African snails threats Kerala human population
Suspected disease found in humans at Kochi
By : rakesh nair
Update: 2014-08-04 05:39 GMT
THIRUVANANTHAPURAM: Does the dwindling firefly population hasten the explosion in numbers of African snails (Achatina Fulica) across districts in Kerala? Yes, say researchers.
The firefly larvae aka glow worm, once found abundantly in Kerala, eats the young ones of African snails, one of the most prolific invasive species in the world. It is threatening agriculture as well as the strength of buildings in ten districts across Kerala. They hog on not less than 500 plant species, including coconut, vegetables, cocoa, papaya, banana, coffee, rubber, sand, cement etc.
Snails can harm humans as they are potential carriers of nematode (worms) named Angiostrongylus contonensis that causes lethal Eosinophilic meningitis disease in humans.
“We have found that around 10 children in Palluruthi, Ernakulam were admitted in hospitals owing to this meningitis. We have collected samples of African snails from the area and are checking them for traces of worms. If confirmed this will be first such incident in Kerala,” said T.K. Maneetha, a researcher at Kerala Forest Research Institute (KFRI).
The bad news is that African snails have increasingly started to threaten paddy fields in Palakkad, the granary of Kerala.
“The snails (weighing up to 450gms) climb paddy crops breaking them,” Maneetha added. The good news is that bird predators like Crow Pheasant (Uppen/ Chemboth) which eat snails are increasing in areas like Ernakulam which are hit by snail infestation. The places with high amount of light pollution (light sources at night) and fewer woods are hampering the growth of firefly population. Ducks also can help in keeping a check on snail infestation.
Will Nature keep a check on the slimy creatures on its own? No, the Giant African snails are hermaphrodites with each having both reproductive organs. There are instances of self-fertilization in areas where the infestation has just started. Each snail can lay around 1,200 eggs and almost all of them can hatch.
The Director of Agricultural Department, R Ajith Kumar said that the department has no funds to combat the snail menace. “We have started control measures under the aegis of KAU,” he said.
Earlier panchayats hired people under National Employment Guarantee scheme to eradicate snails but now there are restrictions to employ them for the task.
As per experts, in Kerala Agricultural University (KAU) there is little awareness among people in power when it comes to the snail menace. When asked by this correspondent about their anti-snail campaigns, the Palakkad district Medical Officer Dr K. Venogopalan claimed that snails pose no threat to humans.
“We had asked the Thiruvananthapuram Corporation to start a campaign to eradicate snails from areas including Poojapura but there was no response. Panchayats in Pathanamthitta have informed that there are no funds to combat snail menace,” an expert said.
Flashback: Journey from Africa to Kerala
Like in the case of every invasive species, the snails were first introduced to the state by a scientist’s mistake. A researcher named P.N. Radhakrishnan of Elapally, Palakkad carried some snails home for research when he visited East Africa in 1955.
He initially reared snails in glass cages in his house and when their population increased, he released them it into his backyard. The snail started eating up crops in Elapally when some ‘smart’ people there decided to pack and throw them at Palakkad municipality area. Though there was an increase in snail population in 1975, they remained untrained for reasons unknown until 2005.
Initially limited to Palakkad municipality, it spread to Konni in Pathanamthitta, Cherthala in Aleppey, Palluruthi in Ernakulam and Poojapura, Shangumughom and Vanchiyoor in Thiruvananthapuram. According to the latest reports, they have spread to Kinginimattom in Kochi, Muhamma and Aroor in Aleppey, Kanjikkodu in Palakkad, Azhiyoor in Mahe, Chittoorkavu in Pathanmthitta and areas across Kannur and Kozhikode. The African snails are not found in Idukki, Kottayam, Thrissur and Malappuram.
Where do they thrive?
The snails burrow in trees and rocks at night time. These nocturnal creatures hide when the temperature goes above 30 degrees. According to T.V. Sajeev, a scientist at Kerala Forest Research institute these creatures can hibernate for over three years.
“They need a lot of calcium and hence eat up plastered, painted walls,” he said.
How to get rid of snails
The home remedy to eliminate snails is to handpick, dump it in a pit and sprinkle salt on the underbelly. However this damages the fertility of the soil.The experts in Kerala Agriculture University have recommended spraying of copper sulphate solution and Pottassium Permanganate to kill the snails.
In Konni and elsewhere people have successfully used water mixed with 60 gm copper sulphate, 25 gm of tobacco juice to kill the snails. Indian researchers are looking for methods to enhance the breeding of fire flies.