RESUMO
Heat shock protein 83 (HSP83) is homologous to the chaperone HSP90. It has pleiotropic functions in Drosophila melanogaster, including the control of longevity and fecundity, and facilitates morphological evolution by buffering cryptic deleterious mutations in wild populations. In the pea aphid Acyrthosiphon pisum, HSP83 expression is moderately induced by bacterial infection but upregulated more strongly in response to heat stress and fungal infection. Stress-inducible heat shock proteins are of considerable evolutionary and ecological importance because they are known to buffer environmental variation and to influence fitness under non-optimal conditions. To investigate the functions of HSP83 in viviparous aphids, we used RNA interference to attenuate its expression and studied the impact on complex parameters. The RNA interference (RNAi)-mediated depletion of HSP83 expression in A. pisum reduced both longevity and fecundity, suggesting this chaperone has an evolutionarily conserved function in insects. Surprisingly, HSP83 depletion reduced the number of viviparous offspring while simultaneously increasing the number of premature nymphs developing in the ovaries, suggesting an unexpected role in aphid embryogenesis and eclosion. The present study indicates that reduced HSP83 expression in A. pisum reveals both functional similarities and differences compared with its reported roles in holometabolous insects. Its impact on aphid lifespan, fecundity, and embryogenesis suggests a function that determines their fitness. This could be achieved by targeting different client proteins, recruiting distinct co-chaperones or transposon activation.
Assuntos
Afídeos/fisiologia , Proteínas de Drosophila/metabolismo , Proteínas de Choque Térmico/metabolismo , Proteínas de Insetos/metabolismo , Animais , Afídeos/crescimento & desenvolvimento , Desenvolvimento Embrionário , Feminino , Fertilidade , LongevidadeRESUMO
Invertebrates can be primed to enhance their protection against pathogens they have encountered before. This enhanced immunity can be passed maternally or paternally to the offspring and is known as transgenerational immune priming. We challenged larvae of the red flour beetle Tribolium castaneum by feeding them on diets supplemented with Escherichia coli, Micrococcus luteus or Pseudomonas entomophila, thus mimicking natural exposure to pathogens. The oral uptake of bacteria induced immunity-related genes in the offspring, but did not affect the methylation status of the egg DNA. However, we observed the translocation of bacteria or bacterial fragments from the gut to the developing eggs via the female reproductive system. Such translocating microbial elicitors are postulated to trigger bacterial strain-specific immune responses in the offspring and provide an alternative mechanistic explanation for maternal transgenerational immune priming in coleopteran insects.
Assuntos
Óvulo/microbiologia , Tribolium/imunologia , Tribolium/microbiologia , Animais , Metilação de DNA , Escherichia coli/fisiologia , Feminino , Trato Gastrointestinal/microbiologia , Masculino , Micrococcus luteus/fisiologia , Óvulo/imunologia , Pseudomonas/fisiologia , Transcriptoma , Tribolium/genéticaRESUMO
Neuropteran larvae are fierce predators that use venom to attack and feed on arthropod prey. Neuropterans have adapted to diverse and sometimes extreme habitats, suggesting their venom may have evolved accordingly, but the ecology and evolution of venom deployment in different families is poorly understood. We applied spatial transcriptomics, proteomics, morphological analysis, and bioassays to investigate the venom systems in the antlion Euroleon nostras and the lacewing Chrysoperla carnea, which occupy distinct niches. Although the venom system morphology was similar in both species, we observed remarkable differences at the molecular level. E. nostras produces particularly complex venom secreted from three different glands, indicating functional compartmentalization. Furthermore, E. nostras venom and digestive tissues were devoid of bacteria, strongly suggesting that all venom proteins are of insect origin rather than the products of bacterial symbionts. We identified several toxins exclusive to E. nostras venom, including phospholipase A2 and several undescribed proteins with no homologs in the C. carnea genome. The compositional differences have significant ecological implications because only antlion venom conferred insecticidal activity, indicating its use for the immobilization of large prey. Our results indicate that molecular venom evolution plays a role in the adaptation of antlions to their unique ecological niche.
