As rapid development threatens to dent Kerala's reputation as an eco haven, Kevin Rushby meets the greens fighting to preserve the traditional way of life

I'm lying on my back. It's night and a tropical rain shower is pattering gently on the thatched coconut leaves. Lovely. But there is something else too: a skittering and rustling sound. A creature is moving quickly across the roof. I flick on the torch. Directly above me in the thatch a hand-span-sized spider is tracking a pale-winged moth back and forth. It's an upside-down mini-safari, a life and death drama. "You wouldn't get this kind of entertainment in a sealed air-conditioned room," I tell myself firmly. "Thank you, Lord, for eco-tourism."

Like an antelope on the savanna, oblivious to the approaching lion, the moth stops and - dies in the predator's jaws. I flick the torch off, listen to the soft scrunching noises, grateful for the doubtful security of the mosquito net.

In the morning my friend Raj is pleased to hear of giant arachnids in his roofs. "They keep the bugs down - all part of the eco-friendly experience." He's built what he claims to be a genuinely "green" house up in the Western Ghat hills of Kerala, and he wants to show me around. "The coconut leaves for the roof are from the trees here. They're cool and airy - no need for air-conditioning. Floors are rammed earth, walls are strengthened with bamboo, our electricity is solar, our water is from a spring."

He takes me on a tour of the hillsides, scrambling up to the viewpoint from where we can see Kerala stretched out beneath us, a sea of coconut trees with hardly a break.

"Don't be misled by the view," Raj warns me. "Below the treetops, Kerala is really struggling. We're on the brink of an environmental disaster."

He's not the only one to think so. Under a recent headline, "God's Disowned Country," lampooning the Keralan state motto, the magazine India Today thundered of, "large-scale devastation of environment at its famed beaches, backwaters and hills."

Even just a decade ago India appeared to be a country with impressive green credentials. Almost everyone travelled by public transport; ox-carts were common; wastes like bottles, boxes and rags were collected, sold and recycled; millions cooked on dried cow dung and drank their tea from terracotta cups. Many people still revered Gandhian ideals of simple self-reliance. It was no surprise when the southern state of Kerala, communist-run since 1957, blazed a trail for the rest of the world with a ground-breaking commitment to eco-tourism. Despite some huge polluting industries and problems of rapid population expansion, Indians did seem to have ready access to traditions of sustainability and environmental responsibility that could make a success out of the Keralan vision. Now, a few years on, some say that commitment is disappearing under a landslide of construction and economic development.

Travelling down from Raj's place in the hills towards the coast, the problems are obvious. Roads are choked with traffic, rice fields lie untended, and everywhere there are new concrete buildings going up. Raj's use of local materials looks eccentric in comparison to these palaces.

"They use local sand for the cement," he points out, "but a lot of it is mined illegally from the backwaters, destroying the rivers."

Piles of tropical hardwood lie waiting to be made into furniture and fittings - most of it taken from Malaysian rainforests. Moving through the state, I am staggered by the scale of the unending construction boom - hardly a break between towns and villages.

At Poovar, an island created by freshwater channels close to the sea, Mark and Sujeewa Reynolds, owners of small-scale resort Friday's Place, told me where the money was coming from. "Dubai. There's a lot of non-resident Indian money flowing in from there."

Poovar is a place that has, as yet, escaped the worst excesses of development. Rivers are lined with coconuts and birdlife abounds. Friday's Place is a delightfully low-key retreat of stilted thatched lodges connected by wooden walkways. Mark is pragmatic about building a resort - wary of any bold claims of eco-friendliness. "We're small - low impact. I did use Malaysian hardwood in construction, but we do lots of other things: local bamboo and coconut thatch, solar power and local staff. People come here for good food and conversation. They lie in hammocks reading and swim in the river. Our footprint is very small."

Further north, near Alleppey, Marari Beach resort is a very different operation, spread over a huge area with all the trappings of an upmarket beachside resort: swimming pools galore and a swanky restaurant. Nevertheless, the place does have some real environmentally sound features. Vegetables and herbs are grown on site and much of the cooking is done on methane produced by a huge bio-digester. I particularly liked the bathrooms where banana trees grow in the soakaway areas.

Adrian Briggs, British owner of nearby Fragrant Nature Resort, has found building an eco-lodge much tougher than he imagined when he sold his London home and set out for Kerala three years ago. He is unimpressed by Keralan government avowals of environmentalist objectives. "Soon after the state government announced the eco-tourism initiative they also abolished the tax discount on non-AC rooms."

Sadly Adrian has decided to leave - a pity since Fragrant Nature is an exceptional place - and his view now is that eco-tourism may do more harm than good. "I think there's a real danger that it can be used as an excuse to open up areas best left undisturbed."

A few miles away I saw what "opening up" an area can mean. Keppel beach, north of the backpacker resort of Varkala, is one of India's best. At sunset, I watched a pod of dolphins cruising north, feeding on the tuna that were following the shoals of anchovies. Next to me fishermen were binding their boats together: three logs of wood wrapped up with coconut fibre - katu maram they call them in Malayalam - "tied logs", the origin of the English word catamaran. A couple of German backpackers sat in the warm sand, chatting and laughing with locals. Among the coconut groves oil lamps started to flicker in the thatched huts.

