Special Issue "Insect Immunity"

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A special issue of Insects (ISSN 2075-4450).

Deadline for manuscript submissions: closed (31 March 2012)

Special Issue Editor

Guest Editor
Dr. Brian P. Lazzaro

Department of Entomology, 3134 Comstock Hall, Cornell University, Ithaca, NY 14853, USA
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Special Issue Information

Dear Colleagues,

The study of infection and immunity in insects has grown to considerable prominence over the past several decades. Early work in the 1950s, 1960s and 1970s focused on the biochemistry of insect immunity and the (fruitless) search for insect analogs of vertebrate antibodies. A transformational element of functional genetics emerged in the 1990s, emphasizing the Drosophila model system, with work from this era earning a share of the 2011 Nobel Prize in Physiology or Medicine. The emergence of widespread genome sequencing in the 2000s allowed comparative genomic analyses that revealed the strikingly high degree of conservation in immune system genes even across insects hundreds of millions of years diverged. The study of insect immunity is now extraordinarily multidisciplinary. Because fundamental aspects of the immune system are conserved across all animals, insects can serve as valuable biomedical models for the study of immune system function and pathogen virulence. The study of insect immunity is also important in its own right, with managed infection at the core of new approaches to the biological control of insect agricultural pests and vectors of human disease. The interactions between insects and their pathogens continue to elucidate basic principles in evolutionary biology, ecology, and the epidemiology of infectious disease. We wish to use this special issue of Insects to highlight the diversity and depth of research into the functional biology, evolution, and translational application of infection and immunity in insects.

Dr. Brian P. Lazzaro
Guest Editor

Keywords

  • insect immunity
  • invertebrate immunity
  • innate immune systems
  • host-pathogen interactions
  • immune system genetics
  • genomics
  • evolution

Published Papers (11 papers)

