Encapsulation is a kind of cellular immune response of insect haemocytes, which results in the formation of capsules around invading parasites. However, the molecular mechanism of this response is largely unknown. In this study, we identified a potential immune-related gene in the cotton bollworm, Helicoverpa armigera, called defence protein 1 (Ha-DFP1). A tissue distribution analysis revealed that Ha-DFP1 protein was expressed in haemocytes and secreted into the haemolymph of Helic. armigera larvae. The Ha-DFP1 mRNA transcript level in haemocy...