scholarly journals Persistence of an extracellular systemic infection across metamorphosis in a holometabolous insect

2018 ◽  
Vol 14 (2) ◽  
pp. 20170771 ◽  
Author(s):  
David F. Duneau ◽  
Brian P. Lazzaro
Keyword(s):  
Larval Stage ◽  
Adult Stage ◽  
A Priori ◽  
Adult Life ◽  
Bacterial Pathogen ◽  
Systemic Infection ◽  
Life Cycles ◽  
Life Stages ◽  
Holometabolous Insect ◽  
Complete Metamorphosis

Organisms with complex life cycles can differ markedly in their biology across developmental life stages. Consequently, distinct life stages can represent drastically different environments for parasites. This difference is especially striking with holometabolous insects, which have dramatically different larval and adult life stages, bridged by a complete metamorphosis. There is no a priori guarantee that a parasite infecting the larval stage would be able to persist into the adult stage. In fact, to our knowledge, transstadial transmission of extracellular pathogens has never been documented in a host that undergoes complete metamorphosis. We tested the hypothesis that a bacterial parasite originally sampled from an adult host could infect a larva, then survive through metamorphosis and persist into the adult stage. As a model, we infected the host Drosophila melanogaster with a horizontally transmitted, extracellular bacterial pathogen, Providencia rettgeri . We found that this natural pathogen survived systemic infection of larvae (L3) and successfully persisted into the adult host. We then discuss how it may be adaptive for bacteria to transverse life stages and even minimize virulence at the larval stage in order to benefit from adult dispersal.

scholarly journals Navigating infection risk during oviposition and larval foraging in a holometabolous insect

2017 ◽  
Author(s):  
Jonathon A. Siva-Jothy ◽  
Katy M. Monteith ◽  
Pedro F. Vale
Keyword(s):  
Larval Stage ◽  
Developmental Stages ◽  
Adult Stage ◽  
Life Stages ◽  
Holometabolous Insect ◽  
Fitness Consequences ◽  
Risk Of Exposure ◽  
Selection For ◽  
Complete Metamorphosis ◽  
Oviposition Sites

AbstractDeciding where to eat and raise offspring carries important fitness consequences for all animals, especially if foraging, feeding and reproduction increase the risk of exposure to pathogens. In insects with complete metamorphosis, foraging occurs mainly during the larval stage, while oviposition decisions are taken by adult-stage females. Selection for infection avoidance behaviours may therefore be developmentally uncoupled. Using a combination of experimental infections and behavioural choice assays, here we tested if Drosophila melanogaster fruit flies avoid potentially infectious environments at distinct developmental stages. When given conspecific fly carcasses as a food source, larval-stage flies did not discriminate between carcasses that were clean or infected with the pathogenic Drosophila C Virus (DCV), even though scavenging was a viable route of DCV transmission. Adult females however, discriminated between different oviposition sites, laying more eggs near a clean rather than an infectious carcass if they were healthy; DCV-infected females did not discriminate between the two environments. While potentially risky, laying eggs near potentially infectious carcasses was always preferred to sites containing only fly medium. Our findings suggest that infection avoidance can play an important role in how mothers provision their offspring, and underline the need to consider infection avoidance behaviours at multiple life-stages.

On the Presence of Wing Buds in the Pupa of Aphaniptera

Parasitology ◽  
1935 ◽  
Vol 27 (3) ◽  
pp. 461-464 ◽  
Author(s):  
M. Sharif
Keyword(s):  
A Priori ◽  
Close Connection ◽  
Holometabolous Insect ◽  
Total Absence ◽  
Group A ◽  
Complete Metamorphosis

The question of the origin of the Aphaniptera has been, so far, considered obscure. It is for the supposed complete absence of wings in all stages that these insects have been thought by some authors to constitute a very sharply defined order having no close connection with any other group of insects (Imms, 1934, p. 688; Patton and Cragg, 1913, p. 434). This total absence of wings in an order of insects which has a complete metamorphosis would have given this group a very anomalous position in the insect world, as there is no holometabolous insect known which does not possess wings in any stage of its existence. For this reason Packard's conclusion (1894, p. 331) ‘Indeed, the three-fold division of the thorax referred to should have a priori forbidden the thought of rudimentary wings’, and Patton and Cragg's statement (1913, p. 434) ‘They bear no recognizable traces of wings, and the structure of the thorax makes it very doubtful if they are descended from winged forms at all’, can scarcely be accepted.

scholarly journals Complete metamorphosis of insects

2019 ◽  
Vol 374 (1783) ◽  
pp. 20190063 ◽  
Author(s):  
Jens Rolff ◽  
Paul R. Johnston ◽  
Stuart Reynolds
Keyword(s):  
Adult Stage ◽  
Pupal Stage ◽  
Life Stages ◽  
Micro Ct ◽  
Larval Form ◽  
Theme Issue ◽  
The Cost ◽  
Ephemeral Resources ◽  
Complete Metamorphosis

