Review of the New World species of Microplitis Foerster (Hymenoptera, Braconidae, Microgastrinae) attacking Sphingidae (Lepidoptera, Bombycoidea)

Microplitis Foerster is a highly diverse and cosmopolitan genus within Microgastrinae (Hymenoptera, Ichneumonoidea, Braconidae). Microplitis ceratomiae Riley, a widely distributed North American species, exclusively attacks sphingid caterpillars. In this paper, M. ceratomiae is reported parasitizing a caterpillar of Sphinx poecila Stephens (Sphingidae) which was collected feeding on Spiraea alba Du Roi (Rosaceae), a species of white meadowsweet native to the wet soils of the Allegheny Mountains and other portions of eastern North America. Here, we report and describe this new host-parasitoid-food plant association in southern New Hampshire, and include a distribution map for the species. Biological, ecological and phylogenetic analyses, and an identification key for the nine known species of Microplitis that attack sphingids in the New World are provided.

Substrate-borne vibrations used during acoustic communication and the existence of courtship songs in some species of the genus Anaxipha (Saussure) (Orthoptera: Trigonidiidae: Trigonidiinae)

Anaxipha (Saussure, 1874) are small, swordtail crickets found in much of eastern North America. Many species within the genus Anaxipha were only recently described and their calling songs characterized. However, little is known about their courtship songs or use of substrate-borne communication (drumming). This study is the first documentation of the existence of courtship songs and substrate-borne vibrational communication in the genus. Courtship songs and substrate-borne vibrational communication were first detected in the following species: Anaxipha exigua (Say, 1825), A. tinnulacita Walker & Funk, 2014, A. tinnulenta Walker & Funk, 2014, and A. thomasi Walker & Funk, 2014. When in the presence of a conspecific female, males of all four species perform courtship songs that are distinctly different in pattern of echeme delivery and syllable details compared to their respective calling songs. Additionally, males of all four species exhibited drumming behavior during courtship singing and variably during calling songs. Examination of video recordings of males drumming during courtship singing showed that they are apparently using the sclerotized portion of their mandibles to impact the substrate on which they are perched to create vibrations. Courtship song and drumming bout characteristics were statistically different among the four species studied here, although A. tinnulacita and A. tinnulenta were similar in some measurements. Drumming during calling songs was common only in A. tinnulacita, where drumming occurs predominately during the first forty percent and last twenty percent of the long echemes of calling songs. Additional study is needed to further explore the use of substrate-borne vibrational communication in this genus.

Limited Range-Filling Among Endemic Forest Herbs of Eastern North America and Its Implications for Conservation With Climate Change

Biodiversity hotspots host a high diversity of narrowly distributed endemic species, which are increasingly threatened by climate change. In eastern North America, the highest concentration of plant diversity and endemism occurs in the Southern Appalachian Mountains (SAM). It has been hypothesized that this region served as a refugium during Pleistocene glacial cycles and that postglacial migration northward was dispersal limited. We tested this hypothesis using species distribution models for eight forest herb species. We also quantified the extent to which the geography of suitable habitat shifted away from the current range with climate change. We developed species distribution models for four forest herb species endemic to the SAM and four that co-occur in the same SAM habitats but have broader ranges. For widespread species, we built models using (1) all occurrences and (2) only those that overlap the SAM hotspot in order to evaluate the extent of Hutchinsonian shortfalls and the potential for models to predict suitable habitat beyond the SAM. We evaluated the extent to which predicted climatically suitable areas are projected to shift away from their current ranges under future climate change. We detected unoccupied but suitable habitat in regions up to 1,100 km north of the endemic species’ ranges. Endemic ranges are disjunct from suitable northern areas due to a ∼100–150 km gap of unsuitable habitat. Under future climate change, models predicted severe reductions in suitable habitat within current endemic ranges. For non-endemic species, we found similar overall patterns and gap of unsuitability in the same geographic location. Our results suggest a history of dispersal limitation following the last glacial maximum along with an environmental barrier to northward migration. Conservation of endemic species would likely require intervention and assisted migration to suitable habitat in northern New England and Canada.

Ecology of Eastern Equine Encephalitis Virus in the Southeastern United States: Incriminating Vector and Host Species Responsible for Virus Amplification, Persistence, and Dispersal

Eastern equine encephalitis virus (EEEV; family Togaviridae, genus Alphavirus) is a mosquito-borne pathogen found in eastern North America that causes severe disease in humans and horses. The mosquito Culiseta melanura (Coquillett) (Diptera: Culicidae) is the primary enzootic vector of EEEV throughout eastern North America while several mosquito species belonging to diverse genera serve as bridge vectors. The ecology of EEEV differs between northern and southern foci, with respect to phenology of outbreaks, important vertebrate hosts, and bridge vector species. Active transmission is limited to roughly half of the year in northern foci (New York, New Hampshire, Massachusetts, Connecticut), while year-round transmission occurs in the southeastern region (particularly Florida). Multiple phylogenetic analyses indicate that EEEV strains circulating in northern foci are likely transported from southern foci by migrating birds. Bird species that overwinter or migrate through Florida, are bitten by Cs. melanura in late spring, and arrive at northern breeding grounds in May are the most likely candidates to disperse EEEV northward. Available data indicate that common yellowthroat and green heron satisfy these criteria and could serve as virus dispersers. Understanding the factors that drive the phenology of Cs. melanura reproduction in the south and the timing of avian migration from southern foci could provide insight into how confluence of these biological phenomena shapes outbreaks of EEE throughout its range. This information could be used to develop models predicting the likelihood of outbreaks in a given year, allowing vector control districts to more efficiently marshal resources necessary to protect their stakeholders.

