scholarly journals Trans-generational immune priming in honeybees

2014 ◽  
Vol 281 (1785) ◽  
pp. 20140454 ◽  
Author(s):  
Javier Hernández López ◽  
Wolfgang Schuehly ◽  
Karl Crailsheim ◽  
Ulrike Riessberger-Gallé
Keyword(s):  
Priming Effect ◽  
Molecular Mechanisms ◽  
Mortality Rates ◽  
Maternal Transfer ◽  
Direct Evaluation ◽  
Immune Priming ◽  
Eusocial Insects ◽  
Resistance To Infection ◽  
Pathogen Exposure ◽  
Colony Level

Maternal immune experience acquired during pathogen exposure and passed on to progeny to enhance resistance to infection is called trans-generational immune priming (TgIP). In eusocial insects like honeybees, TgIP would result in a significant improvement of health at individual and colony level. Demonstrated in invertebrates other than honeybees, TgIP has not yet been fully elucidated in terms of intensity and molecular mechanisms underlying this response. Here, we immune-stimulated honeybee queens with Paenibacillus larvae ( Pl ), a spore-forming bacterium causing American Foulbrood, the most deadly bee brood disease worldwide. Subsequently, offspring of stimulated queens were exposed to spores of Pl and mortality rates were measured to evaluate maternal transfer of immunity. Our data substantiate the existence of TgIP effects in honeybees by direct evaluation of offspring resistance to bacterial infection. A further aspect of this study was to investigate a potential correlation between immune priming responses and prohaemocytes–haemocyte differentiation processes in larvae. The results point out that a priming effect triggers differentiation of prohaemocytes to haemocytes. However, the mechanisms underlying TgIP responses are still elusive and require future investigation.

scholarly journals The Mechanisms of Social Immunity Against Fungal Infections in Eusocial Insects

Toxins ◽  
2019 ◽  
Vol 11 (5) ◽  
pp. 244 ◽  
Author(s):  
Long Liu ◽  
Xing-Ying Zhao ◽  
Qing-Bo Tang ◽  
Chao-Liang Lei ◽  
Qiu-Ying Huang
Keyword(s):  
Fungal Pathogen ◽  
Molecular Basis ◽  
Fungal Pathogens ◽  
Fungal Infections ◽  
Social Immunity ◽  
Immune Priming ◽  
Eusocial Insects ◽  
Chemosensory Genes ◽  
Physiological Adaptations ◽  
Colony Level

Entomopathogenic fungus as well as their toxins is a natural threat surrounding social insect colonies. To defend against them, social insects have evolved a series of unique disease defenses at the colony level, which consists of behavioral and physiological adaptations. These colony-level defenses can reduce the infection and poisoning risk and improve the survival of societal members, and is known as social immunity. In this review, we discuss how social immunity enables the insect colony to avoid, resist and tolerate fungal pathogens. To understand the molecular basis of social immunity, we highlight several genetic elements and biochemical factors that drive the colony-level defense, which needs further verification. We discuss the chemosensory genes in regulating social behaviors, the antifungal secretions such as some insect venoms in external defense and the immune priming in internal defense. To conclude, we show the possible driving force of the fungal toxins for the evolution of social immunity. Throughout the review, we propose several questions involved in social immunity extended from some phenomena that have been reported. We hope our review about social ‘host–fungal pathogen’ interactions will help us further understand the mechanism of social immunity in eusocial insects.

scholarly journals Experimental evolution of insect immune memory versus pathogen resistance

2017 ◽  
Vol 284 (1869) ◽  
pp. 20171583 ◽  
Author(s):  
Imroze Khan ◽  
Arun Prakash ◽  
Deepa Agashe
Keyword(s):  
Secondary Infection ◽  
Pathogen Resistance ◽  
Immune Memory ◽  
High Dose ◽  
Basal Resistance ◽  
Immune Priming ◽  
Resistance To Infection ◽  
Empirical Tests ◽  
Rapid Modulation ◽  
Specific Priming

