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Doctoral thesis, 2022

Out of and into Africa: Odour-mediated interaction and detection of the human commensal Drosophila melanogaster and the invasive fly Drosophila suzukii

Kwadha, Charles

Abstract

Living organisms use their sense of smell to discriminate odours. Humans can sense females of the cosmopolitan Drosophila melanogaster, but whether humans can discriminate the cosmopolitan D. melanogaster strain from the conspecific Zimbabwe strain, was unknown. We showed that the cosmopolitan females emit a pheromonal aldehyde, (4Z)-4-undecenal (Z4-11Al), while Zimbabwe females emit Z4-11Al and (4Z)-4-nonenal (Z4-9Al), and that humans can discriminate the scent of the two strains. The aldehydes are oxidation products of cuticular dienes. Since across Drosophila species dienes have biological activities and can, during oxidization produce aldehydes, we propose that the aldehydes are involved in reproductive isolation. Another part of the thesis addresses a closely related species of D. melanogaster, D. suzukii, which is an invasive pest that damages soft fruits and causes financial losses. Its distribution in Sub-Saharan Africa was unknown. Traps targeting D. suzukii often attract non-target species such as D. melanogaster. We showed that D. suzukii is present in Kenya and that a mutualistic yeast, Hanseniaspora uvarum, can improve selectivity of traps. Curiously, on fruit, presence of D. melanogaster induces oviposition avoidance in D. suzukii. We showed that D. suzukii is present in Kenya and that a mutualistic yeast, Hanseniaspora uvarum, can improve selectivity of traps. We established that Z4-11Al partly induces the avoidance observed in D. suzukii. Altogether, our findings advance our understanding of the principle of olfaction across phylogenetically distant species, the dispersal of D. suzukii in Africa, and the potential of H. uvarum and chemo-ecological interactions in enhancing sound management of D. suzukii.

Keywords

olfaction; semiochemicals; human commensal; Drosophila; egg-laying; heterospecific interaction

Published in

Acta Universitatis Agriculturae Sueciae
2022, number: 2022:41
ISBN: 978-91-7760-957-5, eISBN: 978-91-7760-958-2
Publisher: Swedish University of Agricultural Sciences

Authors' information

Swedish University of Agricultural Sciences, Department of Plant Protection Biology

UKÄ Subject classification

Ecology

URI (permanent link to this page)

https://res.slu.se/id/publ/118534