Far from boring: a new Grenvillian perspective on Mesoproterozoic tectonics

As determining when plate tectonics began on Earth is a highly debated subject, it is crucial to understand the “boring billion” (1.8 to 0.8 billion years ago), a period of tectonic quiescence inferred from proxies, such as the average chemical composition of the mineral zircon on Earth and the isotopic composition of seawater derived from marine rocks. Yet this period saw the construction of what may have been the biggest mountain belt that ever existed, the remnants of which are found in the Grenville Orogen of eastern North-America. This contribution first exposes a compilation of multidisciplinary geological datasets and new geochemical data from igneous suites emplaced during the Grenvillian Orogeny that are incompatible with the current tectonic paradigm. We then present a completely revised model for Grenvillian tectonics. In contrast with the actual Laurentian-centred paradigm, our model involves the construction of a newly revealed continent by amalgamation of volcanic arcs far away from Laurentia (the craton forming the core of actual North-America) and their collision 60 millions year later than the currently accepted timing. This new model resolves the longstanding contradiction between tectonic proxies and geological record and invalidates the view considering the Mesoproterozoic as a tectonically quiet Era.

Cytogeography of the Solidago rugosa Mill. Complex (Asteraceae: Astereae) in Eastern North America

Chromosome numbers are reported here for the first time from 117 individuals of Solidago rugosa and S. fistulosa. Including 178 previously published reports for the two species plus S. latissimifolia, chromosome numbers have been determined from 295 individuals from 269 locations. Only diploids (2n = 18) were found throughout the range of S. fistulosa on the coastal plain in the eastern U.S.A. (44 counts). Diploids (2n = 18) were found in the northern portion of the range of S. latissimifolia, and tetraploids (2n = 36) and hexaploids (2n = 54) were found in the central and southern portions of the range (nine counts in total). Diploids (2n = 18) were found throughout the range of S. rugosa in much of eastern North America in four of the five varieties (northern var. rugosa, var. sphagnophila; southern var. aspera and var. celtidifolia). Tetraploids (2n = 36) were found in all four of these varieties and exclusively in var. cronquistiana in the southern high Appalachian Mountains. Hexaploids (2n = 54) were found in var. sphagnophila at scattered locations. One possible hexaploid in var. rugosa was found in the Allegheny Mountains. The diversity in ploidy levels was independent of the size of the range and the diversity of growing conditions among the three species of S. subsect. Venosae.

A radiocarbon chronology of Holocene climate change and sea-level rise at the Delmarva Peninsula, US Mid-Atlantic Coast

Radiocarbon dates from 176 sites along the Delmarva Peninsula record the timing of deposition and sea-level rise, and non-marine wetland deposition. The dates provide confirmation of the boundaries of the Holocene subepochs (e.g. “early-middle-late” of Walker et al.) in the mid-Atlantic of eastern North America. These data record initial sea-level rise in the early Holocene, followed by a high rate of rise at the transition to the middle Holocene at 8.2 ka, and a leveling off and decrease in the late-Holocene. The dates, coupled to local and regional climate (pollen) records and fluvial activity, allow regional subdivision of the Holocene into six depositional and climate phases. Phase A (>10 ka) is the end of periglacial activity and transition of cold/cool climate to a warmer early Holocene. Phase B (10.2–8.2 ka) records rise of sea level in the region, a transition to Pinus-dominated forest, and decreased non-marine deposition on the uplands. Phase C (8.2–5.6 ka) shows rapid rates of sea-level rise, expansion of estuaries, and a decrease in non-marine deposition with cool and dry climate. Phase D (5.6–4.2 ka) is a time of high rates of sea-level rise, expanding estuaries, and dry and cool climate; the Atlantic shoreline transgressed rapidly and there was little to no deposition on the uplands. Phase E (4.2–1.1 ka) is a time of lowering sea-level rise rates, Atlantic shorelines nearing their present position, and marine shoal deposition; widespread non-marine deposition resumed with a wetter and warmer climate. Phase F (1.1 ka-present) incorporates the Medieval Climate Anomaly and European settlement on the Delmarva Peninsula. Chronology of depositional phases and coastal changes related to sea-level rise is useful for archeological studies of human occupation in relation to climate change in eastern North America, and provides an important dataset for future regional and global sea-level reconstructions.