Lychees and Longans — No Host for Carib Fly

Lychees and longans, tropical fruits gaining in popularity with consumers, have become important crops in southern Florida. Now growers have even more to celebrate than their crops' burgeoning commercial success: Agricultural Research Service scientists have found that neither fruit hosts the dreaded Caribbean fruit fly.

This key finding by scientists with the ARS Subtropical Horticulture Research Laboratory in Miami, Fla., means Florida lychee and longan growers can ship their fruit throughout the United States--even to California, which considered embargoing the fruit because it was thought to harbor the Carib fly.

Working with the Tropical Fruit Growers of South Florida, Inc., the scientists developed a fly-free protocol that California approved.

To develop this protocol, growers supplied 450 South Florida lychees harvested from six groves. One-third of the fruit was held as a control, while the remainder was exposed for a day to fertile female Carib flies. The lychees were then held for 30 days so that any eggs laid inside the fruit could hatch. The fruit remained fly-free. During the fruiting season, scientists also placed fly traps in groves where lychees were picked and checked the traps each week. Again, no flies.

Researchers saw the same results with longans and lychees from the packinghouse. They even covered longans, lychees and guavas (in which the flies lay eggs) on trees with pollination bags holding fertile flies. After 24 hours, the flies had attacked the guavas, but not the longans or lychees.

The full story appears in the January Agricultural Research magazine and is also available on the World Wide Web at:

/is/AR/archive/jan98/flor0198.htm

Scientific contacts: Walter P. Gould, Raymond G. McGuire and Jennifer L. Sharp, ARS Subtropical Horticulture Research Laboratory, Miami, FL 33158, phone (305) 238-9321, fax (305) 238-9330, miarm@ars-grin.gov.