the latest issue of "Tropical Fruit News" (May 1998, 32(5): 10-11) includes
material from the newsletter "The Friends of Chapman Field", Feb 1998
issue. Chapman Field is the Agricultural Research Service (ARS) at the
Subtropical Horticulture Research Station in Miami Florida. "Tropical
Fruit News" is published by the Rare Fruit Council International,
Miami, Florida.

To get to the point, ARS research scientists have discovered that
estragole, a natural oil present in avocado leaves, is a pesticide
and kills the Caribbean fruit fly (a major pest). The leaf oil has been
found in avocados of the Mexican race, but not the Guatemalan or
West Indian races (see "Fruits of Warm Climates" by Julia F. Morton,
for description of avocado races). The article then states:

"Further research is needed to genetically manipulate the gene
responsible for producing estragole to give plants natural resistance
to the Caribbean fruit fly and possibly other insect pests."

Note that the article mentions only avocado leaves, and not the fruit.

Tom Billings