Obligate Parasite Research Articles

Assessing the specificity of the Rosette agent DNA amplification: An optimized protocol for the detection of standard DNA among studies.

Assessing the specificity of the Rosette agent DNA amplification: An optimized protocol for the detection of standard DNA among studies.

Bio-efficacy of new fungicide, Tebuconazole- 430SC against coffee leaf rust disease, Hemileia vastatrix Berk and Broome

Coffee is an important plantation crop cultivated worldwide and used as stimulating drink. Coffee leaf rust (CLR) disease is one of the devastating disease affecting foliage of Coffee, limiting Coffee production worldwide. It is caused by an obligate parasite Hemileia vastatrix, which reduce photosynthetic area in turn results in heavy defoliation and die-back of branches. In India CLR management is accomplished with one contact fungicide spray (Bordeaux mixture @ 0.5%) and effective systemic fungicide spray during pre and post monsoon periods respectively. However, to find an alternative to the recommended fungicide the studies were conducted to know the efficacy of new fungicide Tebuconazole 430 SC against CLR. The results revealed that, in the laboratory conditions, complete inhibition of the uredospore germination was observed in Tebuconazole 430 SC @ 0.5 ml/L and 0.75 ml/L and Hexaconazole 5 EC @ 2 ml/L. However, in lower concentration Tebuconazole 430 SC @0.25 ml/L there was 98.97 per cent inhibition and in Copper Oxychloride 50 WP @ 5.5 g/L 87.49 per cent inhibition was observed over control. Field trials indicated that, at all the locations, Tebuconazole 430SC @ 0.75ml/L was found very effective which recorded maximum disease reduction followed by Tebuconazole 430SC @ 0.5ml/L which was found on-par with the currently recommended fungicide Hexaconazole 5 EC @ 2 ml/L and minimum disease reduction was observed in Copper oxychloride 50 WP @ 5.5g/L.

EXTERNAL OPHTHALMOMYIASIS

Ophthalmomyiasis is a zoonotic disease most often caused by the larvae of oestrus ovis (sheep fly). Thefemale O. ovis retains her eggs within her body until they hatch, and then typically deposits her larvae into thenostrils of sheep and goats. Larvae of Oestrus ovis are obligate parasites of the nasal and sinus cavities of sheep andgoats, so this parasite is widespread in countries where the climate is hot and dry and sheep and goats are numerous.Therefore, it usually occurs in shepherds and farmers in rural areas, but it has also been observed in urban areas andin close contact with animals. In addition to oestrus ovis, there are other species that can cause this disease - thehuman bot fly (Dermatobia Hominis), midge (Fannia), house fly (Musca domestica) and cattle (Hypoderma).Ophthalmomyiasis is classified as external if the larvae are present on the lids or conjunctiva, and internal whenthere is intraocular penetration of the larvae, which affects the retina and if left untreated can lead to blindness.Intraocular penetration of larvae, or ophthalmomyiasis interna, is less common worldwide than ophthalmomyiasisexterna. It is known to occur at various anatomical sites including skin, eye, nose, paranasal sinuses, throat,intestine, and urogenital tract Conjunctival myiasis is the most common form of ophthalmomyiasis, and it is arelatively mild, self-limited, and benign disease.An ocular involvement occurs in about < 5% of all the cases ofhuman myiasis.Risk factors include eye infections, eye sores, advanced age, frailty, poor general health. Symptoms are described asforeign body sensation with lacrimation, conjunctival hyperemia and pruritus followed by eye pain. These initialsigns and symptoms of ophthalmomyiasis externa may mimic conjunctivitis. All movements of the larva are clearlyvisible from the side, which greatly facilitates its detection and diagnosis. Ophthalmomyiasis can be treatedefficiently ,if identified in time The treatment is based on the manual extraction of all larvae under local anesthesia,followed by washing or rinsing the eyes and local treatment. Prevention has always been better than cure. Goodpersonal hygiene can avert significant complications caused by ophthalmomyiasis Cases of ophthalmomiasis havebeen reported in countries around the world including Afghanistan, Pakistan, Kuwait, Iraq, Libya, Tunisia, Russia,India, USA, Canada, Croatia Slovenia. In the Republic of North Macedonia in 2022, 4 cases of ophthalmomiasiswere diagnosed and treated at the Shtip Clinical Hospital. It is characteristic that all the patients are men who areengaged in animal husbandry and agriculture and they are from a rural environment. Myiasis should be consideredas an occupational disease in farmers and shepherds.

