β-Thujone and Its Derivatives Modify the Probing Behavior of the Peach Potato Aphid.

Anna Wróblewska-Kurdyk,Radosław Gniłka,Aleksandra Grudniewska,Katarzyna Dancewicz,Beata Gabryś,Czesław Wawrzeńczyk

doi:10.3390/molecules24101847

Abstract

Thujone is a natural biologically active monoterpene ketone component of essential oils of numerous plants. The aim of the study was to evaluate the effect of β-thujone and β-thujone derivatives bisulfite adduct, lactone, oxime, and lactam application on behavior of Myzus persicae (Sulz.) (Hemiptera: Aphididae) during probing and settling. The choice and no-choice tests (aphid settling and Electrical Penetration Graph (EPG), respectively) revealed that stereochemistry of thujone was important for biological activity (β-thujone caused changes in aphid behavior while α-thujone did not) and that cyclopentane ring modifications and functional groups addition gave derivatives that possessed stronger and more durable deterrent effects. The most effective modification was the incorporation of a lactam moiety into the β-thujone molecule. Application of β-thujone lactam limited aphid settling for at least 24 h, caused restlessness in aphids and a delay or failure in reaching phloem phase by M. persicae. β-Thujone lactam can be considered a deterrent of medium potency with activity expressed at preingestive phase of aphid probing. Other compounds did not restrain aphid stylet penetration in non-phloem tissues but slightly limited sap ingestion (lactone, oxime), and restrained aphid settling for a period of less than 24 h (β-Thujone, bisulphite adduct, lactone).

Highlights

AGnrundanWierwóbslkeaw2s, kCaz-eKsułarwdyWk a1w,* rz,eRńaczdyoksł2aawnGd nBiełaktaa2G,3a, bKraytśar1zyna Dancewicz 1, A1leDkseapnardtmraeGntroufdBnoiteawnyskanad2Ec,oClozgeys, łUanwivWerasiwtyrozfenZicezlyonka2Gaónrda, BSzeaaftraanGaa1b, 6ry5-s516 Zielona Góra, Poland; RAebcsetivraedct::7TMhuarjochne20i1s9a; Ancacteuprtaedl :b1io0lMogaiyca20ll1y9;aPcutibvleishmedo:n1o4teMrpaeyn2e01k9etone component of essential oils of numerous plants
The choice test, which lasted for 24 h, showed that the potency and durability of deterrent effect on M. persicae settling activity after exposure to T. occidentalis essential oil (α-and β-thujone, 69.80% and 9.47% respectively), α-thujone (1), β-thujone (2), and β-thujone derivatives bisulfite adduct (3), lactone (4), oxime (5), lactam (6) depended on the compound applied to the leaves of the host plant
The application of T. occidentalis essential oil and its major component α-thujone (1) did not affect aphid settling in contrast to the other component of the essential oil, β-thujone (2), the application of which caused the avoidance of leaves by M. persicae

Summary

Introduction

AGnrundanWierwóbslkeaw2s, kCaz-eKsułarwdyWk a1w,* rz,eRńaczdyoksł2aawnGd nBiełaktaa2G,3a, bKraytśar1zyna Dancewicz 1, A1leDkseapnardtmraeGntroufdBnoiteawnyskanad2Ec,oClozgeys, łUanwivWerasiwtyrozfenZicezlyonka2Gaónrda, BSzeaaftraanGaa1b, 6ry5-s516 Zielona Góra, Poland; RAebcsetivraedct::7TMhuarjochne20i1s9a; Ancacteuprtaedl :b1io0lMogaiyca20ll1y9;aPcutibvleishmedo:n1o4teMrpaeyn2e01k9etone component of essential oils of numerous plants. S-Limonene inhibited phloem sap ingestion and reduced the number of phloem sap ingestion phases during M. persicae stylet penetration of plant tissues while R-pulegone did not and the chiral center configuration of the S-limonene-derived lactones was important in expression of feeding deterrent activity [23]. Antifeedant, and insecticidal activity of thujone has been examined towards a number of herbivorous insects, the aphid response to this terpenoid has never received full attention. In prologue to the present studies, we discovered that neither T. occidentalis essential oil (containing 69.80% of α-thujone and 9.47% of β-thujone) nor pure α-thujone (1), showed any activity towards the extremely polyphagous and insecticide-resistant M. persicae in aphid settling bioassay in contrast to pure β-thujone (2) that was a strong deterrent [Anna Wróblewska-Kurdyk and Beata Gabrys; MoleMcuolleescu2l0e1s 92,02149,, 1248,4x7 FOR PEER REVIEW

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