Assuntos
Venenos de Artrópodes , Comportamento Predatório , Animais , Venenos de Artrópodes/metabolismo , Venenos de Artrópodes/genética , Ecossistema , Insetos/fisiologia , Larva/fisiologia , Proteômica , Proteínas de Insetos/metabolismo , Proteínas de Insetos/genética , TranscriptomaRESUMO
The harlequin ladybird, Harmonia axyridis, has emerged as a model species for invasion biology, reflecting its remarkable capacity to outcompete native ladybird species when introduced into new habitats. This ability may be associated with its prominent resistance to pathogens and intraguild predation. We recently showed that the constitutive antibacterial activity present in the haemolymph of H. axyridis beetles can be attributed to the chemical defence compound harmonine. Here, we demonstrate that H. axyridis differs from other insects, including the native ladybird Coccinella septempunctata, by reducing rather than increasing the antimicrobial activity of its haemolymph following the injection of bacteria. However, both species produce new or more abundant proteins in the haemolymph, indicating that bacterial challenge induces innate immune responses associated with the synthesis of immunity-related proteins. Our results suggest that H. axyridis beetles can switch from constitutive chemical defence to inducible innate immune responses, supporting hypothesis that inducible antimicrobial peptides protect host beetles against pathogens that survive constitutive defences. These alternative antimicrobial defence mechanisms may reflect a trade-off resulting from fitness-related costs associated with the simultaneous synthesis of harmonine and antimicrobial peptides/proteins.
Assuntos
Besouros/imunologia , Imunidade Inata , AnimaisRESUMO
The harlequin ladybird beetle Harmonia axyridis has been introduced in many countries as a biological control agent, but has become an invasive species threatening the biodiversity of native ladybirds. Its invasive success has been attributed to its vigorous resistance against diverse pathogens. This study demonstrates that harmonine ((17R,9Z)-1,17-diaminooctadec-9-ene), which is present in H. axyridis haemolymph, displays broad-spectrum antimicrobial activity that includes human pathogens. Antibacterial activity is most pronounced against fast-growing mycobacteria and Mycobacterium tuberculosis, and the growth of both chloroquine-sensitive and -resistant Plasmodium falciparum strains is inhibited. Harmonine displays gametocytocidal activity, and inhibits the exflagellation of microgametocytes and zygote formation. In an Anopheles stephensi mosquito feeding model, harmonine displays transmission-blocking activity.
Assuntos
Antibacterianos/isolamento & purificação , Antimaláricos/isolamento & purificação , Besouros/química , Mycobacteriaceae/efeitos dos fármacos , Plasmodium falciparum/efeitos dos fármacos , Alcaloides/isolamento & purificação , Alcaloides/farmacologia , Animais , Antibacterianos/farmacologia , Antimaláricos/farmacologia , Linhagem Celular , Diaminas/isolamento & purificação , Diaminas/farmacologia , Escherichia coli/efeitos dos fármacos , Feminino , Humanos , Testes de Sensibilidade Microbiana , Mariposas/citologia , Especificidade da EspécieRESUMO
Spiders are one of the most successful groups of venomous animals, but surprisingly few species have been examined in sufficient detail to determine the structure of their venom systems. To learn more about the venom system of the family Araneidae (orb-weavers), we selected the wasp spider (Argiope bruennichi) and examined the general structure and morphology of the venom apparatus by light microscopy. This revealed morphological features broadly similar to those reported in the small number of other spiders subject to similar investigations. However, detailed evaluation of the venom duct revealed the presence of four structurally distinct compartments. We propose that these subunits facilitate the expression and secretion of venom components, as previously reported for similar substructures in pit vipers and cone snails.
