Cyclone-hit farmers battle snails

An unidentified freshwater snail has left scores of paddy farmers in southern Myanmar reeling.
 
In the wake of Cyclone Nargis - which left nearly 140,000 people dead or missing in May - farmers cite an increase in the invasive species.  
Experts believe the snails were washed up by the sea’s tidal surge when it submerged more than 783,000ha of rice paddy fields or 63 percent of paddy land in the affected areas.
 
The snails devastate rice fields by feeding on the base of paddy seedlings, as well as on plant leaves and stems, say specialists, and are capable of consuming the young plants overnight.  
They prefer young plant parts that are soft because the snails feed by scraping the plant surface with their rough tongue, the experts add.
 
"We coped with the few snails and sea crabs that appeared before. We simply collected them and destroyed them," said Tint Naing, a paddy farmer from Thonegwa Village, Kunchangone Township, in Myanmar's cyclone-affected Yangon Division, collecting a handful of the pests in his hand.  

But according to specialists, it is unlikely that the freshwater Malaysian Trumpet Snail (Melanoides Tuberculata) in his hands, commonly found in aquariums, is the culprit.

“It seems to me quite strange and even quite impossible that this species was responsible for the damage observed in the rice fields,” one leading snail expert in France told IRIN.  

Such snails feed on minute particles or organic waste and reportedly never feed on aquatic plants, he explained. And though an increase in their numbers in the aftermath of Nargis was possible, a more likely suspect would be the Golden Apple Snail (GAS) (Pomacea Canaliculata), a freshwater snail commonly found in Asia, with a voracious appetite for water plants including lotus, water chestnut, taro and rice, he said.  

Major rice pest

Originally from South America, the GAS is described as one of the world’s 100 worst invasive species by the Global Invasive Species Database, which aims to increase awareness about invasive alien species and to facilitate effective prevention measures.  

Its invasiveness is related to its inherent characteristics: a high reproductive rate, adaptability to harsh environmental conditions, ability to invade diverse habitats through multiple pathways, a wide range and voracious appetite, and an ability to compete with native species and native fauna, stated a report by Revindra Joshi of the Department of Agriculture-Philippine Rice Research Institute.

Once the GAS has established its presence, controlling it is difficult.  

According to the  institute, managing problem snails is only possible once there is a clear understanding of the identity and biology of the pest species.  

Photo: Lynn Maung/IRIN

It's unlikely these snails - Melanoides Tuberculata - are the culprits

Meanwhile, for farmers on the ground the prospects look grim. Many lost everything to Nargis and are struggling to rebuild their lives.    

The rural economy is based on agriculture, primarily rice, and approximately 50 to 60 percent of families in the Ayeyarwady Delta are engaged in agriculture, according to the UN Development Programme (UNDP).

"We have never seen so many. They have destroyed our fields," said 30-year-old Tint Naing.
 
"We're observing how big this issue [snails] is in the delta and will help [farmers] solve it," said Rene Suter, head of the emergency and rehabilitation coordination unit for the UN Food and Agricultural Organization (FAO) in Yangon, the former capital.
 
Yet for many hard-hit farmers it is already too late - many of the snails have already eaten their way through this year's crop.   
 
Dangerous pesticides  
 
Lacking government or international assistance to deal with the menace, many farmers resorted to pesticide, only to have it kill everything else at the same time, including fish.
 
"We don't know the name of it or its active ingredients, but it really kills the crabs though it cannot kill the snails," said one exasperated farmer in Pyapon.
 
Agricultural specialists are cautioning farmers to be better aware of the pesticides they use.
 
"They [farmers] should check what kind of pesticide it is and its active ingredient ... They should also check whether it is registered or not," warned one agricultural expert from the Pioneer Post Harvest Development Group, a semi-governmental organisation.
 
If the ingredient of a pesticide remains active for long time, it could be harmful to humans, the specialist said.
 
Others offer a more conventional solution to the problem. "We would like to recommend mechanical control to get rid of snails and crabs," Aung Kyi, an agricultural expert within FAO's Emergency & Rehabilitation Coordination Unit in Myanmar, said.
 
Traditionally, collecting the snails is easier for the farmers than using pesticides, Aung Kyi said.

“Currently, there is only one solution. Simply pick them up by hand and dispose of them. It's unknown what kind of [pesticide] could destroy them because there has not been any test on it,” one researcher at Myanmar’s Yangon University told IRIN.

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