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Prato A, Fernando Santos E, Mendes Ferreira H, Akemi Oi C, Santos do Nascimento F, Rantala MJ, Krams I, Rodrigues de Souza A. Immune response in paper wasp workers: Task matters more than age. JOURNAL OF INSECT PHYSIOLOGY 2024; 154:104629. [PMID: 38430966 DOI: 10.1016/j.jinsphys.2024.104629] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/13/2023] [Revised: 02/01/2024] [Accepted: 02/27/2024] [Indexed: 03/05/2024]
Abstract
Workers of social hymenopterans (ants, bees and wasps) display specific tasks depending on whether they are younger or older. The relative importance of behavior and age in modulating immune function has seldom been addressed. We compared the strength of encapsulation-melanization immune response (hereafter melanotic encapsulation) in paper wasps displaying age polyethism or experimentally prevented from behavioral specialization. Foragers of Polybia paulista had higher melanotic encapsulation than guards, regardless of their age. Nevertheless, melanotic encapsulation decreased with age when wasps were prevented from behavioral specialization. Thus, in this species, worker melanotic encapsulation seems more sensitive to task than age. Foraging is considered one of the riskier behaviors in terms of pathogen exposure, so upregulating melanotic encapsulation in foragers can possibly improve both individual and colony-level resistance against infections.
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Affiliation(s)
- Amanda Prato
- Departamento de Biologia, Faculdade de Filosofia Ciências e Letras de Ribeirão Preto, Universidade de São Paulo, São Paulo, Brasil.
| | - Eduardo Fernando Santos
- Departamento de Zoologia e Botânica, Instituto de Biociências, Letras e Ciências Exatas, Universidade Estadual Paulista "Júlio de Mesquita Filho", São José do Rio Preto, Brasil
| | | | - Cintia Akemi Oi
- Laboratory of Socioecology and Social Evolution, KU Leuven, Leuven, Belgium; Center for Biodiversity and Environmental Research, Department of Genetics and Evolution, UCL, London, United Kingdom
| | - Fábio Santos do Nascimento
- Departamento de Biologia, Faculdade de Filosofia Ciências e Letras de Ribeirão Preto, Universidade de São Paulo, São Paulo, Brasil
| | | | - Indrikis Krams
- Department of Biotechnology, Daugavpils University, Latvia; Department of Zoology and Animal Ecology, Faculty of Biology, University of Latvia, Latvia; Institute of Ecology and Earth Sciences, University of Tartu, Estonia
| | - André Rodrigues de Souza
- Departamento de Biologia, Faculdade de Filosofia Ciências e Letras de Ribeirão Preto, Universidade de São Paulo, São Paulo, Brasil
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Costantin EC, Viol DL, Del Puppo NP, Elliot SL. Realism in Immune Ecology Studies: Artificial Diet Enhances a Caterpillar's Immune Defense but Does Not Mask the Effects of a Plastic Immune Strategy. FRONTIERS IN INSECT SCIENCE 2022; 1:754571. [PMID: 38468892 PMCID: PMC10926546 DOI: 10.3389/finsc.2021.754571] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/06/2021] [Accepted: 11/29/2021] [Indexed: 03/13/2024]
Abstract
The immune system is considered a functional trait in life-history theory and its modulation is predicted to be costly and highly dependent on the host's nutrition. Therefore, the nutritional status of an individual has a great impact on an animal's immune ecology. Herbivorous insects are commonly used as model organisms in eco-immunology studies and the use of an artificial diet is the predominant rearing procedure to test them. However, this diet differs from what herbivores experience in nature and it is unclear to what degree this distinction might impact on the relevance of these studies for the real world. Here, we compared plant-based vs. artificial diet in a set of three experiments to investigate the interaction of both diets with a plastic immune strategy known as Density-Dependent Prophylaxis (DDP). We used as a model organism the velvetbean caterpillar Anticarsia gemmatalis, which is known to adjust its immune defense in line with the DDP hypothesis. Our main results showed that larvae fed with artificial diet had 20.5% more hemocytes circulating in the hemolymph and died 20% more slowly when infected with an obligate (viral) pathogen. Crucially, however, we did not find any indication of fitness costs related to DDP. The use of artificial diet did not interact with that of DDP except in the case of host survival after infection, where the DDP effect was only observable in this diet. Our findings suggest the use of an artificial diet does not mask resource allocation conflicts between immune investment and fitness related traits, but to some extent it might lead to an overestimation of immune parameters and host survival time after infection. We believe that this is the first study to compare an artificial diet and a host plant covering all these aspects: immune parameters, life-history traits, and host survival after infection. Here we provide evidence that, besides the quantitative effects in immune parameters and host survival time, the use of artificial diet interacts only marginally with a density-dependent immune response. This provides support for the use of artificial diets in eco-immunology studies with insects.
