There is a reason why dragon fruit is considered a rich and famous fruit in Viet Nam: it is exported to 40 countries and return from dragon fruit production is several times higher than from rice production.
In Binh Thuan province, around 29 500 hectares are dedicated to growing the fruit, with a production of nearly 600 000 tonnes last year, and its Department of Agriculture and Rural Development plans to increase that by 2020. However, this plan may be hindered by formidable pests capable of decimating dragon fruit crops: fruit flies.
“Dragon fruit is a favourite crop in Viet Nam because farmers are aware of its potential to earn them a steady income,” said Hien Thanh Thi Nguyen, Deputy Head of the Entomology Division at Viet Nam’s Plant Protection Research Institute. “Unlike many other fruits that are seasonal, dragon fruit can be cultivated all year round and each crop season lasts only two and a half months, so it has great economic importance. The fruit is very important for the province’s economy, but the fruit flies are a big problem for this area.”
Therefore, thePlant Protection Research Institute, along with staff from the Agriculture and Rural Development Department of Binh Thuan province, teamed up with the IAEA and the Food and Agriculture Organization of the United Nations (FAO) in a pilot project to test the effectiveness of implementing an integrated pest management approach, including a form of insect pest control known as the Sterile Insect Technique (SIT). Using this technique, fruit flies are mass-produced and then sterilized using ionizing radiation before being released into the environment to mate with wild flies, producing no offspring.
Towards a coordinated area-wide approach
Methods traditionally used to suppress fruit flies in the province have been uncoordinated, with individual orchards carrying out their own pest management using chemical pesticides on a field-by-field basis. This has limited effectiveness, given the speed at which the flies reproduce – laying up to 500 eggs at a time – and their ability to move easily to untreated crops on neighbouring farms. Integrated pest management using SIT offers the possibility of permanently reducing or eliminating fly populations across a wide area.
The integrated pest management pilot project began in January 2016, covering around 1500 hectares of dragon fruit crops. In the first three-year phase, bait sprays, sanitation and a male annihilation technique were used to reduce fruit fly infestation in the pilot area to half of the infestation levels on untreated farms.
The final stage of the programme is being implemented this year, involving the use of SIT for the first time in Viet Nam. Around one million fruit flies are being reared in special facilities every month, sterilized using irradiation, and then released into the pilot project’s pest-infested areas to further reduce the fruit fly population. If successful, this has the potential to benefit around
30 000 households and 250 dragon fruit trading enterprises in Binh Thuan in the longer term.
“We’ll release the sterile flies by driving through the dragon fruit fields by car and motorbike, throwing packets of irradiated flies out into the fields,” said Hien. “We need to drive through the farms every week following the dragon fruit crop season timeframes.”
Changing farmers’ mindsets
Getting to the point of SIT implementation has not been easy, due to limited knowledge of the technique within the local offices and resistance from dragon fruit farmers, who did not at first understand how releasing more flies into the fields would ultimately reduce the population.
“They didn’t understand that the fruit fly would be sterilized,” said Hien. “They would say, ‘We have so many flies already, how can we combat this by bringing in more flies?’ So, we had to change the way we approached farmers about this with a series of trainings, leaflets and television advertisements, and it took about two years before they started thinking that maybe this could help. It’s important because getting the programme to work depends on the farmers in the entire area actively participating in the pest management.”
Continued FAO/IAEA support
The IAEA and the FAO have supported the pilot project through the IAEA technical cooperation programme, focusing on integrating SIT with other suppression methods. This support has involved collecting baseline data, installing facilities to kick start the application of SIT in the country, supplying materials and equipment, and training experts in area-wide fruit fly management through scientific visits and fellowships.
As the pilot project prepares to enter its final phase, the IAEA and the FAO, through the Joint FAO/IAEA Division of Nuclear Techniques in Food and Agriculture, continue to provide technical advice and knowledge on the use of integrated pest management techniques and SIT.