Host Physiological Condition Research Articles

Effects of buccal cavity parasite Ceratothoa carinata (Isopoda, Cymothoidae) on the condition and reproduction of its host fish Japanese scad Decapterus maruadsi.

All species of the isopod family Cymothoidae are obligate fish parasites, extracting nourishment through hematophagy and tissue consumption. To elucidate the detrimental effects of this parasitic relationship upon the host fish, we examined body length, weight of body, gonad, liver and stomach contents, and condition factor of Japanese scad Decapterus maruadsi infected with the buccal cavity parasite Ceratothoa carinata in different seasons. During the host fish's breeding season in July, the wet weight and condition factor of male and female host fish ages 1 and 2 were conspicuously diminished. No impacts were detected in September, after the breeding season. We found no impact of the parasite on the stomach content weight or signs of prey fish in the stomachs. Thus, parasite infection with C. carinata potentially diminishes the reproductive success of the host fish by negatively impacting the host's physiological condition, particularly during the breeding season.

Medical prospects of cryptosporidiosis in vivo control using biofabricated nanoparticles loaded with Cinnamomum camphora extracts by Ulva fasciata.

Global efforts are continuing to develop preparations against cryptosporidiosis. This study aimed to investigate the efficacy of biosynthesized Ulva fasciata loading Cinnamomum camphora oil extract on new zinc oxide nanoparticles (ZnONPs shorten to ZnNPs) and silver nanoparticles (AgNPs) as alternative treatments for Cryptosporidium parvum experimental infection in rats. Oil extract was characterized by gas chromatography-mass spectrometry, loaded by U. fasciata on ionic-based ZnO and NPs, and then characterized by transmission electron microscopy, scanning electron microscopy, and X-ray diffraction. Biosafety and toxicity were investigated by skin tests. A total of 105 C. parvum oocysts/rat were used (n = 81, 2-3 W, 80-120 g, 9 male rats/group). Oocysts shedding was counted for 21 d. Doses of each preparation in addition to reference drug were administered daily for 7 d, starting on post-infection (PI) day (3). Nitazoxanide (100 mg) was used as the reference drug. After 3 weeks, the rats were sacrificed for postmortem examination and histopathological examination. Two blood samples/rat/group were collected on the 21st day. Ethylenediaminetetraacetic acid blood samples were also used for analysis of biochemistry, hematology, immunology, micronucleus prevalence, and chromosomal abnormalities. C. camphora leaves yielded 28.5 ± 0.3 g/kg oil and 20 phycocompounds were identified. Spherical and rod-shaped particles were detected at 10.47-30.98 nm and 18.83-38.39 nm, respectively. ZnNPs showed the earliest anti-cryptosporidiosis effect during 7-17 d PI. Other hematological, biochemical, immunological, histological, and genotoxicity parameters were significantly fruitful; hence, normalized pathological changes induced by infestation were observed in the NPs treatments groups against the infestation-free and Nitazoxanide treated group. C. camphora, U. fasciata, ZnNPs, and AgNPs have refluxed the pathological effects of infection as well as positively improved host physiological condition by its anticryptosporidial immunostimulant regenerative effects with sufficient ecofriendly properties to be proposed as an alternative to traditional drugs, especially in individuals with medical reactions against chemical commercial drugs.

Shifting effects of host physiological condition following pathogen establishment.

Understanding host persistence with emerging pathogens is essential for conserving populations. Hosts may initially survive pathogen invasions through pre-adaptive mechanisms. However, whether pre-adaptive traits are directionally selected to increase in frequency depends on the heritability and environmental dependence of the trait and the costs of trait maintenance. Body condition is likely an important pre-adaptive mechanism aiding in host survival, although can be seasonally variable in wildlife hosts. We used data collected over 7 years on bat body mass, infection and survival to determine the role of host body condition during the invasion and establishment of the emerging disease, white-nose syndrome. We found that when the pathogen first invaded, bats with higher body mass were more likely to survive, but this effect dissipated following the initial epizootic. We also found that heavier bats lost more weight overwinter, but fat loss depended on infection severity. Lastly, we found mixed support that bat mass increased in the population after pathogen arrival; high annual plasticity in individual bat masses may have reduced the potential for directional selection. Overall, our results suggest that some factors that contribute to host survival during pathogen invasion may diminish over time and are potentially replaced by other host adaptations.