Under strong pathogen pressure, insects often evolve resistance to infection. Many insects are also protected via immune memory (immune priming), whereby sublethal exposure to a pathogen enhances survival after secondary infection. Theory predicts that immune memory should evolve when the pathogen is highly virulent, or when pathogen exposure is relatively rare. However, there are no empirical tests of these hypotheses, and the adaptive benefits of immune memory relative to direct resistance against a pathogen are poorly understood. To determine the selective pressures and ecological conditions that shape immune evolution, we imposed strong pathogen selection on flour beetle ( Tribolium castaneum ) populations, infecting them with Bacillus thuringiensis (Bt) for 11 generations. Populations injected first with heat-killed and then live Bt evolved high basal resistance against multiple Bt strains. By contrast, populations injected only with a high dose of live Bt evolved a less effective but strain-specific priming response. Control populations injected with heat-killed Bt did not evolve priming; and in the ancestor, priming was effective only against a low Bt dose. Intriguingly, one replicate population first evolved priming and subsequently evolved basal resistance, suggesting the potential for dynamic evolution of different immune strategies. Our work is the first report showing that pathogens can select for rapid modulation of insect priming ability, allowing hosts to evolve divergent immune strategies (generalized resistance versus specific immune memory) with potentially distinct mechanisms.

scholarly journals Transcriptomic signatures of ageing vary in solitary and social forms of an orchid bee

2020 ◽  
Author(s):  
Alice C. Séguret ◽  
Eckart Stolle ◽  
Fernando A. Fleites-Ayil ◽  
José Javier G. Quezada-Euán ◽  
Klaus Hartfelder ◽  
...  
Keyword(s):  
Gene Expression ◽  
Juvenile Hormone ◽  
Candidate Genes ◽  
Gene Networks ◽  
Life Histories ◽  
Molecular Mechanisms ◽  
Trade Off ◽  
Eusocial Insects ◽  
Orchid Bee ◽  
Social Forms

AbstractEusocial insect queens are remarkable in their ability to maximise both fecundity and longevity, thus escaping the typical trade-off between these two traits. In species exhibiting complex eusocial behaviour, several mechanisms have been proposed to underlie the remoulding of the trade-off, such as reshaping of the juvenile hormone pathway, or caste-specific susceptibility to oxidative stress. However, it remains a challenge to disentangle the molecular mechanisms underlying the remoulding of the trade-off in eusocial insects from caste-specific physiological attributes that have subsequently arisen due to their different life histories. Socially plastic species such as the orchid bee Euglossa viridissima represent excellent models to address the role of sociality per se in longevity as they allow direct comparisons of solitary and social individuals within a common genetic background. We present data on gene expression and juvenile hormone levels from young and old bees, from both solitary and social nests. We found 940 genes to be differentially expressed with age in solitary females, versus only 14 genes in social dominant females, and seven genes in subordinate females. We performed a weighted gene co-expression network analysis to further highlight candidate genes related to ageing in this species. Primary “ageing gene” candidates were related to protein synthesis, gene expression, immunity and venom production. Remarkably, juvenile hormone titres did not vary with age or social status. These results represent an important step in understanding the proximate mechanisms underlying the remodeling of the fecundity/longevity trade-off that accompanies the evolutionary transition from solitary life to eusociality.Significance statementThe remarkably long lifespan of the queens of eusocial insects despite their high reproductive output suggests that they are not subject to the widespread trade-off between fecundity and longevity that governs solitary animal life histories, yet surprisingly little is known of the molecular mechanisms underpinning their longevity. Using a socially plastic bee in which some individuals of a population are social whilst others are solitary, we identified hundreds of candidate genes and related gene networks that are involved in the remoulding of the fecundity/longevity tradeoff. As well as identifying candidate ageing genes, our data suggest that even in incipient stages of sociality there is a marked reprogramming of ageing; long live the queen.

