Gregarines (Apicomplexa: Eugregarinorida) parasitizing the cave cricket Troglophilus (Orthoptera: Raphidophoridae) in the Slovenian karst

The cave crickets Troglophilus neglectus Krauss, 1879 and T. cavicola (Kollar, 1833) originating from caves in Slovenia were surveyed for gregarines. Two gregarine species were identified. Gregarina troglophili (Golemansky & Lipa, 1991) occurred in both cave cricket species, T. cavicola being reported a new host species. Besides, a new species, Gregarina bernardae sp. n., in­fecting T. neglectus, was identified and described. The two spe­cies often infest the same T. neglectus individuals, but can be well distinguished upon the shape and morphometric indexes of both solitary gregarines and associations. The deutomerite in solitary gamonts of G. troglophili is orbicular to broadly el­liptoid, while in G. bernardae sp. n. it is oblong to dolioform. In associations, the primite deutomerite in G. troglophili is orbicu­lar to broadly elliptoid, while in G. bernardae sp. n. it is shal­lowly oblong to oblong. In contrast to broadly obovoid to finely obdeltoid satellite deutomerite in G. troglophili, it is narrowly dolioform or dolioform to narrowly obdeltoid in G. bernardae sp. n. Both species are new to the faunal list of Slovenia, and to the list of cave-dwelling species in the country. We direct the attention to the parasite diversity of cave-dwelling animals – a promising, but understudied topic that might considerably contribute to the diversity of the subterranean fauna.

Endosymbiotic male-killing Spiroplasma affect the physiological and behavioural ecology of Macrocheles - Drosophil a interactions

While many arthropod endosymbionts are vertically transmitted, phylogenetic studies reveal repeated introductions of hemolymph-dwelling Spiroplasma into Drosophila . Introductions are often attributed to horizontal transmission via ectoparasite vectors. Here, we test if mites prefer to infect Spiroplasma poulsonii MSRO infected flies, and if MSRO infection impairs fly resistance against secondary mite ( Macrocheles subbadius ) attack. First we tested if mites prefer MSRO+ or MSRO– flies using pair-wise-choice tests across fly ages. We then tested whether mite preferences are explained by changes in fly physiology, specifically increased metabolic rate (measured as CO 2 production). We hypothesize that this preference is due in part to MSRO+ flies expressing higher metabolic rates. However, our results showed mite preference depended on an interaction between fly age and MSRO status: mites avoided 14-days old MSRO+ flies relative to MSRO– flies (31% infection), but prefered MSRO + flies (64% infection) among 26-day old flies. Using flow-through respirometry, we found 14 day-old MSRO + flies had higher CO 2 emissions than MSRO– flies (32% greater), whereas at 26 days old the CO 2 production among MSRO+ flies was 20% lower than MSRO– flies. Thus, mite preferences for high metabolic rate hosts did not explain the infection biases in this study. To assess changes in susceptibility to infection, we measured fly endurance using geotaxis assays. Older flies had lower endurance consistent with fly senescence, and this effect was magnified among MSRO+ flies. Given the biological importance of male-killing Spiroplasma, potential changes in the interactions of hosts and potential vectors could impact the ecology and evolution of host species. Importance Male-killing endosymbionts are transmitted mother to daughter and kill male offspring. Despite these major ecological effects, how these endosymbionts colonize new host species is not always clear. Mites are sometimes hypothesized to transfer these bacteria between hosts/host species. Here we test if 1) if mites prefer to infect flies that harbour Spiroplasma poulisoni MSRO and 2) if flies infected with MSRO are less able to resist mite infection. Our results show that flies infected with MSRO have weaker anti-mite resistance but the mite preference/aversion for MSRO+ flies varied with fly age. Given the fitness and population impacts of male-killing Spiroplasma , changes in fly-mite interactions have implications for the ecology and evolution of these symbioses.