Fleas from the Silk Road in Central Asia: identification of Ctenocephalides canis and Ctenocephalides orientis on owned dogs in Uzbekistan using molecular identification and geometric morphometrics

BackgroundThe Silk Road connected the East and West for over 1500 years. Countries in Central Asia are valuable in addressing the hypothesis that parasites on domestic animals were introduced along the Silk Road. Adult fleas are obligate parasites, having worldwide distribution. In dogs, Ctenocephalides canis, C. felis and C. orientis are the most common species identified. The distribution of the Oriental cat flea, C. orientis, is restricted to southeast Asia. The purpose of this study was to determine the diversity of dog fleas from Uzbekistan, a country in Central Asia, with particular reference to C. orientis.MethodsFleas were collected from 77 dogs from 5 locations in Uzbekistan. The cox1 gene sequences from Ctenocephalides spp. were compared to global collection of Ctenocephalides cox1 haplotypes. Landmark-based geometric morphometrics have been applied to the head and curvature to compare C. canis and C. canis using canonical variate analysis and discriminant function analysis.ResultsOverall, 199 fleas were collected and identified as C. canis (n = 115, 58%), C. orientis (n = 53, 27%) and Pulex irritans (n = 22, 11%). None of the fleas were C. felis. All Ctenocephalides spp. fleas were subject to cox1 amplification and 95% (166/175) yielded DNA sequence. There were 25 cox1 haplotypes; 14 (22/25, 88%) were C. canis cox1 haplotypes and 3 (3/25, 12%) were C. orientis cox1 haplotypes. Molecular analysis confirmed the absence of C. felis. Four (4/22) and one (1/3) cox1 haplotypes were identical to cox1 haplotypes belonging to C. canis and C. orientis cox1 haplotypes identified elsewhere, respectively. Overall morphometric analysis confirmed significant differences between the head shape of C. canis and C. orientis and improved four–fivefold the species identification compared to traditional morphological key.ConclusionWe report for the first time the presence of C. orientis in Uzbekistan. Differentiation of C. orientis from C. canis and C. felis remains difficult in regions where these species coexist. Studies in Central and Southeast Asia should confirm species identity using cox1 locus to enable retracing of the distribution of the Ctenocephalides in Asia. The presence of C. orientis suggests that this species may have been introduced from the east along the ancient Silk Road.Graphical

Insights into the Antennal Characteristics and Olfactory Strategy of the Endangered Rhino Stomach Bot Fly Gyrostigma rhinocerontis (Diptera: Oestridae).

Simple SummaryGyrostigma rhinocerontis (Hope), the rhinoceros bot fly, is a rare obligate intestinal parasite of white and black rhinoceroses that can cause severe myiasis and secondary infection, leading to enormous economic and scientific loss. As the main sensory organs of flies, the antennae provide insects with critical information about the environment, playing significant roles in their key activities. The antennal characteristics of G. rhinocerontis remain largely unexplored, probably due to the extreme rarity of adult specimens in collections. In this study, the antennae of G. rhinocerontis were thoroughly examined using light and scanning electron microscopy. The morphology, including detailed ultrastructure, of antennal sensilla are presented. As the largest species of Oestridae Leach, not surprisingly, G. rhinocerontis has significantly larger antennae with more sensilla and sensory pits than any other Oestridae species, which could be an adaptation to locate their rare and endangered hosts.Gyrostigma rhinocerontis (Diptera: Oestridae) is a rare obligate intestinal parasite of both white and black rhinoceroses, which can induce severe myiasis, cause secondary infection, and lead to enormous economic and scientific loss. Antennae are the main sensory organs of G. rhinocerontis, which may have evolved a series of specialized adaptive structures to facilitate the exploitation of their hosts. Here, we thoroughly examine the antennae of G. rhinocerontis via light and scanning electron microscopy. Only microtrichia and chaetic sensilla were observed on the scape and pedicel, and the latter is enlarged, half-enveloping the postpedicel. Four types of sensilla (trichoid sensilla, basiconic sensilla, coeloconic sensilla, and clavate sensilla) and sensory pits are detected on the postpedicel. A set of coeloconic sensilla and a chaetic sensillum are located on the arista. Distribution, type, size, and ultrastructure of antennal sensilla are presented. The antennae of G. rhinocerontis are the largest among Oestridae species, with the most sensilla and the most sensory pits. These antennal characteristics could be correlated to their adaptation for more sensitive and accurate olfactory organs, used to locate their rare and endangered hosts. Accordingly, this morphological evidence supports that the host is an important driving factor in the diversity of antennal morphology in the bot flies.

