Different Effects of Metarhizium anisopliae Strains IMI330189 and IBC200614 on Enzymes Activities and Hemocytes of Locusta migratoria L.

Guangchun Cao,Miao Jia,Zehua Zhang,Guangjun Wang,Xiongbing Tu,Xia Zhao,Xiangqun Nong,Lei Wang,Erjun Ling

doi:10.1371/journal.pone.0155257

Guangchun Cao, Miao Jia + Show 7 more

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https://doi.org/10.1371/journal.pone.0155257

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Abstract

BackgroundMetarhizium is an important class of entomopathogenic fungi in the biocontrol of insects, but its virulence is affected by insect immunity. To clarify the mechanism in virulence of Metarhizium, we compared the immunological differences in Locusta migratoria L. when exposed to two strains of Metarhizium anisopliae (Ma).ResultsThe virulence of Ma IMI330189 was significantly higher than that of Ma IBC200614 to locust, and IMI330189 overcame the hemocytes and began destroying the hemocytes of locust at 72 h after spray, while locust is immune to IBC200614. IMI330189 could overcome the humoral immunity of locust by inhibiting the activities of phenol oxidase (PO), esterases, multi-function oxidases (MFOs) and acetylcholinesterases in locust while increasing the activities of glutathione-S-transferases (GSTs), catalase and aryl-acylamidase (AA). However IBC200614 inhibit the activities of GSTs and AA in locust and increase the activities of MFOs, PO, superoxide dismutase, peroxidase and chitinase in locust. The changes of enzymes activities in period of infection showed that the time period between the 2nd and the 5th day after spray is critical in the pathogenic process.ConclusionThese results found the phenomenon that Ma initiatively broke host hemocytes, revealed the correlation between the virulence of Ma and the changes of enzymes activities in host induced by Ma, and clarified the critical period in the infection of Ma. So, these results should provide guidance for the construction of efficient biocontrol Ma strains.

Highlights

The growing demand to reduce chemical inputs in agriculture, along with the increased resistance to insecticides, has provided great impetus for the development of alternative forms of insect-pest control
IMI330189 could overcome the humoral immunity of locust by inhibiting the activities of phenol oxidase (PO), esterases, multi-function oxidases (MFOs) and acetylcholinesterases in locust while increasing the activities of glutathione-S-transferases (GSTs), catalase and aryl-acylamidase (AA)
IBC200614 inhibit the activities of GSTs and AA in locust and increase the activities of MFOs, PO, superoxide dismutase, peroxidase and chitinase in locust

Summary

Introduction

The growing demand to reduce chemical inputs in agriculture, along with the increased resistance to insecticides, has provided great impetus for the development of alternative forms of insect-pest control. The thickness, structure, and chemical composition of the cuticle are important in preventing the adhesion and germination of conidia, and the penetration of fungal hyphae [7, 8]. It has been documented that the differences in the cuticle of locusts and cockroaches led to differences in the germination and penetration abilities of Metarhizium anisopliae and Metarhizium acridum; the two fungi had significantly different virulence levels in locusts and cockroaches [10]. Many enzymes are involved in these mechanisms and play important roles in the defense of insects against fungal infections [11,12,13,14,15,16,17]. To clarify the mechanism in virulence of Metarhizium, we compared the immunological differences in Locusta migratoria L. when exposed to two strains of Metarhizium anisopliae (Ma)

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