scholarly journals Siblicidal behaviour by larvae of the gregarious parasitoid Cotesia vanessae

2018 ◽  
Vol 67 ◽  
pp. 55-62 ◽  
Author(s):  
Vincent A. D. Hervet ◽  
Robert A. Laird ◽  
Kevin D. Floate
Keyword(s):  
Immune System ◽  
Adult Development ◽  
Brood Size ◽  
Life Histories ◽  
Self Regulation ◽  
Parasitoid Species ◽  
Trade Off ◽  
Complete Development ◽  
Gregarious Parasitoid ◽  
Solitary Species

Contrasting life histories distinguish solitary from gregarious parasitoids. Females of solitary species typically lay one egg in a host; when more than one parasitoid is present in the host, larvae will kill their rivals so that only one parasitoid completes development. Females of gregarious species typically lay multiple eggs in the same host with the resultant larvae co-existing to complete development. Here we provide an unusual report of siblicide by larvae of a gregarious parasitoid; i.e., Cotesiavanessae (Reinhard) (Hymenoptera: Braconidae) developing in noctuid caterpillars (Lepidoptera). Siblicidal behaviour has not previously been reported with larvae of gregarious Braconidae. We speculate that this behaviour reflects a trade-off between the finite amount of resources within the host available for larval development, and selection to optimize use of these resources. ‘Flooding’ the host with eggs allows the female to use the finite resources of the host to their fullest extent, regardless of host size. This strategy also may allow the female to overwhelm the host’s immune system to enhance survival of her progeny in otherwise marginal host species. It further may enhance the ability of the female’s progeny to competitively exclude the larvae of conspecific females or larvae of other parasitoid species co-occurring in the host. Siblicide allows for self-regulation of brood size when host resources are insufficient to support egg-to-adult development of all eggs initially laid in the host.

Pores versus spores: competition between photosynthesis and reproduction is constrained by leaf mass per unit area (LMA) in ferns

2020 ◽  
Author(s):  
K G Srikanta Dani ◽  
Jose Mathew ◽  
T M Nila-Mohan ◽  
Raju Antony ◽  
S Suresh ◽  
...  
Keyword(s):  
Life Histories ◽  
Resource Constraints ◽  
Time Window ◽  
Unit Area ◽  
Stomatal Density ◽  
High Fertility ◽  
Leaf Lifespan ◽  
Trade Off ◽  
Terrestrial Species ◽  
Leaf Mass

Abstract Diversity in plant life histories is primarily that found in the rate and duration of photosynthetic (vegetative) and reproductive growth. However, direct evidence for an anticipated trade-off between photosynthesis and reproduction is lacking in any plant lineage. Ferns allocate leaf space and resources to both photosynthesis and reproduction, potentially leading to competition for leaf resources between stomatal pores and reproductive spores. We hypothesized that a trade-off between stomatal density (StD; a proxy for photosynthetic capacity) and sporangial density (SpD; a measure of fertility) has evolved in monomorphic ferns due to the common space, time and resource constraints imposed by a highly conserved and globally low leaf mass per unit area (LMA) in ferns, where any increase in LMA indicated greater construction cost and longer leaf lifespan. We measured LMA, StD and SpD in 40 fern species in India that represented both monomorphic and dimorphic conditions from both terrestrial and epiphytic habits. Both StD and SpD showed a 50-fold range in monomorphic species whereas LMA was more conserved (six-fold range). LMA of terrestrial ferns was significantly lower than that of epiphytic ferns. Linear regression between LMA and StD was significantly positive in dimorphic terrestrial ferns (showing the lowest LMA among all ferns) and significantly negative in monomorphic epiphytic ferns (showing the highest LMA among all ferns). Dimorphic terrestrial ferns were highly fecund on their fertile leaves and showed a significantly higher StD to LMA ratio on their sterile leaves compared to monomorphic terrestrial ferns. Dimorphic ferns seem to maximize both StD and SpD by physical separation of photosynthesis and reproduction, and their characteristically low LMA (shorter leaf lifespan = smaller time window) potentially selects for high StD and high fertility. The regression between StD and SpD in monomorphic ferns was significantly linear and positive, although comparisons among closely related species (within families) showed negative correlations when both StD and SpD were high, captured also by a significant quadratic regression between StD and SpD in monomorphic ferns. Monomorphic terrestrial species bearing more spores per stomata showed relatively low LMA whereas those producing fewer spores per stomata possessed leaves with relatively high LMA. Monomorphic epiphytes produced as many spores as terrestrial species but showed significantly low StD for their high LMA. We discuss the evolutionary reasons behind these trends and conclude that monomorphic terrestrial ferns with high LMA (long leaf lifespan) tend to prioritize photosynthesis over reproduction, while monomorphic epiphytes (always high LMA) are significantly more fertile for lower photosynthesis. The role of LMA in framing the rules of competition between stomata and sporangia in monomorphic ferns provides a template for how photosynthesis may directly or indirectly influence reproductive strategies (and vice versa) in all land plants.