Phoresy and Mites: More Than Just a Free Ride.

Mites are masters at attaching to larger animals, often insects, in a temporary symbiosis called phoresy that allows these tiny animals to exploit patchy resources. In this article, we examine phoresy in the Acari, including those that feed on their carriers in transit, from a broad perspective. From a phylogenetic perspective, phoresy has evolved several times from free-living ancestors but also has been lost frequently. Rotting logs appear to be the first patchy resource exploited by phoretic mites, but the evolution of rapid life cycles later permitted exploitation of short-lived resources. As phoresy is a temporary symbiosis, most species have off-host interactions with their carrier. These relationships can be highly complex and context dependent but often are exploitative of the carrier's resources or progeny. Transitions from phoresy to parasitism seem widespread, but evidence for transitions from obligate phoretic parasitism to permanent parasitism is weak.

Mussel parasite richness and risk of extinction.

Parasite conservation is important for the maintenance of ecosystem diversity and function. Conserving parasites relies first on understanding parasite biodiversity and second on estimating the extinction risk to that biodiversity. Although steps have been taken independently in both these areas, previous studies have overwhelmingly focused on helminths in vertebrate hosts over broad scales, providing low resolution and excluding a large proportion of possible host and parasite diversity. We estimated both total obligate parasite richness and parasite extinction risk in freshwater mussels (Unionidae and Margaritiferidae) from Europe and the United States to provide a case study for considering parasite conservation in a severely understudied system. We used currently reported host-parasite relationships to extrapolate parasite diversity to all possible mussel hosts and then used the threat levels of those hosts to estimate the extinction risk for both described and undescribed parasites. An estimated 67% of parasite richness in freshwater mussels is undescribed and over 80% of the most host-specific groups (digenean trematodes and ciliates) are undescribed. We estimated that 21% of this total parasite fauna is at immediate risk of extinction, corresponding to 60 unique species, many of which will likely go extinct before being described. Given the important roles parasites play in community structure and function and the strong ecosystem engineering capacities of freshwater mussels, such extinctions are likely to severely affect freshwater ecosystems. Our detailed study of mussel parasites provides compelling evidence for the hidden conservation threat to parasites through extinction cascades and shows parasites are deserving of immediate attention.

KAJIAN KESESUAIAN LARVA HERMETIA ILLUCENS (DIPTERA: STRATIOMYIDAE) PADA PERBANYAKAN NEMATODA ENTOMOPATOGEN STEINERNEMA SPP. SECARA IN VIVO

Entomopathogenic nematodes (EPN) are parasites that are effective in controlling plant pests that can be propagated in vivo. In vivo propagation requires a host because EPN is an obligate parasite, one of which is the larvae of Hermetia illucens (Diptera: Stratiomyidae). These larvae are easy to obtain, easy to cultivate, easy to use, have a short life cycle, and have a high nutritional content. This study aimed to examine the suitability of H. illucens larvae in the entomopathogenic nematode Steinernema spp. in vivo propagation. This research was conducted by examining the mortality rate and infection rate of EPN in H. illucens larvae with variations in wounds, concentrations of infective nematodes, and larval size. The test results were compared with the larvae of T. molitor which are commonly used as hosts. The results of the mortality rate study showed that injured H. illucens larvae were more susceptible to the entomopathogenic nematode Steinernema spp.. There was a significant difference in mortality rates between uninjured and injured although there was no difference in results due to variations in EPN concentrations. The infection rate test showed a significant difference in wound variation and larval size of H. illucens although the results were not good enough when compared to the level of infection of T. molitor larvae. Keywords: Hermetia illucens, Tenebrio molitor, Steinernema spp., Entomopathogenic nematodes, In vivo