scholarly journals Comparison of Twelve Ant Species and Their Susceptibility to Fungal Infection

Insects ◽  
2019 ◽  
Vol 10 (9) ◽  
pp. 271 ◽  
Author(s):  
Nick Bos ◽  
Viljami Kankaanpää-Kukkonen ◽  
Dalial Freitak ◽  
Dimitri Stucki ◽  
Liselotte Sundström
Keyword(s):  
Entomopathogenic Fungi ◽  
Behavioral Response ◽  
Complex Disease ◽  
Experimental Conditions ◽  
Metapleural Gland ◽  
Eusocial Insects ◽  
Fungal Exposure ◽  
The Individual ◽  
Study Species ◽  
Colony Level

Eusocial insects, such as ants, have access to complex disease defenses both at the individual, and at the colony level. However, different species may be exposed to different diseases, and/or deploy different methods of coping with disease. Here, we studied and compared survival after fungal exposure in 12 species of ants, all of which inhabit similar habitats. We exposed the ants to two entomopathogenic fungi (Beauveria bassiana and Metarhizium brunneum), and measured how exposure to these fungi influenced survival. We furthermore recorded hygienic behaviors, such as autogrooming, allogrooming and trophallaxis, during the days after exposure. We found strong differences in autogrooming behavior between the species, but none of the study species performed extensive allogrooming or trophallaxis under the experimental conditions. Furthermore, we discuss the possible importance of the metapleural gland, and how the secondary loss of this gland in the genus Camponotus could favor a stronger behavioral response against pathogen threats.

scholarly journals Reproductive constraint is a developmental mechanism that maintains social harmony in advanced ant societies

2008 ◽  
Vol 105 (46) ◽  
pp. 17884-17889 ◽  
Author(s):  
Abderrahman Khila ◽  
Ehab Abouheif
Keyword(s):  
Molecular Mechanisms ◽  
Worker Reproduction ◽  
Developmental Genetic ◽  
Potential Conflict ◽  
Trophic Eggs ◽  
Maternal Determinants ◽  
Colony Efficiency ◽  
Reproductive Division Of Labor ◽  
Reproductive Division ◽  
Colony Level

A hallmark of eusociality in ants is the reproductive division of labor between queens and workers. Yet, nothing is known about the molecular mechanisms underlying reproduction in this group. We therefore compared the developmental genetic capacity of queens and workers to reproduce in several eusocially advanced species from the two largest subfamilies of ants, the Myrmicinae and Formicinae. In flies, the asymmetric localization of maternally encoded determinants (mRNAs and proteins) during oogenesis establishes oocyte polarity and subsequently ensures proper embryonic development. Vasa and nanos, two key maternal determinants, are properly localized in the posterior of queen oocytes, but their localization is impaired in those of the workers. This mislocalization leads to severe embryonic defects in worker progeny, and therefore, represents a constraint on worker reproduction that we call ‘reproductive constraint.’ We show that reproductive constraint is phylogenetically widespread, and is at high levels in most species tested. Reproductive constraint can simultaneously reduce or eliminate the workers' ability to produce viable eggs for reproduction, while preserving their ability to produce trophic eggs for nutrition, and thus, may have been the basis for the evolutionary retention of worker ovaries in the majority of ants. We propose that high levels of reproductive constraint has most likely evolved as a consequence of selection at the colony level to reduce or eliminate any potential conflict over worker reproduction, therefore maintaining harmony and colony efficiency in advanced ant societies.

scholarly journals Relationship between maternal transfer of immunity and mother fecundity in an insect

2012 ◽  
Vol 279 (1741) ◽  
pp. 3223-3230 ◽  
Author(s):  
C. Zanchi ◽  
J.-P. Troussard ◽  
J. Moreau ◽  
Y. Moret
Keyword(s):  
Egg Production ◽  
Individual Performance ◽  
Variable Number ◽  
Egg Laying ◽  
Maternal Transfer ◽  
Immune Protection ◽  
Immune Priming ◽  
Individual Perception ◽  
Individual Offspring ◽  
Mealworm Beetle

