“Bad Air Day” Will Suffocate Fruit Pests

Scientists with the Agricultural Research Service are devising a method for suffocating Mexican fruit flies trying to hitch a ride in grapefruit shipments. Studies are being conducted under a cooperative research and development agreement with TransFRESH Corp., Salinas, Calif.

Fly invasions can trigger costly eradication programs requiring aerial sprays of insecticide. Plus, the pests can devastate farm production and trade, because quarantines must usually be imposed to prevent their spread. Methyl bromide is the most common quarantine treatment available for grapefruit and other citrus. But this pesticide is slated to be phased out by 2001 for environmental reasons.

A promising alternative is a method called CA--controlled atmosphere. A dramatically altered but precisely determined balance of air’s three main gases--oxygen, nitrogen and carbon dioxide--is pumped into a shipping container carrying fruit. The fruit flies suffocate because the atmosphere holds less than 1 percent oxygen instead of normal air’s 20.9 percent.

ARS scientists have seen promising results from lab tests with, to date, more than 100,000 fruit flies and 5,000 grapefruit. In some tests, all the flies died in 1 to 3 days without compromising fruit quality.

An effective CA method would give shippers a new, in-transit insurance policy. Even if Mexican fruit flies are found infesting a growing area, CA would stop them from surviving the trip to a new locale in outgoing fruit shipments--and the shipments could continue. The scientists also are exploring CA as a quarantine treatment for oranges and to preserve the quality of mangoes during shipping.

A feature article about this research appears in the November 1996 issue of ARS’ Agricultural Research magazine. A hypertext version of the article is on the World Wide Web.

Scientific contacts: Robert Mangan and Krista Shellie, Crop Quality and Fruit Insects Research, Subtropical Agricultural Research Laboratory, Weslaco, Texas, phone (210) 565-2647.