Laboratory Evaluation of Temperature Effects on Germination, Radial Growth and Sporulation of Entomopathogenic Fungi and on Their Pathogenicity to Red Spider Mite, Tetranychus urticae Koch

Background: Entomopathogenic fungus (EPF) can provide safe and efficient insect pest management. Temperature, relative humidity (RH), light, air, nutritional content and host physiological condition are all elements that impact the proliferation and virulence of entomopathogenic fungus. The current study aimed to evaluate the effect of different temperatures on germination, growth, sporulation of entomopathogenic fungi and on their pathogenicity against Tetranychus urticae Koch was studied. Methods: Laboratory experiment was conducted to study the impact of temperature on germination, radial growth and sporulation of five entomopathogenic fungal isolates viz., B. bassiana (Bb 111), B. bassiana (Bb 112), B. bassiana (Bb 113), B. bassiana (Bb 114) and M. flavoviride var. minus. Virulence of five entomopathogenic fungal isolates subjected to different temperature against T. urticae also evaluated through laboratory bioassay techniques. Result: Results one valuation of entomopathogenic fungal isolates with four different temperatures at 20°C, 25°C, 30°C and 35°C showed that 25°C was optimum for germination, radial growth and sporulation. Maximum germination was recorded with the entomopathogenic isolate Beauveria bassiana (Bb 112) (95.67%) at 25°C. Interestingly, at 25°C all the B. bassiana isolates showed a radial growth of more than 50 mm with the highest recorded as 84.67 mm by B. bassiana (Bb 111). Maximum spore production was observed with B. bassiana (Bb 112) at 25°C (1.63 x 106 spores ml-1) followed by B. bassiana (Bb 111) (1.45 x 106 spores ml-1). It was also the most pathogenic against T. urticae at 25 and 30°C. The isolate Bb112 grown at 25°C caused higher mortality of 97.57 per cent against T. urticae. From the findings the isolates of B. bassiana (Bb 112) and (Bb 111) were found promising bio control agent against T. urticae with varying temperature.

Diversity of Epiphytic Bacterial Communities Associated with Adriatic Fucacean Species Phycosphere

The aim of the study was to explore the relationship between membrane-regulating functional lipids of three fucacean species and their associated epiphytic bacterial communities. The analyzed algae Treptacantha barbata, Carpodesmia crinita and Cystoseira compressa, formerly classified under the Cystoseira genus, are indigenous to the Adriatic Sea. The thalli of sampled Fucales species were divided into perennial and annual parts. T. barbata and C. crinita show high contents of mono- and polyunsaturated fatty acids but, however, show a clear distinction between branches, cauloids and apical parts. Along with the highest unsaturation degree (4.32), the C. crinita branches and apical parts demonstrated high proportion of both C18 and C20 polyunsaturated fatty acids, with eicosapentaenoic (C20:5 n-3) and arachidonic (C20:4 n-6) fatty acids up to 5.46% and 13.82%, respectively. The highest proportion of saturated fatty acids was found in thalli of C. compressa, particularly on cauloids and old branches (≥90%). The similarity profile routine analysis of fatty acids and microbial community structure has shown clear separation of the cauloids and apical parts from the branches of C. crinita and T. barbata. Based on the nonmetric multidimensional scaling analysis several representatives of the Gammaproteobacteria class, identified as Vibrionales (Vibrio), Cellvibrionales and Xanthomonadales, which contributed strongly to the separation of T. barbata apical parts and branches, C. compressa receptacles and C. crinita branches from the T. barbata cauloids and C. crinita apical parts and cauloids. The highest richness in polyunsaturated fatty acids, in particular C18:3(n-3), C20:4(n-6) and C20:5(n-3), was observed on branches, accompanied by a distinctive epiphytic microbial structure dominated by numerous representatives with potentially beneficial biological activity. The results showed a strong relationship between fatty acid profiles of the analyzed species and phycosphere community structure, underlining the host physiological condition in shaping the biological interactions and maintaining a healthy microbiome, as well as compiling the ecophysiological and molecular research in order to better assess the resilience of the ecosystem.

