Pulsed Odors from Maize or Spinach Elicit Orientat

Authors: Dariusz Piesik Didier Rochat Jan van der Pers Frédéric MarionPoll

Publish Date: 2009/09/02

Volume: 35, Issue: 9, Pages: 1032-1042

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Abstract

Lepidoptera larvae are capable of orienting towards or away from plants by using odors as cues but whether this attraction is innate or secondarily acquired remains unknown We tested the hypothesis that European corn borer ECB neonate larvae express an innate attraction towards odors released from maize and avoidance towards odors from spinach Neonate larvae were placed on a locomotion compensator within a constant stream of humidified air that was loaded intermittently with airborne odors drawn from potted plants The odor stream was delivered continuously or pulsed 1 to 10 sec pulses at 40 ml/min ECB larvae oriented toward maize odors pulsed at 2 to 6 sec but walked away from maize odors delivered at lower frequencies 9 and 10 sec pulses or to continuous ones They consistently walked away from spinach odors irrespective of the pulsing regime except at 1 sec pulses that did not elicit orientation We further explored odor intensity on orientation towards maize odors by adjusting the odor stream intensity At higher intensity 60 ml/min the direction reversal started at the 6 sec half period while at lower intensity 20 ml/min it showed up only for the continuous stimulus ECB larvae exhibit a striking ability to lock on to a direction which they maintained despite gaps of up to 10 sec in the odor stream Our results demonstrate that ECB neonate larvae express innate orientation preferences towards natural odors from plants These reactions correlate well with the biological value of these plants for ECB maize generally is accepted by ECB larvae and adults while spinach represents a poor host because it produces nonvolatile phytoecdysteroids that are toxic and deterrentWe thank Andrée Berthier Alexandra Popescu Delphine Calas and Ines Datei INRA Versailles for assistance We also thank Romina Barrozo and Katherine Szulewski for reviewing an earlier draft of this manuscript The first author was supported by a grant from MarieCurie Foundation IntraEuropean Fellowships Contract No MEIFCT2005514931 We also thank the three anonymous referees for their suggestions This work was made possible thanks to the generous and friendly participation of Jan van der Pers to whom this paper is dedicated

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