Ectoparasitic fungi of Myrmica ants alter the success of parasitic butterflies

Exploitation of organisms by multiple parasite species is common in nature, but interactions among parasites have rarely been studied. Myrmica ants are rich in parasites. Among others, the ectoparasitic Rickia wasmannii fungus and the parasitic caterpillars of myrmecophilous Phengaris butterflies often infect the same Myrmica colonies. In this study, we examined the effects of R. wasmannii on the adoption, long-term development, and survival of P. alcon. In laboratory conditions, caterpillars introduced into nests of Myrmica scabrinodis uninfected with R. wasmannii survived significantly longer compared to caterpillars introduced into infected nests. In the field, joint infection was less common than expected if both parasites exploited M. scabrinodis colonies independently. Pre-pupal caterpillars of P. alcon were somewhat larger in nests infected with R. wasmannii than those found in uninfected nests. Based on these results it seems that R. wasmannii infection of M. scabrinodis affects the survival and development of P. alcon caterpillars, suggesting competition between these two ant parasites.

Ectoparasitic fungi Rickia wasmannii infection is associated with smaller body size in Myrmica ants

Parasitism-generated negative effects on ant societies are multifaceted, implying individual and colony-level responses. Though laboratory based evidence shows that the sublethal fungus Rickia wasmannii is responsible for physiological and behavioral responses that may negatively affect individual workers’ resilience and life expectancy in Myrmica ant workers, colony-level stress response to this parasite is largely unknown. Here, we focus on understanding of a long-term, colony-level effect of Rickia infection on Myrmica scabrinodis ant populations by tracking trait size-based changes. We collected worker specimens from infected and uninfected colonies from the same population in order to: (1) compare body size in response to parasitism, (2) assess the extent to which possible changes in size are associated with the severity of infection, and (3) investigate shifts in body size in response to infection over time by testing correlation of workers’ ages and sizes. We found that workers from infected colonies were significantly smaller than their healthy congeners, but neither infection level nor the age of the workers showed significant correlation with the size in infected colonies. Decreasing body sizes in infected colonies can be ascribed to workers’ mediated effect toward developing larvae, which are unable to attain the average body size before they pupate.

Entomopathogenic Rickia wasmannii fungal infection generated colony-level stress effects cause size decline in Myrmica ants

Parasitism-generated negative effects on ant societies are multifaceted, implying individual and colony-level responses. Though laboratory based evidence shows that the sublethal fungus Rickia wasmannii is responsible for physiological and behavioral responses that may negatively affect individual workers’ resilience and life expectancy in Myrmica ant workers, colony-level stress response to this parasite is largely unknown. Here, we focus on understanding of a long-term, colony-level effect of Rickia infection on Myrmica scabrinodis ant populations by tracking trait size-based changes. We collected worker specimens from infected and uninfected colonies from the same population in order to: (i) compare body size in response to parasitism, (ii) assess the extent to which possible changes in size are associated with the severity of infection, and (iii) investigate shifts in body size in response to infection over time by testing correlation of workers’ ages and sizes. We found that workers from infected colonies were significantly smaller than their healthy congeners, but neither infection level nor the age of the workers showed significant correlation with the size in infected colonies. Decreasing body sizes in infected colonies can be ascribed to workers’ mediated stress toward developing larvae, which are unable to attain the average body size before they pupate.

A Unique Population in a Unique Area: The Alcon Blue Butterfly and Its Specific Parasitoid in the Białowieża Forest

Caterpillars of the Alcon blue butterfly Phengaris alcon are initially endophytic and feed inside the flowerheads of Gentiana plants, but complete their development as social parasites in the nests of Myrmica ants, where they are fed by workers. Its specific and complicated ecological requirements make P. alcon a very local, threatened species, sensitive to environmental changes. We investigated an isolated and previously unknown population in an area of high nature value—the Białowieża Forest (NE Poland). Using the mark–release–recapture method we estimated the seasonal number of adults at 1460 individuals, and their density (850/ha) was the highest among all populations using G. pneumonanthe studied so far. The site is also unique due to the presence of the specific parasitoid Ichneumon cf. eumerus, and parasitoids are considered the ultimate indicators of the biodiversity of Phengaris systems. Since 75.5% of P. alcon pupae were infested we could estimate the seasonal population of adult wasps at about 4500 individuals. The high abundance of both P. alcon and its parasitoid may be explained by favorable habitat characteristics, i.e., the strong presence of host plants and the high density of nests of Myrmica scabrinodis, which is the only local host ant of the butterfly.