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Affiliation(s)
| | | | | | - Simon L. Elliot
- Laboratory of Insect-Microbe Interactions, Department of Entomology, Universidade Federal de Viçosa, Viçosa, Brazil
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Dragičević P, Grbin D, Maguire I, Blažević SA, Abramović L, Tarandek A, Hudina S. Immune Response in Crayfish Is Species-Specific and Exhibits Changes along Invasion Range of a Successful Invader. BIOLOGY 2021; 10:1102. [PMID: 34827095 PMCID: PMC8615248 DOI: 10.3390/biology10111102] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/24/2021] [Revised: 10/23/2021] [Accepted: 10/24/2021] [Indexed: 12/21/2022]
Abstract
Immunity is an important component of invasion success since it enables invaders' adaptation to conditions of the novel environment as they expand their range. Immune response of invaders may vary along the invasion range due to encountered parasites/microbial communities, conditions of the local environment, and ecological processes that arise during the range expansion. Here, we analyzed changes in the immune response along the invasion range of one of the most successful aquatic invaders, the signal crayfish, in the recently invaded Korana River, Croatia. We used several standard immune parameters (encapsulation response, hemocyte count, phenoloxidaze activity, and total prophenoloxidaze) to: i) compare immune response of the signal crayfish along its invasion range, and between species (comparison with co-occurring native narrow-clawed crayfish), and ii) analyze effects of specific predictors (water temperature, crayfish abundance, and body condition) on crayfish immune response changes. Immune response displayed species-specificity, differed significantly along the signal crayfish invasion range, and was mostly affected by water temperature and population abundance. Specific immune parameters showed density-dependent variation corresponding to increased investment in them during range expansion. Obtained results offer baseline insights for elucidating the role of immunocompetence in the invasion success of an invertebrate freshwater invader.
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Affiliation(s)
- Paula Dragičević
- Department of Biology, Faculty of Science, University of Zagreb, Rooseveltov Trg 6, 10000 Zagreb, Croatia; (P.D.); (I.M.); (S.A.B.); (L.A.); (A.T.)
| | - Dorotea Grbin
- Department of Biochemical Engineering, Faculty of Food Technology and Biotechnology, University of Zagreb, Pierottijeva Ulica 6, 10000 Zagreb, Croatia;
| | - Ivana Maguire
- Department of Biology, Faculty of Science, University of Zagreb, Rooseveltov Trg 6, 10000 Zagreb, Croatia; (P.D.); (I.M.); (S.A.B.); (L.A.); (A.T.)
| | - Sofia Ana Blažević
- Department of Biology, Faculty of Science, University of Zagreb, Rooseveltov Trg 6, 10000 Zagreb, Croatia; (P.D.); (I.M.); (S.A.B.); (L.A.); (A.T.)
| | - Lucija Abramović
- Department of Biology, Faculty of Science, University of Zagreb, Rooseveltov Trg 6, 10000 Zagreb, Croatia; (P.D.); (I.M.); (S.A.B.); (L.A.); (A.T.)
| | - Anita Tarandek
- Department of Biology, Faculty of Science, University of Zagreb, Rooseveltov Trg 6, 10000 Zagreb, Croatia; (P.D.); (I.M.); (S.A.B.); (L.A.); (A.T.)
| | - Sandra Hudina
- Department of Biology, Faculty of Science, University of Zagreb, Rooseveltov Trg 6, 10000 Zagreb, Croatia; (P.D.); (I.M.); (S.A.B.); (L.A.); (A.T.)