First record of Telenomus kolbei (Hymenoptera, Scelionidae) in France, parasitizing the eggs of Nymphalis antiopa and Aglais io (Lepidoptera, Nymphalidae)

Telenomus kolbei is newly reported in France, parasitizing two new host species: Aglais io and Nymphalis antiopa. Oviposition by the parasitoid into eggs of both species was observed. Films were made, to which links are given. DNA sequences were obtained and deposited in Genbank.

Regressive evolution of an effector following a host jump in the Irish Potato Famine Pathogen Lineage

In order to infect a new host species, the pathogen must evolve to enhance infection and transmission in the novel environment. Although we often think of evolution as a process of accumulation, it is also a process of loss. Here, we document an example of regressive evolution in the Irish potato famine pathogen (Phytophthora infestans) lineage, providing evidence that a key sequence motif in the effector PexRD54 has degenerated following a host jump. We began by looking at PexRD54 and PexRD54-like sequences from across Phytophthora species. We found that PexRD54 emerged in the common ancestor of Phytophthora clade 1b and 1c species, and further sequence analysis showed that a key functional motif, the C-terminal ATG8-interacting motif (AIM), was also acquired at this point in the lineage. A closer analysis showed that the P. mirabilis PexRD54 (PmPexRD54) AIM appeared unusual, the otherwise-conserved central residue mutated from a glutamate to a lysine. We aimed to determine whether this PmPexRD54 AIM polymorphism represented an adaptation to the Mirabilis jalapa host environment. We began by characterizing the M. jalapa ATG8 family, finding that they have a unique evolutionary history compared to previously characterized ATG8s. Then, using co-immunoprecipitation and isothermal titration calorimetry assays, we showed that both full-length PmPexRD54 and the PmPexRD54 AIM peptide bind very weakly to the M. jalapa ATG8s. Through a combination of binding assays and structural modelling, we showed that the identity of the residue at the position of the PmPexRD54 AIM polymorphism can underpin high-affinity binding to plant ATG8s. Finally, we conclude that the functionality of the PexRD54 AIM was lost in the P. mirabilis lineage, perhaps owing to as-yet-unknown pressure on this effector in the new host environment.Author SummaryPathogens evolve in concert with their hosts. When a pathogen begins to infect a new host species, known as a “host jump,” the pathogen must evolve to enhance infection and transmission. These evolutionary processes can involve both the gain and loss of genes, as well as dynamic changes in protein function. Here, we describe an example of a pathogen protein that lost a key functional domain following a host jump, a salient example of “regressive evolution.” Specifically, we show that an effector protein from the plant pathogen Phytopthora mirabilis, a host-specific lineage closely related to the Irish potato famine pathogen Phytopthora infestans, has a derived amino acid polymorphism that results in a loss of interaction with certain host machinery.

Molecular Evolution of the Influenza A Virus Non-structural Protein 1 in Interspecies Transmission and Adaptation

The non-structural protein 1 (NS1) of influenza A viruses plays important roles in viral fitness and in the process of interspecies adaptation. It is one of the most polymorphic and mutation-tolerant proteins of the influenza A genome, but its evolutionary patterns in different host species and the selective pressures that underlie them are hard to define. In this review, we highlight some of the species-specific molecular signatures apparent in different NS1 proteins and discuss two functions of NS1 in the process of viral adaptation to new host species. First, we consider the ability of NS1 proteins to broadly suppress host protein expression through interaction with CPSF4. This NS1 function can be spontaneously lost and regained through mutation and must be balanced against the need for host co-factors to aid efficient viral replication. Evidence suggests that this function of NS1 may be selectively lost in the initial stages of viral adaptation to some new host species. Second, we explore the ability of NS1 proteins to inhibit antiviral interferon signaling, an essential function for viral replication without which the virus is severely attenuated in any host. Innate immune suppression by NS1 not only enables viral replication in tissues, but also dampens the adaptive immune response and immunological memory. NS1 proteins suppress interferon signaling and effector functions through a variety of protein-protein interactions that may differ from host to host but must achieve similar goals. The multifunctional influenza A virus NS1 protein is highly plastic, highly versatile, and demonstrates a diversity of context-dependent solutions to the problem of interspecies adaptation.