New Data on Landscape Distribution of Ants of the Genus Myrmica Latr. (Hymenoptera, Formicidae) in the Baikal Region

Ants of the genus Myrmica Latr. are one of the abundant insects in many ecosystems of the Baikal region. Information on their landscape distribution is of great theoretical and practical value because Myrmica ants have important functions in the terrestrial ecosystems. The ants had been collected in the Irkutsk Region and the Republic of Buryatia from 2002 to 2011. The method of route survey with a strip width of 2 m was used. Garmin GPS 12 was used to register the geographical coordinates of the locations of the ants' nests. The collected ant specimens were fixed and stored in 1.5 ml Eppendorf microtubes filled with 95% ethanol. In total 151 nest samples were investigated. All material used in this study is stored in the entomological collection of the Core Facilities Center “Bioresource Center” at the Siberian Institute of Plant Physiology and Biochemistry SB RAS (Irkutsk, Russia). The analysis was carried out by means of GIS technology. The published map "Landscapes of the south of East Siberia" was the basis for this analysis. The V.B. Sochava’s methodical developments in the field of landscape studies were used. The main mapping units were geomes. Determination of the landscape distribution of ants was conducted by SQL-queries using a vector landscape layer and a point vector layer of the locations of the nests of ants. 14 species were identified during data processing. It has been found that the nests of ants were located within 15 geomes. M. angulinodis and M. ruginodis are the most common ants of the genus Myrmica in the Baikal region. The most of M. angulinodis nests (32.5%) were recorded in mountain taiga larch forests of limited development and the most of M. ruginodis nests (48.6%) are in the foothill subtaiga pine forests. The largest species number was recorded in the foothill subtaiga pine forests (six species) and the mountain west-transbaikalia geosystems of daurian type (five species). A more detailed picture of the landscape distribution of Myrmica ants was obtained in comparison with previous works. The obtained data on the landscape distribution of ants were in good agreement with field and literary data.

An Ant-Plant Mesocosm Experiment Reveals Dispersal Patterns of Myrmecochorous Plants

For Central European herbs, ants are one common dispersal vector acting at relatively small spatial scales. Though extensively studied concerning the different benefits to plants, specific dispersal patterns mediated by ants have been reportedly very sparsely and without any validation. Thus, we studied the seed dispersal pattern of a set of myrmecochorous plant species in a novel mesocosm experiment. We examined the seed dispersal distances of four forest herbs (Hollow Root–Corydalis cava (L.) Schweigg. & Körte, Alpine Squill–Scilla bifolia L., and Common Dog-violet–Viola riviniana Rchb. and the annual Ivy-leaved Speedwell–Veronica hederifolia L.) by the red ant Myrmica ruginodis Nylander in 8.25 m² large plots under natural conditions with and without ants. In the presence of Myrmica ants, the bulb geophytes C. cava and S. bifolia showed a significantly higher fraction of dispersed seedlings and a maximum dispersal distance of 322 cm. Estimated by nearest neighbor analyses, distances between single C. cava seedlings were significantly higher in ant plots than in exclosures without ants. The annual species Veronica hederifolia showed a few dispersed seedlings in ant plots only, while the diplochorous hemicryptophyte Viola riviniana germinated in a widely scattered manner with distances up to 241 cm due to ballochorous dispersal in both ant and exclosure plots, but with a maximum of 324 cm only by means of ants. Our results indicate the escape from the mother plant and dispersal for distance as an important benefit for myrmecochorous species, potentially accompanied by benefits through reduced competition.

Evolution and Diversity of Inherited Spiroplasma Symbionts in Myrmica Ants

ABSTRACT Microbial partners play important roles in the biology and ecology of animals. In insects, maternally transmitted symbionts are especially common and can have host effects ranging from reproductive manipulation to nutrient provisioning and defense against natural enemies. In this study, we report a genus-wide association of Myrmica ants with the inherited bacterial symbiont Spiroplasma . We screen Myrmica ants collected from the wild, including the invasive European fire ant, Myrmica rubra , and find an extraordinarily high prevalence of this symbiont—8 of 9 species, 42 of 43 colonies, and 250 of 276 individual workers harbored Spiroplasma —only one host species was uninfected. In our screens, each host species carried a distinct Spiroplasma strain, and none were infected with more than one strain. All symbionts belong to the citri clade, allied most closely with pathogenic strains of Spiroplasma infecting corn crops and honeybees, and there is strong evidence of host-symbiont persistence across evolutionary time scales. Genome sequencing of two Spiroplasma symbionts revealed candidate genes that may play a part in the symbiosis, a nutrient transporter absent from other Spiroplasma strains, and a ribosome-inactivating protein previously implicated in parasite defense. These results together suggest long-term, likely mutualistic, relationships atypical of Spiroplasma -insect associations with potential significance for broad ecological interactions with Myrmica . IMPORTANCE Animal-associated microbial symbionts can dramatically affect the biology of their hosts. The identification and characterization of these intimate partnerships remain an essential component of describing and predicting species interactions, especially for invasive host species. Ants perform crucial ecological functions as ecosystem engineers, scavengers, and predators, and ants in the genus Myrmica can be aggressive resource competitors and reach high densities in their native and invaded habitats. In this study, a novel symbiosis is identified between Myrmica ants and the facultative bacterial symbiont Spiroplasma . Broad host distribution, high frequencies of infection, and host-symbiont codivergence over evolutionary time scales, an uncommon feature of Spiroplasma associations, suggest an important likely mutualistic interaction. Genome sequencing identified highly divergent gene candidates that may contribute to Spiroplasma 's role as a possible defensive or nutritional partner in Myrmica .

Two new species of Batrisodes Reitter (Coleoptera: Staphylinidae: Pselaphinae) from China

Two new species, Batrisodes linyejiei Jiang and Yin, new species and Batrisodes petalosus Jiang and Yin, new species, are described from China. The former species is associated with Formica ants and the latter with Myrmica ants. A key to all 11 Batrisodes species known to occur in China is provided.