Functional characterization of a venom protein calreticulin in the Ectoparasitoid Pachycrepoideus vindemiae

Authors: YANG, LEI - ZHEJIANG UNIVERSITY OF TECHNOLOGY; WANG, BEIBEI - ZHEJIANG UNIVERSITY OF TECHNOLOGY; QIU, LIMING - ZHEJIANG UNIVERSITY OF TECHNOLOGY; WAN, BIN - ZHEJIANG UNIVERSITY OF TECHNOLOGY; YANG, YI - ZHEJIANG UNIVERSITY OF TECHNOLOGY; LIU, MINGMING - ZHEJIANG UNIVERSITY OF TECHNOLOGY; WANG, FANG - ZHEJIANG UNIVERSITY OF TECHNOLOGY; FANG, QI - ZHEJIANG UNIVERSITY OF TECHNOLOGY; Stanley, David; YE, GONGYIN - ZHEJIANG UNIVERSITY OF TECHNOLOGY

Submitted to: Insects
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/24/2019
Publication Date: 12/31/2019
Citation: Yang, L., Wang, B., Qiu, L., Wan, B., Yang, Y., Liu, M., Wang, F., Fang, Q., Stanley, D.W., Ye, G. 2019. Functional characterization of a venom protein calreticulin in the Ectoparasitoid Pachycrepoideus vindemiae. Insects. 11(1):29. https://doi.org/10.3390/insects11010029.
DOI: https://doi.org/10.3390/insects11010029

Interpretive Summary: Long-term agricultural sustainability is severely threatened by widespread use of classical insecticides. Threats include increasing resistance to insecticides and sharply decreasing environmental quality. The biological control of insects is a potentially powerful alternative to classical insecticides, based on the idea that direct application of certain insect-specific predators, pathogens and parasites can reduce pest insect populations to a point that the pests exert only negligible economic damage. A major problem, however, is that many insect parasites have a very narrow range of hosts. This limits the usefulness of any given parasite species in biological control programs. In this paper, we examined the relationship of a parasitic insect and its host, a pest insect, by identifying a new venom-specific protein in the parasite. We learned that this protein will guide continued research into how venom proteins influence the narrow range of hosts in the parasite. Scientists who study host/parasite relationships will use this information in research designed to understand how parasite venom can be manipulated to broaden the host range of a parasite. Ultimately, this research will benefit growers who produce vegetable crops and the people who consume vegetables.

Technical Abstract: Venom proteins act in the immunological interactions between parasitoids and their host insects. The effect of venom proteins on host immunity is not fully understood in pupal parasitoids. We identified the functions of a venom protein, calreticulin (PvCRT), in the pupal ectoparasitoid Pachycrepoideus vindemiae. Here, we report that PvCRT features a signal peptide and two conserved “calreticulin” domains. Multiple sequence alignments show that PvCRT shares 83.54% amino acid identity with CRT from both Pteromalus puparum and Nasonia vitripennis, which infers a close relationship among these three species. Using qPCR analysis, we found a lower expression level of PvCRT (0.27-fold) in the venom apparatus compared to the corresponding carcass. Immunohistochemical localization revealed that PvCRT was ubiquitously expressed in venom gland. The expression of the PvCRT gene in Drosophila transgenic lines via the UAS/Gal4 binary expression system reduced the self-encapsulation phenotype of tu(1)Sz1 mutants. Additionally, studies on humoral immunity indicate that PvCRT does not affect the antimicrobial immune responses of the host. This work on an ectoparasitoid will increase our understanding of venom–mediated host-parasitoid interactions.