scholarly journals Generalized conditions for coexistence of competing parasitoids on a shared host

2020 ◽  
Author(s):  
Abhyudai Singh
Keyword(s):  
Discrete Time ◽  
Life Histories ◽  
Host Density ◽  
Host Community ◽  
Reproduction Rate ◽  
Parasitoid Species ◽  
Slow Increase ◽  
Time Formalism ◽  
Adult Parasitoid ◽  
The Stability

AbstractMotivated by the univoltine life histories of insects residing in the temperate-regions of the world, there is a rich tradition of modeling arthropod host-parasitoid interactions using a discrete-time formalism. We introduce a general class of discrete-time models for capturing the population dynamics of two competing parasitoid species that attack the same vulnerable stage of the host species. These models are characterized by two density-dependent functions: an escape response defined by the fraction of hosts escaping parasitism; and a competition response defined by the fraction of parasitized hosts that develop into adult parasitoids of either species. Model analysis reveals remarkably simple stability conditions for the coexistence of competing parasitoids. More specifically, coexistence occurs, if and only if, the adult host density increases with host reproduction rate, and the log sensitivity of the competition response is less than half. The latter condition implies that any increase in the adult parasitoid density will result in a sufficiently slow increase in the fraction of parasitized hosts that develop into parasitoids of that type. We next consider a model motivated by differences in parasitism risk among individual hosts with risk from the two parasitoid species assumed to be independently distributed as per a Gamma distribution. In such models, the heterogeneity in host risk to each parasitoid is quantified by the corresponding Coefficient of Variation (CV). Our results show that parasitoid coexistence occurs for sufficiently large reproduction rate, if and only if, the sum of the inverse of the two CV squares is less than one. This result generalizes the “CV greater than one” rule that defined the stability for a single parasitoid-host system to a multi parasitoid-host community.

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.

Toward a Social Phenomenology of Aging: Studying the Self Process in Biographical Work

1983 ◽  
Vol 16 (4) ◽  
pp. 255-270 ◽  
Author(s):  
Jerold M. Starr
Keyword(s):  
Life Course ◽  
Adult Development ◽  
Cultural Context ◽  
Life Histories ◽  
The Self ◽  
Theories Of Aging ◽  
Cohort Differences ◽  
Conceptual Clarity ◽  
Development And Aging ◽  
Social Phenomenology

In recent years, the study of aging has come to be increasingly multidisciplinary and to encompass the whole life course. The well established life history approach has been reformulated to include the macro-structural and cultural context of aging. Over the past decade research on adult development and aging, cohort differences in aging patterns, and historical changes in life course differentiation has challenged the validity of the established “stability” and “ordered change” theories of aging. An “aleatoric” account of aging, which calls attention to the flexibility of developmental patterns, has been proposed in their stead. Consistent with this development is the need to replace the old conception of the self as a passive object of outside social forces with a new conception of the self as an active, self-reflexive agent in society. The author demonstrates the utility of certain core concepts in social phenomenology and ethnomethodology, in particular Schutz's concept of biographical work, for developing this new conception of the self. It is proposed that more attention to the practical procedures of reality construction involved in biographical work would provide the epistemological basis and conceptual clarity needed for empirical research on the dynamics of life histories.

Trade-off-invariant rules for evolutionary stable life histories

Nature ◽  
1997 ◽  
Vol 387 (6631) ◽  
pp. 393-394 ◽  
Author(s):  
Eric L. Charnov
Keyword(s):  
Life Histories ◽  
Trade Off

scholarly journals Personality predicts individual responsiveness to the risks of starvation and predation

2011 ◽  
Vol 279 (1735) ◽  
pp. 1919-1926 ◽  
Author(s):  
J. L. Quinn ◽  
E. F. Cole ◽  
J. Bates ◽  
R. W. Payne ◽  
W. Cresswell
Keyword(s):  
Life Histories ◽  
Parus Major ◽  
Poor Quality ◽  
Trade Off ◽  
Quality Food ◽  
Individual Personality ◽  
Temporal And Spatial ◽  
Time Spent Feeding ◽  
Individual Responsiveness ◽  
Starvation Risk

