Masakazu Sano

Ancient and modern colonization of North America by hemlock woolly adelgid, Adelges tsugae (Hemiptera: Adelgidae), an invasive insect from East Asia

Hemlock woolly adelgid, Adelges tsugae, is an invasive pest of hemlock trees (Tsuga) in eastern North America. We used 14 microsatellites and mitochondrial COI sequences to assess its worldwide genetic structure and reconstruct its colonization history. The resulting information about its life cycle, biogeography and host specialization could help predict invasion by insect herbivores. We identified eight endemic lineages of hemlock adelgids in central China, western China, Ulleung Island (South Korea), western North America, and two each in Taiwan and Japan, with the Japanese lineages specializing on different Tsuga species. Adelgid life cycles varied at local and continental scales with different sexual, obligately asexual and facultatively asexual lineages. Adelgids in western North America exhibited very high microsatellite heterozygosity, which suggests ancient asexuality. The earliest lineages diverged in Asia during Pleistocene glacial periods, as estimated using approximate Bayesian computation. Colonization of western North America was estimated to have occurred prior to the last glacial period by adelgids directly ancestral to those in southern Japan, perhaps carried by birds. The modern invasion from southern Japan to eastern North America caused an extreme genetic bottleneck with just two closely related clones detected throughout the introduced range. Both colonization events to North America involved host shifts to unrelated hemlock species. These results suggest that genetic diversity, host specialization and host phylogeny are not predictive of adelgid invasion. Monitoring non‐native sentinel host trees and focusing on invasion pathways might be more effective methods of preventing invasion than making predictions using species traits or evolutionary history.

Morphological phylogeny of gall‐forming aphids of the tribe Eriosomatini (Aphididae: Eriosomatinae)

Aphids of the tribe Eriosomatini are typically associated with the tree genera Ulmus and Zelkova as the primary host, on which they induce several types of leaf gall. To elucidate evolutionary changes in the aphid–host associations and gall morphology, phylogenetic relationships were inferred using 36 species (28 in the ingroup) and based on 52 morphological characters. Phylogenetic analysis with equal character weighting led to hundreds of most‐parsimonious trees, and the strict consensus of these was poorly resolved. However, the successive weighting of characters yielded three most‐parsimonious trees. The strict consensus of these supported the monophyly of the Eriosomatini and the monophyly of most genera. Reconstruction of the aphid–host associations on the consensus tree indicated that the ancestral Eriosomatini were associated with Zelkova and that the association with Ulmus evolved twice independently. Ancestral reconstruction suggests that galls of the leaf‐roll type are ancestral to those of the completely and incompletely closed pouch type, and that each type of pouch galls evolved independently. It is suggested that despite early diversification of the Eriosomatini on Zelkova species, Zelkova‐associated eriosomatines had become extinct or survived as relict parthenogens on the secondary host due to the elimination of Zelkova in most regions since the late Tertiary. In contrast, two large genera in the Eriosomatini, Eriosoma and Tetraneura, are associated with the largest elm section Ulmus whose elements are distributed widely in Eurasia, including boreal regions. Therefore, the available evidence suggests that the present species diversity and distribution patterns of the eriosomatines have been largely affected by the diversification and extinction of their host plants during the late Tertiary and Quaternary.

Moduli fixing and T duality in type II brane gas models

We consider a compactification with a six-dimensional torus in the type II brane gas models. We show that the dilaton and the scale of each cycle of the internal space are fixed in the presence of NS5-branes and Kaluza-Klein monopoles as well as D-branes with the gauge fields. We can construct various models that lead to fixed moduli by using T-duality transformations.

Variation and evolution of the complex life cycle in Adelgidae (Hemiptera)

The family Adelgidae is a small group of insects within Aphidoidea (Hemiptera). Adelgids are typically holocyclic with host‐alternation between the primary and secondary hosts, but some anholocyclic species persist either on the primary or secondary host. Like Aphididae, complexities and variation of adelgid life cycles are good models for understanding the evolution of complex life cycles. In this review, we outline the complex life cycles of adelgids, and current status and recent advances in adelgid life cycle studies. We also discuss the evolution of adelgid life cycles by comparing them to closely related aphid life cycles. A switch from holocycly to anholocycly on the primary host needs evolutionary innovations in gallicola behavior and reproduction. This radical evolution can be explained by mutations in a regulatory system that controls the sequence of gene sets producing phenotypes of one morph. In contrast, anholocycly on the secondary host consists of a series of exulis generations already existing in the holocycle. Thus, it may evolve by loss of primary‐host generations through extinction of the primary host, expansion beyond the geographical range of the primary host, or loss of male‐producing sexuparae that return to the primary host. Although the holocycle and its anholocyclic derivatives have been regarded as different species, morphological, ecological and genetic differences are too subtle to separate them into different species. The holocycle and its anholocyclic derivatives should not be split into different species without clearly identifiable morphological differences.

