In many countries of Africa, vegetables and fruits have an important role in providing a balanced nutrition in the otherwise staple-based diets of the rural and urban poor. Horticultural production for local and export markets is also one of the most profitable agricultural enterprises in the continent. In particular, the cultivation of fruits and vegetables enables many small-scale farmers to make a decent living from their minute landholdings.

If the technique succeeds, farmers will greatly improve mango yields to about 10 tonnes compared to about four tonnes when pesticides are used'.

Special report by Xinhua Correspondent Ejidiah Wangui

Mango farmers in Kenya are headed for better days following the introduction of a new way to control pests ravaging the crop.

The farmers will soon reap huge profits from their produce after the introduction of a parasitic wasp and a combination of other Integrated Pest Management (IPM) techniques to control fruit flies which cause great damage to the mango fruit.

The fruit fly parasite referred to as Fopius arisanus was brought into the country from Hawaii after a new fruit fly species from Sri Lanka invaded the country accidentally, destroying all the other pest control practices that had been implemented since the species proved to be very aggressive.

The technique which is the brain child of the International Centre for Plant Physiology and Ecology (icipe), the Kenya Agricultural Research Institute (KARI) and the Ministry of Agriculture in collaboration with other players in the private sector have proved to be a new biological weapon against fruit flies hence saving a lot of farmers from counting losses any more.

Dr Sunday Ekesi told Xinhua recently that a senior scientist at icipe said that the parasitic wasp is highly efficient in controlling the fruit fly menace and can be used alongside other measures that are applied against the pest.

The Kenya Plant Health Inspectorate Service (KEPHIS) and the Ministry of Agriculture, he told Xinhua, have collaborated in releasing the wasps across Kenya in mango-producing regions. Tanzania, Benin, Senegal and Mozambique are countries also seeking the help of the wasp.

"As much as it was difficult to go back to the farmers advising them to switch to this new technique, it is proving to be successful as more farmers are now adopting it as it can destroy both the native and other foreign parasites that cause massive damage to the mangoes," Dr Ekesi said.

The parasite is self perpetuating, works free and needs no input from the grower.

"If the technique succeeds, farmers will greatly improve the mango yields to about 10 tonnes compared to about four tonnes when pesticides are used," the scientist explained.

For the parasite to work effectively, mango farmers must minimize cover spray of pesticides in their orchards to avoid killing them.

The scientist, during an interview with Xinhua, said that the parasite attacks the eggs of the fruit fly and develops through the larval stages of the fruit fly before killing the host.

On the other hand, he said, there are four dangerous types of fruit flies which destroy mangoes and other fruit trees.

Additionally, icipe promotes a combination of methods through the use of Integrated Pest Management techniques such as baiting, use of bio pesticides which are very friendly to the environment.

icipe has also encouraged use of fungal pathogens, mechanical fruit protection as well as practicing orchard sanitation since poorly managed or abandoned orchards and a variety of wild hosts can result in high population build up of fruit flies.

Red ants also have a tendency of chasing away the fruit flies. Currently, mango farmers across the country are being educated on the new innovations for effective control of the fruit fly.

Dr Ekesi explained that the baiting technique for example, is a very simple and effective method compared to the use of boom sprays.

"A farmer can choose a one square metre of mango canopy where the protein bait is applied in low volumes.

"The flies are then pulled on the spot to feed on the bait and end up dying," he added.

He further pointed out that IPM methods reduce the population of the fruit fly in the mango fields to over 80 per cent.

The methods are also more effective and cheaper to apply as compared to the use of pesticides which apart from being expensive also contaminate the environment and the water system. The fruits are not spared either.

Other methods include the cold and heat treatments which are recommended for farmers intending to export their fruits.

This is a post-harvest treatment which ensures that the fruits are not contaminated by the flies hence safe for consumption.

According to Ekesi, the cold treatment is applied to decrease the temperature of the fruit below the thermal limit of the fruit fly.

"The fruits are placed in a cold chamber of about 1.11 degrees celcius for 14 days killing all the eggs and maggots, making them safe for export," explained the scientist.

This method is mostly applied in citrus and avocado fruits.

The heat treatment on the other hand is applied in mangoes. The fruits are placed in a large container with water that has been heat to about 46 degree celcius.

The farmer can place the fruits for a specific time period varying from 30 minutes to one hour and on removal, all the eggs will have been killed.

Carrying out these treatments increases the yields and improves the quality of the fruits.

So far, icipe has been getting a lot of requests from farmers to educate them on the new techniques which have almost 50 percent increase in the yields.

Farmers could save a lot by abandoning use of chemicals and adopt the Integrated Pest Management techniques to their farming methods.