Cellular response to bacterial infection in the grasshopper Oxya chinensis

Oxya chinensis is one of the most widespread grasshopper species found in China and one of the most common pests against rice. In view of the importance of haemocytes in insect immunity in general, and the lack of information on the haemocytes of O. chinensis, we examined the haemocytes of this species in detail. We challenged the cellular response of this grasshopper with the bacteria Escherichia coli, Staphylococcus aureus, and Bacillus subtilis. Haemocyte morphology was observed using light, scanning electron and transmission electron microscopy, which revealed distinct morphological varieties of haemocytes. Granulocytes and plasmatocytes responded to the bacterial challenge by phagocytosis. Histochemical staining indicated the presence of acid phosphatase in plasmatocytes and granulocytes. We also observed non-phagocytic prohemocytes and vermicytes, but their functions in the circulation are unclear. Insect haemocytes play a crucial role in cellular immunity, and further research is needed for a comprehensive understanding.