Extinction risk modeling predicts range-wide differences of climate change impact on Karner blue butterfly

The Karner blue butterfly (Lycaeides melissa samuelis), an endangered species in decline due to multiple factors, including habitat loss, can be further threatened by climate change. Evaluating how climate shapes the population dynamics and distribution of the Karner blue (Kbb) is necessary for developing adaptive. Demographic models generally used for insect populations are often either density-dependent or applied to population presence-absence data in a density-independent manner. In contrast, we used scale-based, mixed density-dependent and density-independent (hereafter “endo-exogenous”) models for the Kbb, based on long-term count data of abundance during flight periods, to understand how different environmental variables, including climate, affected Kbb extinction risk through the middle of the 21st century. Our endo-exogenous models showed that density-dependent and environmental variables, including climate, topography, and tree canopy coverage, were essential drivers of Kbb population dynamics. We also found that Kbb’s response to climate differed between the species’ two annual generations and across its range: higher temperature and precipitation in summer generally benefited the second-generation populations, whereas there were uncertainties of the effects on the populations in different ecoregions during the first generation. These results imply that population-specific biotic/abiotic factors need to be incorporated into plans to manage the recovery of Kbb under climate change.

Museum genomics reveals the Xerces blue butterfly ( Glaucopsyche xerces ) was a distinct species driven to extinction

The last Xerces blue butterfly was seen in the early 1940s, and its extinction is credited to human urban development. This butterfly has become a North American icon for insect conservation, but some have questioned whether it was truly a distinct species, or simply an isolated population of another living species. To address this question, we leveraged next-generation sequencing using a 93-year-old museum specimen. We applied a genome skimming strategy that aimed for the organellar genome and high-copy fractions of the nuclear genome by a shallow sequencing approach. From these data, we were able to recover over 200 million nucleotides, which assembled into several phylogenetically informative markers and the near-complete mitochondrial genome. From our phylogenetic analyses and haplotype network analysis we conclude that the Xerces blue butterfly was a distinct species driven to extinction.

Nutrient Imbalance of the Host Plant for Larvae of the Pale Grass Blue Butterfly May Mediate the Field Effect of Low-Dose Radiation Exposure in Fukushima: Dose-Dependent Changes in the Sodium Content

The pale grass blue butterfly Zizeeria maha is sensitive to low-dose radioactive pollution from the Fukushima nuclear accident in the field but is also highly tolerant to radioactive cesium (137Cs) in an artificial diet in laboratory experiments. To resolve this field-laboratory paradox, we hypothesize that the butterfly shows vulnerability in the field through biochemical changes in the larval host plant, the creeping wood sorrel Oxalis corniculata, in response to radiation stress. To test this field-effect hypothesis, we examined nutrient contents in the host plant leaves from Tohoku (mostly polluted areas including Fukushima), Niigata, and Kyushu, Japan. Leaves from Tohoku showed significantly lower sodium and lipid contents than those from Niigata. In the Tohoku samples, the sodium content (but not the lipid content) was significantly negatively correlated with the radioactivity concentration of cesium (137Cs) in leaves and with the ground radiation dose. The sodium content was also correlated with other nutrient factors. These results suggest that the sodium imbalance of the plant may be caused by radiation stress and that this nutrient imbalance may be one of the reasons that this monophagous butterfly showed high mortality and morphological abnormalities in the field shortly after the accident in Fukushima.

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.

Notes on a communal roosting of two oakblues (Lepidoptera: Lycaenidae: Arhopala) and the Common Emigrant (Pieridae: Catopsilia pomona) butterflies in Uttarakhand, India

Communal roosting on an over-nightly basis is common in butterflies for resting and for avoiding predation. Having a source of nectar and safeguarding from harsh weather conditions are also notable parameters to consider a site as a potential roosting spot. Roosting differs from a congregation in the fact that the latter happens mainly in the exposed plant part or the oozing out of fluid, which attracts the butterflies to extract chemicals from the same. The current study has been conducted on an Elephant-apple tree Dillenia indica in the New Forest campus of Dehradun, Uttarakhand, India to observe the roosting behaviour of three blue butterfly species, namely: Large Oakblue Arhopala amantes, Indian Oakblue Arhopala atrax, and pierid butterfly Common Emigrant Catopsilia pomona. The roosting observation was first noted during mid-October. The coinciding of the roosting period and the fruiting season of the tree may mark the importance of having a food source in a potent roosting site. Moreover, the site would provide a shady area with dense foliage, which would also include safeguards against predation.

Multiple colonisations and Wolbachia infections influence the fine-scale population structure of the widespread Common Blue butterfly (Polyomattus icarus) in the British Isles

Deeply divergent mitochondrial genomes can reveal hidden diversity within species, however robust assessments of diversity require corroborative divergence in the nuclear genome. Previous phylogeographic analysis of the Common Blue butterfly (Polyommatus icarus) revealed a deeply divergent mitotype in Europe. Here, we reconstruct the phylogeography of this butterfly in the British Isles using both mitochondrial and nuclear DNA. We found strong geographical structuring of three distinct CO1 mitotypes with an ancient lineage restricted to the Outer Hebrides. The short time (c. 20,000 years) available for colonization of the British Isles and an expanded CO1 phylogeography from the species’ entire range supports a hypothesis of at least 3 colonization events with sequential replacement of mtDNA. Analysis of ddRADSeq genomic markers from 184 individuals across the British Isles indicates that genetic clustering is similar but divergence weaker at the nuclear level, consistent with a biogeographic scenario of multiple colonisations. We were also able to use the ddRADSeq to infer the infection status of all individuals sequenced. Interestingly, we found evidence for high frequency (>70%) infections by two different Wolbachia strains, with strong mitotype associations, in the Northern populations of the British Isles. Wolbachia-induced cytoplasmic incompatibility may be sufficient to explain the mito-nuclear discordance observed across an admixture zone on the mainland and the complete dominance of a deeply divergent mitotype on the Outer Hebrides. Moreover, the strain (wIca1), largely restricted to the Outer Hebrides potentially causes phenotypic feminisation of genetic males, a known but rare phenotypic effect of Wolbachia in Lepidoptera. Therefore, the impact of Wolbachia on the biology and genetic diversity of this butterfly merits further attention.

Host Ant Change of a Socially Parasitic Butterfly (Phengaris alcon) through Host Nest Take-Over

The socially parasitic Alcon blue butterfly (Phengaris alcon) starts its larval stage by feeding on the seeds of gentians, after which it completes development in the nests of suitable Myrmica ant species. The host plant and host ant species can differ at the population level within a region, and local adaptation is common, but some host switches are observed. It has been suggested that one mechanism of change is through the re-adoption of caterpillars by different ant species, either through occupation of abandoned nests or take-over of established nests by competitively superior colonies. To test this question in the lab we introduced relatively strong colonies (50 workers) of alien Myrmica species to the arenas of weaker colonies (two caterpillars with six workers), and to orphaned caterpillars (two caterpillars without ants). We used caterpillars from a xerophylic population of P. alcon, and both local hosts, M. sabuleti and M. scabrinodis, testing the possibility of host switch between these two host ant species during larval development. Most of the caterpillars were successfully readopted by alien ants, and survived well. Our results suggest higher ecological plasticity in host ant usage of this butterfly than generally thought.