Assuntos
Estruturas Animais/anatomia & histologia , Venenos de Aranha/metabolismo , Aranhas/anatomia & histologia , Estruturas Animais/metabolismo , Animais , Via Secretória , Picada de Aranha , Aranhas/metabolismoRESUMO
The clothes moth Tineola bisselliella is one of a few insects that can digest keratin, leading to the destruction of clothing, textiles and artwork. The mechanism of keratin digestion is not yet fully understood, partly reflecting the lack of publicly available genomic and transcriptomic data. Here we present a high-quality gut transcriptome of T. bisselliella generated from larvae reared on keratin-rich and keratin-free diets. The overall transcriptome consists of 428,221 contigs that were functionally annotated and screened for candidate enzymes involved in keratin utilization. As a mechanism for keratin digestion, we identified cysteine synthases, cystathionine ß-synthases and cystathionine γ-lyases. These enzymes release hydrogen sulfite, which may reduce the disulfide bonds in keratin. The dataset also included 27 differentially expressed contigs with trypsin domains, among which 20 were associated with keratin feeding. Finally, we identified seven collagenases that were upregulated on the keratin-rich diet. In addition to this enzymatic repertoire potentially involved in breaking down keratin, our analysis of poly(A)-enriched and poly(A)-depleted transcripts suggested that T. bisselliella larvae possess an unstable intestinal microbiome that may nevertheless contribute to keratin digestion.
Assuntos
Sequenciamento de Nucleotídeos em Larga Escala/métodos , Queratinas/metabolismo , Larva/genética , Lepidópteros/genética , Transcriptoma , Animais , Ontologia Genética , Lepidópteros/crescimento & desenvolvimentoRESUMO
The volatile alkylpyrazines methyl- and methoxypyrazines (MPs) present in the reflex bleeds of coccinellid beetles such as the harlequin ladybird beetle Harmonia axyridis are important semiochemicals that function in antipredatory defense behavior. Pyrazines have also been coadapted from a primarily defensive role into pheromones that function in intraspecific communication, attraction, and aggregation behavior. However, the biosynthesis of MPs in ladybird beetles is poorly understood. Here, we tested the hypothesis that MPs could be produced by microbial symbionts in H. axyridis, which generates four different MPs. The evaluation of tissue-specific MP production showed that MP concentrations were highest in the gut tissue and hemolymph of the beetles rather than the fat body tissue as the presumed site of MP biosynthesis. Furthermore, manipulation of gut microbiota by antibiotic-containing diets resulted in a lower MP content in adult beetles. The analysis of the bacterial community of the digestive tract revealed the presence of bacteria of the genera Serratia and Lactococcus which are reportedly able to produce MPs. In line with the known diet-dependent production of MP in H. axyridis, we determined that the presence or relative abundance of some of the potential MP producers (Enterococcus and Staphylococcus) is also diet-dependent. We hypothesize a potential role of the microbiota in MP production in H. axyridis as a possible example for outsourcing the synthesis of ecologically important semiochemicals to its gut bacteria.
RESUMO
Ant venoms contain many small, linear peptides, an untapped source of bioactive peptide toxins. The control of agricultural insect pests currently depends primarily on chemical insecticides, but their intensive use damages the environment and human health, and encourages the emergence of resistant pest populations. This has promoted interest in animal venoms as a source of alternative, environmentally-friendly bio-insecticides. We tested the crude venom of the predatory ant, Manica rubida, and observed severe fitness costs in the parthenogenetic pea aphid (Acyrthosiphon pisum), a common agricultural pest. Therefore, we explored the M. rubida venom peptidome and identified a novel decapeptide U-MYRTX-MANr1 (NH2-IDPKVLESLV-CONH2) using a combination of Edman degradation and de novo peptide sequencing. Although this myrmicitoxin was inactive against bacteria and fungi, it reduced aphid survival and reproduction. Furthermore, both crude venom and U-MYRTX-MANr1 reversibly paralyzed injected aphids and induced a loss of body fluids. Components of M. rubida venom may act on various biological targets including ion channels and hemolymph coagulation proteins, as previously shown for other ant venom toxins. The remarkable insecticidal activity of M. rubida venom suggests it may be a promising source of additional bio-insecticide leads.