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Research

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Open AccessArticle Variation in a Host–Parasitoid Interaction across Independent Populations
Insects 2012, 3(4), 1236-1256; doi:10.3390/insects3041236
Received: 13 September 2012 / Revised: 9 November 2012 / Accepted: 13 November 2012 / Published: 5 December 2012
Cited by 3 | PDF Full-text (501 KB) | HTML Full-text | XML Full-text
Abstract
Antagonistic relationships between parasitoids and their insect hosts involve multiple traits and are shaped by their ecological and evolutionary context. The parasitoid wasp Cotesia melitaearum and its host butterfly Melitaea cinxia occur in several locations around the Baltic sea, with differences in landscape
[...] Read more.
Antagonistic relationships between parasitoids and their insect hosts involve multiple traits and are shaped by their ecological and evolutionary context. The parasitoid wasp Cotesia melitaearum and its host butterfly Melitaea cinxia occur in several locations around the Baltic sea, with differences in landscape structure, population sizes and the histories of the populations. We compared the virulence of the parasitoid and the susceptibility of the host from five populations in a reciprocal transplant-style experiment using the progeny of five independent host and parasitoid individuals from each population. The host populations showed significant differences in the rate of encapsulation and parasitoid development rate. The parasitoid populations differed in brood size, development rate, pupal size and adult longevity. Some trait differences depended on specific host-parasitoid combinations, but neither species performed systematically better or worse in experiments involving local versus non-local populations of the other species. Furthermore, individuals from host populations with the most recent common ancestry did not perform alike, and there was no negative effect due to a history of inbreeding in the parasitoid. The complex pattern of variation in the traits related to the vulnerability of the host and the ability of the parasitoid to exploit the host may reflect multiple functions of the traits that would hinder simple local adaptation. Full article
(This article belongs to the Special Issue Insect Immunity)
Open AccessArticle cDNA Cloning and Expression Analysis of Pattern Recognition Proteins from the Chinese Oak Silkmoth, Antheraea pernyi
Insects 2012, 3(4), 1093-1104; doi:10.3390/insects3041093
Received: 9 April 2012 / Revised: 12 October 2012 / Accepted: 15 October 2012 / Published: 24 October 2012
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Abstract
Pattern recognition receptors play an important role in insect immune defense. We cloned the β-1,3-glucan recognition protein, lectin-5 and C-type lectin 1 genes of Antheraea pernyi and examined the expression profiles of immune-stimulated pupae. After infection with Bacillus subtilis, Escherichia coli,
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Pattern recognition receptors play an important role in insect immune defense. We cloned the β-1,3-glucan recognition protein, lectin-5 and C-type lectin 1 genes of Antheraea pernyi and examined the expression profiles of immune-stimulated pupae. After infection with Bacillus subtilis, Escherichia coli, Antheraea pernyi nuclear polyhedrosis virus (ApNPV) and Saccharomyces cerevisiae, respectively, the pupae showed different gene expression levels in the different tissues examined (midgut, fatbody, epidermis, testis, and hemocytes). ApβGRP and Aplectin-5 was induced by all the microorganisms, and mainly in epidermis and hemocytes, but not in testis; Aplectin-5 was also expressed in fatbody. Ap C-type lectin 1 was, on the contrary, highly expressed in testis and also in fatbody, but not in hemocytes. Unlike ApβGRP and Aplectin-5, Ap C-type lectin 1 was not induced by Gram-positive bacteria. The results suggest that the cloned lectins may have different functions in different tissues of A. pernyi. Full article
(This article belongs to the Special Issue Insect Immunity)
Open AccessArticle RNA-Seq Study of Microbially Induced Hemocyte Transcripts from Larval Heliothis virescens (Lepidoptera: Noctuidae)
Insects 2012, 3(3), 743-762; doi:10.3390/insects3030743
Received: 13 June 2012 / Revised: 13 July 2012 / Accepted: 2 August 2012 / Published: 14 August 2012
Cited by 5 | PDF Full-text (210 KB) | HTML Full-text | XML Full-text
Abstract
Larvae of the tobacco budworm are major polyphagous pests throughout the Americas. Development of effective microbial biopesticides for this and related noctuid pests has been stymied by the natural resistance mediated innate immune response. Hemocytes play an early and central role in activating
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Larvae of the tobacco budworm are major polyphagous pests throughout the Americas. Development of effective microbial biopesticides for this and related noctuid pests has been stymied by the natural resistance mediated innate immune response. Hemocytes play an early and central role in activating and coordinating immune responses to entomopathogens. To approach this problem we completed RNA-seq expression profiling of hemocytes collected from larvae following an in vivo challenge with bacterial and fungal cell wall components to elicit an immune response. A de novo exome assembly was constructed by combination of sequence tags from all treatments. Sequence tags from each treatment were aligned separately with the assembly to measure expression. The resulting table of differential expression had > 22,000 assemblies each with a distinct combination of annotation and expression. Within these assemblies > 1,400 were upregulated and > 1,500 downregulated by immune activation with bacteria or fungi. Orthologs to innate immune components of other insects were identified including pattern recognition, signal transduction pathways, antimicrobial peptides and enzymes, melanization and coagulation. Additionally orthologs of components regulating hemocytic functions such as autophagy, apoptosis, phagocytosis and nodulation were identified. Associated cellular oxidative defenses and detoxification responses were identified providing a comprehensive snapshot of the early response to elicitation. Full article
(This article belongs to the Special Issue Insect Immunity)
Open AccessArticle Incidence of Non-Immunological Defenses of Soil White Grubs on Parasitism Success of Mallophora ruficauda Larva (Diptera: Asilidae)
Insects 2012, 3(3), 692-708; doi:10.3390/insects3030692
