Coffee plantations in northern parts of Kodagu district in Karnataka have been troubled by an infestation of giant African land snails in recent years. Planters lose up to Rs 12,000 per acre in efforts to get rid of the pest.Arriving through trade routes, this alien invasive species are voracious eaters of coffee plants. In 2017, they wreaked havoc in 300 acres in 45 plantations in Shanivarasanthe area of northern Kodagu.A catch-and-kill method devised by the Central Coffee Research Institute has been successful in containing the pestilence. The bait has been successful in killing 90% of snails in a co-ordinated operation. The monsoon rains have arrived late this year in the verdant hills of Kodagu (Coorg) in Karnataka, the coffee capital of India. For some planters, it’s a mixed blessing. A delayed monsoon is bad news in the Western Ghats mountain range, where farmers and planters have found themselves at the receiving end of extreme weather events triggered by climate change. Last year in August, unprecedented rains and floods harmed crops and coffee plantations, affecting many lives and livelihoods. In recent years, the rains have brought another problem with them — an infestation of giant African land snails that have caused massive losses to some 40-45 plantations spread over 300 acres of land in northern parts of Kodagu. The foreign pest, which is thought to have arrived in India through trade routes, attacks young coffee plants and devours tender leaves and stems, completely destroying the plants. These giant snails, whose shells can grow up to 20 cm in length, are not picky eaters. They eat over 500 plant species and adapt easily to different ecosystems, researchers have found. Giant African land snail, an invasive species, infest a coffee plant in Kodagu, Karnataka. Planters lose up to Rs 12,000 per acre in efforts to get rid of the pest. Photo by Pradeep Kumar. A fast breeder, this snail has emerged as a major problem for planters in the Shanivarasanthe area of Somwarpet taluk (administrative sub-district) in Kodagu. “They multiply in large numbers within a short span of time,” said Pradeep B. Shekar, who owns 40 acres of a coffee plantation. The giant African land snail, locally known as shanku hoola (conch worm) due to the shape of its shell, appeared in Kodagu for the first time in 2012-13 in 50-60 acres of coffee plantations in Shanivarsanthe. The local plantation owners fought the infestation and thought they have ridden themselves of the pest. But in 2017, the snails reappeared, wreaking havoc in an expanded area of 300 acres belonging to some 40-45 plantations. The planters say the pest attack costs them an additional expense of between Rs 10,000 and Rs 12,000 per acre, mainly due to the efforts to contain them. This shrinks their profit margins from the produce. Invasive species The International Union for Conservation of Nature (IUCN) lists the giant African land snail (Achatina fulica) as one of the worst invasive species in the world. An invasive alien species is “a problematic species introduced outside its natural, past or present distribution,” the IUCN says. “They may lead to changes in the structure and composition of ecosystems, detrimentally affecting ecosystem services, human economy and wellbeing.” African snails spread to new locations via trade routes, piggybacking on agricultural products, equipment, cargo, and plant or soil matter. While there is no consensus on how they found their way into the pristine landscape of Kodagu, it is certain that these pesky visitors have come with no exit plan. Giant African land snails in their early development stages inside a coffee estate in Handli village, Kodagu district. These fast-breeding snails have a lifespan of almost 15 years and can produce approximately 1000 eggs in that period. Photo by Abhishek N. Chinnappa. Achatina fulica is one of the four species of giant snails belonging to the Achatinidae gastropod family native to Africa. It is classified as an obligate-outcrossing hermaphrodite, which means that just one externally fertilised snail can establish a population. These snails reproduce in large numbers. The snails begin laying eggs at six months of age and can lay around 100 eggs in their first year, and up to 500 in the second year. Their life expectancy is around five years, and one snail can produce up to 1,000 eggs by then. The shell length of these snails ranges from 5 cm to 10 cm, though some adults may exceed 20 cm, and their average weight is about 32 gm.