Theory suggests that individual personality is tightly linked to individual life histories and to environmental variation. The reactive–proactive axis, for example, is thought to reflect whether individuals prioritize productivity or survival, mutually exclusive options that can be caused by conflicts between foraging and anti-predation behaviour. Evidence for this trade-off hypothesis, however, is limited. Here, we tested experimentally whether exploration behaviour (EB), an assay of proactivity, could explain how great tits ( Parus major ) respond to changes in starvation and predation risk. Individuals were presented with two feeders, holding good or poor quality food, which interchanged between safe and dangerous positions 10 m apart, across two 24 h treatments. Starvation risk was assumed to be highest in the morning and lowest in the afternoon. The proportion of time spent feeding on good quality food (PTG) rather than poor quality food was repeatable within treatments, but individuals varied in how PTG changed with respect to predation- and starvation-risk across treatments. This individual plasticity variation in foraging behaviour was linked to EB, as predicted by the reactive–proactive axis, but only among individuals in dominant social classes. Our results support the trade-off hypothesis at the level of individuals in a wild population, and suggest that fine-scale temporal and spatial variation may play important roles in the evolution of personality.

WITHIN-HOST PARASITE DYNAMICS, EMERGING TRADE-OFF, AND EVOLUTION OF VIRULENCE WITH IMMUNE SYSTEM

Evolution ◽  
2003 ◽  
Vol 57 (7) ◽  
pp. 1489 ◽  
Author(s):  
Jean-Baptiste André ◽  
Jean-Baptiste Ferdy ◽  
Bernard Godelle
Keyword(s):  
Immune System ◽  
Trade Off ◽  
Evolution Of Virulence ◽  
Host Parasite ◽  
Parasite Dynamics

scholarly journals Assessment of macrocyclic lacton group products for ectoparasitosis of carp

2020 ◽  
Vol 22 (98) ◽  
pp. 16-21
Author(s):  
Yu. V. Loboiko ◽  
Ye. O. Barylo ◽  
B. S. Barylo
Keyword(s):  
Immune System ◽  
T Lymphocytes ◽  
Self Regulation ◽  
The Body ◽  
Macrocyclic Lactones ◽  
Emamectin Benzoate ◽  
Immunological Parameters ◽  
Humoral Factors ◽  
Industry Group ◽  
Antiparasitic Drugs

The material for the study were Lubin carp of one year old spontaneously invaded by the ectoparasites Lernaea cyprinacea and Dactylogyrus vastator. For the experiment we used drugs: "Brovermectin-granulate" (development of “BFP” serial production; 1 g of the preparation contains: active substance (ADR) ivermectin – 3.5 mg; tocopherol acetate (20 mg) and Emamectin benzoate (manufactured by King Quenson Industry Group; 1 g of preparation contains ADR emamectin benzoate (50 mg). Analyzing morphological, biochemical and immunological parameters of blood and organs of fish, it is possible to state that the fact that the anti-parasitic drugs “Brovermectin granulate” and “Emamectin benzoate” has a pronounced antiparasitic effect, normalizing the homeostasis of the body. The results obtained showed significant fluctuations in the number neutrophils, eosinophils and lymphocytes. In ectoparasites infested of fishes used for macrocyclic lactones, y leukocyte formula sharply increases the percentage of rod-shaped neutrophils and at the same time decreases the proportion of lymphocytes. At the same time, there is an increase in the number of eosinophils that perform the function of protecting the body of fish from parasites. Eosinophilia, as in the higher vertebrates, is one of objective indicators of allergy (sensitization) of the body, nature the course of inflammatory processes. The results obtained indicate a decrease in the production of total T-lymphocytes are cells that play a key role in the immune system protection in the body of carp for damage by ectoparasites. In analyzing the above data, attention is drawn to the lower functional the activity of the blood T-lymphocyte system in ectoparasites infested with fish, than those given antiparasitic drugs. From this it follows that the ability of the blood lymphocytes of the fish to which the drugs from the group were given of macrocyclic lactones, before pathogen binding and production of antigens the antibodies that neutralize them are much higher than the fish affected ectoparasites. The immune system in fish provides self-regulation through direct contact of cells (macrophages, neutrophils, cytotoxic T-lymphocytes) as well as due to humoral factors (lysozyme, complement). The use of drugs from the group of macrocyclic lactones promotes the release of infested fish from ectoparasites with the following normalization of their life, increase of immune status and resistance.

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