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opencc-zeroDec 2021View details →

Effects of oviposition in a non-host species on foraging behaviour of the parasitoid Cotesia glomerata

Parasitoids lay their eggs in or on a host, usually another insect. During foraging, parasitoids can encounter insects that differ in terms of host suitability and quality. At one extreme end of this spectrum are non-hosts that are unsuitable for offspring development. Non-hosts are generally ignored but parasitization does occur and occasionally also results in egg deposition. Here, we investigate how oviposition in a non-host influences subsequent foraging behaviour of a parasitoid and whether this is mediated by learning. Our study system consists of the endoparasitoid Cotesia glomerata and the presumed non-host caterpillar Mamestra brassicae. In the presence of Pieris brassicae hosts and/or their traces (frass), we observed that C. glomerata inserts its ovipositor into M. brassicae caterpillars. Eggs were deposited, but all eggs disappeared within 96h, confirming the non-host status of M. brassicae. In contrast to our expectation, there was no memory retention after oviposition in a non-host and parasitoids did not alter their behaviour with respect to non-host contacts and ovipositions. Instead, C. glomerata became more motivated to forage on a non-host infested leaf. We propose that egg deposition in non-hosts by C. glomerata might be due to their high egg load, which is thought to make parasitoids less selective on host quality, especially when they have few reproductive opportunities. In such cases, fitness costs to individual females are low. Egg deposition in non-hosts might ultimately lead to host range expansion if parasitoids overcome the defence response of non-hosts over evolutionary time.

Drosophila melanogaster hosts coevolving with Pseudomonas entomophila pathogen show sex-specific patterns of local adaptation

Background: In spatially structured populations, local adaptation improves organisms' fitness in their native environment. Host and pathogens can rapidly adapt to their local antagonist. Since males and females can differ in their immunocompetence, the patterns of local adaptation can be different between the sexes. However, there is little information about sex differences in local adaptation in host-pathogen systems. Results: In the current study, we experimentally coevolved four different replicate populations of Drosophila melanogaster (host) and Pseudomonas entomophila (pathogen) along with appropriate controls. We used the four host-pathogen coevolution populations to investigate the occurrence of local adaptation separately in males and females of the coevolving hosts. We also assessed local adaptation in pathogens. We set up a reciprocal infection experiment where we infected each of the four coevolving hosts with their local pathogen or non-local pathogens from the other three replicate populations. We found that overall, male and female hosts had better survivorship when infected with local pathogens, indicating that they were locally adapted. Interestingly, males were more susceptible to non-local pathogens compared to females. In addition, we found no fecundity cost in females infected with either local or non-local pathogens. We found no evidence of local adaptation among the pathogens. Conclusion: Our study showed sex-specific adaptation in the coevolving hosts where female hosts had a broader response against allopatric coevolving pathogens with no cost in fecundity. Thus, our results might suggest a novel mechanism that can maintain variation in susceptibility in spatially structured populations.

No evidence of bacterial symbionts influencing host specificity in Aphis gossypii Glover (Hemiptera: Aphididae)

The cotton-melon aphid, Aphis gossypii Glover, is a polyphagous insect pest with many host-specialized biotypes, such as Cucurbitaceae- and Malvaceae-specialized (CU and MA) biotype. Bacterial symbionts were reported to determine host range in some aphids. Whether this is the case in A. gossypii remains unknown. Here, we tested host specificity of CU and MA biotype and compared host specificity between wingless and winged morph within the same biotype, and analyzed the composition of bacterial symbionts. The reproduction of CU and MA biotype reduced by 66.67% and 82.79% respectively on non-native hosts, compared with that on native hosts. The composition of bacterial symbionts was not significantly different between CU and MA biotype, with Buchnera abundance >95% in both biotypes. While, winged morph produced significantly more nymphs than wingless morph on non-native hosts, and<a name="OLE_LINK1"></a> Buchnera abundance in winged morph was only about 10% of that in wingless morph. There seemed to be a relationship between Buchnera abundance and host specificity. We regulated Buchnera abundance by temperature and antibiotics, but did not find that low Buchnera abundance resulted in high reproduction on non-native hosts. We conclude that host specificity of A. gossypii is not controlled by specific bacterial symbionts or by Buchnera abundance.

