These inducible immune-like responses are common throughout the plant kingdom and are being studied to demonstrate their adaptive nature and potential as an alternative to chemical pesticides in agricultural crops.

The UC Davis study, which will appear in the Feb. 20 issue of the journal Science, confirms the benefit of these responses and raises the question of why such defensive mechanisms evolved in such a way that they can be switched on and off, rather than remaining constantly active.

"Inducible responses have been observed in plants for more than 100 years, but were experimentally confirmed only in the last two decades," said Anurag Agrawal, the study author and a population biology doctoral candidate in the UC Davis entomology department. "Researchers in this field have predicated much of their work on the presumption that plants do benefit from induced responses. This study confirms those assumptions."

"Learning how and when plants benefit from inducible responses is absolutely essential if we are going to try to use similar responses for pest management in agriculture," says Richard Karban, a Davis professor of entomology and an authority on the interactions between insects and their host plants.

The study was conducted using wild radish [Raphanus sativus L. (brassicacea)] as an experimental model. The plant is a member of the mustard family, members of which are found in most parts of the world.

Agrawal gathered wild radish seeds and planted them in an experimental plot. When the young plants grew to the four-leaf stage he caged a cabbage worm -- the larval stage of the cabbage white butterfly -- onto one leaf of eac
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Contact: Patricia Bailey
pjbailey@ucdavis.edu
(530) 752-9843
University of California - Davis
13-Feb-1998