Population density and feeding duration of cabbage looper larvae on tomato plants alter the levels of plant volatile emissions.
BACKGROUND
As part of their indirect defense, plants under herbivore attack release volatile chemicals that attract natural enemies of the herbivore. This is a very well-documented phenomenon. However, relatively few studies have investigated the response of plants to different population levels of herbivores and their feeding duration.


RESULTS
Working with larvae of the cabbage looper, Trichoplusia ni (Hübner), and tomato plants, Lycopersicon esculentum Mill cv. clarence, and using an ultrafast gas chromatograph (the zNose™) for volatile analyses, the authors studied the effect of larval density and feeding duration on levels of plant volatile emissions. Intense herbivory caused higher emission levels of the herbivore-induced plant volatiles (HIPVs) (Z)-3-hexenyl acetate, (E)-β-ocimene and β-caryophyllene than those caused by moderate herbivory. When herbivory had ceased following 12-24 h of larval feeding, plants kept releasing HIPVs at a high level for a longer period of time than they did following only 6 h of larval feeding. The plants' slow adjustment in their volatile emissions following prolonged larval feeding might be strategic, as such feeding is more likely to have ceased just temporarily.


CONCLUSIONS
This information may help in the development of a pest monitoring system that is based on herbivore-induced plant volatiles.
Energy Biosciences Institute, Department of Entomology, University of Illinois Urbana-Champaign, Urbana, IL, USA. saber@illinois.edu
Saber
S
Miresmailli
Regine
R
Gries
Gerhard
G
Gries
Ruben H
RH
Zamar
Murray B
MB
Isman
D000818:Animals; D005247:Feeding Behavior; D007814:Larva / Q000502:physiology; D018551:Solanum lycopersicum / Q000378:metabolism* / Q000469:parasitology*; D009036:Moths / Q000254:growth & development / Q000502:physiology*; D011156:Population Density; D055549:Volatile Organic Compounds / Q000378:metabolism*
D055549:Volatile Organic Compounds