opencc-by-4.0May 2022View details →

Data and code for Host and pathogen drivers of infection-induced changes in social aggregation behavior

Raw data and R code  DistanceInds.xlsx contains pairwise distances between pairs of flies, measured within groups of 12 every 30 mins for 4 hours post-infection with one of four bacterial pathogens, at either a low or high dose.  NND-Boyle.csv contains nearest-neighbor distances between pairs of flies, measured within groups of 12 following infections with Pseudomonas entomophila.

Effect of resource limitation on host post-infection survival and systemic pathogenic growth

In the experiments presented here, we explore the effect of resource limitation, in form of starvation (which leads to decrease in accessible resources and depletion of reserves) and sexual activity (which leads to reallocation of resources from somatic defence towards reproduction), on immune function of female Drosophila melanogaster flies. We infected females with five bacterial pathogens and measured their post-infection survival when subjected to either starvation or sexual activity (mating). Additionally, we measured within host pathogen levels in case of three of these pathogens. Based on previous literature, we predicted that both modes of resource limitation will increase post-infection mortality, but only sexual activity will lead to increase of pathogen load (because of compromised immune function), while starvation will either not affect or reduce pathogen loads (because of reduced availability of resources for the pathogen to proliferate within the host). Our results indicate that both starvation and sexual activity can lead to increased within-host pathogen levels, in addition to increased post-infection mortality, but in a pathogen-specific manner.

Behavioral and postural analyses establish sleep-like states for mosquitoes that can impact host landing and blood feeding

Sleep is an evolutionarily conserved process that has been described in different animal systems. For insects, sleep characterization has been primarily achieved using behavioral and electrophysiological correlates in a few systems. Sleep in mosquitoes, which are important vectors of disease-causing pathogens, has not been directly examined. This is surprising as circadian rhythms, which have been well studied in mosquitoes, influence sleep in other systems. In this study, we characterized sleep in mosquitoes using body posture analysis and behavioral correlates and quantified the effect of sleep deprivation on sleep rebound, host landing and blood-feeding propensity. Body and appendage position metrics revealed a clear distinction between the posture of mosquitoes in their putative sleep and awake states for multiple species, which correlate with a reduction in responsiveness to host cues. Sleep assessment informed by these posture analyses indicated significantly more sleep during periods of low activity. Nighttime and daytime sleep deprivation resulting from the delivery of vibration stimuli induced sleep rebound in the subsequent phase in day and night active mosquitoes, respectively. Lastly, sleep deprivation suppressed host landing in both laboratory and field settings, and impaired blood-feeding of a human host when mosquitoes would normally be active. These results suggest that quantifiable sleep states occur in mosquitoes and highlight the potential epidemiological importance of mosquito sleep.

opencc-by-4.0Feb 2022View details →

Wheat stem rust back in Europe: Diversity, prevalence and impact on host resistance

SSR genotypes of European Puccinia graminis isolates based on 17 SSR markers, updated version

Data for: The visual ecology of selective predation: Are unhealthy hosts less stealthy hosts?

Predators can strongly influence disease transmission and evolution, particularly when they prey selectively on infected hosts. Although selective predation has been observed in numerous systems, why predators select infected prey remains poorly understood. Here, we use a mathematical model of predator vision to test a longstanding hypothesis about the mechanistic basis of selective predation in a Daphnia-microparasite system, which serves as a model for the ecology and evolution of infectious diseases. Bluegill sunfish feed selectively on Daphnia infected by a variety of parasites, particularly in water uncolored by dissolved organic carbon. The leading hypothesis for selective predation in this system is that infection-induced changes in the transparency of Daphnia render them more visible to bluegill. Rigorously evaluating this hypothesis requires that we quantify the effect of infection on the visibility of prey from the predator's perspective, rather than our own. Using a model of the bluegill visual system, we show that three common parasites, Metschnikowia bicuspidata, Pasteuria ramosa and Spirobacillus cienkowskii, decrease the transparency of Daphnia, rendering infected Daphnia darker against a background of downwelling light. As a result of this increased brightness contrast, bluegill can see infected Daphnia at greater distances than uninfected Daphnia - between 19-33% further, depending on the parasite. Pasteuria and Spirobacillus also increase the chromatic contrast of Daphnia. These findings lend support to the hypothesis that selective predation by fish on infected Daphnia could result from the effects of infection on Daphnia's visibility. However, contrary to expectations, the visibility of Daphnia was not strongly impacted by water color in our model. Our work demonstrates that models of animal visual systems can be useful in understanding ecological interactions that impact disease transmission.