Assuntos
Venenos de Formiga/análise , Inseticidas/isolamento & purificação , Oligopeptídeos/isolamento & purificação , Sequência de Aminoácidos , Animais , Venenos de Formiga/farmacologia , Afídeos , Inseticidas/farmacologia , Oligopeptídeos/química , Oligopeptídeos/farmacologia , CicatrizaçãoRESUMO
The harlequin ladybird Harmonia axyridis has emerged as a model species in the context of invasion biology and possesses an expanded repertoire of antimicrobial peptides (AMPs). Here we measured the expression of 22 AMP genes in adult beetles from native and introduced populations, and from a biocontrol population, allowing us to compare populations differing in terms of invasive performance. Strikingly, we observed population-specific expression profiles for particular AMPs. Following an immune challenge, the genes for Coleoptericin1 (Col1), Coleoptericin-likeB and Defensin1 were induced up to several thousand times more strongly in the invasive populations compared to the native and biocontrol populations. To determine the role of Col1 in pathogen resistance, the corresponding gene was silenced by RNA interference (RNAi), causing higher mortality in beetles subsequently infected with the entomopathogen Pseudomonas entomophila. The RNAi-triggered susceptibility to this pathogen was reversed by the injection of a synthetic Col1 peptide. We show that a native population is more susceptible to P. entomomophila infection than an invasive population. This is the first study demonstrating population-specific differences in the immune system of an invasive species and suggests that rapid gene expression changes and a highly adaptive immune system could promote pathogen resistance and thereby invasive performance.
Assuntos
Anti-Infecciosos/farmacologia , Besouros/microbiologia , Peptídeos/farmacologia , Animais , Espécies Introduzidas , Pseudomonas/efeitos dos fármacos , Pseudomonas/patogenicidade , Interferência de RNARESUMO
The spread of the invasive harlequin ladybird (Harmonia axyridis) in Europe is accompanied by the decline of the native and non-invasive two-spotted ladybird (Adalia bipunctata). Here we show that microsporidia carried by H. axyridis can kill A. bipunctata following the oral uptake of spores, suggesting that their horizontal transmission via intraguild predation may help the invader to outcompete its native competitor. The native seven-spotted ladybird (Coccinella septempunctata) is thought to be less susceptible both to the spread of H. axyridis and to its microsporidia. To investigate whether the distinct levels of pathogen susceptibility in these three ladybird species are determined by their immune systems, we compared the immunity-related transcriptomes of untreated beetles and beetles challenged with suspensions of bacteria and yeast. We found that H. axyridis carries three and four times as many genes encoding antimicrobial peptides representing the attacin, coleoptericin and defensin families than C. septempunctata and A. bipunctata, respectively. Gene expression studies following the injection of bacteria and yeasts into beetles revealed that members of these three antimicrobial peptide families are also induced more strongly in H. axyridis than C. septempunctata or A. bipunctata. Our results therefore support the hypothesis that a superior immune system promotes the performance of invasive species.
