A specific primed immune response in red palm weevil, Rhynchophorus ferrugineus, is mediated by hemocyte differentiation and phagocytosis. (June 2022)

• Record Type: Journal Article
• Authors: Zhang, He; Tan, An-Ran; Li, Peng-Ju; Lu, Sheng-Ping; Jia, Qing-Chen; Huang, Shu-Ning; Bai, Juan; Hou, You-Ming
• Is Part Of: Developmental and comparative immunology. Volume 131(2022)
• Publication Date: 2022-06
• Subjects: Innate immune priming -- Specificity -- Phagocytosis -- Rhynchophorus ferrugineus -- Hemocyte differentiation -- Serotonin; Immunology -- Periodicals; Developmental immunology -- Periodicals; 616.079
• DOI: 10.1016/j.dci.2022.104380
• Languages: English
• ISSNs: 0145-305X

Abstract

Abstract: Red palm weevil, Rhynchophorus ferrugineus, is an invasive and destructive pest that causes serious damages to palm trees. Like other invertebrates, red palm weevil relies solely on its innate immune response to fight invading microbes; by definition, innate immunity lacks adaptive characteristics. However, we show here that priming the red palm weevil larvae with heat-killed Bacillus thuringiensis specifically increased survival of the larvae during a secondary lethal infection with live bacteria, and B. thuringiensis primed larvae also showed a higher clearance efficiency for this bacterium, which indicated that the red palm weevil larvae possessed a strong immune priming response. The degree of enhanced immune protection was positively correlated with hemocyte proliferation and the level of phagocytic ability of hemocytes. Moreover, the red palm weevil larvae primed by B. thuringiensis induced the continuous synthesis of serotonin in the hemolymph, which in turn enhanced the phagocytic ability and pathogen clearance ability of the host, representing an important mechanism for the red palm weevil to achieve priming protection. Our findings reveal a specific immune priming of the red palm weevil larvae mediated by the continuous secretion of serotonin, and provide new insights into the mechanisms of invertebrates immune priming. Highlights: Red palm weevil possessed specific immune priming response against B. thuringiensis. Immune priming can significantly improve the survival rate and pathogen clearance ability of larvae. The enhanced immune protection was positively correlated with hemocyte proliferation and phagocytosis. Priming induced the continuous synthesis of serotonin in the hemolymph, which in turn enhanced the phagocytosis of larvae.