Ectoparasites reduce scope for growth in a rocky-shore mussel (Perna perna) by raising maintenance costs

Endolithic cyanobacteria are ubiquitous colonisers of organic and inorganic carbonate substrata that frequently attack the shells of mussels, eroding the shell to extract carbon, often with population infestation rates of >80%. This reduces host physiological condition and ultimately leads to shell collapse and mortality, compromising the services provided by these important ecosystem engineers. While the ecological implications of this and similar interactions have been examined, our understanding of the underlying mechanisms driving the physiological responses of infested hosts remains limited. Using field and laboratory experiments, we assessed the energetic costs of cyanobacterial infestation to the intertidal brown mussel (Perna perna). In the field we found that growth (measured as both increase in shell length and rate of biomineralization) and reproductive potential of clean mussels are greater than those of infested individuals. To explore the mechanisms behind these effects, we compared the energy allocation of parasite-free and infested mussels using the scope for growth (SFG) framework. This revealed a lower SFG in parasitized mussels attributed to an energetic imbalance caused by increased standard metabolic rates, without compensation through increased feeding or reduced excretion of ammonia. Separate laboratory assays showed no differences in calcium uptake rates, indicating that infested mussels do not compensate for shell erosion through increased mineralization. This suggests that the increased maintenance costs detected reflect repair of the organic component of the inner nacreous layer of the shell, an energetically more demanding process than mineralization. Thus, parasite-inflicted damage reduces SFG directly through the need for increased basal metabolic rate to drive shell repair without compensatory increases in energy intake. This study provides a first perspective of the physiological mechanisms underlying this parasite-host interaction, a critical step towards a comprehensive understanding of the ecological processes driving dynamics of this intertidal ecosystem engineer.

Deciphering the effect of food availability, growth and host condition on disease susceptibility in a marine invertebrate.

Food provisioning influences disease risk and outcome in animal populations in two ways. On the one hand, unrestricted food supply improves the physiological condition of the host and lowers its susceptibility to infectious disease, reflecting a trade-off between immunity and other fitness-related functions. On the other hand, food scarcity limits the resources available to the pathogen and slows the growth and metabolism of the host on which the pathogen depends to proliferate. Here, we investigated how food availability, growth rate and energetic reserves drive the outcome of a viral disease affecting an ecologically relevant model host, the Pacific oyster, Crassostrea gigas We selected fast- and slow-growing animals, and we exposed them to high and low food rations. We evaluated their energetic reserves, challenged them with a pathogenic virus, monitored daily survival and developed a mortality risk model. Although high food levels and oyster growth were associated with a higher risk of mortality, energy reserves were associated with a lower risk. Food availability acts both as an enabling factor for mortality by increasing oyster growth and as a limiting factor by increasing their energy reserves. This study clarifies how food resources have an impact on susceptibility to disease and indicates how the host's physiological condition could mitigate epidemics. Practically, we suggest that growth should be optimized rather than maximized, considering that trade-offs occur with disease resistance or tolerance.

Relative importance of chemical attractiveness to parasites for susceptibility to trematode infection.