Intra- and Cross-Species Transmission of Astroviruses

Astroviruses are non-enveloped, single-stranded RNA viruses that infect mammalian and avian species. In humans, astrovirus infections are one of the most common causes of gastroenteritis in children. Infection has also been linked to serious neurological complications, especially in immunocompromised individuals. More extensive disease has also been characterized in non-human mammalian and avian species. To date, astroviruses have been detected in over 80 different avian and mammalian hosts. As the number of hosts continues to rise, the need to understand how astroviruses transmit within a given species as well as to new host species becomes increasingly important. Here, we review the current understanding of astrovirus transmission, the factors that influence viral spread, and the potential for cross-species transmission. Additionally, we highlight the current gaps in knowledge and areas of future research that will be key to understanding astrovirus transmission and zoonotic potential.

Noteworthy lichenicolous fungi and lichens from Russia

Notes are presented on seven species of lichenicolous, non-lichenized and lichenized fungi found in the Asian part of Russia. Endococcus pseudocarpus is reported for the first time for Northern Asia as well as for the Irkutsk Region of Russia. Plectocarpon hypogymniae and P. nephromeum are reported new to the Irkutsk Region, Taeniolella diploschistis new to the Republic of Sakha (Yakutia), Steinia geophana new to Chukotka Autonomous Area, and Epigloea soleiformis new to the north of the Krasnoyarsk Territory of Russia. Hypogymnia physodes is reported as a new host species for Plectocarpon hypogymniae.

Primate malarias as a model for cross-species parasite transmission

Parasites regularly switch into new host species, representing a disease burden and conservation risk to the hosts. The distribution of these parasites also gives insight into characteristics of ecological networks and genetic mechanisms of host-parasite interactions. Some parasites are shared across many species, whereas others tend to be restricted to hosts from a single species. Understanding the mechanisms producing this distribution of host specificity can enable more effective interventions and potentially identify genetic targets for vaccines or therapies. With increasing ecological connections to local animal populations, the risk to human health is increasing. Which of these parasites will fizzle out and which have potential to become widespread in humans? We consider the case of primate malarias, caused by Plasmodium parasites, to understand the interacting ecological and evolutionary mechanisms that put humans at risk for disease. Plasmodium host switching from primates to humans led to ancient introductions of the most common malaria-causing agents in humans today, and new parasite switching is a growing threat, especially in Asia and South America. Based on a wild host-Plasmodium occurrence database, we highlight geographic areas of concern and potential areas to target further sampling. Finally, we discuss methodological developments that will facilitate clinical and field-based interventions to improve human health based on this eco-evolutionary perspective.

Natural selection in the evolution of SARS-CoV-2 in bats created a generalist virus and highly capable human pathogen

Virus host shifts are generally associated with novel adaptations to exploit the cells of the new host species optimally. Surprisingly, Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) has apparently required little to no significant adaptation to humans since the start of the Coronavirus Disease 2019 (COVID-19) pandemic and to October 2020. Here we assess the types of natural selection taking place in Sarbecoviruses in horseshoe bats versus the early SARS-CoV-2 evolution in humans. While there is moderate evidence of diversifying positive selection in SARS-CoV-2 in humans, it is limited to the early phase of the pandemic, and purifying selection is much weaker in SARS-CoV-2 than in related bat Sarbecoviruses. In contrast, our analysis detects evidence for significant positive episodic diversifying selection acting at the base of the bat virus lineage SARS-CoV-2 emerged from, accompanied by an adaptive depletion in CpG composition presumed to be linked to the action of antiviral mechanisms in these ancestral bat hosts. The closest bat virus to SARS-CoV-2, RmYN02 (sharing an ancestor about 1976), is a recombinant with a structure that includes differential CpG content in Spike; clear evidence of coinfection and evolution in bats without involvement of other species. While an undiscovered “facilitating” intermediate species cannot be discounted, collectively, our results support the progenitor of SARS-CoV-2 being capable of efficient human–human transmission as a consequence of its adaptive evolutionary history in bats, not humans, which created a relatively generalist virus.