Caffeine Foils Snails
By Marcia Wood
June 26, 2002
Caffeine can repel or kill snails that might otherwise eat and
ruin plants, Agricultural Research
Service scientists report in the June 27, 2002 issue of the scientific
An environmentally acceptable, natural compound, caffeine has
great potential as an alternative to today's snail- and slug-killing chemicals.
That's according to
G. Hollingsworth, a research biologist with the agency's
U.S. Pacific Basin Agricultural Research
Center in Hilo, Hawaii.
Hollingsworth conducted caffeine studies in collaboration with
research entomologist John W.
Armstrong at the Hilo Center and Earl Campbell of the
U.S. Fish and Wildlife Service, Honolulu.
The idea of using caffeine to quell pests isn't new. But
Hollingsworth and colleagues apparently are the first to report its prowess in
clobbering pesky molluscs such as Hawaii's orchid snail, Zonitoides
arboreus. The tiny snail is a common and costly pest to growers of Hawaii's
colorful and exotic tropical orchids. These orchid farms are world renowned for
the quality, quantity and variety of the flowers that they produce.
In preliminary experiments at his research greenhouse in Hilo,
Hollingsworth applied a 2 percent solution of caffeine in water as a spray to
the coconut husk-chips material in which orchids are grown. This growth medium,
called coir, was infested with the tiny snails. The scientists found that the
caffeine spray killed up to 95 percent of the snails.
In another experiment, the researchers showed that growth medium
treated with the 2 percent caffeine solution had only 5 snails, when checked 30
days after the spray was applied. That's in contrast to the 35 snails that they
found in growth medium that had been treated with a standard dose of
metaldehyde, a common molluscicide.
Future investigations will provide further details about the
ability of caffeine sprays to protect floral crops from marauding molluscs.
Caffeine, a naturally occurring compound in coffee and chocolate, for example,
is ranked "generally recognized as safe" by the Federal government.
ARS is the U.S. Department of
Agriculture's chief research agency.