Male-Produced (−)-δ-Heptalactone, Pheromone of Fruit Fly Rhagoletis batava (Diptera: Tephritidae), a Sea Buckthorn Berries Pest

Abstract

The plantation area of sea buckthorn (Hippophae rhamnoides L.) is expanding in many European countries due to increasing demand for berries, thus creating suitable conditions for the rapid expansion of the fruit fly Rhagoletis batava, a pest of economic importance. To decrease insecticide use, effective means for pest population monitoring are required, including the use of pheromones. Male fruit flies emit (-)-δ-heptalactone as revealed by gas chromatography-mass spectrometry analyses of samples obtained using headspace methods. The two enantiomers of δ-heptalactone were synthesized using enantioselective synthesis. A gas chromatography-electroantennographic detection analysis of both stereoisomers revealed that only (-)-δ-heptalactone elicited electrophysiological responses, whereas no signal was registered to (+)-δ-heptalactone in fruit flies of either sex. In the field assay, traps baited with (-)-δ-heptalactone caught significantly more fruit flies compared with the unbaited traps. Our results are the first to demonstrate the efficacy of (-)-δ-heptalactone as a bait for trapping R. batava. As a behaviorally attractive compound to R. batava fruit flies of both sexes, (-)-δ-heptalactone is attributed to aggregation pheromones. This is the first report of an aggregation pheromone within the genus Rhagoletis.

Tephritid Fruit Fly Semiochemicals: Current Knowledge and Future Perspectives

“…For example, males of Rhagoletis pomonella (Walsh), Rhagoletis cerasi (L.), Rhagoletis ribicola Doane and Rhagoletis mendax Curran individually search for potential mates mainly on host fruits and the top surface of leaves [ 58 ], mostly during the late afternoon and at dusk [ 52 , 59 , 60 ]. However, in Rhagoletis batava Hering individuals have been reported to form small groups in response to male-released pheromone that might be considered leks [ 61 ]. While olfactory cues seem not to play a role in lek location for Anastrepha obliqua (Macquart) and Anastrepha ludens (Loew), data are rather controversial for C. capitata , B. dorsalis , and Z. cucurbitae [ 54 ].…”

“…To elucidate whether the composition of the pheromone components is related to feeding strategies of different species, we analysed the lists of volatile compounds identified in all species of the genera Anastrepha, Ceratitis , Bactrocera and Zeugodacus . This analysis could not be extended to Rhagoletis genus, as only the volatiles emitted by R. cerasi have been identified [ 226 ] so far, and a single compound has been isolated in R. batava [ 61 ].…”

“…In a recent work on C. capitata volatiles, divinylbenzene/carboxen/polydimethylsiloxane (DVB/CAR/PDMS) combined with GC-MS and gas chromatography-flame ionization detection (GC-FID) techniques resulted in the identification of 27, 23 and 29 compounds from larvae, pupae and adults, respectively [ 266 ]. PDMS/DVB SPME fibres have been applied to collect volatiles produced by B. zonata males and females and R. batava males, respectively [ 61 , 213 ].…”

“…For identification of the absolute configuration of tephritid volatile semiochemicals, the chiral column or chiral GC-MS can be used, as recently applied for pheromone identification of R. batava [ 61 ]. Most commercial chiral GC phases currently available are composed of modified cyclodextrins, which give a wide range of enantiomeric separations, but have the disadvantage of being thermally unstable above 200 °C, and are therefore useful for relatively volatile compounds only.…”

“…In this last species, Buda and colleagues recently applied GC-MS analyses of fly headspace and found that males emit (-)-δ-heptalactone. The authors then synthesised the two enantiomers of (-)-δ-heptalactone using enantioselective synthesis and found that only (-)-δ-heptalactone elicited an electrophysiological response in both sexes, proposing that this chemical may act as aggregation pheromone [ 61 ].…”