Assuntos
Peptídeos Catiônicos Antimicrobianos/genética , Infecções Bacterianas/imunologia , Besouros/imunologia , Sistema Imunitário , Imunidade Inata/genética , Proteínas de Insetos/genética , Microsporidiose/imunologia , Animais , Peptídeos Catiônicos Antimicrobianos/metabolismo , Evolução Biológica , Transmissão de Doença Infecciosa , Regulação da Expressão Gênica , Predisposição Genética para Doença , Proteínas de Insetos/metabolismo , Comportamento Predatório , Especificidade da Espécie , TranscriptomaRESUMO
This study presents histological and cytological findings on the structural differentiation of the mantle of Nautilus pompilius in order to characterize the cells that are responsible for shell formation. The lateral and front mantle edges split distally into three folds: an outer, middle, and inner fold. Within the upper part of the mantle the mantle edge is divided into two folds only; the inner fold disappears where the hood is attached to the mantle. At the base of the outer fold of the lateral and front mantle edge an endo-epithelial gland, the mantle edge gland, is localized. The gland cells are distinguished by a distinct rough endoplasmic reticulum and by numerous secretory vesicles. Furthermore, they show a strong accumulation of calcium compounds, indicating that the formation of the shell takes place in this region of the mantle. Numerous synaptic contacts between the gland cells and the axons of the nerve fibers reveal that the secretion in the area of the mantle edge gland is under nervous control. The whole mantle tissue is covered with a columnar epithelium having a microvillar border. The analyses of the outer epithelium show ultrastructural characteristics of a transport active epithelium, indicating that this region of the mantle is involved in the sclerotization of the shell. Ultrastructural findings concerning the epithelium between the outer and middle fold suggest that the periostracum is formed in this area of the mantle, as it is in other conchiferan molluscs.
Assuntos
Moluscos/anatomia & histologia , Animais , Microscopia Eletrônica de Varredura , Moluscos/fisiologiaRESUMO
Invasive species are characterized by the rapid growth and spread of their populations after establishing a foothold in new habitats, and there are now many examples of such species negatively affecting biodiversity and the economy. It is unclear why some species can become successful invaders, whereas most (even if closely related) remain noninvasive. We previously proposed a hypothesis that parasites associated with invading species can promote their invasive success if they are harmless toward the invaders but harmful to their competitors and/or predators in the newly colonized habitat. Here we discuss whether microsporidia that have recently been discovered in the invasive ladybird Harmonia axyridis contribute to its invasive success. We show that all H. axyridis beetles sourced from diverse collection sites all over the world carry abundant microsporidia. This suggests that both native and invasive H. axyridis populations are associated with these tolerated parasites, which were likely to have existed in native populations before expansion rather than being acquired in newly colonized areas. We describe the pathogenesis of the microsporidia during different developmental stages of H. axyridis and we address the possibility that the predation of its infected eggs and larvae by competing native ladybird species may lead to their infection and ultimately to their decline. Finally, we discuss our initial hypothesis: microsporidia that are tolerated by an invasive vector insect can be active against susceptible native competitors and/or predator species.
Assuntos
Besouros/microbiologia , Microsporídios/isolamento & purificação , Animais , Evolução Biológica , Espécies Introduzidas , Larva/microbiologia , Óvulo/microbiologia , Comportamento PredatórioRESUMO
Nine intraepithelial ciliated cell types that are presumed to be sensory cells were identified in the epithelium of the pre- and postocular tentacles, the digital tentacles, and the rhinophore of the juvenile tetrabranchiate cephalopod Nautilus pompilius L. The morphological diversity and specialization in distribution of the different ciliated cell types analyzed by SEM methods suggest that these cells include receptors of several sensory functions. Ciliated cell types in different organs that show similar surface features were combined in named groups. The most striking cell, type I, is characterized by a tuft of long and numerous cilia. The highest density of this cell type occurs in ciliary fields in the epithelium of the lamellae of the pre- and postocular tentacles, in the olfactory pits of the rhinophores, and in the lamellae of four pairs of lateral digital tentacles, but not in the epithelium of the medial digital tentacles. The similar morphological data, together with behavioral observations on feeding habits, suggest that this cell type may serve in long-distance chemosensory function. The other ciliated cell types are solitary cells with specific spatial distributions in the various organs. Cell types with tufts of relatively short, stiff cilia (types III, IV, VIII), which are distributed in the lateral and aboral areas of the tentacles and at the base of the tentacle-like process of the rhinophore, are considered to be employed in mechanosensory transduction, while the solitary cells with bristle-like cilia at the margin of the ciliary fields (type II) and at the base of the rhinophore (type IX) may be involved in chemoreception. Histological investigation of the epithelium and the nerve structures of the different organs shows the proportion and distribution of the sensory pathways. Two different types of digital tentacles can be distinguished according to their putative functions: lateral slender digital tentacles in four pairs, of which the lowermost are the so-called long digital tentacles, participate in distance chemoreception, and the medial digital tentacles, whose terminal axial nerve cord may represent a specialized neuromechanosensory structure, appear to have contact chemoreceptive abilities.
