Sea Buckthorn Hippophae rhamnoides and Fruit Flies Rhagoletis batava: Search for Volatile Semiochemicals Involved in Pest Attraction

Laima Blažytė-Čereškienė,Violeta Apšegaitė,Raimondas Mozūraitis,Dominykas Aleknavičius,Sandra Radžiutė,Vincas Būda,Jurga Būdienė

doi:10.3390/horticulturae8020179

Abstract

Rhagoletis batava (Diptera: Tephritidae), is the most important pest of Hippophae rhamnoides fruits. For detection and monitoring of R. batava, traps supplied with nonspecific attractants are used. Thus, new, more specific attractants for environment-friendly pest control are needed. Such attractants could be fruit-related semiochemicals that are involved in the host location by flies. Behavioural Y-olfactometer tests revealed that R. batava males were attracted to ripe fruit odour, while females preferred unripe and semi-ripe fruits. Thermal desorption gas chromatography-mass spectrometry (GC-MS) analysis revealed substantial quantitative and qualitative changes in volatiles between unripe and ripe fruits. In the unripe fruit emission, 41 volatile compounds were isolated, whereas 64 compounds were sampled from the ripe fruits. The total amount of volatiles increased five times during the fruit ripening. Gas chromatography-electroantennogram detection (GC-EAD) and GC-MS analyses of the fruit headspace volatiles revealed at least 26 compounds in unripe and 27 compounds in ripe fruits eliciting antennal responses of R. batava for both sexes. The fruits of these two ripening stages differed qualitatively in the single EAD-active compound only, i.e., 3-methylbutyl 2-methylpropionate. Esters were the most abundant volatiles, composing 84% and 93% of EAD-active compounds in the emissions of unripe and ripe fruits, respectively. Based on the persistent EAG responses, 17 compounds were selected as the most promising candidates for kairomone attractants of the sea buckthorn pest R. batava.

Highlights

Sea buckthorn, Hippophae rhamnoides L. (Rosales: Elaeagnaceae) is a fruit-bearing bush naturally distributed in Northern and Central Europe, Caucasus, and Asia [1]
The goal of this study was to compare volatiles released by ripe and unripe H. rhamnoides fruits, as well as to determine at which ripening stage the fruits were preferred by R. batava fruit flies, and to identify semiochemicals that could mediate host-plant location by the flies
It is known that plant volatiles act as important chemical signals for a few Rhagoletis species in host-plant selection and could be used as attractants or synergists in integrated pest management [19–24]

Summary

Introduction

Hippophae rhamnoides L. (Rosales: Elaeagnaceae) is a fruit-bearing bush naturally distributed in Northern and Central Europe, Caucasus, and Asia [1]. (Rosales: Elaeagnaceae) is a fruit-bearing bush naturally distributed in Northern and Central Europe, Caucasus, and Asia [1]. Sea buckthorn is cultivated in many European countries, Canada, Russia, and China as a highly valuable plant [2,3]. Sea buckthorn fruits as a raw material are used for various purposes in the food, medicine, and cosmetic industries [2]. As the demand for sea buckthorn raw material in the global market rises, the area of sea buckthorn plantations increases every year [6]. The sea buckthorn fruits have become more and more damaged by the fruit fly Rhagoletis batava Hering (Diptera: Tephritidae), an insect pest that began to spread rapidly in central and eastern European countries [7–9].

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