Scientists to Caterpillar Pests: Chew on
December 13, 1999
Chemical cues in the spit of tobacco budworm and corn earworm caterpillars
cause plants to send out defensive signals when the caterpillars chew on them,
Agricultural Research Service scientists
have discovered. Small wasps, natural enemies of the caterpillars, then follow
the defensive signals to find and sting the caterpillars.
The larvae of these insect pests are a major problem in cotton crops, but
also in corn, soybeans, sorghum, sunflowers, tobacco and peanuts.
In laboratory studies at the ARS Center
for Medical, Agricultural and Veterinary Entomologys Chemistry
Research Unit in Gainesville, Fla., chemists James H. Tumlinson
and Naoki Mori discovered the chemicals in the spit of the budworm (Heliothis
virescens) and earworm (Heliocoverpa zea).
This research builds on previous findings that beet armyworm caterpillars
elicit a chemical S.O.S. response in plants. Surprisingly, they
found that budworms and earworms produce the same compounds that are present in
the spit of beet armyworms.
Oddly, plants are able to distinguish which insect is nibbling on their
leaves and give off the proper distress signal to attract that insects
The scientists hope that by studying plant-insect interactions, they can
develop plant varieties with more powerful chemical defenses against insect
Mori will present these findings at the Entomological Society of Americas
Annual Meeting to be held
this week, December 12-16, in Atlanta, Ga.
Scientific contacts: Naoki Mori or James H. Tumlinson, ARS Center
for Medical, Agricultural and Veterinary Entomology, Gainesville,
Fla., phone (352) 374-5731, fax (352) 374-5781, firstname.lastname@example.org.