This study examines how the dynamics of fungus-insect interactions can be modulated by temperature. The wax moth, Galleria mellonella, is a well-studied and important model insect whose larvae in the wild develop opti...This study examines how the dynamics of fungus-insect interactions can be modulated by temperature. The wax moth, Galleria mellonella, is a well-studied and important model insect whose larvae in the wild develop optimally at around 34 ℃ in beehives. However, surprisingly little research on wax moths has been conducted at relevant temperatures. In this study, the entomopathogenic fungus Metarhizium robertsii inflicted rapid and substantial mortality on wax moth larvae maintained at a constant temperature of 24 ℃, but at 34 ℃ a 10 fold higher dose was required to achieve an equivalent mortality. The cooler temperature favored fungal pathogenicity, with condial adhesion to the cuticle, germination and hemocoel invasion all significantly enhanced at 24 ℃, compared with 34 ℃. The wax moth larvae immune responses altered with the temperature, and with the infective dose of the fungus. Enzyme-based immune defenses （lysozyme and phenoloxidase） exhibited enhanced activity at the warmer temperature. A dramatic upregulation in the basal expression of galiomicin and gallerimycin was triggered by cooling, and this was augmented in the presence of the fungus. Profiling of the predominant insect epicuticular fatty acids revealed a 4-7 fold increase in palmetic, oleic and linoleic acids in larvae maintained at 24 ℃ compared with those at 34 ℃, but these failed to exert fungistatic effects on topically applied fungus. This study demonstrates the importance of choosing environmental conditions relevant to the habitat of the insect host when determining the dynamics and outcome of insect/fungus interactions, and has particular significance for the application of entomopathogens as biocontrol agents.展开更多
基金The authors gratefully acknowledge funding from the Russian Foundation for Basic Research （project No. 16- 54-53033 to VYK and MVT）, Grant of Russian Federation President （MK-6278.2015.4 to ONY）. IMD gratefully acknowledge funding from the Russian Science Foundation （project No.16-14-10067） for support in the model development and immunological study. TMB was supported by a grant funded jointly by the Biotechnology and Biological Sciences Research Council, the Department For Environment, Food And Rural affairs, the Economic and Social Research Council, the Forestry Commission, the Natural Environment Research Council and the Scottish Government, under the Tree Health and Plant Biosecurity Initiative.
文摘This study examines how the dynamics of fungus-insect interactions can be modulated by temperature. The wax moth, Galleria mellonella, is a well-studied and important model insect whose larvae in the wild develop optimally at around 34 ℃ in beehives. However, surprisingly little research on wax moths has been conducted at relevant temperatures. In this study, the entomopathogenic fungus Metarhizium robertsii inflicted rapid and substantial mortality on wax moth larvae maintained at a constant temperature of 24 ℃, but at 34 ℃ a 10 fold higher dose was required to achieve an equivalent mortality. The cooler temperature favored fungal pathogenicity, with condial adhesion to the cuticle, germination and hemocoel invasion all significantly enhanced at 24 ℃, compared with 34 ℃. The wax moth larvae immune responses altered with the temperature, and with the infective dose of the fungus. Enzyme-based immune defenses （lysozyme and phenoloxidase） exhibited enhanced activity at the warmer temperature. A dramatic upregulation in the basal expression of galiomicin and gallerimycin was triggered by cooling, and this was augmented in the presence of the fungus. Profiling of the predominant insect epicuticular fatty acids revealed a 4-7 fold increase in palmetic, oleic and linoleic acids in larvae maintained at 24 ℃ compared with those at 34 ℃, but these failed to exert fungistatic effects on topically applied fungus. This study demonstrates the importance of choosing environmental conditions relevant to the habitat of the insect host when determining the dynamics and outcome of insect/fungus interactions, and has particular significance for the application of entomopathogens as biocontrol agents.