Morphological measurements of two host specialists of the dipteran Tephritis conura, both in sympatry and allopatry

<div> <div> <div> <div> Adaptation to new ecological niches is known to spur population diversification and may lead to speciation if gene flow is ceased. While adaptation to the same ecological niche is expected to be parallel, it is more difficult to predict whether selection against maladaptive hybridization in secondary sympatry results in parallel divergence also in traits that are not directly related to the ecological niches. Such parallelisms in response to selection for reproductive isolation can be identified through estimating parallelism in reproductive character displacement across different zones of secondary contact. Here, we use a host shift in the phytophagous peacock fly Tephritis conura, with both host races represented in two geographically separate areas East and West of the Baltic Sea to investigate convergence in morphological adaptations. We asked i) if there are consistent morphological adaptations to a host plant shift and ii) if the response to secondary sympatry with the alternate host race is parallel across contact zones. We found surprisingly low and variable, albeit significant, divergence between host races. Only one trait, the length of the female ovipositor, which serves an important function in the interaction with the hosts, was consistently different between host races. Instead, co-existence with the other host race significantly affected the degree of morphological divergence, but the divergence was largely driven by different traits in different contact zones. Thus, local stochastic fixation or reinforcement could generate trait divergence, and additional evidence is needed to conclude whether divergence is locally adaptive. </div> </div> </div> </div>

Cross-continental comparison of parasite communities in a wide-ranging carnivore suggests associations with prey diversity and host density

Parasites are integral to ecosystem functioning yet often overlooked. Improved understanding of host-parasite associations is important, particularly for wide-ranging species for which host range shifts and climate change could alter host-parasite interactions and their effects on ecosystem function. Among the most widely distributed mammals with diverse diets, grey wolves (Canis lupus) host parasites that are transmitted among canids and via prey species. Grey wolf-parasite associations may therefore influence the population dynamics and ecological functions of both wolves and their prey. Our goal was to identify large-scale processes that shape host-parasite interactions across populations, with the grey wolf as a model organism. By compiling data from various studies, we examined the faecal prevalence of gastrointestinal parasites in six wolf populations from two continents in relation to wolf density, diet diversity, and other ecological conditions. As expected, we found that the faecal prevalence of parasites transmitted directly to wolves via contact with other canids or their excreta was positively associated with wolf density. Contrary to our expectations, the faecal prevalence of parasites transmitted via prey was negatively associated with prey diversity. We also found that parasite communities reflected landscape characteristics and specific prey items available to wolves. Several parasite taxa identified in this study, including hookworms and coccidian protozoans, can cause morbidity and mortality in canids, especially in pups, or in combination with other stressors. The density-prevalence relationship for parasites with simple lifecycles may reflect a regulatory role of gastrointestinal parasites on wolf populations. Our result that faecal prevalence of parasites was lower in wolves with more diverse diets could provide insight into the mechanisms by which biodiversity may regulate disease. A diverse suite of predator-prey interactions could regulate the effects of parasitism on prey populations and mitigate the transmission of infectious agents, including zoonoses, spread via trophic interactions.

