Department of Biochemistry, University of Nevada, Reno, NV.
Department of Biology, University of Nevada, Reno, NV.
J Insect Sci. 2020 Sep 1;20(5). doi: 10.1093/jisesa/ieaa116.
An important goal of disease ecology is to understand trophic interactions influencing the host-pathogen relationship. This study focused on the effects of diet and immunity on the outcome of viral infection for the polyphagous butterfly, Vanessa cardui Linnaeus (Lepidoptera: Nymphalidae) (painted lady). Specifically, we aimed to understand the role that larval host plants play when fighting a viral pathogen. Larvae were orally inoculated with the entomopathogenic virus, Junonia coenia densovirus (JcDV) (Parvovirididae: Densovirinae, Lepidopteran Potoambidensovirus 1) and reared on two different host plants (Lupinus albifrons Bentham (Fabales: Fabaceae) or Plantago lanceolata Linnaeus (Lamiales: Plantaginaceae)). Following viral infection, the immune response (i.e., phenoloxidase [PO] activity), survival to adulthood, and viral load were measured for individuals on each host plant. We found that the interaction between the immune response and survival of the viral infection was host plant dependent. The likelihood of survival was lowest for infected larvae exhibiting suppressed PO activity and feeding on P. lanceolata, providing some evidence that PO activity may be an important defense against viral infection. However, for individuals reared on L. albifrons, the viral infection had a negligible effect on the immune response, and these individuals also had higher survival and lower viral load when infected with the pathogen compared to the controls. Therefore, we suggest that host plant modifies the effects of JcDV infection and influences caterpillars' response when infected with the virus. Overall, we conclude that the outcome of viral infection is highly dependent upon diet, and that certain host plants can provide protection from pathogens regardless of immunity.
疾病生态学的一个重要目标是了解影响宿主-病原体关系的营养相互作用。本研究侧重于饮食和免疫对多食物种蝴蝶 Vanessa cardui Linnaeus（鳞翅目：蛱蝶科）（凤蝶）病毒感染结果的影响。具体来说，我们旨在了解幼虫宿主植物在与病毒病原体作斗争时所起的作用。幼虫经口接种昆虫病原病毒 Junonia coenia densovirus（JcDV）（细小病毒科：浓核病毒科，鳞翅目 Potoambidensovirus 1），并在两种不同的宿主植物（ Lupinus albifrons Bentham（豆目：豆科）或 Plantago lanceolata Linnaeus（车前目：车前科））上饲养。在病毒感染后，测量每个宿主植物上个体的免疫反应（即酚氧化酶[PO]活性）、成虫存活率和病毒载量。我们发现，免疫反应与病毒感染的存活率之间的相互作用取决于宿主植物。表现出 PO 活性受抑制且以 P. lanceolata 为食的感染幼虫的存活率最低，这为 PO 活性可能是抵抗病毒感染的重要防御机制提供了一些证据。然而，对于在 L. albifrons 上饲养的个体，病毒感染对免疫反应几乎没有影响，与对照相比，感染该病原体的个体的存活率更高，病毒载量更低。因此，我们认为宿主植物会改变 JcDV 感染的影响，并影响幼虫在感染病毒时的反应。总的来说，我们得出结论，病毒感染的结果高度依赖于饮食，某些宿主植物可以在不依赖免疫的情况下提供对病原体的保护。
