Almost half of the food produced in the world today is lost to pests, despite the fact that world pesticide use will reach a record 4.1 billion pounds this year.

That amounts to more than a pound of pesticide for every man, woman and child on earth. Dr. David Pimintel of Gornell University told the annual meeting of the American Association for the Advancement of Science, last month. He saidnce, last month. He said that is an increase of 20 per cent in the last five years.

Progress is not being made against the world's pests, Pimintel and the University of California's Dr. Ray F. Smith said, because the pests are developing a growing immunity to pesticides and because so much pesticide is being used that it is destroying the predators and parasites that are the natural enemies of the pests.

"Fully 90 per cent of all the eggs and larvae of crop pests would be destroyed by their own natural enemies if we made better use of pesticide," Smith said at a press conference. "We're not doing any better than half that, because of our overuse of pesticide."

The leading users of pesticide are the Central American countries of El Salvador, Guatemala, Honduras and Nicaragua, where 70 million pounds of insecticide are used to kill cotton pests every year. In El Salvador alone, an estimated 2,400 pounds are used on every square mile of cotton fields. The tiny country consumes one-fifth of the world's parathion, a leading insecticide.

Cotton yields have not increased in Central America, Pimintel said, because overuse of insecticide has killed off the parasites that destroy the boll weevil and bollworm. At the same time, the indiscriminate use of pesticide is responsible for 4,000 to 5,000 human poisonings every year in Central America, he said.

Moreover, mosquito populations along the coastal plains of Central America have grown so resistant to pesticides that they have begun to carry and spread malaria in all four countries, the scientists said; in El Salvador alone, the incidence of malaria rose from 25,000 cases three years ago to more than 80,000 last year.

Pimintel and Smith said that about 33 per cent of the food lost in the world is lost to pests before it can be harvested.Another 9 per cent is lost after harvest, much of it to rats before it can be marketed.

Dr. Max Milner of the Massachusetts Institute of Technology said that in one recent year rats consumed 50 per cent of the sugar and corn and up to 90 per cent of the rice harvested in the Philippine Islands. Milner said that in India alone it would take a train 3,000 miles long to haul the grain eaten by rats in a single year.