Assuntos
Moluscos/anatomia & histologia , Órgãos dos Sentidos/anatomia & histologia , Animais , Células Quimiorreceptoras/ultraestrutura , Cílios/fisiologia , Cílios/ultraestrutura , Epitélio/anatomia & histologia , Comportamento Alimentar , Mecanorreceptores/ultraestrutura , Microscopia Eletrônica , Microscopia Eletrônica de Varredura , Moluscos/citologia , Moluscos/fisiologiaRESUMO
Parents invest in their offspring by preparing them for defense against pathogens and parasites that only the parents have encountered, a phenomenon known as trans-generational immune priming. We investigated the underlying mechanism using the established lepidopteran model host Galleria mellonella. When larvae were fed with non-pathogenic bacteria, or the entomopathogenic species Pseudomonas entomophila and Serratia entomophila, the activity of lysozyme and phenoloxidase increased in the hemolymph, and immunity-related genes encoding antibacterial proteins such as gloverin were induced. Remarkably, the ingestion of bacteria by female larvae resulted in the differential expression of immunity-related genes in the eggs subsequently laid by the same females, providing evidence for trans-generational immune priming in G. mellonella. To determine the fate of these ingested microbes, the larval diet was supplemented with bacteria carrying a fluorescent label. We observed these bacteria crossing the midgut epithelium, their entrapment within nodules in the hemocoel, their accumulation within the ovary, and ultimately their deposition in the eggs. Therefore, we propose that trans-generational immune priming in Lepidoptera can be mediated by the maternal transfer of bacteria or bacterial fragments to the developing eggs.
Assuntos
Translocação Bacteriana , Larva/crescimento & desenvolvimento , Mariposas/imunologia , Mariposas/microbiologia , Pseudomonas/fisiologia , Serratia/fisiologia , Animais , Feminino , Larva/imunologia , Larva/microbiologia , Masculino , Mariposas/crescimento & desenvolvimento , Pseudomonas/imunologia , Serratia/imunologiaRESUMO
Invasive species that proliferate after colonizing new habitats have a negative environmental and economic impact. The reason why some species become successful invaders, whereas others, even closely related species, remain noninvasive is often unclear. The harlequin ladybird Harmonia axyridis, introduced for biological pest control, has become an invader that is outcompeting indigenous ladybird species in many countries. Here, we show that Harmonia carries abundant spores of obligate parasitic microsporidia closely related to Nosema thompsoni. These microsporidia, while not harming the carrier Harmonia, are lethal pathogens for the native ladybird Coccinella septempunctata. We propose that intraguild predation, representing a major selective force among competing ladybird species, causes the infection and ultimate death of native ladybirds when they feed on microsporidia-contaminated Harmonia eggs or larvae.
Assuntos
Besouros/fisiologia , Besouros/parasitologia , Cadeia Alimentar , Espécies Introduzidas , Nosema/fisiologia , Animais , Hemócitos/parasitologia , Hemolinfa/parasitologia , Nosema/ultraestruturaRESUMO
Comments by de Jong et al., Solter et al., and Sloggett question the ecological relevance of the abundant microsporidia found in the invasive ladybird Harmonia axyridis. We contend that there is abundant evidence that native ladybirds feed on H. axyridis eggs and that interspecific microsporidial transfer is a common phenomenon, supporting the proposed role of these parasites as biological weapons.