Distribution of bisexual and unisexual species in the aphid genus Colopha Monell (Aphididae: Eriosomatinae), with the description of a new species in Japan

Aphids of the genus Colopha are represented by three bisexual and three unisexual species. The bisexual species are associated with two Ulmus species that are most closely related, being distributed disjunctively in Europe and eastern North America on the host plants. A new unisexual species of Colopha, collected from Setaria chondrachne (Poaceae) in Japan, is described under the name Colopha setaricola sp. nov. The distribution of the three unisexual species is discussed in relation to aphid‐plant associations and historical changes in the distribution of the host plants. It is suggested that these unisexual species have persisted on the secondary hosts through parthenogenetic reproduction since the extinction of the primary host plants, Ulmus species section Blepharocarpus. Therefore, the unisexual species in Colopha exemplify Mordvilkos hypothesis that unisexual species on the secondary host plants have remained as relics in the region where the primary host was once distributed but then became extinct.

Catalog of the adelgids of the world (Hemiptera, Adelgidae)

Abstract A taxonomic and nomenclatural Catalogue of the adelgids (Hemiptera: Adelgidae) is presented. Six family-group names are listed, five being synonyms of Adelgidae. Twenty-two genus-group names, of which nine are subjectively valid and in use, are presented with their type species, etymology, and grammatical gender. One hundred and six species-group names are listed, of which 70 are considered subjectively valid.

Revision of the Lema (Lema) concinnipennis Baly, 1865 species group (Coleoptera: Chrysomelidae: Criocerinae) in Japan

Three species of the Lema (Lema) concinnipennis Baly, 1865 species group are found in Japan: L. concinnipennis Baly, 1865; L. cyanella (Linnaeus, 1758); and L. cirsicola Chûjô, 1959. Their apparent similarity causes confusion in identification. We have therefore revised their classification and provide the following taxonomic treatments: the syntypes of L. concinnipennis var. ventralis Kuwayama, 1932 have been identified as L. concinnipennis and L. cyanella, and the latter is designated the lectotype; L. inaequalicollis Pic, 1924 and L. concinnipennis var. ventralis are resurrected from synonymy with L. concinnipennis and newly synonymized under L. cyanella; we have found that L. cyanella ab. nigricans Jacobs, 1926 is an unavailable name, although the name had been accepted as available for a long time; L. sapporensis Matsumura, 1911 is resurrected from synonymy with L. cyanella. In addition, we provide a key to three species, diagnosis, and redescriptions for the three species.

Integrable cosmological models from higher dimensional Einstein equations

We consider the cosmological models for the higher dimensional space-time which includes the curvatures of our space as well as the curvatures of the internal space. We find that the condition for the integrability of the cosmological equations is that the total space-time dimensions are D = 10 or D = 11 which is exactly the conditions for superstrings or M theory. We obtain analytic solutions with generic initial conditions in the four-dimensional Einstein frame and study the accelerating universe when both our space and the internal space have negative curvatures.

Nipponaphis species (Aphididae: Hormaphidinae) that form green galls on Distylium racemosum in Japan

Some species of the aphid genus Nipponaphis (Nipponaphidini) form green, globular or fig‐shaped galls on the evergreen Distylium racemosum, their primary host. Molecular phylogenetic analyses of aphid samples collected from both their galls and secondary hosts indicated the occurrence of four species in Japan: N. distychii, N. distyliicola, N. loochooensis and N. machilicola. The four species could also be discriminated from one another in morphology. The name N. litseae turned out to be a junior synonym of N. distychii. Galls formed by N. machilicola are reported for the first time in this paper. The life cycles of the four species are briefly reviewed.

Taxonomic identity of a galling adelgid (Hemiptera: Adelgidae) from three spruce species in Central Japan

Gall‐forming insects are commonly highly host‐specific, and galling species once thought to be oligo‐ or polyphagous are often found to represent a complex of host‐specific races or cryptic species. A recent DNA barcoding study documented that an unidentified species of the genus Adelges is a gall‐former associated with four spruce species (Picea bicolor, P. koyamai, P. maximowiczii, P. polita) as the primary hosts, with little genetic differentiation among insects on different host species. In this study, we investigated the morphology of this galling adelgid to determine its taxonomic identity. Morphological inspection of insects collected from three of the spruce species confirmed that this adelgid is a single galling species, and is identified as Adelges (Sacchiphantes) kitamiensis, which was previously known only from the secondary host. We described the gallicola adults of this species, as well as the first‐instar exules which are the offspring of gallicolae. Finally, we verified the taxonomic identity of this species and discuss its life cycle and host distribution.