SCIENCE-BRAZIL: Scientists Fight White Fly Menace

By Mario Osava Reprint | | Print |

Mario Osava

RIO DE JANEIRO, Aug 9 1998 (IPS) - Brazilian researchers sat down Sunday to examine ways to step up their war against one of the worst plagues to hit local agriculture this century: the dreaded white fly.

The insect, whose scientific name is Bemisia argentifolii, already has caused damage estimated at 700 million dollars in Brazil, according to the Agricultural Research Company of Brazil (Embrapa), which is coordinating projects related to it.

The fly was identified more than 100 years ago but was hardly a source of concern, since it affected only a few species and did not seriously threaten agricultural production.

However, mutation has made the white fly more aggressive and broadened its range. Today, it is present in 18 of Brazil’s 26 states, attacks more than 700 kinds of plants and has been spreading rapidly throughout the world, decreasing farm production by billions of dollars.

Cotton, various fruits and some vegetables are the fly’s main targets in Brazil, where one of the worst affected regions is the northeast, an area that is also frequently hit by devastating droughts such as one that is now going on.

The insect’s ability to reproduce and spread quickly, travelling seven kilometers a day in huge cloud-like swarms make make many see it as the plague of the century.

The immediate fight against the fly in Brazil will consist of a combination of poisons and biological control with the aim of containing its spread, according to entomologist Maria Regina Vilarinho of the Center for Genetic Resources and Biotechnology, one of the dozen or so institutes under Embrapa’s coordination.

The plague was also the topic of an international seminar which, three months ago, brought together some 300 experts in the northeast Brazilian town of Fortaleza.

The fly is not expected to be eradicated in the immediate future. “The United States has lived with this plague for 12 years” because the insect quickly becomes resistant to the chemical products developed to fight it, according to Vilarinho.

U.S. researcher David Akkey estimated that losses caused by the fly in the United States have reached at least two billion dollars, although in some regions it is considered under control.

The small white fly, which is 8 to 9 millimetres long, lives for 3 to 4 weeks in temperatures around 25 degrees Celsius. It sucks the sap of plants, killing them or greatly reducing their productivity, and also transports viruses harmful to agriculture.

In Brazil, it has caused the loss of 30 to 100 percent of fruits and garden vegetables in affected areas, while the market price of cotton has dropped because its fibres have been altered by the plague.

The fly is the main item on the agenda of the XVIIth Brazilian Congress of Entomology that began Sunday. Some 1,500 scientists and researchers are scheduled to attend the meeting which continues to Aug 14 and will examine some 1,000 different studies.

The Congress will also pay attention to other insects, like the locust, which is plaguing agriculture in central and western Brazil.

Congress president, Eurpedes Barsanulfo Menezes, a professor at the Federal Rural University of Rio de Janeiro, is an expert on termites, which in his opinion, constitute the greatest danger for the next millennium. Termites, Menezes has said, have been causing an estimated one billion dollars in losses in the southern United States per year.

The meeting also will look at the many useful insects which contribute to biological balance and even help control pests.