Bactrocera dorsalis attacks more than 500 different plant varieties among fruit and vegetable crops. “It causes between 15 and 100% yield losses on mangoes for example, depending on the countries where these observations were made and the crop varieties affected and other factors (climate, control measures),” specifies our expert.
If it is difficult to compare its virulence to that of pests in France, its regulatory status clearly “reflects its dangerousness”: “ Bactrocera dorsalis is one of the 20 priority quarantine organisms at European level, given the seriousness of the potential economic problems it can cause, which means that surveillance and control measures concerning it are obligatory in all European countries. »
If this fly is reported in France, a national emergency health response plan will be activated. The State services concerned can implement insecticide treatments, trapping of male individuals to limit reproduction and restrictions on the movement of plants. “This clearly shows that it is one of the most damaging pests for French and European agriculture in general,” says the scientific coordinator.
How to fight against the installation of this exotic fly in France?
The numerous international movements of goods and people make the application of European rules regarding the surveillance of this fruit fly complex. “The expertise recalls that despite the current regulations for the importation of fruit from infested areas, we still intercept Bactrocera dorsalis, on mangoes for example, points out Christine Tayeh. The requirements would not necessarily be respected.”
In addition to strengthening these controls, ANSES is therefore proposing to extend them to other products. “There are fruits (avocados, passion fruit) which are not included in the current regulations but which would play a role in the entry of the fly into our territory. »
To learn more about invasive species
In addition to the import channel for products likely to bring this oriental fly to France, it is also a matter of monitoring the behavior of passengers, who are sometimes inclined to bring exotic fruits back in their suitcases. “Anses recommends, for passengers, a ban on the transport of fruit that could carry Bactrocera dorsalis, underlines Christine Tayeh. Mainly because these fruits are not originally intended for export and perhaps do not meet European health standards” with regard to the dreaded fly. However, the application and control of these measures prove to be particularly complicated and could work in favor of the pest.