Identification and Behavioral Assays of Alarm Pheromone in the Vetch Aphid Megoura viciae

Abstract

Aphids are destructive insect pests worldwide, and alarm pheromones play a key role in their chemical ecology. However, the composition and key active components of alarm pheromone differentiate among aphid species. Here we conducted a detailed analysis of the terpenoid compounds in the vetch aphid Megoura viciae and its host plant Pisum sativum by using gas chromatography-mass spectrometry. The results showed that a variety of terpenoid compounds existed in the aphid, with four major terpene components, i.e., (-)-β-pinene (49.74%), (E)-β-farnesene (32.64%), (-)-α-pinene (9.42%) and (+)-limonene (5.24%), in addition to a trace amount of minor terpenoid components (3.14%). In contrast, the terpenoid compounds were relatively scarce in the host plant, mainly consisting of squalene (66.13%) and its analogue 2,3-epoxysqualene (31.59%) in addition to some minor components. Quantitative analysis of the dynamics of four major terpene components during different developmental stages showed that the monoterpenes increased with continuous development, while the sesquiterpene reached peak at the 3rdinstar; all terpene components remained at a high level in the 4th -instar, with (-)-β-pinene accounting for the highest proportion during all developmental stages. Behavioral assays with single components and mixtures at different concentrations were conducted in a three-compartment olfactometer, revealing that the repellent activities of single components varied in a concentration-dependent manner, but two mixtures (1:44.4:6.5:2.2 and 1:18.4:1.3:0.8) prepared according to the proportions of four major components at the 3rd -and 4th -instar stages maintained a signi cant repellent activity at all concentrations tested. Our results suggested that (-)-α-pinene and (-)-β-pinene were the major active components of alarm pheromone in M. viciae, but the mixtures of single components play a key role in the alarm behavior of M. viciae. Our study helps to understand the chemical ecology of insects and design alternative control strategies against aphids.

Farnesyl/geranylgeranyl diphosphate synthases regulate the biosynthesis of alarm pheromone in a unique manner in the vetch aphid Megoura viciae

“…The vetch aphid Megoura viciae causes serious damage to the pea Pisum sativum (Kunert et al, 2008). Its AAP contains four major components, that is, (−)‐β‐pinene (49.74%), EβF (32.64%), (−)‐α‐pinene (9.42%) and (+)‐limonene (5.24%) (Francis et al, 2005; Song et al, 2021). This is different from the single major AAP component (EβF) in the majority of aphid species, and thus can be used as a good reference for comparative studies.…”

Functional analysis of odorant-binding proteins for the parasitic host location to implicate convergent evolution between the grain aphid and its parasitoid Aphidius gifuensis

“…2J). (− )-α-Pinene, (− )-β-pinene and (+)-limonene are 3 active components of aphid alarm pheromones reported in a few aphids, such as M. viciae [60]. AgifOBP8 also showed a strong binding property to (− )-α-pinene, with a Ki value of 1.94 ± 0.02 mМ (Fig.…”

“…To investigate the ligand-binding property of AgifOBPs, five groups of competitive ligands were used: (i) aphid alarm pheromone components, including E-β-farnesene (EBF), (− )-α-pinene, (− )-β-pinene and (+)-limonene, which are released by other aphids following natural enemy predation or physical damage [11,60]; (ii) main components of the aphid sex pheromone (4aSR,7SR,7aRS)-Nepetalactone); (iii) green leaf volatiles of wheat (Z)-3-hexen-1-ol); (iv) aphid-induced plant volatiles (methyl salicylate and 6-methyl-5-hepten-2-one (MHO)); and (V) an EBF derivative artificial chemical, namely, CAU-II-11 ((E)-3,7dimethylocta-2,6-dien-1-yl-2-hydroxy-3-methoxybenzoate), which showed a high affinity for aphid EBF-binding proteins (OBP3/7/9) [32]. The classes, CAS numbers, and purity of the chemicals used in this study are listed in Table 2.…”

Functional characterization of two different decaprenyl diphosphate synthases in the vetch aphid Megoura viciae

“…The vetch aphid Megoura viciae , as an important agricultural pest insect, caused serious damage to the pea Pisum sativum (Kunert et al, 2008; Song et al, 2021). Here, we cloned the complementary DNAs (cDNAs) encoding three subunits of DPPS, designated as MvDPPS1 , MvDPPS2a , and MvDPPS2b , from M. viciae based on transcriptome data.…”