Altered immune function of Octodonta nipae (Maulik) to its pupal endoparasitoid, Tetrastichus brontispae Ferrière

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• 作者：E Meng^a ; ^b ; ¹ ; Baozhen Tang^a ; ^b ; ¹ ; Youming Hou^a ; ^b ; ^{ymhou@fafu.edu.cn" class="auth_mail" title="E-mail the corresponding author} ; Xinxin Chen^a ; ^b ; Jiantu Chen^a ; ^b ; Xiao-Qiang Yu^a ; ^c
• 关键词：Hemocyte types ; Hemocyte loads ; Melanization ; Octodonta nipae ; Parasitism ; Phenoloxidase ; Tetrastichus brontispae
• 刊名：Comparative Biochemistry and Physiology Part B: Biochemistry and Molecular Biology
• 出版年：2016
• 出版时间：August 2016
• 年：2016
• 卷：198
• 期：Complete
• 页码：100-109
• 全文大小：1536 K

文摘

Most studies on the contribution of the altered immune response by endoparasitoid have been restricted to the interactions between Ichneumonoidea and their hosts, while effects of parasitism by Chalcidoidea on the hosts have rarely been characterized except some wasps such as Pteromalidae. Endoparasitoid Tetrastichus brontispae Ferrière, belonging to Eulophidae (Hymenoptera), has a great potential to control some Coleopteran beetles such as Octodonta nipae, one invasive species in southern China. However, the physiological mechanism underlying the escape from the melanotic encapsulation in O. nipae pupae has not been demonstrated. In the present study, effects of parasitism on the immune function of its pupal host O. nipae were investigated. The combining results that granulocytes and plasmatocytes could phagocytize bacteria from 2 to 48 h and granulocytes, plasmatocytes and oenocytoids were prophenoloxidase/phenoloxidase positive hemocytes indicated that granulocytes, plasmatocytes and oenocytoids were the main immunocompetent hemocytes in O. nipae pupae. Parasitism by T. brontispae resulted in a significant increase in the percentage of hemocytes viability and spreading at 96 h, growing percentage of granulocytes at 24 h but no effects on the total hemocyte counts, and an enhanced phenoloxidase activity only at 12 and 72 h while a significantly longer melanization time of the hemolymph at 96 h following parasitism. These results indicate that mixtures of systemic active and local active regulation are used for T. brontispae to escape host encapsulation in O. nipae pupae. The present study contributes to the understanding of the diversity of virulence strategies used by parasitoids.