Trans-generational immune priming (TGIP) corresponds to the plastic adjustment of offspring immunity as a result of maternal immune experience. TGIP is expected to improve mother's fitness by improving offspring individual performance in an environment where parasitism becomes more prevalent. However, it was recently demonstrated that maternal transfer of immunity to the offspring is costly for immune-challenged female insects. Thus, these females might not provide immune protection to all their offspring because of the inherent cost of other fitness-related traits. Females are therefore expected to adjust their investment to individual offspring immune protection in ways that maximize their fitness. In this study, we investigated how bacterially immune-challenged females of the mealworm beetle, Tenebrio molitor , provision their eggs with immune protection according to egg production. We found that immune-challenged females provide a variable number of their eggs with internal antibacterial activity along egg-laying bouts. Furthermore, within the first immune-protected egg-laying bout (2–4 days after the maternal immune challenge), the number of eggs protected was strongly dependent on the number of eggs produced. Immune-challenged females might therefore adjust their investment into TGIP and fecundity according of their individual perception of the risk of dying from the infection and the expected parasitic conditions for the offspring.

scholarly journals Pharaoh ant colonies dynamically regulate colony demography by culling young queen and male-destined larvae

2017 ◽  
Author(s):  
Michael R. Warner ◽  
Jessica Lipponen ◽  
Timothy A. Linksvayer
Keyword(s):  
Resource Allocation ◽  
Social Insect ◽  
Molecular Mechanisms ◽  
Allocation Of Resources ◽  
Dynamic Allocation ◽  
Individual Level ◽  
Colony Demography ◽  
Insect Colonies ◽  
Egg Density ◽  
Colony Level

AbstractThe success of social insect colonies is dependent upon efficient and dynamic allocation of resources to alternate queen and worker castes. The developmental and molecular mechanisms regulating the caste fate of individual larvae in response to environmental cues have been the focus of intense study. However, the mechanisms regulating colony-level resource allocation into alternate castes (i.e. caste allocation ratios) are less well studied. Here, we systematically manipulate colony demography to elucidate the social regulatory mechanisms of caste allocation in the antMonomorium pharaonis. We find that differences in caste allocation result from differences in timing and efficiency of culling of very young reproductive-destined larvae, which are always present in colonies. Based on our results, we develop a conceptual model depicting how colonies integrate numerous individual-level caste determination decisions to regulate colony-level caste allocation. We propose that adult workers make decisions about culling larvae based on the ratio of the number of workers to the number of eggs contained in colonies, likely signalled by pheromone present on eggs. This strategy is a bet-hedging strategy which enables the dynamic alteration of colony demography in response to internal and external conditions. The strategy is likely key to the ability ofM. pharaonisand similar ants to thrive in disturbed habitats and to become widespread invasive species.Significance StatementThe defining feature of social insect societies is the presence of alternate queen (reproductive) and worker (non-reproductive) castes of individuals. The fitness of social insect colonies is dependent upon efficient allocation of resources to alternate castes, particularly in the case of highly polygynous (multi-queen) societies. However, the mechanisms by which such societies regulate caste allocation are largely unknown. In this study, we show that colonies manipulate their production of queens (and also males) versus workers according to the present density of eggs in the colony, which serves as a reliable indicator of queens’ fertility. Provided egg density is high, colonies kill queen-and male-destined larvae; when egg density falls, colonies begin to rear queens and males. This flexible resource allocation strategy is key to the ability of highly polygynous species to thrive in marginal (often human-associated) habitats.

scholarly journals Mating precedes selective immune priming which is maintained throughout bumblebee queen diapause

