Keeping Flies Away from Olives

 Every year in Catalonia, Spain, farmers have to fight the olive fruit flies so they don’t ruin the year’s crop. PHOTO: Wikipedia

Every year in Catalonia, Spain, farmers have to fight the olive fruit flies so they don’t ruin the year’s crop. PHOTO: Wikipedia

The olive fly (Bactrocera oleae) is the single major pest for olives, causing widespread crop damage and significant financial losses to Europe’s olive farmers. The control of the fly has been largely based on the use of chemicals, but the intense use of insecticides leads to development of insecticide resistance, which makes control problematic. In addition, legislation on insecticides have seen some of them being phased out. An alternative? The almost-DIY fly trap.

The female olive fly is slightly larger than the male, and can be spotted by the spike at the end of its abdomen. This spike is used to inject eggs into the olive flesh while they are still on the tree. When the eggs hatch, the young feed on the olive pulp.

These flies are endemic to the Baix Ebre and the Montsià regions of Catalonia. In 2014, 40% of the harvest was lost to olive flies and drought. Spraying can be effective, but is a big job, has to be repeated, and is less effective when it’s windy because the spray just blows away. This year, 400,000 traps were deployed to try a different approach.

The trap is as simple as it gets. Supplied as flat sheets of plastic, the traps are twisted into a cone shape on site and hung from trees. Instead of the usual liquid bait, these traps use a solid attractant (mostly diammonium phosphate) contained in a sachet made of a porous membrane. Imagine those little sachets of desiccant you find in your new electronics and you’ll be close enough. These packets are moistened overnight by dew, ready to bait flies in the morning. The traps work all season long, and keep going through the winter which, thanks to the pleasant local climate, isn’t always cold enough to kill off the flies.

While it must be noted the trap cannot keep flies off the fruit on its own, it is a small step towards decreasing dependence and transmission of chemicals via the food chain. Read more here.

One thought on “Keeping Flies Away from Olives

  1. Pingback: Wild Tomatoes Reduce Need for Pesticides | Raxa Collective

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