While the host immune system is often considered the most important physiological mechanism against parasites, precontact mechanisms determining exposure to parasites may also affect infection dynamics. For instance, chemical cues released by hosts can attract parasite transmission stages. We used the freshwater snail Lymnaea stagnalis and its trematode parasite Echinoparyphium aconiatum to examine the role of host chemical attractiveness, physiological condition, and immune function in determining its susceptibility to infection. We assessed host attractiveness through parasite chemo‐orientation behavior; physiological condition through host body size, food consumption, and respiration rate; and immune function through two immune parameters (phenoloxidase‐like and antibacterial activity of hemolymph) at an individual level. We found that, although snails showed high variation in chemical attractiveness to E. aconiatum cercariae, this did not determine their overall susceptibility to infection. This was because large body size increased attractiveness, but also increased metabolic activity that reduced overall susceptibility. High metabolic rate indicates fast physiological processes, including immune activity. The examined immune traits, however, showed no association with susceptibility to infection. Our results indicate that postcontact mechanisms were more likely to determine snail susceptibility to infection than variation in attractiveness to parasites. These may include localized immune responses in the target tissue of the parasite. The lack of a relationship between food consumption and attractiveness to parasites contradicts earlier findings that show food deprivation reducing snail attractiveness. This suggests that, although variation in resource level over space and time can alter infection dynamics, variation in chemical attractiveness may not contribute to parasite‐induced fitness variation within populations when individuals experience similar environmental conditions.

High-density lipoprotein suppresses tumor necrosis factor alpha production by mycobacteria-infected human macrophages

Immune responses to parasitic pathogens are affected by the host physiological condition. High-density lipoprotein (HDL) and low-density lipoprotein (LDL) are transporters of lipids between the liver and peripheral tissues, and modulate pro-inflammatory immune responses. Pathogenic mycobacteria are parasitic intracellular bacteria that can survive within macrophages for a long period. Macrophage function is thus key for host defense against mycobacteria. These basic facts suggest possible effects of HDL and LDL on mycobacterial diseases, which have not been elucidated so far. In this study, we found that HDL and not LDL enhanced mycobacterial infections in human macrophages. Nevertheless, we observed that HDL remarkably suppressed production of tumor necrosis factor alpha (TNF-α) upon mycobacterial infections. TNF-α is a critical host-protective cytokine against mycobacterial diseases. We proved that toll-like receptor (TLR)-2 is responsible for TNF-α production by human macrophages infected with mycobacteria. Subsequent analysis showed that HDL downregulates TLR2 expression and suppresses its intracellular signaling pathways. This report demonstrates for the first time the substantial action of HDL in mycobacterial infections to human macrophages.

Flavanol plasma bioavailability is affected by metabolic syndrome in rats

Flavanols, which exert several health benefits, are metabolized after ingestion. Factors such as the host physiological condition could affect the metabolism and bioavailability of flavanols, influencing their bioactivities. This study aimed to qualitatively evaluate whether a pathological state influenced flavanol plasma bioavailability. Standard and cafeteria (CAF) diet fed rats, a robust model of metabolic syndrome (MeS), were administered 1000mg/kg of flavanol enriched grape seed polyphenol extract (GSPE). Flavanols and their metabolites were quantified by HPLC-MS/MS in plasma before and at 2, 4, 7, 24, and 48h after GSPE ingestion. Results showed that in CAF administered rats the maximum time of plasma flavanol concentration was delayed and these animals presented higher levels of plasma phase-II metabolites as well as altered microbial metabolites. In conclusion, this study demonstrated that MeS pathological state modified flavanol bioavailability, supporting the hypothesis that flavanol metabolism, and therefore flavanol functionality, depend on the organism’s state of health.

Stress-host-parasite interactions: a vicious triangle?

The potential for synergy between host physiological condition and infection has recently been recognised. Here we review the evidence to support the idea that stress may play a key role in the interplay between host and parasite, integrating a three-way circular synergistic interaction between stressors, infections and host response: chronic stress can elicit responses that impoverish the host’s physiological condition (including its immune function), which predisposes to infection, which results in more stress, and so on. We argue that this introduces additional explanatory power to previous ideas posited by the authors, by including stress as a third interacting factor that intervenes in the synergy between condition and infection. This in turn, may have important implications. In nature, evolutionary forces appear to select against stress-related disease or exacerbated parasite virulence. Nonetheless, under certain circumstances, parasites and (other) stressors interact generating a vicious spiral that may affect host fitness and survival. At high host densities, this becomes a mechanism of population regulation. Also, anthropogenic stressors may cause this mechanism to misfire, with significant implications for biological conservation and public health.