A case of frozen behaviour: A flat wasp female with a beetle larva in its grasp in 100-million-year-old amber

Parasitism, a malignant form of symbiosis, wherein one partner, the parasite, derives benefits to the detriment of another, the host, is a widespread phenomenon. Parasitism sensu lato is understood here to include many phenomena, like parasitoidism, kleptoparasitism, phoresy and obligate parasitism. Insecta has many in-groups that have evolved a parasitic life-style; one of the largest in-groups of these is probably the group of Hymenoptera. Bethylidae, the group of flat wasps, is a smaller in-group of Aculeata, the group of hymenopterans with venom stings; representatives of Bethylidae are parasitic. They are more specifically larval ectoparasitoids, meaning that their immature stages are externally developing parasites that kill their host organism at pupation (end of interaction). They mostly parasitise immature representatives of Coleoptera and Lepidoptera. Female flat wasps search for a host for their progeny, paralyse it with their venom sting and then oviposit onto it.Herein we describe one of the oldest findings of parasitic interactions of parasitoid wasps with their progenies’ hosts, specifically a flat wasp female grasping and (potentially) stinging a beetle immature in Cretaceous Kachin (Myanmar) amber (ca. 100 million years old). This finding indicates that this type of parasitic interaction existed since the Cretaceous, temporally close to the earliest findings of representatives of Bethylidae.

Cytokinins Induce Prehaustoria Coordinately with Quinone Signals in the Parasitic Plant Striga hermonthica.

Orobanchaceae parasitic plants are major threats to global food security, causing severe agricultural damage worldwide. Parasitic plants derive water and nutrients from their host plants through multicellular organs called haustoria. The formation of a prehaustorium, a primitive haustorial structure, is provoked by host-derived haustorium-inducing factors (HIFs). Quinones, including 2,6-dimethoxy-p-benzoquinone (DMBQ), are of the most potent HIFs for various species in Orobanchaceae, but except non-photosynthetic holoparasites, Phelipanche and Orobanche spp. Instead, cytokinin (CK) phytohormones were reported to induce prehaustoria in Phelipanche ramosa. However, little is known about whether CKs act as HIFs in the other parasitic species to date. Moreover, the signaling pathways for quinones and CKs in prehaustorium induction are not well understood. This study shows that CKs act as HIFs in the obligate parasite Striga hermonthica but not in the facultative parasite Phtheirospermum japonicum. Using chemical inhibitors and marker gene expression analysis, we demonstrate that CKs activate prehaustorium formation through a CK-specific signaling pathway that overlaps with the quinone HIF pathway at downstream in S. hermonthica. Moreover, host root exudates activated S. hermonthica CK biosynthesis and signaling genes, and DMBQ and CK inhibitors perturbed the prehaustorium-inducing activity of exudates, indicating that host root exudates include CKs. Our study reveals the importance of CKs for prehaustorium formation in obligate parasitic plants.

Zoonotic Enterocytozoon bieneusi genotypes in free-ranging and farmed wild ungulates in Spain.

Microsporidia comprises a diverse group of obligate, intracellular, and spore-forming parasites that infect a wide range of animals. Among them, Enterocytozoon bieneusi is the most frequently reported species in humans and other mammals and birds. Data on the epidemiology of E. bieneusi in wildlife are limited. Hence, E. bieneusi was investigated in eight wild ungulate species present in Spain (genera Ammotragus, Capra, Capreolus, Cervus, Dama, Ovis, Rupicapra, and Sus) by molecular methods. Faecal samples were collected from free-ranging (n=1058) and farmed (n=324) wild ungulates from five Spanish bioregions. The parasite was detected only in red deer (10.4%, 68/653) and wild boar (0.8%, 3/359). Enterocytozoon bieneusi infections were more common in farmed (19.4%, 63/324) than in wild (1.5%, 5/329) red deer. A total of 11 genotypes were identified in red deer, eight known (BEB6, BEB17, EbCar2, HLJD-V, MWC_d1, S5, Type IV, and Wildboar3) and three novel (DeerSpEb1, DeerSpEb2, and DeerSpEb3) genotypes. Mixed genotype infections were detected in 15.9% of farmed red deer. Two genotypes were identified in wild boar, a known (Wildboar3) and a novel (WildboarSpEb1) genotypes. All genotypes identified belonged to E. bieneusi zoonotic Groups 1 and 2. This study provides the most comprehensive epidemiological study of E. bieneusi in Spanish ungulates to date, representing the first evidence of the parasite in wild red deer populations worldwide. Spanish wild boars and red deer are reservoir of zoonotic genotypes of E. bieneusi and might play an underestimated role in the transmission of this microsporidian species to humans and other animals.

