Physics of blood clotting in insects

Insects have an open circulatory system that makes any physical damage to their bodies extremely dangerous. Insects developed a fast and effective way of creating a primary seal to the wound halting the blood loss or invasion of microorganisms. The formed blood clot is also used as a scaffold for formation of the new tissue. We studied surface properties of different Lepidoptera species (Manduca sexta, Vanessa cardui and Enyo lugubris) to compare with aqueous Apolipophorin-III (ApoLp-III) protein  solutions from Manduca sexta and Bombyx mori. We showed that the surface tension of hemolymph can be explained by adsorption of ApoLp-III to the hemolymph-air interface. Applying silanization we modified glass surfaces and demonstrated that due to its low surface tension, hemolymph spreads and adheres to both hydrophilic and hydrophobic surfaces. We then studied formation of crust over the air-blood interface and related it to the kinetics of wound sealing. Microscopy observations revealed that the concentration of blood cells is small and could not influence the crust formation questioning the mechanism of blood clotting in insects.