The majority of described hexapod species are holometabolous insects, undergoing an extreme form of metamorphosis with an intercalated pupal stage between the larva and adult, in which organs and tissues are extensively remodelled and in some cases completely rebuilt. Here, we review how and why this developmental strategy has evolved. While there are many theories explaining the evolution of metamorphosis, many of which fit under the hypothesis of decoupling of life stages, there are few clear adaptive hypotheses on why complete metamorphosis evolved. We propose that the main adaptive benefit of complete metamorphosis is decoupling between growth and differentiation. This facilitates the exploitation of ephemeral resources and enhances the probability of the metamorphic transition escaping developmental size thresholds. The evolution of complete metamorphosis comes at the cost of exposure to predators, parasites and pathogens during pupal life and requires specific adaptations of the immune system at this time. Moreover, metamorphosis poses a challenge for the maintenance of symbionts and the gut microbiota, although it may also offer the benefit of allowing an extensive change in microbiota between the larval and adult stages. The regulation of metamorphosis by two main players, ecdysone and juvenile hormone, and the related signalling cascades are now relatively well understood. The mechanics of metamorphosis have recently been studied in detail because of the advent of micro-CT and research into the role of cell death in remodelling tissues and organs. We support the argument that the adult stage must necessarily have preceded the larval form of the insect. We do not resolve the still contentious question of whether the larva of insects in general originated through the modification of existing preadult forms or through heterochrony as a modified embryonic stage (pronymph), nor whether the holometabolous pupa arose as a modified hemimetabolous final stage larva. This article is part of the theme issue ‘The evolution of complete metamorphosis’.

Aedes Mosquito: Harbinger of Dread

2019 ◽  
Vol 3 (1) ◽  
Author(s):  
Kalpana Singh ◽  
Shilpa Nandan
Keyword(s):  
Yellow Fever ◽  
Zika Virus ◽  
World Health ◽  
Life Stages ◽  
Aedes Mosquito ◽  
Holometabolous Insect ◽  
The World ◽  
Health Organization ◽  
Complete Metamorphosis ◽  
Maxillary Palps

Mosquitoes (Insecta: Diptera) are well known vector for many bacterial, viral and protozoan diseases. The chief culprits belong to mainly three genuses viz. Culex, Anopheles, Aedes. The morphology of Aedes (Diptera: Culicidae) mosquito is unique as they have pattern of light and dark bands on their leg and light and dark scales are found on thorax and abdomen. The females are distinguished by the shape of abdomen which is usually pointed at the tip and their maxillary palps are shorter than their proboscis. It is a holometabolous insect having all the four life stages of complete metamorphosis viz. egg, larvae, pupa and adult. There are about 950 species of Aedes found throughout the world. Aedes females are vector for transmitting the deadly diseases like Dengue, Yellow fever, Chikungunia and Zika virus. According to World Health Organization (W.H.O) about 50-100 million of dengue cases are reported every year.

scholarly journals Robustness of life histories to environmental variability in complex versus simple life cycles

2021 ◽  
Author(s):  
Annie Jonsson
Keyword(s):  
Growth Rate ◽  
Life Histories ◽  
Environmental Variability ◽  
Life Cycles ◽  
Relative Advantage ◽  
Complex Life Cycle ◽  
Life Stages ◽  
Vital Rates ◽  
Habitat Separation ◽  
Simple Life

AbstractMost animal species have a complex life cycle (CLC) with metamorphosis. It is thus of interest to examine possible benefits of such life histories. The prevailing view is that CLC represents an adaptation for genetic decoupling of juvenile and adult traits, thereby allowing life stages to respond independently to different selective forces. Here I propose an additional potential advantage of CLCs that is, decreased variance in population growth rate due to habitat separation of life stages. Habitat separation of pre- and post-metamorphic stages means that the stages will experience different regimes of environmental variability. This is in contrast to species with simple life cycles (SLC) whose life stages often occupy one and the same habitat. The correlation in the fluctuations of the vital rates of life stages is therefore likely to be weaker in complex than in simple life cycles. By a theoretical framework using an analytical approach, I have (1) derived the relative advantage, in terms of long-run growth rate, of CLC over SLC phenotypes for a broad spectrum of life histories, and (2) explored which life histories that benefit most by a CLC, that is avoid correlation in vital rates between life stages. The direction and magnitude of gain depended on life history type and fluctuating vital rate. One implication of our study is that species with CLCs should, on average, be more robust to increased environmental variability caused by global warming than species with SLCs.

scholarly journals Molecular Correlation between Larval, Deutonymph and Adult Stages of the Water Mite Arrenurus (Micruracarus) Novus