Empirical evidence of coevolution between the channel-billed cuckoo and its host, the pied currawong

Abstract Avian obligate brood parasites and their hosts exhibit coevolution, where parasites respond to the evolution of host defences with counter-adaptations, such as egg mimicry, which can then lead to the evolution of more efficient host defences. Using objective measurements and avian visual modelling, we quantified the degree of similarity between the eggs of the channel-billed cuckoo (Scythrops novaehollandiae) and the eggs of three host species from the hosts’ visual perspective. We found no evidence that this cuckoo species has host-specific egg types, but it does appear to mimic one of its primary hosts, the pied currawong (Strepera graculina), in both colour and pattern. Currawongs showed significantly higher interclutch variation in colour and luminance than the other two hosts and had significantly lower intraclutch variation in pattern than interclutch variation. High interclutch and low intraclutch variation in a host could make it more difficult for a cuckoo to match closely any particular host clutch, potentially allowing a host to detect a parasitic egg more easily. This is the first empirical study using objective measurements to quantify the degree of egg mimicry in the channel-billed cuckoo and the results suggest a potential host defence to egg mimicry that merits further investigation.

Did extreme nest predation favor the evolution of obligate brood parasitism in a duck?

Obligate brood parasites depend entirely on other species to raise their offspring. Most avian obligate brood parasites have altricial offspring that require enormous amounts of posthatching parental care, and the large fecundity boost that comes with complete emancipation from parental care likely played a role in the independent evolution of obligate parasitism in several altricial lineages. The evolution of obligate parasitism in the black‐headed duck, however, is puzzling because its self‐feeding precocial offspring should not constrain parental fecundity of a potential brood parasite in the way that altricial offspring do. We used an experimental nest predation study to test the idea that high nest predation rates played a role in the evolution of brood parasitism in this enigmatic duck. Experimental duck eggs in untended nests suffered massive rapid predation, while eggs in tended nests of the three main hosts, all aggressive nest defenders, had very high success, illustrating the benefits of parasitizing these ‘bodyguard’ hosts.

Fibrillarin RNA methylase is an interacting protein of Cryptosporidium parvum calmodulin-like protein (CpCML).

Cryptosporidium parvum is an obligate protozoan parasite invading epithelial cells of small intestine of human and animals, and causing diarrheal disease. In apicomplexan parasites, calcium signaling can regulate many essential biological processes such as invasion and migration. As the main intracellular receptor for calcium ions, calmodulins control the activities of hundreds of enzymes and proteins. Calmodulin-like protein (CML) is an important member of the calmodulin family and may play a key role in C. parvum, however, the actual situation is still not clear. The present study aimed to identify the parasite interaction partner proteins of C. parvum calmodulin-like protein (CpCML). By constructing the cpcml bait plasmid, 5 potential CpCML - interacting proteins in C. parvum oocyst were screened by yeast-two-hybrid system (Y2H). Bimolecular fluorescence complementation (BiFC) and Co-immunoprecipitation (Co-IP) were performed as subsequent validations. Fibrillarin RNA methylase (FBL) was identified via this screening method as CpCML interacting protein in C. parvum. The identification of this interaction made it possible to get a further understanding of the function of CpCML and its contribution to the pathogenicity of C. parvum.

