Horsefly object-directed polarotaxis is mediated by a stochastically distributed ommatidial subtype in the ventral retina

Meglič, Andrej (author), Ilić, Marko (author), Pirih, Primož (author), Škorjanc, Aleš (author), Wehling, Martin F. (author), Kreft, Marko (author), Belušič, Gregor (author)

The ventral compound eye of many insects contains polarization-sensitive photoreceptors, but little is known about how they are integrated into visual functions. In female horseflies, polarized reflections from animal fur are a key stimulus for host detection. To understand how polarization vision is mediated by the ventral compound eye, we investigated the band-eyed brown horsefly Tabanus bromius using anatomical, physiological, and behavioral approaches. Serial electron microscopic sectioning of the retina and single-cell recordings were used to determine the spectral and polarization sensitivity (PS) of photoreceptors. We found 2 stochastically distributed subtypes of ommatidia, analogous to pale and yellow of other flies. Importantly, the pale analog contains an orthogonal analyzer receptor pair with high PS, formed by an ultraviolet (UV)-sensitive R7 and a UV- and blue-sensitive R8, while the UV-sensitive R7 and green-sensitive R8 in the yellow analog always have low PS. We tested horsefly polarotaxis in the field, using lures with controlled spectral and polarization composition. Polarized reflections without UV and blue components rendered the lures unattractive, while reflections without the green component increased their attractiveness. This is consistent with polarotaxis being guided by a differential signal from polarization analyzers in the pale analogs, and with an inhibitory role of the yellow analogs. Our results reveal how stochastically distributed sensory units with modality-specific division of labor serve as separate and opposing input channels for visual guidance.

• Language: English
• Keywords: polarization vision, rhabdomere, insect photoreceptor, retinal mosaic, pale
• Work type: Article
• Typology: 1.01 - Original Scientific Article
• Organization: BF - Biotechnical Faculty; MF - Faculty of Medicine
• Publication status: Published
• Publication version: Version of Record
• Year: 2019
• Number of pages: Str. 21843-21853
• Numbering: Vol. 116, no. 43
• PID: 20.500.12556/RUL-128327
• UDC: 591.1
• ISSN on article: 0027-8424
• DOI: 10.1073/pnas.1910807116
• COBISS.SI-ID: 5188175
• Publication date in RUL: 08.07.2021

Record is a part of a journal

• Title: Proceedings of the National Academy of Sciences of the United States of America
• Shortened title: Proc. Natl. Acad. Sci. U. S. A.
• Publisher: National Academy of Sciences
• ISSN: 0027-8424
• COBISS.SI-ID: 286487

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• License: CC BY-NC-ND 4.0, Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International
• Link: http://creativecommons.org/licenses/by-nc-nd/4.0/
• Description: The most restrictive Creative Commons license. This only allows people to download and share the work for no commercial gain and for no other purposes.
• Licensing start date: 22.10.2019