Ecological speciation by sympatric host shifts in a clade of herbivorous sea slugs, with introgression and localized mitochondrial capture between species

Host shifting in insect-plant systems was historically important to the development of ecological speciation theory, yet surprisingly few studies have examined whether host shifting drives the diversification of marine herbivores. When small-bodied consumers feed and also mate on a preferred host, disruptive selection can split a population into host races despite gene flow. Support for host shifts is notably lacking for invertebrates associated with macroalgae, where the scale of dispersal by planktonic larvae often far exceeds the grain of host patchiness, and adults are typically less specialized than terrestrial herbivores. Here, we present a candidate example of ecological speciation in a clade of sea slugs that primarily consume green algae in the genus Caulerpa, including highly invasive species. Ancestral character state reconstructions supported 'sea grapes' (C. racemosa, C. lentillifera) as the ancestral host for a tropical radiation of 12 Elysia spp., with one shift onto alternative Caulerpa spp. in the Indo-Pacific. A Caribbean radiation of three species included symaptric host shifts to Rhipocephalus brevicaulis in the ancestor of E. pratensis Ortea & Espinosa, 1996, and to C. prolifera in E. hamanni Krug, Vendetti & Valdes 2016, plus a niche expansion to a range of Caulerpa spp. in E. subornata Verrill, 1901. All three species are broadly sympatric across the Caribbean but are host-partitioned at a fine grain, and distinct by morphology and at nuclear loci. However, non-recombining mtDNA revealed a history of gene flow between E. pratensis and E. subornata: COI haplotypes from E. subornata were 10.4% divergent from E. pratensis haplotypes from four sites, but closely related to all E. pratensis haplotypes sampled from six Bahamian islands, indicating historical introgression and localized "mitochondrial capture." Disruptive selective likely fueled divergence and adaptation to distinct host environments, indicating ecological speciation may be an under-appreciated driver of diversification for marine herbivores as well as epibionts and other resource specialists.

Impact of host demography and evolutionary history on endosymbiont molecular evolution: a test in carpenter ants (Genus Camponotus) and their Blochmannia endosymbionts

Obligate endosymbioses are tight associations between symbionts and the hosts they live inside. Hosts and their associated obligate endosymbionts generally exhibit codiversification, which has been documented in taxonomically diverse insect lineages. Host demography (e.g., effective population sizes) may impact the demography of endosymbionts, which may lead to an association between host demography and the patterns and processes of endosymbiont molecular evolution. Here, we used whole-genome sequencing data for carpenter ants (Genus Camponotus; subgenera Camponotus and Tanaemyrmex) and their Blochmannia endosymbionts as our study system to address whether Camponotus demography shapes Blochmannia molecular evolution. Using whole-genome phylogenomics, we confirmed previous work identifying codiversification between carpenter ants and their Blochmannia endosymbionts. We found that Blochmannia genes have evolved at a pace ~30× faster than that of their hosts' molecular evolution and that these rates are positively associated with host rates of molecular evolution. Using multiple tests for selection in Blochmannia genes, we found signatures of positive selection and shifts in selection strength across the phylogeny. Host demography was associated with Blochmannia shifts toward increased selection strengths, but not associated with Blochmannia selection relaxation, positive selection, genetic drift rates, or genome size evolution. Mixed support for relationships between host effective population sizes and Blochmannia molecular evolution suggests weak or uncoupled relationships between host demography and Blochmannia population genomic processes. Finally, we found that Blochmannia genome size evolution was associated with genome-wide estimates of genetic drift and number of genes with relaxed selection pressures. --

Data and code from: Mixed infection, risk projection and misdirection: Interactions among pathogens alter links between host resources and disease