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Kong H, Liu Z, Yang P, Yuan L, Jing W, Dong C, Zheng M, Tian Z, Hou Q, Zhu S. Effects of Larval Density on Plutella xylostella Resistance to Granulosis Virus. INSECTS 2020; 11:insects11120857. [PMID: 33276568 PMCID: PMC7761614 DOI: 10.3390/insects11120857] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/12/2020] [Revised: 11/29/2020] [Accepted: 11/30/2020] [Indexed: 11/16/2022]
Abstract
Simple Summary Generally, the transmission of pathogens is positively density-dependent; therefore, the risk of insects becoming infected by diseases increases with increasing population density. It has been reported that some phase-polyphenic insects from high-density conditions are more resistant (or susceptible or identical) to pathogens than those from low-density conditions. This phenomenon is termed “density-dependent prophylaxis” (DDP). The diamondback moth (DBM), Plutella xylostella, one of the most destructive insect pests affecting cruciferous crops, is non phase-polyphenic. Biological control, especially by pathogens, plays an important role in the integrated pest management program of DBM. However, whether the P. xylostella larval population exhibits DDP has not been elucidated. The resistance of DBM larvae to P. xylostella granulosis virus (Plxy GV) and their immune response to the virus under different density treatments were investigated under laboratory conditions. Our results demonstrated that P. xylostella larvae exhibited DDP within a certain limited density. This study may help to elucidate the biocontrol effect of different density populations of P. xylostella by granulosis virus and guide improvements in future management strategy. Abstract It has been reported that some phase-polyphenic insects from high-density conditions are more resistant to pathogens than those from low-density conditions. This phenomenon is termed “density-dependent prophylaxis” (DDP). However, whether non phase-polyphenic insects exhibit DDP has rarely been elucidated. The diamondback moth (DBM), Plutella xylostella, one of the most destructive insect pests affecting cruciferous crops, is non phase-polyphenic. In this study, the resistance of DBM larvae to P. xylostella granulosis virus (Plxy GV) and their immune response to the virus when reared at densities of 1, 2, 5, 10, 15, and 20 larvae per Petri dish were investigated under laboratory conditions. Compared with larvae reared at lower densities, larvae reared at moderate density showed a significantly higher survival rate, but the survival rate significantly decreased with further increases in rearing density. Furthermore, the phenoloxidase, lysozyme and antibacterial activity and total hemocyte count in the hemolymph of the larvae, regardless of whether they were challenged with the virus, from different larval densities corresponded to the observed differences in resistance to Plxy GV. These results demonstrated that P. xylostella larvae exhibited DDP within a certain limited density. This study may help to elucidate the biocontrol effect of different density populations of P. xylostella by granulosis virus and guide improvements in future management strategy.
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Affiliation(s)
- Hailong Kong
- College of Horticulture and Plant Protection, Yangzhou University, Wenhui East Road, NO. 48, Yangzhou 225009, China; (Z.L.); (L.Y.); (W.J.); (C.D.); (M.Z.); (Z.T.); (Q.H.); (S.Z.)
- Correspondence: ; Tel.: +86-514-8797-8110
| | - Zhonglin Liu
- College of Horticulture and Plant Protection, Yangzhou University, Wenhui East Road, NO. 48, Yangzhou 225009, China; (Z.L.); (L.Y.); (W.J.); (C.D.); (M.Z.); (Z.T.); (Q.H.); (S.Z.)
| | - Pingjun Yang
- Suzhou Plant Protection and Plant Quarantine Station, Stadium Road, NO. 4, Suzhou 215006, China;
| | - Lin Yuan
- College of Horticulture and Plant Protection, Yangzhou University, Wenhui East Road, NO. 48, Yangzhou 225009, China; (Z.L.); (L.Y.); (W.J.); (C.D.); (M.Z.); (Z.T.); (Q.H.); (S.Z.)
| | - Wanghui Jing
- College of Horticulture and Plant Protection, Yangzhou University, Wenhui East Road, NO. 48, Yangzhou 225009, China; (Z.L.); (L.Y.); (W.J.); (C.D.); (M.Z.); (Z.T.); (Q.H.); (S.Z.)
| | - Chuanlei Dong
- College of Horticulture and Plant Protection, Yangzhou University, Wenhui East Road, NO. 48, Yangzhou 225009, China; (Z.L.); (L.Y.); (W.J.); (C.D.); (M.Z.); (Z.T.); (Q.H.); (S.Z.)
| | - Minyuan Zheng
- College of Horticulture and Plant Protection, Yangzhou University, Wenhui East Road, NO. 48, Yangzhou 225009, China; (Z.L.); (L.Y.); (W.J.); (C.D.); (M.Z.); (Z.T.); (Q.H.); (S.Z.)
| | - Zhen Tian
- College of Horticulture and Plant Protection, Yangzhou University, Wenhui East Road, NO. 48, Yangzhou 225009, China; (Z.L.); (L.Y.); (W.J.); (C.D.); (M.Z.); (Z.T.); (Q.H.); (S.Z.)
| | - Qiuli Hou
- College of Horticulture and Plant Protection, Yangzhou University, Wenhui East Road, NO. 48, Yangzhou 225009, China; (Z.L.); (L.Y.); (W.J.); (C.D.); (M.Z.); (Z.T.); (Q.H.); (S.Z.)
| | - Shude Zhu
- College of Horticulture and Plant Protection, Yangzhou University, Wenhui East Road, NO. 48, Yangzhou 225009, China; (Z.L.); (L.Y.); (W.J.); (C.D.); (M.Z.); (Z.T.); (Q.H.); (S.Z.)
