Stayin’ alive: Optimizing wing geometric morphometrics toward a harmless method

Abstract

Wing geometric morphometrics is a widely used tool for taxonomic and ecological studies. The conventional method involves killing insects and cutting the wings for preparation on slides and microscope photography. In this work, we proposed an alternative method to avoid killing and wing cutting, using honey bees as model species. We validated three more sustainable practices: using a smartphone to photograph the wings instead of the microscope; analyzing images of wings left attached to the bees; and using live anesthetized bees without sacrificing them. The results of geometric morphometrics and statistical analyses demonstrated the validity of using the smartphone to capture wing images of adequate quality to correctly digitize the landmarks at the veins intersection. Wings left attached to the bees and photographed without any support were significantly different in shape from those cut and taped to a sheet of paper. Probably the position of the wings was not parallel enough to the smartphone, which caused image distortions. This problem was overcome by placing the wings in a homemade portable clamp to flatten them and keep them more parallel to the smartphone. In this way, the morphology of the wings left attached to the bees was equal to that of the cut wings. Lastly, analyses of wing images of anesthetized live bees showed no differences compared with those of cut wings. These results set the basis for the non-destructive application of geometric morphometrics on museum specimens and for field applications on caught and released individuals, avoiding the unnecessary killing of insects.