Methyl Salicylate and Sesquiterpene Emissions Are Indicative for Aphid Infestation on Scots Pine

Minna Kivimäenpää,Jarmo K Holopainen,Aishat B Babalola,Jorma Joutsensaari

doi:10.3390/f11050573

Minna Kivimäenpää, Jarmo K Holopainen + Show 2 more

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https://doi.org/10.3390/f11050573

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Journal: Forests	Publication Date: May 20, 2020
Citations: 11	License type: CC BY 4.0

Affiliation: University of Eastern Finland

Abstract

Biotic stresses on forest trees are caused by various pest insects and plant pathogens. Attack by these parasites is known to induce the emissions of various biogenic volatile organic compounds (BVOCs), and the profile of these emissions often differs between infested and healthy plants. This difference in emission profile can be used for the non-destructive early-stage diagnosis of the stressor organism. We studied how phloem feeding by a large pine aphid (Cinara pinea Mordvilko) on the branch bark of Scots pine (Pinus sylvestris L.) affects BVOC emissions compared to those of healthy plants in two experiments. We found that in aphid-infested plants, methyl salicylate (MeSA) emissions significantly increased, and the emission rates were dependent on aphid density on the studied branch. Aphid infestation did not significantly affect total monoterpene emission, while the emissions of total sesquiterpenes were substantially higher in aphid-infested saplings than in uninfested plants. Sesquiterpene (E, E)-α-farnesene was emitted at increased rates in both experiments, and the aphid alarm pheromone sesquiterpene (E)-β-farnesene, only in the experiment with higher aphid pressure. We conclude that the rapid increase in MeSA emissions is the most reliable indicator of aphid infestation in pine trees together with (E, E)-α-farnesene.

Highlights

The non-destructive early-stage diagnosis of plant pathogen and insect pest infestations is important for successful plant protection in agriculture and horticulture [1,2]
In addition to traditional gas-chromatography mass-spectrometry (GC-MS) analysis and fast on-line proton-transfer-reaction mass spectrometry (PTR-MS) analysis with leaf and shoot enclosures [7,15], various portable [2] and aerial monitoring systems have been recently developed for the detection of biogenic volatile organic compounds (BVOCs) emissions indicating plant stress [16,17]
Experiment 1: In 2015, the number of aphids occurring on aphid-infested plants increased over time since the beginning of the experimental trial, reaching an average of 77 ± 27 aphids per sapling

Summary

Introduction

The non-destructive early-stage diagnosis of plant pathogen and insect pest infestations is important for successful plant protection in agriculture and horticulture [1,2]. Plant volatiles form the majority of the biogenic volatile organic compounds (BVOCs) emitted to the atmosphere, and their composition and ratio in the emission bouquet contain valuable information about the physiological and pathological status of the emitting plant [1,2,3,4]. Forests are one of the most significant sources of BVOCs [5,6,7,8], and the emissions are sensitive to abiotic and biotic stresses [9,10,11,12,13]. In addition to traditional gas-chromatography mass-spectrometry (GC-MS) analysis and fast on-line proton-transfer-reaction mass spectrometry (PTR-MS) analysis with leaf and shoot enclosures [7,15], various portable [2] and aerial monitoring systems have been recently developed for the detection of BVOC emissions indicating plant stress [16,17]. For some BVOCs, the remote sensing of emissions from larger forested areas by satellite applications is under development [18]

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