Structural and transcriptional evidence of mechanotransduction in the Drosophila suzukii ovipositor

• Published in: Journal of insect physiology Vol. 125; p. 104088
• Main Authors: Crava, Cristina Maria, Zanini, Damiano, Amati, Simone, Sollai, Giorgia, Crnjar, Roberto, Paoli, Marco, Rossi-Stacconi, Marco Valerio, Rota-Stabelli, Omar, Tait, Gabriella, Haase, Albrecht, Romani, Roberto, Anfora, Gianfranco
• Format: Journal Article
• Language: English
• Published: England Elsevier Ltd 01-08-2020
• Subjects: Animals; comparative RNA-seq; Drosophila - genetics; Drosophila - physiology; Drosophila - ultrastructure; Female; mechanosensitive bristles; Mechanotransduction, Cellular - genetics; Microscopy, Electron, Scanning; Microscopy, Electron, Transmission; Oviposition - genetics; Oviposition - physiology; Sensilla; Species Specificity; spotted wing drosophila; Taste Perception; ultrastructure; comparative RNA-seq; ultrastructure; spotted wing drosophila; mechanosensitive bristles
• ISSN: 0022-1910; 1879-1611
• DOI: 10.1016/j.jinsphys.2020.104088

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•Drosophila suzukii ovipositor pegs and sensilla have a mechanosensilla-like structure.•D. suzukii and Drosophila melanogaster ovipositor pegs are mono-innervated.•Terminalia gene expression overlaps across Drosophila species with different ovipositor shapes.•The D. suzukii ovipositor is likely involved in mechanotransduction.•This function is likely conserved among Drosophila species.
Drosophila suzukii is an invasive pest that prefers to lay eggs in ripening fruits, whereas most closely related Drosophila species exclusively use rotten fruit as oviposition site. This behaviour is allowed by an enlarged and serrated ovipositor that can pierce intact fruit skin, and by multiple contact sensory systems (mechanosensation and taste) that detect the optimal egg-laying substrates. Here, we tested the hypothesis that bristles present in the D. suzukii ovipositor tip contribute to these sensory modalities. Analysis of the bristle ultrastructure revealed that four different types of cuticular elements (conical pegs type 1 and 2, chaetic and trichoid sensilla) are present on the tip of each ovipositor plate. All of them have a poreless shaft and are innervated at their base by a single neuron that ends in a distal tubular body, thus resembling mechanosensitive structures. Fluorescent labelling in D. suzukii and D. melanogaster revealed that pegs located on the ventral side of the ovipositor tip are innervated by a single neuron in both species. RNA-sequencing profiled gene expression, notably sensory receptor genes of the terminalia of D. suzukii and of three other Drosophila species with changes in their ovipositor structure (from serrated to blunt ovipositor: Drosophila subpulchrella, Drosophila biarmipes and D. melanogaster). Our results revealed few species-specific transcripts and an overlapping expression of candidate mechanosensitive genes as well as the presence of some chemoreceptor transcripts. These experimental evidences suggest a mechanosensitive function for the D. suzukii ovipositor, which might be crucial across Drosophila species independently from ovipositor shape.