In a small persimmon orchard in northern Greece, scientists carefully open paper bags to release thousands of flies, in an experiment designed to show the devastating impact of a new invasive species.
The insects are sterile Mediterranean fruit flies ( Ceratitis capitata ), pests that cause significant damage to crops every year in Naousa, where much of Greece’s notable export, peaches, is produced.
But the project ultimately aims to curb an even bigger threat: a fruit fly species from Asia that has begun to appear in southeastern Europe as climate change increases local temperatures.
The four-year, EU-funded project called React brings together researchers from 12 different countries, including the UK, Israel and South Africa.
The program budget is 6.65 million euros ($7.8 million).
“Our approach is to locally eradicate Mediterranean fruit fly populations and then apply this knowledge to other species of interest, such as the oriental fruit fly and the peach fruit fly,” said project participant Nikos Papadopoulos, professor of applied entomology at the University of Thessaly.
Bacterial supplement
The male flies are bred at the University of Patras and fed a bacterial supplement that makes them more active, resilient and competitive, said George Tsiamis, director of the University’s Microbiology Systems Laboratory, during a media tour organized by the research team at NAOUS.
“This means they are more likely to survive in the wild, fly longer distances, live longer and, most importantly, mate with wild females,” he added.
“Because males are sterile, these mates do not produce offspring, gradually reducing and ultimately eliminating harmful populations.”
The enhanced sterile insect technique (enhanced sat) is pesticide-free, environmentally friendly and compatible with organic farming practices, according to Tsiamis.
The orchard owner, Savvas Pastopoulos, an agronomist by training, has welcomed the project and is tasked with winning over other nausa fruit growers.
“At first they were a little skeptical when they saw these bags with insects, but after it was explained to them, they understand,” the 40-year-old told AFP.
“There have been seasons when we lost production in just 15 days due to Mediterranean fruit flies,” he said.
Scientists note that invasive fruit flies are among the most destructive threats to global food production.
Two of the species, Bactrocera dorsalis (eastern fruit fly) and Bactrocera zonata (peach fruit fly), have caused enormous economic damage worldwide.
In Southeast Asia, they are now threatening to invade Europe.
According to Papadopoulos, the oriental fruit fly has been observed repeatedly in Europe. Several cases are reported around Naples each year, and the species has also been recorded in France and Belgium.
“The threat of these fruit flies is real for the Mediterranean countries. We expect impacts on nations such as Greece, the Croatian coast, Italy, Spain and Portugal,” he said.
Climate change risk
Climate change is making the situation worse, as both invasive species thrive in warm weather, said Vasilis Rodovitis, a doctoral candidate in the Laboratory of Entomology and Agricultural Zoology at the University of Thessaly.
“These two insects were found to be able to overwinter in warmer parts of Europe, such as Crete and Valencia,” he said.
“In other temperate regions, such as Naples and Thessaloniki, we observed a small survival rate, but enough to establish new populations after winter, in early spring.”
The team chose NaoUS as the testing site because the Mediterranean fly population in the region appears to be at low levels, reminiscent of those in the early stages of an invasion by that new species.
“This is the first European field trial of sterile insect release on such a small, targeted scale using our improved sterile insects,” said project coordinator Mark F. Schetelig.
“Our initial findings are very encouraging: the releases have shown a measurable reduction in the native pest population, which we will monitor this year and next,” he said.
The local community has already expressed strong support for an approach that avoids heavy pesticide use, said Scheteliga, a professor of plant protection insect biotechnology at the University of Giessen in Germany.
“This small-scale trial serves as a model for Europe: smart, local action that benefits the entire continent,” he added.
Published – September 15, 2025 04:37 PM IST