2019 ◽  
Author(s):  
Thomas J Colgan ◽  
Sive Finlay ◽  
Mark JF Brown ◽  
James C Carolan
Keyword(s):  
Antimicrobial Peptides ◽  
Evolutionary Biology ◽  
Molecular Mechanisms ◽  
Bombus Terrestris ◽  
Molecular Evidence ◽  
Biological Processes ◽  
Arrested Development ◽  
Immune Priming ◽  
Female Behaviour

Abstract Background: Understanding the mechanisms by which organisms adapt to unfavourable conditions is a fundamental question in ecology and evolutionary biology. One such mechanism is diapause, a period of dormancy typically found in nematodes, fish, crustaceans and insects. This state is a key life-history event characterised by arrested development, suppressed metabolism and increased stress tolerance and allows an organism to avoid prolonged periods of harsh and inhospitable environmental conditions. For some species, diapause is preceded by mating which can have a profound effect on female behaviour, physiology and key biological processes, including immunity. However, our understanding of how mating impacts long-term immunity and whether these effects persist throughout diapause is currently limited. To address this, we explored molecular changes in the haemolymph of the ecologically important pollinator, the buff-tailed bumblebee Bombus terrestris . B. terrestris queens mate prior to entering diapause, a non-feeding period of arrested development that can last 6-9 months. Using mass-spectrometry-based proteomics, we quantified changes in the pre-diapause queen haemolymph after mating, as well as the subsequent protein expression of mated queens during and post-diapause. Results: Our analysis identified distinct proteome profiles associated with diapause preparation, maintenance and termination. More specifically, mating pre-diapause was followed by an increase in the abundance of antimicrobial peptides, key effectors of the immune system. Furthermore, we identified the elevated abundance of these proteins to be maintained throughout diapause. This finding was in contrast to a general reduction in immune proteins during diapause suggestive of selective immune priming and expression during diapause. Diapause also affected the expression of proteins involved in cuticular maintenance, olfaction, as well as proteins of unknown function, which may have roles in diapause regulation. Conclusions: Our results provide clear molecular evidence for the consequences and benefits of mating at the immune level as it precedes the selective increased abundance of antimicrobial peptides that are sustained throughout diapause. In addition, our results provide novel insights into the molecular mechanisms by which bumblebees prepare for, survive, and recover from diapause, insights that may have implications for our general understanding of these processes in other insect groups.

Relationships between free carbohydrate levels and resistance or susceptibility of Capsicum annuum to Phytophthora capsici

1984 ◽  
Vol 62 (5) ◽  
pp. 1036-1043 ◽  
Author(s):  
Michel Bounias ◽  
Claude Coulomb ◽  
Philippe J. Coulomb
Keyword(s):  
Molecular Mechanisms ◽  
Phytophthora Capsici ◽  
Susceptible Variety ◽  
Resistant Variety ◽  
Resistant Varieties ◽  
Resistant Strains ◽  
Resistance To Infection ◽  
Cellular Pathways ◽  
Carbohydrate Levels ◽  
Free Carbohydrates

The chromatographic analysis of the free carbohydrate content of leaves and stems of pepper showed 19 major fractions which were gathered in 8 structural classes. A number of correlations were found between the respective carbohydrate levels of two varieties of pepper, one susceptible and the other resistant to downy mildew, and also between those of healthy and inoculated tissues. Some cases of departures from the established correlations were observed and discussed with respect to their hypothetical involvement in the character of resistance and susceptibility to the infection. The concentrations of free carbohydrates of the dideoxyhexose group are increased in inoculated leaves of both susceptible and resistant varieties and those of the rhamnose group are depressed in inoculated leaves of the sole susceptible variety. Sucrose strongly increases in inoculated stems but decreases in the inoculated leaves of the sole resistant variety; concomitantly glucose and fructose also increase in inoculated stems, whereas they decrease in inoculated leaves of both susceptible and resistant strains. The results suggest a number of hypotheses concerning the molecular mechanisms of the host resistance to infection in relation to the cellular pathways of sugar translocation.

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