IRIN
MYANMAR: Cyclone-hit farmers battle snails
26 September 2008


THONEGWA, 26 September 2008 (IRIN) - 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 [see: http://www.issg.org/database/welcome/], 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 [see: 
http://www.irri.org/publications/irrn/pdfs/vol30no2/mini.pdf].

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

According to the institute [see: http://www.philrice.gov.ph/], managing 
problem snails is only possible once there is a clear understanding of 
the identity and biology of the pest species.

Growing numbers

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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