THE DEVELOPMENTAL AND BIOCHEMICAL FEATURES OF LEISHMANIA DONOVANI PROMASTIGOTE AND THEIR REPRESSION BY DATURA STRAMONIUM PLANT EXTRACT

Leishmania is an intracellular digenetic obligate parasite spread by insects and poses grave health issues throughout the world. Extensive use of antimony compounds as drugs poses high toxicity and cost and therefore, a position has been identied for herbal medicine. This study has been carried out to explore the developmental biochemical characteristics of Leishmania donovani promastigote. In addition, the mode of action of Datura stramonium (Solanaceae) plant extract on promastigote form of leishmania have been examined. Friedman's repeated measures analysis showed that 96hr of development is the junction point in promastigotes ontogeny. Post 96hr, it grows with a long stationary phase with higher enzymatic activities viz., acid phosphatase, superoxide dismutase and glutathione (oxidized and reduced). Total protein estimated, showed a linear relationship (R2 = 0.999). Phytochemical screening of extracts showed the presence of alkaloid, avonoid, xed oil and fats, saponin, tannin and phenolic compounds etc, and showed an effectual free radical scavenging in the DPPH assay with an IC50 value of extract of D. stramonium (55.63 µg/ml). A concentration of 250 µg/mL of the plant extract completely inhibited the L. donovani promastigotes in vitro while concentrations of 50 µg/mL and 100 µg/mL decreased the survival level by 25-50%. Our ndings corroborate the ethnopharmacological use of this plant for the treatment of Leishmaniasis. Also, our results are promoters as potential sources to search antileishmanial bioactive agents.

Multi-queen breeding is associated with the origin of inquiline social parasitism in ants

Social parasites exploit the brood care behavior of their hosts to raise their own offspring. Social parasites are common among eusocial Hymenoptera and exhibit a wide range of distinct life history traits in ants, bees, and wasps. In ants, obligate inquiline social parasites are workerless (or nearly-so) species that engage in lifelong interactions with their hosts, taking advantage of the existing host worker forces to reproduce and exploit host colonies’ resources. Inquiline social parasites are phylogenetically diverse with approximately 100 known species that evolved at least 40 times independently in ants. Importantly, ant inquilines tend to be closely related to their hosts, an observation referred to as ‘Emery’s Rule’. Polygyny, the presence of multiple egg-laying queens, was repeatedly suggested to be associated with the origin of inquiline social parasitism, either by providing the opportunity for reproductive cheating, thereby facilitating the origin of social parasite species, and/or by making polygynous species more vulnerable to social parasitism via the acceptance of additional egg-laying queens in their colonies. Although the association between host polygyny and the evolution of social parasitism has been repeatedly discussed in the literature, it has not been statistically tested in a phylogenetic framework across the ants. Here, we conduct a meta-analysis of ant social structure and social parasitism, testing for an association between polygyny and inquiline social parasitism with a phylogenetic correction for independent evolutionary events. We find an imperfect but significant over-representation of polygynous species among hosts of inquiline social parasites, suggesting that while polygyny is not required for the maintenance of inquiline social parasitism, it (or factors associated with it) may favor the origin of socially parasitic behavior. Our results are consistent with an intra-specific origin model for the evolution of inquiline social parasites by sympatric speciation but cannot exclude the alternative, inter-specific allopatric speciation model. The diversity of social parasite behaviors and host colony structures further supports the notion that inquiline social parasites evolved in parallel across unrelated ant genera in the formicoid clade via independent evolutionary pathways.

An Improved 1.5-Gigabase Draft Assembly of Massospora cicadina (Zoopagomycota), an Obligate Fungal Parasite of 13- and 17-Year Cicadas

ABSTRACTA 1.488-Gb draft genome sequence was assembled for the fungus Massospora cicadina, an obligate parasite of periodical cicadas. The M. cicadina genome has experienced massive expansion via transposable elements (TEs), which account for 92% of the genome.

Using Surrogate Insects in Acid Bioassays for Development of New Controls for Varroa destructor (Arachnida: Varroidae).

Resistance to traditional synthetic compounds by Varroa destructor Anderson and Trueman and shortcomings of the organic acid class of acaracides commonly used in varroa management requires continual development of new controls. V. destructor, however, are difficult to obtain for use in control bioassays because they are obligate parasites that cannot be easily reared outside of a honey bee colony. We conducted bioassays using other, more easily obtainable species to find organisms that could be used as surrogates for V. destructor when testing new potential controls. We compared the toxicities of acetic acid, lactic acid, formic acid, and oxalic acid at 0.005%, 0.05%, 0.5%, 5%, and 50% (20% oxalic acid only) concentrations based on natural volatility (nonheated) for the control of two beetle species, Oryzaephilus surinamensis L. and Alphitobius diaperinus Panzer, greater wax moth larvae, Galleria mellonella L., and V. destructor. The assay results were consistent across all species with formic acid and acetic acid showing 100% mortality of all four test species at 50% concentration. The assays also provided insight into the method of application (vaporization or contact) needed to cause mortality. Our results show that other organisms can be used in place of V. destructor for initial testing of acids and possibly other chemicals for control of the ectoparasite.

