Chemical stimuli from apple influence the behavior of neonate caterpillarsof the generalist herbivore, Epiphyas postvittana

Citation
Mo. Harris et al., Chemical stimuli from apple influence the behavior of neonate caterpillarsof the generalist herbivore, Epiphyas postvittana, J CHEM ECOL, 25(8), 1999, pp. 1717-1738
Citations number
23
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Environment/Ecology
Journal title
JOURNAL OF CHEMICAL ECOLOGY
ISSN journal
0098-0331 → ACNP
Volume
25
Issue
8
Year of publication
1999
Pages
1717 - 1738
Database
ISI
SICI code
0098-0331(199908)25:8<1717:CSFAIT>2.0.ZU;2-K
Abstract
When introduced into a wind tunnel with low windspeeds (0.2-0.3 m/sec), neo nate E. postvittana larvae were more likely to walk in a downwind rather th an upwind direction. This tendency to walk downwind did not change when odo rs from apple leaves or fruit were introduced into the wind tunnel. In a se cond assay that measured travel times of larvae as they walked from the cen ter to the edge of filter paper disks, larvae moved more slowly on disks tr eated with extracts of apple leaves or extracts of apple fruit, but did not slow their movement on disks treated with extracts of a nonhost, Coprosma repens. Analysis of videorecords revealed that larvae on disks treated with a dichloromethane extract of apple leaves took more circuitous routes, wal ked more slowly, and stopped more frequently than larvae walking on solvent -treated disks. When the dosage of this dichloromethane apple leaf extract was increased or when larvae were held without food prior to testing, diffe rences between travel rimes on solvent- and extract-treated disks did not i ncrease significantly. The dichloromethane apple leaf extract, when tested in the wind tunnel with low windspeeds, also caused larvae to delay spinnin g down on a silken thread after reaching the edge of the disk, but had no e ffect on spin-down times when tested in still-air conditions. Testing of ro tary evaporated apple leaf extracts and fractionation of these extracts ind icated that a number of both volatile and relatively involatile chemicals c ontribute to the behavioral responses of E. postvittana larvae.