The Pest

Mediterranean Fruit Fly (Medfly)

The Mediterranean fruit fly (Ceratitis capitata), known also as Medfly, is one of the most devastating pests known to agriculture world-wide. The female flies lay their eggs inside ripening fruit, the larvae which hatch from the eggs, feed on the fruit and cause decomposition.

The Medfly is widespread in nearly all of the world's tropical and sub-tropical regions. It is damaging to more than 250 plant varieties, including: citrus, mango, guava, plum, apricot, peach, nectarine, apple, pear, loquat, grape, persimmon and pomegranate. 

In addition to the direct damage the Medfly causes to agricultural produce, which can reach a level of 100% damage without suitable pest control, it also causes indirect damage: in countries that are Medfly free (such as Japan, the US, Korea and others) the Medfly is defined as a quarantine pest, and these countries do not permit importing of fruit from regions afflicted by Medfly. 

The population levels of the Medfly in countries with warm climates, and especially in Mediterranean countries, are very high. For example: in Israel over the past decade there has been a substantial increase in the number of chemical treatments used against this pest: about 30% of all chemical pesticides used for pest control in Israel are used to control the Mediterranean fruit fly. 

Conventional pest control methods

Cover spray

In this method, in order to eradicate the fly at its various stages, the entire tree, and entire orchard is sprayed with chemical pesticides that are non-selective and residual.

The method has several major drawbacks that have resulted in decreased use in recent years:       

• Chemical pesticide residue, that is toxic to humans, remains on the fruit even after the pesticide has become inactive against the pest;
• Pesticides sprayed on extensive areas penetrate into groundwater and pollute it;
• The pesticides used are non-selective, and are harmful to the orchard's ecological balance: they also cause damage to beneficial insects that control secondary pests in the orchard and cause outbreaks of these pests. 
  

Bait spray

In this method, parts of trees or entire trees are sprayed, in one of every few rows in an orchard, with poisoned bait: the mature flies are attracted to the bait and are exterminated by the pesticide (toxin) inside the bait. The toxin most often used in this method is the insecticide Malathion.

The greatest drawback of this method is the use of Malathion, which is an organophosphate compound that is harmful to humans and the environment, and is included in the group of compounds that are designated to be banned in coming years. 

In recent years, another toxin has been developed, that is non-toxic to mammals and is based on the Spinosad insecticide, used as a toxin in bait treatment against mature flies.
The method's drawback: this insecticide is not selective, is harmful to the orchard's ecological balance, and it also damages beneficial insects that fight other pests in the orchard, causing outbreaks of these pests.