Received: 24 May 2012 / Revised: 7 July 2012 / Accepted: 10 July 2012 / Published: 26 July 2012
Cited by 1 | PDF Full-text (191 KB) | HTML Full-text | XML Full-text
Abstract
White grubs are larvae of Coleoptera of the family Scarabaeidae. They are known because of their intensive feeding habits on crop roots. Mallophora ruficauda (Diptera: Asilidae) is a dipteran parasitoid whose larva is a natural enemy for white grubs. This species is a
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White grubs are larvae of Coleoptera of the family Scarabaeidae. They are known because of their intensive feeding habits on crop roots. Mallophora ruficauda (Diptera: Asilidae) is a dipteran parasitoid whose larva is a natural enemy for white grubs. This species is a solitary ectoparasitoid, where both female and larva realize different steps in the host location process. Female place its eggs in high grasslands and then, the larva finds and parasitizes the host in the ground. There are nine potential hosts in the area of action of this parasitoid; however a high preference for Cyclocephala signaticollis has been observed (87% of field parasitism). It is known that many insects have developed defensive and immunological mechanisms when attacked by a parasitoid, which can be behavioral, physiological, chemical or genetic. The objectives of this work were to investigate what kind of defense and non-immunological associated mechanisms the white grubs have against this parasitoid and to understand why M. ruficauda have such a high preference for masked chafer grubs or Cyclocephala species. In particular, for each white grub species, we asked: (1) If there is a differential behavioral reaction when a parasitoid attack is simulated; (2) If body attributes of white grubs species have influence on defense behavior, and particularly for the masked chafer C. signaticollis; and (3) Why this species is the most selected by M. ruficauda. It was found that behavioral defenses of white grubs would explain the parasitism pattern of M. ruficauda larvae and its preference for C. signaticollis. Full article
(This article belongs to the Special Issue Insect Immunity)
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Open AccessArticle How Varroa Parasitism Affects the Immunological and Nutritional Status of the Honey Bee, Apis mellifera
Insects 2012, 3(3), 601-615; doi:10.3390/insects3030601
Received: 18 April 2012 / Revised: 25 May 2012 / Accepted: 18 June 2012 / Published: 27 June 2012
Cited by 10 | PDF Full-text (164 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
We investigated the effect of the parasitic mite Varroa destructor on the immunological and nutritional condition of honey bees, Apis mellifera, from the perspective of the individual bee and the colony. Pupae, newly-emerged adults and foraging adults were sampled from honey bee
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We investigated the effect of the parasitic mite Varroa destructor on the immunological and nutritional condition of honey bees, Apis mellifera, from the perspective of the individual bee and the colony. Pupae, newly-emerged adults and foraging adults were sampled from honey bee colonies at one site in S. Texas, USA. Varroa‑infested bees displayed elevated titer of Deformed Wing Virus (DWV), suggestive of depressed capacity to limit viral replication. Expression of genes coding three anti-microbial peptides (defensin1, abaecin, hymenoptaecin) was either not significantly different between Varroa-infested and uninfested bees or was significantly elevated in Varroa-infested bees, varying with sampling date and bee developmental age. The effect of Varroa on nutritional indices of the bees was complex, with protein, triglyceride, glycogen and sugar levels strongly influenced by life-stage of the bee and individual colony. Protein content was depressed and free amino acid content elevated in Varroa-infested pupae, suggesting that protein synthesis, and consequently growth, may be limited in these insects. No simple relationship between the values of nutritional and immune-related indices was observed, and colony-scale effects were indicated by the reduced weight of pupae in colonies with high Varroa abundance, irrespective of whether the individual pupa bore Varroa. Full article
(This article belongs to the Special Issue Insect Immunity)
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Open AccessArticle Effects of Banana Plantation Pesticides on the Immune Response of Lepidopteran Larvae and Their Parasitoid Natural Enemies
Insects 2012, 3(3), 616-628; doi:10.3390/insects3030616
Received: 12 May 2012 / Revised: 28 May 2012 / Accepted: 18 June 2012 / Published: 27 June 2012
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Abstract
Basic research on the insect immune response has progressed dramatically within the last two decades, showing that immunity is one of the most effective defenses against foreign invaders. As such, it is important to understand the causes of variation in this response. Here,
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Basic research on the insect immune response has progressed dramatically within the last two decades, showing that immunity is one of the most effective defenses against foreign invaders. As such, it is important to understand the causes of variation in this response. Here, we investigate the effects of pesticides used in Costa Rican banana plantations on the immune response of the lepidopteran larva, Caligo memnon (Brassolinae). In addition, we performed a parasitism survey of the banana plantations and surrounding forests to provide a broader assessment of pesticide effects on parasitoid populations. All caterpillars for the immune assay were collected from two banana plantations and brought to La Selva Biology Station for immune challenge. Individuals were fed leaves from the plantations (pesticide) or leaves from La Selva (pesticide-free), then immune challenged with injected sephadex beads. We found that individuals feeding on pesticide leaves had significantly lower bead melanization compared to individuals feeding on pesticide-free leaves. Nonetheless, the parasitism survey showed that caterpillars from the banana plantations had lower parasitism rates compared to caterpillars from the La Selva forest. This study adds to the growing body of evidence documenting negative effects of pesticides on the insect immune response and on adult parasitoids, and underscores the need for more research at the intersection between ecological entomology and immunology. Full article
(This article belongs to the Special Issue Insect Immunity)

