The scaling and allometry of organ size associated with miniaturization in insects: A case study for Coleoptera and Hymenoptera

The study of the influence of body size on structure in animals, as well as scaling of organs, is one of the key areas of functional and evolutionary morphology of organisms. Most studies in this area treated mammals or birds; comparatively few studies are available on other groups of animals. Insects, because of the huge range of their body sizes and because of their colossal diversity, should be included in the discussion of the problem of scaling and allometry in animals, but to date they remain insufficiently studied. In this study, а total of 28 complete (for all organs) and 24 partial 3D computer reconstructions of body and organs have been made for 23 insect species of 11 families and five orders. The relative volume of organs was analyzed based on these models. Most insect organs display a huge potential for scaling and for retaining their organization and constant relative volume. By contrast, the relative volume of the reproductive and nervous systems increases by a considerable factor as body size decreases. These systems can geometrically restrain miniaturization in insects and determine the limits to the smallest possible body size.