Life ◽  
2020 ◽  
Vol 10 (7) ◽  
pp. 108
Author(s):  
Pedro María Alarcón-Elbal ◽  
Ricardo García-Jiménez ◽  
María Luisa Peláez ◽  
Jose Luis Horreo ◽  
Antonio G. Valdecasas
Keyword(s):  
Culex Pipiens ◽  
Adult Stage ◽  
Gravid Female ◽  
Morphological Characters ◽  
Species Level ◽  
Life Stages ◽  
Water Mite ◽  
Molecular Correlation ◽  
The Common ◽  
Morphological Transformations

The systematics of many groups of organisms has been based on the adult stage. Morphological transformations that occur during development from the embryonic to the adult stage make it difficult (or impossible) to identify a juvenile (larval) stage in some species. Hydrachnidia (Acari, Actinotrichida, which inhabit mainly continental waters) are characterized by three main active stages—larval, deutonymph and adult—with intermediate dormant stages. Deutonymphs and adults may be identified through diagnostic morphological characters. Larvae that have not been tracked directly from a gravid female are difficult to identify to the species level. In this work, we compared the morphology of five water mite larvae and obtained the molecular sequences of that found on a pupa of the common mosquito Culex (Culex) pipiens with the sequences of 51 adults diagnosed as Arrenurus species and identified the undescribed larvae as Arrenurus (Micruracarus) novus. Further corroborating this finding, adult A. novus was found thriving in the same mosquito habitat. We established the identity of adult and deutonymph A. novus by morphology and by correlating COI and cytB sequences of the water mites at the larval, deutonymph and adult (both male and female) life stages in a particular case of ‘reverse taxonomy’. In addition, we constructed the Arrenuridae phylogeny based on mitochondrial DNA, which supports the idea that three Arrenurus subgenera are ‘natural’: Arrenurus, Megaluracarus and Micruracarus, and the somewhat arbitrary distinction of the species assigned to the subgenus Truncaturus.

scholarly journals Age-dependent intra-specific competition in pre-adult life stages and its effects on adult population dynamics

2015 ◽  
Vol 27 (1) ◽  
pp. 131-156
Author(s):  
RONGSONG LIU ◽  
GERGELY RÖST ◽  
STEPHEN A. GOURLEY
Keyword(s):  
Disease Transmission ◽  
Adult Population ◽  
Adult Life ◽  
Life Stages ◽  
Larval Competition ◽  
Amphibian Species ◽  
Age Dependent ◽  
Age Structured ◽  
Delay Differential ◽  
Boundedness And Persistence

Intra-specific competition in insect and amphibian species is often experienced in completely different ways in their distinct life stages. Competition among larvae is important because it can impact on adult traits that affect disease transmission, yet mathematical models often ignore larval competition. We present two models of larval competition in the form of delay differential equations for the adult population derived from age-structured models that include larval competition. We present a simple prototype equation that models larval competition in a simplistic way. Recognising that individual larvae experience competition from other larvae at various stages of development, we then derive a more complex equation containing an integral with a kernel that quantifies the competitive effect of larvae of ageāon larvae of agea. In some parameter regimes, this model and the famous spruce budworm model have similar dynamics, with the possibility of multiple co-existing equilibria. Results on boundedness and persistence are also proved.

Speciation of cestoda. Evidence for two sibling species in the complex Bothrimonus nylandicus (Schneider 1902) (Cestoda: Cyathocephalidea)

Parasitology ◽  
1988 ◽  
Vol 97 (1) ◽  
pp. 139-147 ◽  
Author(s):  
F. Renaud ◽  
C. Gabrion
Keyword(s):  
Sibling Species ◽  
Definitive Host ◽  
Parasite Species ◽  
Adult Stage ◽  
Life Cycles ◽  
The Other ◽  
Congeneric Species ◽  
Biochemical Genetic ◽  
Autumn And Winter ◽  
Biological Differences

SUMMARYUsing biochemical genetic methods, we have distinguished 2 sibling species in the complex Bothrimonus nylandicus (Schneider, 1902), which infest 2 congeneric species of sole (Solea lascaris and Solea impar) on European coasts (Atlantic and Mediterranean). Neither of the parasite species is specific for either of the sole species, but one of them is present all year round, whereas the other is absent in the autumn and winter and only appears in the spring, subsequently disappearing at the end of the summer. Only S. impar lives in the Mediterranean, and is equally infested by both cestodes, whereas both species occur in the Atlantic and each of them is preferentially infested by 1 species of cestode. The shortness of the adult stage of the parasite in the definitive host and the presence of 2 life-cycles associated with competition between the 2 hosts in the Atlantic could be responsible for the biological differences observed and for maintaining the sibling species in sympatry.

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