The olive fruit fly (Bactrocera oleae) began infesting Mediterranean olives around the 3rd century. These nasty little pests feed exclusively on olives by tunneling into the fruit, destroying the pulp and making the olive susceptible to other bacteria and fungi that ultimately decay the fruit. A single adult female can lay up to 400 eggs, usually depositing an egg in each olive that it visits, making the fruit extra sensitive to oxidation and microbial breakdown. The subsequent premature rotting that takes place in the fruit gives the oil that it produces a somewhat rancid, “off” flavor. That’s not a good thing. And it is estimated that the damage done by the larvae results in a 30% loss of the olive crop in Italy every year.
Enter Dimethoate, fenthion, omethoate, chlorpyrifos, methamidophos, parathion-methyl, parathion, methidathion, and malathion. These pesticides are highly toxic and have been used on olive groves since the mid-1950’s to paralyze and kill the olive fruit fly by inhibiting enzymes that catalyzes a reaction necessary for normal functioning of the nervous system. Unfortunately, if ingested in large enough quantities, these substances can also be toxic to humans, targeting the nervous system, respiratory tract and cardiovascular system.
The good news is that the Food and Agriculture Organization of the United Nations (FAO) created the Codex Alimentarius Commission in 1963 to develop guidelines and codes of practice to insure the coordination of safe food standards by international governing bodies. The IOOC recognizes the Codex committee’s standards for acceptable pesticide residue limits in their classifications of olive oil. Exhaustive studies of Mediterranean commercial olive oil have detected only very small traces of organophosphorus pesticides in their samples, and those traces were well under the limits set by the Codex.
The development of more sophisticated pest management systems has also minimized (but hasn’t entirely eliminated) the use of most costly chemical pesticides in Europe. And finally, farmers have cut back dramatically on pesticide and herbicide use, in part to appease increased consumer awareness that has stimulated a market for an “organic” olive oil – which (supposedly) must be processed according to European Union Regulations. So everyone can rest a little easier knowing that the olive oil for sale at the local grocery store probably has evels of organophosphorus pesticide well within the acceptable Codex limits. Reassuring, isn’t it?
This year, the fruit fly in the Chianti area has been especially devastating to the olive groves. Most people who own land have at least some olive trees that they harvest for their own personal supply of olive oil. And virtually everyone we talked to this fall has no plans to harvest their olives because of the fruit fly infestation.
So, how does Matteo manage the fly problem at Pornanino? Olive fruit flies thrive best in cooler coastal climates (optimally between 68 and 86 degrees), but are also found in many hot, dry regions of the Mediterranean. They are very mobile and have the ability to seek out olive groves within a range of up to 2.5 miles to find hosts for their evil doing. But thanks to their hillside location lying about 1,300 feet above sea level, the Pornanino olive groves are well sheltered from the humid sea breezes that blow in from the nearby coast; therefore, according to Matteo, the bactrocera oleae troublemaker has yet to feast on a single Pornanino olive! This incredibly fortunate set of circumstances has allowed Matteo to cultivate his olives without the aid of pesticides or any other chemicals.