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Li HB, Dai CG, Hu Y. Characterization and expression analysis of genes encoding three small heat shock proteins in the oriental armyworm, Mythimna separata (Walker). PLoS One 2020; 15:e0235912. [PMID: 32776931 PMCID: PMC7417081 DOI: 10.1371/journal.pone.0235912] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2020] [Accepted: 06/24/2020] [Indexed: 11/18/2022] Open
Abstract
Small heat shock proteins (sHsps) function in the response of insects to abiotic
stress; however, their role in response to biotic stress has been
under-investigated. Mythimna separata, the oriental armyworm,
is polyphenetic and exhibits gregarious and solitary phases in response to high
and low population density, respectively. In this study, three genes were
identified encoding sHsps, namely
MsHsp19.7,
MsHsp19.8 and
MsHsp21.4, and expression levels in
solitary and gregarious M. separata were
compared. The deduced protein sequences of the three MsHsps had
molecular weights of 19.7, 19.8 and 21.4 kDa, respectively, and contained a
conserved α-crystalline domain. Real-time PCR analyses revealed that the three
sHsps were transcribed in all developmental stages and were
dramatically up-regulated at the 6th larval stage in gregarious
individuals. Expression of the three MsHsps was variable in
different tissues of 6th instar larvae, but exhibited consistent up-
and down-regulation in the hindgut and Malpighian tubules of gregarious
individuals, respectively. In addition,
MsHsp19.7 and
MsHsp19.8 were significantly induced when
solitary forms were subjected to crowding for 36 h, but all three
MsHsps were down-regulated when gregarious forms were
isolated. Our findings suggest that population density functions as a stress
factor and impacts MsHsps expression in M.
separata.
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Affiliation(s)
- Hong-Bo Li
- Institute of Plant Protection, Guizhou Academy of
Agricultural Sciences, Guiyang, China
- * E-mail:
| | - Chang-Geng Dai
- Institute of Plant Protection, Guizhou Academy of
Agricultural Sciences, Guiyang, China
| | - Yang Hu
- Institute of Plant Protection, Guizhou Academy of
Agricultural Sciences, Guiyang, China
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Williams T, Virto C, Murillo R, Caballero P. Covert Infection of Insects by Baculoviruses. Front Microbiol 2017; 8:1337. [PMID: 28769903 PMCID: PMC5511839 DOI: 10.3389/fmicb.2017.01337] [Citation(s) in RCA: 46] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2017] [Accepted: 07/03/2017] [Indexed: 12/19/2022] Open
Abstract
Baculoviruses (Baculoviridae) are occluded DNA viruses that are lethal pathogens of the larval stages of some lepidopterans, mosquitoes, and sawflies (phytophagous Hymenoptera). These viruses have been developed as biological insecticides for control of insect pests and as expression vectors in biotechnological applications. Natural and laboratory populations frequently harbor covert infections by baculoviruses, often at a prevalence exceeding 50%. Covert infection can comprise either non-productive latency or sublethal infection involving low level production of virus progeny. Latency in cell culture systems involves the expression of a small subset of viral genes. In contrast, covert infection in lepidopterans is associated with differential infection of cell types, modulation of virus gene expression and avoidance of immune system clearance. The molecular basis for covert infection may reside in the regulation of host-virus interactions through the action of microRNAs (miRNA). Initial findings suggest that insect nudiviruses and vertebrate herpesviruses may provide useful analogous models for exploring the mechanisms of covert infection by baculoviruses. These pathogens adopt mixed-mode transmission strategies that depend on the relative fitness gains that accrue through vertical and horizontal transmission. This facilitates virus persistence when opportunities for horizontal transmission are limited and ensures virus dispersal in migratory host species. However, when host survival is threatened by environmental or physiological stressors, latent or persistent infections can be activated to produce lethal disease, followed by horizontal transmission. Covert infection has also been implicated in population level effects on host-pathogen dynamics due to the reduced reproductive capacity of infected females. We conclude that covert infections provide many opportunities to examine the complexity of insect-virus pathosystems at the organismal level and to explore the evolutionary and ecological relationships of these pathogens with major crop and forest pests.
