Ontogenetic changes in eye morphology and sensitivity are associated with wing development in kissing bugs

Kissing bugs are the vectors of Chagas disease, one of the major endemic diseases in the Americas, now spreading to other continents. We used Rhodnius prolixus as a model species to characterize compound eye growth throughout the post-embryonic development of this hemimetabolous insect. We found that the adult eye is larger than expected from ontogeny. Moreover, while the eye grows symmetrically across nymphal instars, adults show greater ventral growth, resulting in a dorsoventrally asymmetrical eye. By studying a bright pseudopupil in natural mutant animals, we observed no major differences in sampling resolution between the last nymphal instar and the adult stage. However, the adult eye possesses significantly larger ommatidia, particularly in the ventral region, shifting the area of highest sensitivity from the equatorial region in nymphs to the ventral region in adults. A similar growth pattern was observed in Triatoma infestans and Panstrongylus megistus. Analysis of photographic records from 39 species across 10 genera indicates that an asymmetrical eye is the predominant pattern in adult kissing bugs. Notable exceptions in species in which adults are wingless reveal a tight association between a large asymmetrical eye and the presence of wings, suggesting that vision may support dispersal and host-seeking flights.