Non-Native Ambrosia Beetles as Opportunistic Exploiters of Living but Weakened Trees.

Exotic Xylosandrus spp. ambrosia beetles established in non-native habitats have been associated with sudden and extensive attacks on a diverse range of living trees, but factors driving their shift from dying/dead hosts to living and healthy ones are not well understood. We sought to characterize the role of host physiological condition on preference and colonization by two invaders, Xylosandrus germanus and Xylosandrus crassiusculus. When given free-choice under field conditions among flooded and non-flooded deciduous tree species of varying intolerance to flooding, beetles attacked flood-intolerant tree species over more tolerant species within 3 days of initiating flood stress. In particular, flood-intolerant flowering dogwood (Cornus florida) sustained more attacks than flood-tolerant species, including silver maple (Acer saccharinum) and swamp white oak (Quercus bicolor). Ethanol, a key host-derived attractant, was detected at higher concentrations 3 days after initiating flooding within stems of flood intolerant species compared to tolerant and non-flooded species. A positive correlation was also detected between ethanol concentrations in stem tissue and cumulative ambrosia beetle attacks. When adult X. germanus and X. crassiusculus were confined with no-choice to stems of flood-stressed and non-flooded C. florida, more ejected sawdust resulting from tunneling activity was associated with the flood-stressed trees. Furthermore, living foundresses, eggs, larvae, and pupae were only detected within galleries created in stems of flood-stressed trees. Despite a capability to attack diverse tree genera, X. germanus and X. crassiusculus efficiently distinguished among varying host qualities and preferentially targeted trees based on their intolerance of flood stress. Non-flooded trees were not preferred or successfully colonized. This study demonstrates the host-selection strategy exhibited by X. germanus and X. crassiusculus in non-native habitats involves detection of stress-induced ethanol emission and early colonization of living but weakened trees.

Experimental evidence for host preference in a tick parasitizing songbird nestlings

Mechanisms of host preference in ectoparasites are important to the understanding of host‐parasite interactions. Since ectoparasites negatively affect the condition of their hosts, while the hosts’ condition itself may affect the parasites’ choice, separating the factors that drive host preference from parasite impact asks for experiments. We combined the data of two choice experiments to investigate the preference of the nidicolous tick Ixodes arboricola when exposed to the nestlings of a passerine bird (Parus major). In the first experiment, in which complete broods at hatching were exposed to an ecologically relevant number of ticks, the relationship between tick loads and nestlings’ developmental status was characterized by a distribution with the highest tick loads on the more developed nestlings. Host preference became more apparent at a smaller brood size, suggesting a role for host density. In a second experiment we evaluated host choice in a pairwise choice experiment, exposing pairs of siblings with contrasting developmental status to eight ticks. In the first and the second pair, a median developed nestling was linked with the most developed and the least developed nestling, respectively. Seventy‐two h after tick exposure we measured the innate constitutive humoral immunity and haematocrit. No differences were found in innate immunity, but the least developed nestlings had on average a lower haematocrit than the median and most developed nestlings. Significantly fewer ticks attached on the least developed nestling compared to the median nestling, and this difference was more pronounced when the innate immunity of the median developed nestling was higher. No difference in tick load was found among the median and best developed nestlings. The linkage between host preference and host physiological condition provide further insight in the mechanisms driving ectoparasite aggregation, which is important for the population dynamics of host, ticks and tick‐transmitted pathogens.

