Europe debates use of modified olive fly for pest control

As Spain revs up its annual campaign against one of its olive crop’s biggest enemies – the olive fly – another campaign is underway in Europe against allowing a genetically modified (GM) ‘sterile’ fly to be used as a chemical-free alternative.

Every year, aerial spraying and ground control including pheromone baits are used in Spain to reduce infestation but the stakes are particularly high now with the country deeper in financial crisis, and drought, frosts and other factors expected to at least halve output next season, which officially starts in October.

And in world olive oil capital Andalusia the regional government is reported to have withdrawn subsidies for olive fly control at the same time as farmers face a national sales tax hike.

Olimerca reports that in the Baena Denomination of Origin, olive growers will bear the up to €170,000 ($214,000) cost of aerial spraying 60,000 hectares.

Meanwhile, a European Food Safety Authority panel has just ended public consultation on a document that could pave the way for use of GM olive flies. This was one of the possible future applications of GM insects listed in its “Guidance on the environmental risk assessment of genetically modified animals.”

GeneWatch UK says such a move would be a “massive gamble with our food supplies and the environment” and “billions of GM insect eggs and caterpillars would be left in vegetables and fruit”, including olives.

But British biotech company Oxitec – which has developed male olive flies genetically modified so their offspring die – says treatment can be timed so that "insects are very low or absent at the time of harvest, therefore preventing presence of insect eggs and caterpillars in fruit.”

Oxitec says the olive fly (Bactrocera oleae) is “the single biggest problem facing the majority of olive plantations around the world” and “even at low levels makes table olives unmarketable and adversely affects the acidity, and hence quality and value of olive oil.”

It claims current controls largely rely on chemical insecticides but the cost is high, resistance is reducing effectiveness, and several insecticides have been, or are being, phased out due to environmental or health concerns.

Its olive fly strains have undergone contained trials “with excellent results” and are ready for open field trials, it says.