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Meraj S, Salcedo-Porras N, Lowenberger C, Gries G. Activation of immune pathways in common bed bugs, Cimex lectularius, in response to bacterial immune challenges - a transcriptomics analysis. Front Immunol 2024; 15:1384193. [PMID: 38694504 PMCID: PMC11061471 DOI: 10.3389/fimmu.2024.1384193] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2024] [Accepted: 04/02/2024] [Indexed: 05/04/2024] Open
Abstract
The common bed bug, Cimex lectularius, is an urban pest of global health significance, severely affecting the physical and mental health of humans. In contrast to most other blood-feeding arthropods, bed bugs are not major vectors of pathogens, but the underlying mechanisms for this phenomenon are largely unexplored. Here, we present the first transcriptomics study of bed bugs in response to immune challenges. To study transcriptional variations in bed bugs following ingestion of bacteria, we extracted and processed mRNA from body tissues of adult male bed bugs after ingestion of sterile blood or blood containing the Gram-positive (Gr+) bacterium Bacillus subtilis or the Gram-negative (Gr-) bacterium Escherichia coli. We analyzed mRNA from the bed bugs' midgut (the primary tissue involved in blood ingestion) and from the rest of their bodies (RoB; body minus head and midgut tissues). We show that the midgut exhibits a stronger immune response to ingestion of bacteria than the RoB, as indicated by the expression of genes encoding antimicrobial peptides (AMPs). Both the Toll and Imd signaling pathways, associated with immune responses, were highly activated by the ingestion of bacteria. Bacterial infection in bed bugs further provides evidence for metabolic reconfiguration and resource allocation in the bed bugs' midgut and RoB to promote production of AMPs. Our data suggest that infection with particular pathogens in bed bugs may be associated with altered metabolic pathways within the midgut and RoB that favors immune responses. We further show that multiple established cellular immune responses are preserved and are activated by the presence of specific pathogens. Our study provides a greater understanding of nuances in the immune responses of bed bugs towards pathogens that ultimately might contribute to novel bed bug control tactics.
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Affiliation(s)
- Sanam Meraj
- Department of Biological Sciences, Simon Fraser University, Burnaby, BC, Canada
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Xu J, Zheng L, Tan M, Wu H, Yan S, Jiang D. The susceptibility of Hyphantria cunea larvae to microbial pesticides Bacillus thuringiensis and Mamestra brassicae nuclear polyhedrosis virus under Cd stress. PESTICIDE BIOCHEMISTRY AND PHYSIOLOGY 2023; 191:105383. [PMID: 36963948 DOI: 10.1016/j.pestbp.2023.105383] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/21/2022] [Revised: 02/17/2023] [Accepted: 03/03/2023] [Indexed: 06/18/2023]
Abstract
Heavy metal pollution is an abiotic factor that can affect the efficiency of pest control. In this study, two microbial pesticides, Bacillus thuringiensis and Mamestra brassicae nuclear polyhedrosis virus (MbNPV), were used to treat Hyphantria cunea larvae with Cd pre-exposure, and the humoral and cellular immunity of H. cunea larvae with Cd exposure were evaluated. The results showed that Cd exposure increased the susceptibility of H. cunea larvae to microbial pesticides B. thuringiensis and MbNPV, and the lethal effect of Cd exposure and microbial pesticides on H. cunea larvae was synergistic. Cd exposure significantly decreased the expression of pathogen recognition genes (GNBP1 and GNBP3), signal transduction genes (Relish, Myd88, Tube, and Imd), and antimicrobial peptide gene (Lebocin) in the humoral immunity of H. cunea larvae compared with the untreated larvae. Parameters of cellular immunity, including the number of hemocytes, phagocytic activity, melanization activity, encapsulation activity, and the expression of three phagocytic regulatory genes (HEM1, GALE1, GALE2), were also found to decrease significantly in Cd-treated larvae. TOPSIS analysis showed that humoral immunity, cellular immunity, and total immunity levels of H. cunea larvae with Cd exposure were weaker than those in untreated larvae. Correlation analysis showed that the mortality of two microbial pesticides investigated in H. cunea larvae was negatively correlated with the humoral and cellular immunity of larvae. Taken togther, Cd exposure results in immunotoxic effects on H. cunea larvae and the use of microbial pesticides are an effective strategy for pest control in heavy metal-polluted areas.
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Affiliation(s)
- Jinsheng Xu
- School of Forestry, Northeast Forestry University, Harbin 150040, PR China; Key Laboratory of Sustainable Forest Ecosystem Management-Ministry of Education, Northeast Forestry University, Harbin 150040, PR China
| | - Lin Zheng
- School of Forestry, Northeast Forestry University, Harbin 150040, PR China; Key Laboratory of Sustainable Forest Ecosystem Management-Ministry of Education, Northeast Forestry University, Harbin 150040, PR China
| | - Mingtao Tan
- School of Forestry, Northeast Forestry University, Harbin 150040, PR China; Key Laboratory of Sustainable Forest Ecosystem Management-Ministry of Education, Northeast Forestry University, Harbin 150040, PR China
| | - Hongfei Wu
- School of Forestry, Northeast Forestry University, Harbin 150040, PR China; Key Laboratory of Sustainable Forest Ecosystem Management-Ministry of Education, Northeast Forestry University, Harbin 150040, PR China
| | - Shanchun Yan
- School of Forestry, Northeast Forestry University, Harbin 150040, PR China; Key Laboratory of Sustainable Forest Ecosystem Management-Ministry of Education, Northeast Forestry University, Harbin 150040, PR China
| | - Dun Jiang
- School of Forestry, Northeast Forestry University, Harbin 150040, PR China; Key Laboratory of Sustainable Forest Ecosystem Management-Ministry of Education, Northeast Forestry University, Harbin 150040, PR China.
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