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Affiliation(s)
| | - Cristina Virto
- Bioinsecticidas Microbianos, Instituto de Agrobiotecnología, Consejo Superior de Investigaciones Científicas, Universidad Pública de NavarraMutilva, Spain
- Laboratorio de Entomología Agrícola y Patología de Insectos, Departamento de Producción Agraria, Universidad Pública de NavarraPamplona, Spain
| | - Rosa Murillo
- Bioinsecticidas Microbianos, Instituto de Agrobiotecnología, Consejo Superior de Investigaciones Científicas, Universidad Pública de NavarraMutilva, Spain
- Laboratorio de Entomología Agrícola y Patología de Insectos, Departamento de Producción Agraria, Universidad Pública de NavarraPamplona, Spain
| | - Primitivo Caballero
- Bioinsecticidas Microbianos, Instituto de Agrobiotecnología, Consejo Superior de Investigaciones Científicas, Universidad Pública de NavarraMutilva, Spain
- Laboratorio de Entomología Agrícola y Patología de Insectos, Departamento de Producción Agraria, Universidad Pública de NavarraPamplona, Spain
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Molecular Characterization of a Lysozyme Gene and Its Altered Expression Profile in Crowded Beet Webworm (Loxostege sticticalis). PLoS One 2016; 11:e0161384. [PMID: 27575006 PMCID: PMC5019359 DOI: 10.1371/journal.pone.0161384] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2016] [Accepted: 08/04/2016] [Indexed: 11/19/2022] Open
Abstract
There is growing evidence that insects living in high-density populations exhibit an increase in immune function to counter a higher risk of disease. This phenomenon, known as density-dependent prophylaxis, has been experimentally tested in a number of insect species. Although density-dependent prophylaxis is especially prevalent in insects exhibiting density-dependent phase polyphenism, the molecular mechanism remains unclear. Our previous study demonstrated that the antibacterial activity of lysozyme is important for this process in the beet webworm Loxostege sticticalis. In this study, a lysozyme cDNA from L. sticticalis was cloned and characterized. The full-length cDNA is 1078 bp long and contains an open reading frame of 426 bp that encodes 142 amino acids. The deduced protein possesses structural characteristics of a typical c-type lysozyme and clusters with c-type lysozymes from other Lepidoptera. LsLysozyme was found to be expressed throughout all developmental stages, showing the highest level in pupae. LsLysozyme was also highly expressed in the midgut and fat body. Elevated LsLysozyme expression was observed in L. sticticalis larvae infected by Beauveria bassiana and in larvae reared under crowding conditions. In addition, the expression level of LsLysozyme in infected larvae reared at a density of 10 larvae per jar was significantly higher compared to those reared at a density of l or 30 larvae per jar. These results suggest that larval crowding affects the gene expression profile of this lysozyme. This study provides additional insight into the expression of an immune-associated lysozyme gene and helps us to better understand the immune response of L. sticticalis under crowding conditions.
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Aragão-Silva CW, Andrade MS, Ardisson-Araújo DMP, Fernandes JEA, Morgado FS, Báo SN, Moraes RHP, Wolff JLC, Melo FL, Ribeiro BM. The complete genome of a baculovirus isolated from an insect of medical interest: Lonomia obliqua (Lepidoptera: Saturniidae). Sci Rep 2016; 6:23127. [PMID: 27282807 PMCID: PMC4901303 DOI: 10.1038/srep23127] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2015] [Accepted: 02/25/2016] [Indexed: 01/08/2023] Open
Abstract
Lonomia obliqua (Lepidoptera: Saturniidae) is a species of medical importance due to the severity of reactions caused by accidental contact with the caterpillar bristles. Several natural pathogens have been identified in L. obliqua, and among them the baculovirus Lonomia obliqua multiple nucleopolyhedrovirus (LoobMNPV). The complete genome of LoobMNPV was sequenced and shown to have 120,022 bp long with 134 putative open reading frames (ORFs). Phylogenetic analysis of the LoobMNPV genome showed that it belongs to Alphabaculovirus group I (lepidopteran-infective NPV). A total of 12 unique ORFs were identified with no homologs in other sequenced baculovirus genomes. One of these, the predicted protein encoded by loob035, showed significant identity to an eukaryotic transcription terminator factor (TTF2) from the Lepidoptera Danaus plexippus, suggesting an independent acquisition through horizontal gene transfer. Homologs of cathepsin and chitinase genes, which are involved in host integument liquefaction and viral spread, were not found in this genome. As L. obliqua presents a gregarious behavior during the larvae stage the impact of this deletion might be neglectable.