One of the fishermen, Abdulsamad, stops work to fill me in on the reality of this apparently idyllic spot. "They are building a road along the beach - to bring in more tourists," he says. "Tourism is very strong now. How can we fight it? They will take our beach and our livelihood."

Another man takes me to see the concrete surveying markers which villagers have tried, and failed, to destroy. "The new road and sea wall will cut us off from the sea. Then they will sell the land from under us for development."

"Where will you go?"

He shrugs. "I'm too old to go anywhere. My sons will go sand-mining or, God willing, to jobs in Dubai."

The coast and backwaters are the focus of many problems in Kerala. Move inland and it is still possible to find a slower, more traditional way of life. At Palakkad, I discovered a place called Ayurveda Mana, an ayurvedic retreat built around an ancient royal palace of the Thampurans, a ruling dynasty.

Sajeev Kurup, a descendant of that ruling family, explained to me how the Mana had been created. "Our family always had strong interests in Keralan cultural arts like the martial art, kalari, and also elephant-training and elephant medicine." He grins at my reaction. "Yes, we practise elephant Ayurveda - you can even train to be a mahout here."

Among all the Ayurvedic treatment centres around India, Ayurveda Mana must have strong claims to being the most authentic. Medicines are made in the traditional way: in bronze cauldrons in a room inside the local temple, the plants having been brought in by local tribal women who collect in the forest. The founding father of the place was the late Aram Thampuran, a legendary master in ayurveda, yoga and kalari, the Keralan martial art. His legacy is an integrated treatment centre that offers a unique range of treatments and activities - all done in accordance with ancient principles. After a vigorous foot massage, for example (that's a massage done with the feet) - I was escorted to my airy spacious bedroom by an attendant with an umbrella, as is required by Ayurvedic texts. Food is plain. There is no alcohol - a waiter went into shock when I asked for a beer. But with links to local musicians, yoga experts and martial arts masters, a stay here can be made into something truly memorable.

Gopinath Parayil is a local emigre who came home and saw how the loss of these ancient traditions were impoverishing the state. "My home river, the Nila, was dying - over-mined, over-fished, over-used," he told me over breakfast at Ayurveda Mana. "And communities around the riverbanks were disappearing too. As a child I remember seeing the Pulluvar people, snake-worshippers, come to the door. They'd sing to celebrate the rice harvest. Now there is no harvest and they don't come any more."

Gopi decided to do something positive. He went in search of the snake-worshippers and found them. Their culture was dying with the decline of rice-growing and their children didn't want to learn archaic songs with titles like The Tale of the Eight-headed Cobra. Pulluvars were the traditional bards of Kerala, but they had not found a place in the new tourist-friendly culture, perhaps because of their low-caste status.

Gopi soon realised that there were other groups in the same position: the Manans were a low-caste community of drumming people whose astonishing musical skills were ignored by the Keralan establishment and unvisited by tourists. Gopi set up Blue Yonder to bring visitors to the musicians and dancers.

"Money from tourism just doesn't reach people like this," he explained to me. "I realised that real eco-tourism needs these communities to thrive."

He even started paying illegal sand-miners to take tourists on boat trips. "No one knows the backwaters like the sand-smugglers," he says. "I wanted to show them they could make money from their knowledge - without destroying their environment."

Gopi's hunch is that some tourists want to see genuine music and dance, not lacklustre hotel performances. That evening, by lamplight, we watch Joti, a local Pullavar woman, hammer out a song called - she tells me - The Origin of Snakes. This is what it must have felt like seeing Robert Johnson play Delta Blues at the crossroads in 1929: raw and heartfelt and utterly mesmerising.

Joti and her husband Gopalikrishnan tell me that since visitors started coming to see them perform, their children have started to take an interest in learning the songs - an interest they had previously not had.

"This is what I'm hoping for," says Gopi. "If we can convince the kids to stay and learn about their own roots, not go off to Dubai, then we might have a chance in fighting to save the environment."

Back in Trivandrum's Chelai Market I find old and new India in a head-to-head confrontation: an ox-cart versus a 4x4 car. The ox-cart driver is sitting, impassively, watching the car-driver honk himself into a frenzy. "India at the crossroads," I muse. "Old and new struggling to co-exist." And at that moment, a man dressed in traditional lunghi, pushing a fine old bicycle, threads his way neatly past the cow-car confrontation. On his handlebars is a package of vegetables wrapped in a leaf and tied up with a length of raffia. As he passes, I hear the mobile phone tucked in his shirt pocket start to ring.

Getting there

Emirates (0844 800 2777, emirates.com/uk) flies to Trivandrum, via Dubai, from Heathrow, Gatwick, Birmingham, Manchester, Newcastle and Glasgow from £484.40, including taxes.

Where to stay

Colours of India (020-8343 3446, colours-of-india.co.uk) tailormake a two-week itinerary to Kerala & Tamil Nadu, with stays at Fragrant Nature, Ayurveda Mana and Friday's Place, from £1,676, including flights and chauffeur driven transfers. Marari Beach resort (casinogroupkerala.com) doubles from US$175 B&B.