A special feature article recently published in the The Royal Society Biology Letters journal presents a study on caterpillar response to polarized light through the caterpillar organ responsible for polarized light vision. The paper called "Spatial orientation of social caterpillars is influenced by polarized light" presents information about experimental research performed on two caterpillar species, namely the European Thaumetopoea pityocampa, and Ochrogaster lunifer in Australia.

 

Anatomy of O. lunifer (a–d) and T. pityocampa (e–h) stemmata. Source: Uemura M, Meglič A, Zalucki MP, Battisti A, Belušič G. 2021 Spatial orientation of social caterpillars is influenced by polarized light. Biol. Lett. 17: 20200736. https://doi.org/10.1098/rsbl.2020.0736

Through manipulative behavioural field experiments on caterpillars and morphological analysis of larval stemmata, the authors of the article, amongst whom are HOMED PhD student Mizuki Uemura and researcher Prof. Andrea Battisti of the University of Padova, discovers that caterpillars strongly react to the presentation of polarized light and identify the likely visual organ for its detection - stemma I. The morphological analysis demonstrates that the stemma responsible to detect polarized light in social caterpillars is anatomically similar to a single ommatidium in the DRA of adult moths.

By manipulating larval locomotion with a linear polarizing filter (PF), researchers show that polarization vision is one of the mechanisms that guides social behaviour of the caterpillars. The article concludes that social behaviour and organized locomotion exert strong selective pressure on the visual organs of the examined species’ caterpillars, and provides a direction for further analysis of this topic towards other species of the Notodontidae moth family.

Click here to access the paper.