Host physiological condition regulates parasitic plant performance: Arceuthobium vaginatum subsp. cryptopodum on Pinus ponderosa

Much research has focused on effects of plant parasites on host-plant physiology and growth, but little is known about effects of host physiological condition on parasite growth. Using the parasitic dwarf mistletoe Arceuthobium vaginatum subsp. cryptopodum (Viscaceae) and its host Pinus ponderosa, we investigated whether changes in host physiological condition influenced mistletoe shoot development in northern Arizona forests. We conducted two studies in two consecutive years and used forest thinning (i.e., competitive release) to manipulate host physiological condition. We removed dwarf mistletoe shoots in April, before the onset of the growing season, and measured the amount of regrowth in the first season after forest thinning (Study I: n=38 trees; Study II: n=35 trees). Thinning increased tree uptake of water and carbon in both studies, but had no effect on leaf N concentration or delta13C. Mistletoe shoot growth was greater on trees with high uptake of water and carbon in thinned stands than trees with low uptake in unthinned stands. These findings show that increased resource uptake by host trees increases resources to these heterotrophic dwarf mistletoes, and links mistletoe performance to changes in host physiological condition.

Effects of Crown Scorch on Ponderosa Pine Resistance to Bark Beetles in Northern Arizona

We conducted a study linking mechanistic relationships among fire injury, tree physiological condition, and bark beetle (Coleoptera: Scolytidae) susceptibility. Crown scorch of 40 Pinus ponderosa trees was estimated in a naturally regenerated stand that was thinned and prescribed burned in winter and early spring 2000. Net photosynthetic rate (Pn) of undamaged foliage was higher in heavily and severely than moderately and lightly scorched trees. This trend was more pronounced in the dry season (June) than the wet season (August). This suggests the mechanism underlying the increase in Pn was an improvement in water relations. This was also supported by differences observed in predawn water potential and stomatal conductance (gs). Constitutive resin volume did not differ among crown scorch classes in June, but was negatively related to crown scorch intensity in September. This suggests that constitutive resin was formed and stored before fire injury, and therefore not strongly affected by crown scorch levels in June. Induced resin production (resin produced after depletion of constitutive resin) generally decreased with increasing crown scorch in both June and September. Induced resin appeared to be related to carbon available for resin synthesis. The proportion of successful colonization attempts by Ips spp. and Dendroctonus spp. was low throughout the season. Colonization of Ips sp. and Dendroctonus spp. was not spatially separated in host trees. Colonization attempts were generally positively related to intensity of crown scorch in both pheromone and no-pheromone treatments. This finding suggests that pheromones attracted insects to the tree, but host physiological condition or other factors ultimately determined host colonization. Our results also suggest that intensity of crown scorch may affect colonization attempts of Ips and Dendroctonus spp. on P. ponderosa trees.

Absence of blood parasites in Griffon vultures from Spain.

Hematozoan parasites were not found on blood smears fron any of 82 Griffon vultures (Gyps fulvus) examined from Spain. These vultures represented samples of diverse temporal and spatial origin, and there was a great disparity in host ages (nestlings to > 5-yr-old adults) and physiological condition (growing, food-stressed, injured, and healthy birds).

Parasitoid Encapsulation as a Defense Mechanism in the Coccoidea (Homoptera) and Its Importance in Biological Control

Abstract Encapsulation is a common defense mechanism exerted by a host insect in response to invasion by a metazoan parasitoid or other foreign organisms. In the process of encapsulation, the host forms a capsule around the parasitoid egg or larva, which is usually composed of host blood cells and the pigment melanin. The capsule may kill the parasitoid and thus prevent successful parasitism. Encapsulation may adversely affect the degree of biological control effected by parasitoids as it may either prevent the establishment of exotic parasitoids in new regions or reduce parasitoid efficacy. A high incidence of encapsulation may also cause difficulties in mass rearing of parasitoids. In the Coccoidea (Homoptera), parasitoid encapsulation has so far been recorded in three families: Coccidae (soft scale insects), Diaspididae (armored scale insects), and Pseudococcidae (mealybugs). Important factors that affect the frequency of parasitoid encapsulation in the Coccoidea include: Host and parasitoid species, the host's physiological age and physiological condition, the host origin (or strain), superparasitism, the rearing and/or ambient temperature, and the host plant. The effects of these factors on the incidence of parasitoid encapsulation in the Coccidae, Diaspididae, and Pseudococcidae are described.