A growing body of literature links resources of hosts to their risk of infectious disease. Yet most hosts encounter multiple pathogens, and projections of disease risk based on resource availability could be fundamentally wrong if they do not account for interactions among pathogens within hosts. Here, we measured infection risk of grass hosts (Avena sativa) exposed to three naturally-co-occurring viruses either singly or jointly (barley and cereal yellow dwarf viruses [B/CYDVs]: CYDV-RPV, BYDV-PAV, and BYDV-SGV) along experimental gradients of nitrogen and phosphorus supply. We asked whether disease risk (i.e., infection prevalence) differed in single versus co-inoculations, and whether these differences varied with rates and ratios of nitrogen and phosphorus supply. In single inoculations, the viruses did not respond strongly to nitrogen or phosphorus. However, in co-inoculations, we detected illustrative cases of 1) resource-dependent antagonism (RPV with increasing N; possibly due to competition), 2) resource-dependent facilitation (SGV with decreasing N:P; possibly due to immunosuppression), and 3) weak or no interactions within hosts (for PAV). Together, these within-host interactions created emergent patterns for co-inoculated hosts, with both infection prevalence and viral richness increasing with the combination of low nitrogen and high phosphorus supply. We demonstrate that knowledge of multiple pathogens is essential for predicting disease risk from host resources, and that projections of risk that fail to acknowledge resource-dependent interactions within hosts could be qualitatively wrong. Expansions of theory from community ecology theory may help anticipate such relationships linking host resources to diverse pathogen communities.

opencc-by-4.0Jun 2022View details →

Potential wild hosts of Echinococcus vogeli

O helminto Echinococcus vogeli Rausch & Bernstein, 1972 é o agente causador da Equinococose Neotropical, uma doença zoonótica crônica e endêmica da região Neotropical.  Este parasito é transmitido entre o cachorro-vinagre (Speothos venaticus) e suas presas, como pacas (Cuniculus paca Linnaeus, 1766) e cutias (Dasyprocta spp.). No Brasil, a maioria dos casos humanos de Equinococose Neotropical é registrada nos estados do Acre e Pará, embora existam poucos dados disponíveis sobre a ocorrência de potenciais hospedeiros definitivos e intermediários de E. vogeli na Amazônia. No presente estudo, foram investigadas áreas de floresta ao redor de 46 comunidades humanas localizadas dentro e fora de quatro áreas protegidas de uso sustentável no sudoeste da bacia amazônica, Brasil por meio de armadilhas fotográficas digitais para verificar a presença de potenciais hospedeiros silvestres de E. vogel, onde os mesmos foram registrados circulando na região.

opencc-by-4.0Mar 2022View details →

Pre-processed data for "Does host plant drive variation in microbial gut communities in a recently shifted pest?"

Pre-processed fastqs files generated by Illumina sequencing associated with the publication by Javal et al. entitled "Does host plant drive variation in microbial gut communities in a recently shifted pest?".

High levels of inbreeding with spatial and host-associated structure in lice of an endangered freshwater seal

Host-specialist parasites of endangered large vertebrates are in many cases more endangered than their hosts. In particular, low host population densities and reduced among-host transmission rates are expected to lead to inbreeding within parasite infrapopulations living on single host individuals. Furthermore, spatial population structures of directly-transmitted parasites should be concordant with those of their hosts. Using population genomic approaches, we investigated inbreeding and population structure in a host-specialist seal louse (Echinophthirius horridus) infesting the Saimaa ringed seal (Phoca hispida saimensis), which is endemic to Lake Saimaa in Finland and is one of the most endangered pinnipeds in the world. We conducted genome resequencing of pairs of lice collected from 18 individual Saimaa ringed seals throughout the Lake Saimaa complex. Our analyses showed high genetic similarity and inbreeding between lice inhabiting the same individual seal host, indicating low among-host transmission rates. Across the lake, genetic differentiation among individual lice was correlated with their geographic distance, and assignment analyses revealed a marked break in the genetic variation of the lice in the middle of the lake, indicating substantial population structure. These findings indicate that movements of Saimaa ringed seals across the main breeding areas of the fragmented Lake Saimaa complex may in fact be more restricted than suggested by previous population-genetic analyses of the seals themselves.