Assuntos
Besouros/fisiologia , Besouros/parasitologia , Cadeia Alimentar , Espécies Introduzidas , Nosema/fisiologia , AnimaisRESUMO
BACKGROUND: Matrix metalloproteinases (MMPs) are evolutionarily conserved and multifunctional effector molecules in development and homeostasis. In spite of previous, intensive investigation in vitro and in cell culture, their pleiotrophic functions in vivo are still not well understood. METHODOLOGY/PRINCIPAL FINDINGS: We show that the genetically amenable beetle Tribolium castaneum represents a feasible model organism to explore MMP functions in vivo. We silenced expression of three insect-type Tribolium MMP paralogs and their physiological inhibitors, TIMP and RECK, by dsRNA-mediated genetic interference (RNAi). Knock-down of MMP-1 arrested development during pupal morphogenesis giving phenotypes with altered antennae, compound eyes, wings, legs, and head. Parental RNAi-mediated knock-down of MMP-1 or MMP-2 resulted in larvae with non-lethal tracheal defects and with abnormal intestines, respectively, implicating additional roles of MMPs during beetle embryogenesis. This is different to findings from the fruit fly Drosophila melanogaster, in which MMPs have a negligible role in embryogenesis. Confirming pleiotrophic roles of MMPs our results also revealed that MMPs are required for proper insect innate immunity because systemic knock-down of Tribolium MMP-1 resulted in significantly higher susceptibility to the entomopathogenic fungus Beauveria bassiana. Moreover, mRNA levels of MMP-1, TIMP, and RECK, and also MMP enzymatic activity were significantly elevated in immune-competent hemocytes upon stimulation. To confirm collagenolytic activity of Tribolium MMP-1 we produced and purified recombinant enzyme and determined a similar collagen IV degrading activity as observed for the most related human MMP, MMP-19. CONCLUSIONS/SIGNIFICANCE: This is the first study, to our knowledge, investigating the in vivo role of virtually all insect MMP paralogs along with their inhibitors TIMP and RECK in both insect development and immunity. Our results from the Tribolium model insect indicate that MMPs regulate tracheal and gut development during beetle embryogenesis, pupal morphogenesis, and innate immune defense reactions thereby revealing the evolutionarily conserved roles of MMPs.
Assuntos
Desenvolvimento Embrionário , Metaloproteinases da Matriz/metabolismo , Fungos Mitospóricos/classificação , Fungos Mitospóricos/patogenicidade , Morfogênese , Tribolium/crescimento & desenvolvimento , Tribolium/imunologia , Sequência de Aminoácidos , Animais , Diferenciação Celular , Colágeno Tipo IV/metabolismo , Imunidade/fisiologia , Inibidores de Metaloproteinases de Matriz , Metaloproteinases da Matriz/genética , Fungos Mitospóricos/imunologia , Dados de Sequência Molecular , Micoses/microbiologia , Fenótipo , Filogenia , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , RNA Interferente Pequeno/farmacologia , Homologia de Sequência de Aminoácidos , Inibidores Teciduais de Metaloproteinases/genética , Inibidores Teciduais de Metaloproteinases/metabolismo , Tribolium/enzimologiaRESUMO
Beetles share with other eukaryotes an innate immune system that mediates endogenous defense against pathogens. In addition, larvae of some taxa produce fluid exocrine secretions that contain antimicrobial compounds. In this paper, we provide evidence that larvae of the brassy willow leaf beetle Phratora vitellinae constitutively release volatile glandular secretions that combat pathogens in their microenvironment. We identified salicylaldehyde as the major component of their enveloping perfume cloud, which is emitted by furrow-shaped openings of larval glandular reservoirs and which inhibits in vitro the growth of the bacterial entomopathogen Bacillus thuringiensis. The suggested role of salicylaldehyde as a fumigant in exogenous antimicrobial defense was confirmed in vivo by its removal from glandular reservoirs. This resulted in an enhanced susceptibility of the larvae to infection with the fungal entomopathogens Beauveria bassiana and Metarhizium anisopliae. Consequently, we established the hypothesis that antimicrobial defense in beetles can be expanded beyond innate immunity to include external disinfection of their microenvironment, and we report for the first time the contribution of fumigants to antimicrobial defense in animals.