Giant snails threaten to conquer more areas in Kerala

Likely to infest at least 41 locations in four districts

Giant African Snails (Achatina fulica Bowtich) are likely to infest at least 41 locations in four districts in the State, according to a scientific prediction. Their presence has already been reported from 10 districts.

The Kerala Forest Research Institute (KFRI), Peechi, Thrissur, has come up with a prediction after assessing 20 parameters in the areas from where severe attack of the invasive snail species was reported. The parameters to make a prediction model included, elevation from the mean sea level, precipitation during the wettest and coldest months, mean monthly temperature and maximum temperature during the warmest month, said T.V. Sajeev, the invasive species expert who led the KFRI team.

Experts have predicted 70 to 100 per cent possibility of the snails establishing themselves in these districts.

Palakkad has been identified as the most vulnerable district with the study predicting attack in 22 locations. Puthunagaram, Kodumbu, Peruvembu, Mundur, Puthuppariyaram, Marutha Road, Kannadi, Koduvayur, Chittur-Thathamangalam, Mathur, Pirayiri, Vadavannur and Thenkurissi are some of the vulnerable areas in the district.

Parali, Kuzhalmannam, Pallassana and Polppully are also susceptible to the attack.

In Kollam, Neendakara, Thrikkadavoor, Thekkumbhagam and Chavara are at risk, followed by Kochi Corporation area, Chellanam, Thripunithura, Njarakkal, Udayamperoor, Mulavukad and Elamkunnapuzha of Ernakulam district. The other areas in Kochi include, Cheranallur, Thiruvankulam, Nayarambalam, Maradu, Kumbalam and Kadamakkudy. Perumbalam and Panavally are the two vulnerable areas in Alappuzha district.

The researchers surveyed the State from Valiyathura in Thiruvananthapuram to Manjeswaram in Kasaragod in 2010 and located 29 distinct populations of the mollusc. Large populations were found in Konni in Pathanamthitta, Kolenchery in Ernakulam and Muzhupilangad and Parassinikkadavu in Kannur district. The presence of the pest has already been reported from Alapuzha, Ernakulam, Kozhikode, Kannur, Kasaragod, Mahe, Malappuram, Palakkad, Pathanamthitta and Thiruvananthapuram districts. Konni in Pathanamthitta was one of the worst hit areas.

The species has been listed as one of the “100 World's Worst Invaders.” The snails, which live up to six years in favourable conditions, feed on over 500 different plant species. This include some of the economically important plants like cocoa, papaya, peanut, rubber and most types of beans, peas, cucumbers, melons, lichens, algae and fungi. The infestation was found to be intense in areas with high population density. Areas with untreated garbage and places of water logging are their favourite spots, Dr. Sajeev said.

Experts have recommended the use of calcium arsenate and Metaldehyde under expert supervision in areas of high infestation. However, they advise to desist from the use of salt to kill the pest as it alters the soil pH. The meat of the snails thus killed will rot with foul smell. Moreover, the application of salt will become untenable during rainy days, researchers said.