Automated Measurement of Ommatidia in the Compound Eyes of Beetles

Abstract

The size of the ommatidia that compose the insect compound eye is linked to visual capacity, physiological performance, and cell size. Therefore, rapid and reliable methods for measuring ommatidia can advance research on insect ecology and evolution. We developed an automated method to measure ommatidia in nail polish imprints of the eyes of three Carabidae beetle species using the widely available, free software ImageJ. Our automated method was equivalent to a traditional manual method in terms of accuracy but had the advantage of being 70 times faster. We provide access to our algorithm, which can be used to investigate biological phenomena ranging from the functional architecture of the compound eye to the cellular basis of the evolution of body size and metabolic rates.

Seed size in mountain herbaceous plants changes with elevation in a species-specific manner

“…The sheets with seeds were photographed with a digital camera (Canon 600D, f = 50 mm) with a ring flash lamp, mounted on a regulated stand. The digital images were analyzed with a modified automated method of Schramm et al [ 26 ]. This procedure automatically recognized seeds from artifacts, counted seeds and measured the area of their vertical projection.…”

Not all cells are equal: effects of temperature and sex on the size of different cell types in the Madagascar ground gecko Paroedura picta

“…Addressing the role of cell size changes in the cellular mechanisms related to body size changes, we also hypothesized that cell size changes were involved in the origin of the thermal- and sex-dependence of body size. To infer organism-wide trends in cell sizes, the majority of research on this topic has focused on singe cell types, e.g., erythrocytes in vertebrates ( Gregory, 2001a , b ; Starostová et al, 2005 ), or proxies of cell size, e.g., ommatidia in insects ( Chown et al, 2007 ; Schramm et al, 2015 ), assuming that cell size is developmentally coordinated among different tissues in the body, as suggested by earlier studies ( Heinrich et al, 2011 ; Kozlowski et al, 2010 ; Stevenson et al, 1995 ). However, there are counterexamples indicating the need to further examine the organism-wide coordination of cell size changes ( Czarnoleski et al, 2016 ; Kozlowski et al, 2010 ).…”

Influence of photoperiod on thermal responses in body size, growth and development in Lycaena phlaeas (Lepidoptera: Lycaenidae)

“…Counting and measuring all adult body cells was not feasible, therefore we required a measurable tissue or organ (such as wing or eye), where individual body cells are easily discerned. Previous studies have used the size of the ommatidia that make up the eye as a proxy for cell size (e.g Schramm et al., 2015 ., 2021 ). Here, we measured the ommatidia of adult eyes (as a proxy for cell size), using nail polish to create an imprint from the external surface of the eye ( Arya & Lakhotia, 2006 ; Schramm et al., 2015 ).…”

“…Previous studies have used the size of the ommatidia that make up the eye as a proxy for cell size (e.g Schramm et al., 2015 ., 2021 ). Here, we measured the ommatidia of adult eyes (as a proxy for cell size), using nail polish to create an imprint from the external surface of the eye ( Arya & Lakhotia, 2006 ; Schramm et al., 2015 ). Butterflies were decapitated with a sharp needle under a binocular stereo microscope, and a small drop of transparent nail polish was placed on the right eye of the butterflies.…”