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16 million sterile fruit flies released in bid to control plague in Peru

The department of agrarian health (short: Senasa) of Peru’s Ministry of Agriculture released on Tuesday morning 16 million sterile fruit flies in diverse areas of the Santa Rosa valley in Huacho, to control a plague of the insects.

Senasa unit chief José Ochoa Delgado de La Flor informed that today’s countermeasure is part of a campaign initiated by the State, in coordination with the Inter-American Development Bank (IADB) to fight the plagues in various parts of the country.

The sterile flies were released over an area of 11,000 hectares of citrus plantations destined for export to markets in the United States and Europe. The flies were transferred in truck refrigerators from the Senasa laboratories in La Molina.

Ochoa emphasized that this procedure formally began in 1998 and extended until 2005, thanks to a US$ 75 million loan of the IADB. The second stage, carried out between 2006 and 2009, will cost US$ 27 million, of which US$ 15 million comes from the IADB and US$ 12 million from the Peruvian State.

In 1998 agricultural areas in the southern regions of Tacna and Moquegua received the initial treatment and today they are practically plague-free, according to Ochoa.

The sterile insects were originally captured in several countries and then genetically treated by the International Atomic Energy Agency (IAEA).

“These flies have special genes that are sensitive to heat which allows to eliminate the females in embryo state. Later on they are irradiated by using cobalt-60 which disrupts the final formation of their testes and they become sterile”, Ochoa explained.

From an economic point of view, Ochoa stated that in Tacna and Moquegua, which has about 40.000 hectares, annual losses of US$ 1.2 million have been avoided since the plague was wiped out.

Fruit flies can be a problem year round because they are attracted to ripened or fermenting fruits and vegetables. Tomatoes, melons, squash, grapes and other perishable items brought in from the garden are often the cause of an infestation developing indoors. Fruit flies are also attracted to rotting bananas, potatoes, onions and other unrefrigerated produce purchased at the grocery store.

They are common in homes, restaurants, supermarkets and wherever else food is allowed to rot and ferment. Adults are about 1/8 inch long and usually have red eyes. The reproductive potential of fruit flies is enormous; given the opportunity, they will lay about 500 eggs. The entire lifecycle from egg to adult can be completed in about a week. Fruit flies are primarily nuisance pests. However, they also have the potential to contaminate food with bacteria and other disease-producing organisms.

Prevention

The best way to avoid problems with fruit flies is to eliminate sources of attraction. Produce which has ripened should be eaten, discarded or refrigerated. Cracked or damaged portions of fruits and vegetables should be cut away and discarded in the event that eggs or larvae are present in the wounded area. A single rotting potato or onion forgotten at the back of a closet, or fruit juice spillage under a refrigerator can breed thousands of fruit flies. So can a recycling bin stored in the basement which is never emptied or cleaned.

People who can their own fruits and vegetables, or make wine, cider or beer should ensure that the containers are well sealed; otherwise, fruit flies will lay their eggs under the lid and the tiny larvae will enter the container upon hatching. Windows and doors should be equipped with tight-fitting (16 mesh) screens to help prevent adult fruit flies from entering from outdoors. Unfortunately, screens are not very common in Peru and thus hard to come by.

Eradication

Once a structure is infested with fruit flies, all potential breeding areas must be located and eliminated. Unless the breeding sites are removed or cleaned, the problem will continue no matter how often insecticides are applied to control the adults. Finding the source(s) of attraction and breeding can be very challenging and often will require much thought and persistence. Potential breeding sites which are inaccessible (e.g., garbage disposals and drains) can be inspected by taping a clear plastic food storage bag over the opening overnight. If flies are breeding in these areas, the adults will emerge and be caught in the bag.

If you prefer to refrain from using insecticides there is also an alternative approach:

You can construct a trap by placing a paper funnel (rolled from a sheet of notebook paper) into a jar which is then baited with a few ounces of cider vinegar. Place the jar trap(s) wherever fruit flies are seen. This simple but effective trap will soon catch any remaining adult flies which can then be killed or released outdoors.

(with information from the University of Kentucky, USA)

Wolfy Becker

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