Transcriptome of Epibiont Saccharibacteria Nanosynbacter lyticus Strain TM7x During the Establishment of Symbiosis.

Saccharibacteria Nanosynbacter lyticus strain TM7x is a member of the broadly distributed candidate phylum radiation. These bacteria have ultrasmall cell sizes, have reduced genomes, and live as epibionts on the surfaces of other bacteria. The mechanisms by which they establish and maintain this relationship are not yet fully understood. The transcriptomes of the epibiont TM7x and its host bacteria Schaalia odontolytica strain XH001 were captured across the establishment of symbiosis during both the initial interaction and stable symbiosis. The results showed a dynamic interaction with large shifts in gene expression for both species between the initial encounter and stable symbiosis, notably in transporter genes. During stable symbiosis, the host XH001 showed higher gene expression for peptidoglycan biosynthesis, mannosylation, cell cycle and stress-related genes, whereas it showed lower expression of chromosomal partitioning genes. This was consistent with the elongated cell shape seen in XH001 infected with TM7x and our discovery that infection resulted in thickened cell walls. Within TM7x, increased pili, type IV effector genes, and arginine catabolism/biosynthesis gene expression during stable symbiosis implied a key role for these functions in the interaction. Consistent with its survival and persistence in the human microbiome as an obligate epibiont with reduced de novo biosynthetic capacities, TM7x also showed higher levels of energy production and peptidoglycan biosynthesis, but lower expression of stress-related genes, during stable symbiosis. These results imply that TM7x and its host bacteria keep a delicate balance in order to sustain an episymbiotic lifestyle. IMPORTANCE Nanosynbacter lyticus type strain TM7x is the first cultivated member of the Saccharibacteria and the candidate phyla radiation (CPR). It was discovered to be ultrasmall in cell size with a highly reduced genome that establishes an obligate epibiotic relationship with its host bacterium. The CPR is a large, monophyletic radiation of bacteria with reduced genomes that includes Saccharibacteria. The vast majority of the CPR have yet to be cultivated, and our insights into these unique organisms to date have been derived from only a few Saccharibacteria species. Being obligate parasites, it is unknown how these ultrasmall Saccharibacteria, which are missing many de novo biosynthetic pathways, are maintained at a high prevalence within the human microbiome as well as in the environment.

Female Cuckoo Calls Deceive Their Hosts by Evoking Nest-Leaving Behavior: Variation under Different Levels of Parasitism.

The common cuckoo (Cuculus canorus) is an obligate brood parasite that has evolved a series of strategies to trick its hosts. The female cuckoo has been hypothesized to mimic the appearance and sounds of several raptors to deceive the hosts into exhibiting anti-predator behavior. Such behavior would relax the protection of the host nest and thus allow the female cuckoo to approach the host nest unopposed. Many anti-parasite strategies have been found to vary among geographical populations due to different parasitic pressures from cuckoos. However, the effect of female cuckoo calls related to different levels of parasitic pressure has not been examined. Here, we studied the effect of female cuckoo calls on the oriental reed warbler (Acrocephalus orientalis), one of the major hosts of the common cuckoo, in two geographical populations experiencing different levels of parasite pressure. Four kinds of sounds were played back to the hosts: the calls from female common cuckoos, male common cuckoos, sparrowhawks (Accipiter nisus), and oriental turtle doves (Streptopelia orientalis). The results showed that the female cuckoo calls induced the hosts to leave their nests more frequently than the male cuckoo or dove calls in both populations, and two populations of the hosts reacted similarly to the female cuckoo calls, implying that the function of female cuckoo calls would not be affected by the difference in parasitism rate. This study indicates that female cuckoo calls function to distract the hosts' attention from protecting their nests. However, we propose that such a deception by the female cuckoo call may not be due to the mimicry of sparrowhawk calls, but rather that the rapid cadence of the call that causes a sense of anxiety in the hosts.