Data from: Bighorn sheep show similar in-host responses to the same pathogen strain in two contrasting environments

Ecological context – the biotic and abiotic environment, along with its influence on population mixing dynamics and individual susceptibility – are thought to have major bearing on epidemic outcomes. However, direct comparisons of disease events in contrasting ecological contexts in wildlife systems are often confounded by concurrent differences in host genetics, exposure histories, or pathogen strains. Here, we compare disease dynamics of a Mycoplasma ovipneumoniae spillover event that affected bighorn sheep populations in two contrasting ecological contexts. One event occurred on the herd's home range near the Rio Grande Gorge in New Mexico, while the other occurred in a captive facility at Hardware Ranch in Utah. While data collection regimens varied between the two sites, general patterns of antibody signal strength and symptom emergence were consistent. Symptoms appeared in the captive setting an average of 12.9 days post-exposure, average time to seroconversion was 24.9 days, and clinical signs peaked at approximately 36 days post-infection. These patterns were consistent with serological testing and subsequent declines in symptom intensity in the free-ranging herd. At the captive site, older animals exhibited more severe declines in body condition and loin thickness, higher symptom burdens, and slower antibody response to the pathogen than younger animals. Younger animals were more likely than older animals to clear infection by the time of sampling at both sites. The patterns presented here suggest that environment may not be a major determinant of epidemiological outcomes in the bighorn sheep - M. ovipneumoniae system, elevating the possibility that host- or pathogen-factors may be responsible for observed variation.

Host plant specificity of the monarch butterfly Danaus plexippus: A systematic review and meta-analysis

The preference-performance hypothesis explains host specificity in phytophagous insects, positing that host plants chosen by adults confer the greatest larval fitness. However, adults sometimes oviposit on plants supporting low larval success because the components of host specificity (adult preference, plant palatability, and larval survival) are non-binary and not necessarily correlated. Palatability (willingness to eat) is governed by chemical cues and physical barriers such as trichomes, while survival (ability to complete development) depends upon nutrition and toxicity. Absence of a correlation between the components of host specificity results in low-performance hosts supporting limited larval development. Most studies of specificity focus on oviposition behavior leaving the importance and basis of palatability and survival under-explored. We conducted a comprehensive review of 127 plant species that have been claimed or tested to be hosts for the monarch butterfly Danaus plexippus to classify them as non-hosts, low performance, or high performance. We performed a meta-analysis to test if performance status could be explained by the properties of neurotoxic cardenolides or trichome density. We also conducted a no-choice larval feeding experiment to identify the causes of low performance. We identified 34 high performance, 42 low performance, 33 non-hosts, and 18 species with unsubstantiated claims. Mean cardenolide concentration was greater in high- than low-performance hosts and a significant predictor of host status, suggesting possible evolutionary trade-offs in monarch specialization. Other cardenolide properties and trichome density were not significant predictors of host status. In the experiment, we found, of the 62% of larvae that attempted to eat low-performance hosts, only 3.5% survived to adult compared to 85% of those on the high-performance host, demonstrating that multiple factors affect larval host plant specificity. Our study is the first to classify all known host plants for monarchs and has conservation implications for this threatened species.

opencc-by-4.0Jun 2022View details →

Still standing: the heat protection delivered by a facultative symbiont to its aphid host is resilient to repeated thermal stress

This is the dataset for the article "Still standing: the heat protection delivered by a facultative symbiont to its aphid host is resilient to repeated thermal stress". This experimental study focused on the heat-protective mutualism between the pea aphid Acyrthosiphon pisum and the facultative bacterium Serratia symbiotica. We exposed two aphid lines (5A: deprived of S. symbiotica, 5AR: infected by S. symbiotica) to a varying number of heat shocks (35°C for 2 h) applied during insect immature development: none (control), one, two, or three. We recorded aphid immature survival rate, total longevity, immature development time, lifetime fecundity and hind tibia length (body size). . Individual = identification of the individual . Line = aphid clonal line, either deprived of (5A) or infected by S. symbiotica (5AR) . Temp = thermal treatment, defined by the number of heat shocks applied during aphid juvenile life (0 = control, 1, 2 or 3) . Survival = whether (Y) or not (N) the individual survived until reproduction  . Adulthood = time elapsed between birth and first reproduction (in days) . Longevity = time elapsed between birth and death (in days) . Fecundity = total number of larvae produced by each aphid throughout lifetime . Wing = whether (Y) or not (N) the individual developed wings following imaginal moult . Tibia = hind tibia length as a proxy of body size (in mm)