Review

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Open AccessReview Behavioral Immunity in Insects
Insects 2012, 3(3), 789-820; doi:10.3390/insects3030789
Received: 27 May 2012 / Revised: 3 July 2012 / Accepted: 10 July 2012 / Published: 15 August 2012
Cited by 21 | PDF Full-text (388 KB) | HTML Full-text | XML Full-text
Abstract
Parasites can dramatically reduce the fitness of their hosts, and natural selection should favor defense mechanisms that can protect hosts against disease. Much work has focused on understanding genetic and physiological immunity against parasites, but hosts can also use behaviors to avoid infection,
[...] Read more.
Parasites can dramatically reduce the fitness of their hosts, and natural selection should favor defense mechanisms that can protect hosts against disease. Much work has focused on understanding genetic and physiological immunity against parasites, but hosts can also use behaviors to avoid infection, reduce parasite growth or alleviate disease symptoms. It is increasingly recognized that such behaviors are common in insects, providing strong protection against parasites and parasitoids. We review the current evidence for behavioral immunity in insects, present a framework for investigating such behavior, and emphasize that behavioral immunity may act through indirect rather than direct fitness benefits. We also discuss the implications for host-parasite co-evolution, local adaptation, and the evolution of non-behavioral physiological immune systems. Finally, we argue that the study of behavioral immunity in insects has much to offer for investigations in vertebrates, in which this topic has traditionally been studied. Full article
(This article belongs to the Special Issue Insect Immunity)
Open AccessReview Influences of Plant Traits on Immune Responses of Specialist and Generalist Herbivores
Insects 2012, 3(2), 573-592; doi:10.3390/insects3020573
Received: 30 April 2012 / Revised: 25 May 2012 / Accepted: 13 June 2012 / Published: 19 June 2012
Cited by 10 | PDF Full-text (145 KB) | HTML Full-text | XML Full-text
Abstract
Specialist and generalist insect herbivore species often differ in how they respond to host plant traits, particularly defensive traits, and these responses can include weakened or strengthened immune responses to pathogens and parasites. Accurate methods to measure immune response in the presence and
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Specialist and generalist insect herbivore species often differ in how they respond to host plant traits, particularly defensive traits, and these responses can include weakened or strengthened immune responses to pathogens and parasites. Accurate methods to measure immune response in the presence and absence of pathogens and parasites are necessary to determine whether susceptibility to these natural enemies is reduced or increased by host plant traits. Plant chemical traits are particularly important in that host plant metabolites may function as antioxidants beneficial to the immune response, or interfere with the immune response of both specialist and generalist herbivores. Specialist herbivores that are adapted to process and sometimes accumulate specific plant compounds may experience high metabolic demands that may decrease immune response, whereas the metabolic demands of generalist species differ due to more broad-substrate enzyme systems. However, the direct deleterious effects of plant compounds on generalist herbivores may weaken their immune responses. Further research in this area is important given that the ecological relevance of plant traits to herbivore immune responses is equally important in natural systems and agroecosystems, due to potential incompatibility of some host plant species and cultivars with biological control agents of herbivorous pests. Full article
(This article belongs to the Special Issue Insect Immunity)
Open AccessReview Endosymbiont Tolerance and Control within Insect Hosts
Insects 2012, 3(2), 553-572; doi:10.3390/insects3020553
Received: 21 April 2012 / Revised: 31 May 2012 / Accepted: 5 June 2012 / Published: 15 June 2012
Cited by 12 | PDF Full-text (119 KB) | HTML Full-text | XML Full-text
Abstract
Bacterial endosymbioses are very common in insects and can range from obligate to facultative as well as from mutualistic to pathogenic associations. Several recent studies provide new insight into how endosymbionts manage to establish chronic infections of their hosts without being eliminated by
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Bacterial endosymbioses are very common in insects and can range from obligate to facultative as well as from mutualistic to pathogenic associations. Several recent studies provide new insight into how endosymbionts manage to establish chronic infections of their hosts without being eliminated by the host immune system. Endosymbiont tolerance may be achieved either by specific bacterial adaptations or by host measurements shielding bacteria from innate defense mechanisms. Nevertheless, insect hosts also need to sustain control mechanisms to prevent endosymbionts from unregulated proliferation. Emerging evidence indicates that in some cases the mutual adaptations of the two organisms may have led to the integration of the endosymbionts as a part of the host immune system. In fact, endosymbionts may provide protective traits against pathogens and predators and may even be required for the proper development of the host immune system during host ontogeny. This review gives an overview of current knowledge of molecular mechanisms ensuring maintenance of chronic infections with mutualistic endosymbionts and the impact of endosymbionts on host immune competence. Full article
