The white truffle season has started in Italy, but the crop is seriously depleted.

Hailed as the "diamond of the kitchen", the fragrant white truffle is a delicacy like no other. They are thought of as superior to their black counterparts, partly because they are notoriously difficult to find.

Unlike black truffles they can't be cultivated in plantations and will only grow in their natural, wild environment, in the woods of northwest Italy and central Europe.

They are found five to 20 centimetres below the ground near the roots of trees, and can only be found by well-trained animals.

Traditionally, pigs were used to hunt for truffles. Pigs have an excellent sense of smell, but they are rather too keen on the taste of the delicacy and they tended to gobble up their treasure. They were also deemed too bullish in finding their treats.

A truffle is the fruiting body of a fungal colony, but the fungus cannot produce its own nutrients. They are what is known as mycorrhizal, which means that they grow in association with the roots of another plant, stealing the carbohydrates and nutrients that they need from that other plant.

If this delicate fungal colony is disturbed, then it could prevent truffles growing the following year. The over-enthusiastic pigs often damaged the colony, so much so that they have been outlawed in Italy for hunting truffles.

Now dogs are used to hunt for the treasure instead during the season which runs from autumn to late February.

However, over the last 25 years there has been a 30 percent decrease in the number of truffles, and in some places they have disappeared altogether.

Truffles don't like extremes of temperature or extremes of moisture. The soil must be well-drained, but it cannot be bone dry.

It is thought that the drought that has gripped Italy over the past few years has had a large impact on the delicacy. This, together with recent severe storms, as well as the increased plantation of vines, has severely reduced the crop size.

Despite the reduction in the number of truffles, the International White Truffle Fair is currently taking place in Alba, northwest Italy.

A highlight is the auction, which has live satellite links to Dubai and Hong Kong, and it was Hong Kong which offered the winning bid of this year's largest truffle.

A well-rounded truffle, weighing 850g attracted a price of $87,000.

However, the record price ever paid for a single white truffle, was $330,000 in 2007 by the owner of a casino in Macau. He is clearly a man who loves his food!