A locust swarm can wreak havoc

Dr Tingle told Farming Today: "Fipronil was a cause for concern, because we knew this was the first large-scale use of it.

"There had been no trials done on a small scale within the specific and unique conditions of Madagascar before it was used in an emergency, where obviously the amount of insecticide sprayed and the areas covered are very large."

He found evidence of a decline in several species where Fipronil had been sprayed, including the Madagascar bee eater and the island's kestrel. But the biggest impact was on termites. Ten months after spraying, 90% of colonies surveyed were destroyed.

Dr Tingle said: "There was a risk there of affecting the soil ecology quite profoundly. The other thing that is very important is that termites are a very valuable source of food for a whole range of other animals.

Contradictory findings

He recommended a ban on Fipronil for barrier spraying. But Aventis CropScience, the chemical's maker, said the answer would have been to use larger barriers to isolate the locust swarms, and lower doses.

It said Dr Tingle's findings were at odds with research from South Africa, Ethiopia, Senegal and Mauritania.

Termites are key to the food chain

The UN Food and Agriculture Organisation provided technical assistance for the spraying. It maintains that evidence that Fipronil can cause cancer in laboratory rats is irrelevant to humans, although people in Madagascar eat locusts and feed them to their pigs.

An FAO eco-toxicologist, James Ewerts, told Farming Today: "Fipronil does not accumulate in food chains. There's no risk whatsoever for consumers of directly-exposed organisms."

The European Union has proposed ending Fipronil's use on agricultural products intended for children's food, but still defends paying for its use in Madagascar.

Non-existent problem

A spokesman said it was "the only chemical at the time which could be used against flying adult locusts and also against the larvae."

But an anonymous contributor to Farming Today, who made a covert assessment of the locust threat for the US Government, said the entire control programme had been a waste.

"I couldn't find any agricultural damage caused by the locusts. This programme was extremely damaging to Madgascar's ecology.

"It was a tremendous waste of aid money. A solution was used for a problem that didn't exist."