(This article belongs to the Special Issue Insect Immunity)
Open AccessReview New Insights into Control of Arbovirus Replication and Spread by Insect RNA Interference Pathways
Insects 2012, 3(2), 511-531; doi:10.3390/insects3020511
Received: 1 April 2012 / Revised: 11 May 2012 / Accepted: 16 May 2012 / Published: 29 May 2012
Cited by 21 | PDF Full-text (262 KB) | HTML Full-text | XML Full-text
Abstract
Arthropod-borne (arbo) viruses are transmitted by vectors, such as mosquitoes, to susceptible vertebrates. Recent research has shown that arbovirus replication and spread in mosquitoes is not passively tolerated but induces host responses to control these pathogens. Small RNA-mediated host responses are key players
[...] Read more.
Arthropod-borne (arbo) viruses are transmitted by vectors, such as mosquitoes, to susceptible vertebrates. Recent research has shown that arbovirus replication and spread in mosquitoes is not passively tolerated but induces host responses to control these pathogens. Small RNA-mediated host responses are key players among these antiviral immune strategies. Studies into one such small RNA-mediated antiviral response, the exogenous RNA interference (RNAi) pathway, have generated a wealth of information on the functions of this mechanism and the enzymes which mediate antiviral activities. However, other small RNA-mediated host responses may also be involved in modulating antiviral activity. The aim of this review is to summarize recent research into the nature of small RNA-mediated antiviral responses in mosquitoes and to discuss future directions for this relatively new area of research. Full article
(This article belongs to the Special Issue Insect Immunity)
Open AccessReview Eicosanoids: Exploiting Insect Immunity to Improve Biological Control Programs
Insects 2012, 3(2), 492-510; doi:10.3390/insects3020492
Received: 15 March 2012 / Revised: 24 April 2012 / Accepted: 9 May 2012 / Published: 16 May 2012
Cited by 7 | PDF Full-text (379 KB) | HTML Full-text | XML Full-text
Abstract
Insects, like all invertebrates, express robust innate, but not adaptive, immune reactions to infection and invasion. Insect immunity is usually resolved into three major components. The integument serves as a physical barrier to infections. Within the hemocoel, the circulating hemocytes are the temporal
[...] Read more.
Insects, like all invertebrates, express robust innate, but not adaptive, immune reactions to infection and invasion. Insect immunity is usually resolved into three major components. The integument serves as a physical barrier to infections. Within the hemocoel, the circulating hemocytes are the temporal first line of defense, responsible for clearing the majority of infecting bacterial cells from circulation. Specific cellular defenses include phagocytosis, microaggregation of hemocytes with adhering bacteria, nodulation and encapsulation. Infections also stimulate the humoral component of immunity, which involves the induced expression of genes encoding antimicrobial peptides and activation of prophenoloxidase. These peptides appear in the hemolymph of challenged insects 6–12 hours after the challenge. Prostaglandins and other eicosanoids are crucial mediators of innate immune responses. Eicosanoid biosynthesis is stimulated by infection in insects. Inhibition of eicosanoid biosynthesis lethally renders experimental insects unable to clear bacterial infection from hemolymph. Eicosanoids mediate specific cell actions, including phagocytosis, microaggregation, nodulation, hemocyte migration, hemocyte spreading and the release of prophenoloxidase from oenocytoids. Some invaders have evolved mechanisms to suppress insect immunity; a few of them suppress immunity by targeting the first step in the eicosanoid biosynthesis pathways, the enzyme phospholipase A2. We proposed research designed to cripple insect immunity as a technology to improve biological control of insects. We used dsRNA to silence insect genes encoding phospholipase A2, and thereby inhibited the nodulation reaction to infection. The purpose of this article is to place our view of applying dsRNA technologies into the context of eicosanoid actions in insect immunity. The long-term significance of research in this area lies in developing new pest management technologies to contribute to food security in a world with a rapidly growing human population. Full article
(This article belongs to the Special Issue Insect Immunity)
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