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J Exp Biol

Title:		Peripheral modulation of pheromone response by inhibitory host compound in a beetle
Author(s):		Andersson MN; Larsson MC; Blazenec M; Jakus R; Zhang QH; Schlyter F;
Address:		"Chemical Ecology, Department of Plant Protection Biology, Swedish University of Agricultural Sciences, SE-230 53 Alnarp, Sweden. martin.andersson@ltj.slu.se"
Journal Title:		J Exp Biol
Year:		2010
Volume:		213
Issue:		Pt 19
Page Number:		3332 - 3339
DOI:		10.1242/jeb.044396
ISSN/ISBN:		1477-9145 (Electronic) 0022-0949 (Linking)
Abstract:		"We identified several compounds, by gas chromatographic-electroantennographic detection (GC-EAD), that were antennally active in the bark beetle Ips typographus and also abundant in beetle-attacked spruce trees. One of them, 1,8-cineole (Ci), strongly inhibited the attraction to pheromone in the field. Single-sensillum recordings (SSRs) previously showed olfactory receptor neurons (ORNs) on I. typographus antennae selectively responding to Ci. All Ci neurons were found within sensilla co-inhabited by a pheromone neuron responding to cis-verbenol (cV); however, in other sensilla, the cV neuron was paired with a neuron not responding to any test odorant. We hypothesized that the colocalization of ORNs had a functional and ecological relevance. We show by SSR that Ci inhibited spontaneous activity of the cV neuron only in sensilla in which the Ci neuron was also present. Using mixtures of cV and Ci, we further show that responses to low doses (1-10 ng) of cV were significantly reduced when the colocalized Ci neuron simultaneously responded to high doses (1-10 mug) of Ci. This indicated that the response of the Ci neuron, rather than ligand-receptor interactions in the cV neuron, caused the inhibition. Moreover, cV neurons paired with Ci neurons were more sensitive to cV alone than the ones paired with the non-responding ORN. Our observations question the traditional view that ORNs within a sensillum function as independent units. The colocalization of ORNs might sharpen adaptive responses to blends of semiochemicals with different ecological significance in the olfactory landscape"
Keywords:		Animals Coleoptera/drug effects/*pathogenicity/*physiology Cyclohexanols/pharmacology Eucalyptol Gas Chromatography-Mass Spectrometry Host-Parasite Interactions Monoterpenes/pharmacology Odorants Olfactory Receptor Neurons/drug effects/physiology Pheromon;
Notes:		"MedlineAndersson, Martin N Larsson, Mattias C Blazenec, Miroslav Jakus, Rastislav Zhang, Qing-He Schlyter, Fredrik eng Research Support, Non-U.S. Gov't England 2010/09/14 J Exp Biol. 2010 Oct 1; 213(Pt 19):3332-9. doi: 10.1242/jeb.044396"