Work

An arylphorin secreted by endoparasitoid larvae Microplitis mediator regulates cellular and humoral immunity of the host insect, Mythimna separata

Year: 2026

Type: article

Abstract: BACKGROUND: Endoparasitoid larvae expend their development facing immune threats in the hemocoel of their hosts. In addition to maternal-derived factors such as venom and virus-like particles, parasitoid larvae are also capable of regulating host immunity; however, few studies have investigated this regulation. RESULTS: In this study, we recovered endoparasitoid wasp Microplitis mediator (Haliday, 1834) larvae from the host, oriental armyworm Mythimna separata (Walker, 1865), and cultured them in vitro. After injection of culture medium containing larvae-secreted proteins into the hosts, we observed inhibition of the host hemolymph phenoloxidase (PO) activity. Using sodium dodecyl sulfate-polyacrylamide gel electrophoresis followed by mass spectrometry, we identified an arylphorin (MmAry) and an apolipophorin-II/I (MmApo) secreted by the parasitoid larvae. We then investigated the functions of MmAry in the regulation of cellular and humoral responses in the host using both RNA interference and biochemical assays. We discovered that the knockdown of MmAry expression resulted in an increase in the host PO activity. In addition, the recombinant MmAry protein suppressed the expression of antimicrobial peptide genes, cellular phagocytosis and encapsulation processes in the host. Pull-down and co-immunoprecipitation analyses indicated that the host apolipophorin (MsApo) is the target of the wasp larval arylphorin, and this was confirmed using a glutathione S-transferase pull-down experiment. Using recombinant MmAry and MmAry antibody, we observed that MmAry improves the rate of parasitoid pupation. CONCLUSIONS: The endoparasitoid larva secretes certain proteins to counteract the host's immune responses ensuring their successful development inside the host. © 2026 Society of Chemical Industry.

Source: Pest Management Science

DOI: 10.1002/ps.70502

Authors: Lin Zhou, Lizhen Zhou, Chang Liu, Zhen Zou, Zhiqiang Lu

Institutions: Northwest A&F University, Chinese Academy of Sciences, University of Chinese Academy of Sciences, Institute of Zoology

Language: English

Topic: Invertebrate Immune Response Mechanisms

Subfield: Immunology

Field: Immunology and Microbiology

Domain: Life Sciences

Open Access status: bronze

Funders: National Natural Science Foundation of China, State Key Laboratory of Integrated Pest Management

Award: G1707038586