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Affiliation(s)
- C W Aragão-Silva
- Departamento de Biologia Celular, Instituto de Ciências Biológicas, Universidade de Brasília, Brasília, DF, Brazil
| | - M S Andrade
- Departamento de Biologia Celular, Instituto de Ciências Biológicas, Universidade de Brasília, Brasília, DF, Brazil
| | - D M P Ardisson-Araújo
- Departamento de Biologia Celular, Instituto de Ciências Biológicas, Universidade de Brasília, Brasília, DF, Brazil
| | - J E A Fernandes
- Departamento de Biologia Celular, Instituto de Ciências Biológicas, Universidade de Brasília, Brasília, DF, Brazil
| | - F S Morgado
- Departamento de Biologia Celular, Instituto de Ciências Biológicas, Universidade de Brasília, Brasília, DF, Brazil
| | - S N Báo
- Departamento de Biologia Celular, Instituto de Ciências Biológicas, Universidade de Brasília, Brasília, DF, Brazil
| | - R H P Moraes
- Departamento de Entomologia, Instituto Butantan, Av. Vital Brasil, 1500, São Paulo, Brazil
| | - J L C Wolff
- Laboratório de Biologia Molecular e Virologia, Centro de Ciências Biológicas e da Saúde (CCBS), Universidade Presbiteriana Mackenzie, São Paulo, SP, Brazil
| | - F L Melo
- Departamento de Biologia Celular, Instituto de Ciências Biológicas, Universidade de Brasília, Brasília, DF, Brazil
| | - B M Ribeiro
- Departamento de Biologia Celular, Instituto de Ciências Biológicas, Universidade de Brasília, Brasília, DF, Brazil
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9
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Silva FWS, Elliot SL. Temperature and population density: interactional effects of environmental factors on phenotypic plasticity, immune defenses, and disease resistance in an insect pest. Ecol Evol 2016; 6:3672-3683. [PMID: 27195105 PMCID: PMC4851648 DOI: 10.1002/ece3.2158] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2016] [Revised: 04/01/2016] [Accepted: 04/06/2016] [Indexed: 01/06/2023] Open
Abstract
Temperature and crowding are key environmental factors mediating the transmission and epizooty of infectious disease in ectotherm animals. The host physiology may be altered in a temperature‐dependent manner and thus affects the pathogen development and course of diseases within an individual and host population, or the transmission rates (or infectivity) of pathogens shift linearly with the host population density. To our understanding, the knowledge of interactive and synergistic effects of temperature and population density on the host–pathogen system is limited. Here, we tested the interactional effects of these environmental factors on phenotypic plasticity, immune defenses, and disease resistance in the velvetbean caterpillar Anticarsia gemmatalis. Upon egg hatching, caterpillars were reared in thermostat‐controlled chambers in a 2 × 4 factorial design: density (1 or 8 caterpillars/pot) and temperature (20, 24, 28, or 32°C). Of the immune defenses assessed, encapsulation response was directly affected by none of the environmental factors; capsule melanization increased with temperature in both lone‐ and group‐reared caterpillars, although the lone‐reared ones presented the most evident response, and hemocyte numbers decreased with temperature regardless of the population density. Temperature, but not population density, affected considerably the time from inoculation to death of velvetbean caterpillar. Thus, velvetbean caterpillars succumbed to Anticarsia gemmatalis multiple nucleopolyhedrovirus (AgMNPV) more quickly at higher temperatures than at lower temperatures. As hypothesized, temperature likely affected caterpillars' movement rates, and thus the contact between conspecifics, which in turn affected the phenotypic expression of group‐reared caterpillars. Our results suggest that environmental factors, mainly temperature, strongly affect both the course of disease in velvetbean caterpillar population and its defenses against pathogens. As a soybean pest, velvetbean caterpillar may increase its damage on soybean fields under a scenario of global warming as caterpillars may reach the developmental resistance faster, and thus decrease their susceptibility to biological control by AgMNPV.
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Affiliation(s)
- Farley W S Silva
- Post-graduate Program in Entomology Department of Entomology Universida de Federal de Viçosa (UFV) Av. PH Rolfs 36570-900 Viçosa Minas Gerais Brazil
| | - Simon L Elliot
- Post-graduate Program in Entomology Department of Entomology Universida de Federal de Viçosa (UFV) Av. PH Rolfs 36570-900 Viçosa Minas Gerais Brazil
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