Jun-ichi Kojima

Novel Clade of Rickettsia spp. from Leeches

ABSTRACT Intracellular rickettsia-like structures were found in the tissues of a glossiphoniid leech, Torix tagoi, by transmission electron microscopy. Diagnostic PCR analysis using specific primers suggested that of the nine glossiphoniid species examined, two species, T. tagoi and Hemicrepsis marginata, harbored bacteria of the genus Rickettsia. A 1.5-kb eubacterial 16S rRNA gene segment obtained from each of these species was amplified by PCR, cloned, and sequenced. Phylogenetic analysis of the 16S rRNA gene demonstrated that the Rickettsia species found in the leeches constituted a novel clade that is distinct from the clade of arthropod-associated Rickettsia species. In natural populations, 97.7% (43 of 44) of T. tagoi leeches and 100% (9 of 9) of H. marginata leeches carried Rickettsia, suggesting that infection with Rickettsia is prevalent in these leeches. This is the first report of Rickettsia found in annelids.

Intra-colony, inter-colony and seasonal variations of cuticular hydrocarbon profiles in Formica japonica (Hymenoptera, Formicidae)

Summary. The cuticular hydrocarbons of a formicine ant, Formica japonica, were characterized by gas chromatography and gas chromatography-mass spectrometry. Variations in cuticular hydrocarbon profiles of two natural colonies of F. japonica collected in central Japan were compared in spring, summer and autumn through one active season. Principal component analyses (PCA) showed that variations of cuticular hydrocarbon profiles occurred at intra-colony, inter-colony and seasonal levels. The order of importance of variation levels was found to be seasonal variation > inter-colony variation > intra-colony variation. PCA analyses also revealed that two F. japonica colonies had a similar trend in the seasonal variation of cuticular hydrocarbon profiles. The implications of dynamic cuticular hydrocarbon profiles in ants are discussed.

Parthenogenetic reproduction in neotenics of the subterranean termite Reticulitermes speratus (Isoptera: Rhinotermitidae)

Experiments with artificial colonies consisting of only female workers and those of female nymphs and workers of a subterranean termite, Reticulitermes speratus, showed that neotenics (ergatoids and nymphoids) can reproduce parthenogenetically. The larvae hatched from the eggs produced partheno‐genetically by the neotenics were all female and did not have any aberrant external morphology. They had 42 chromosomes and were diploid. The analysis of genotypes at microsatellite loci revealed that the eggs produced parthenogenetically had only one of the two alleles that the mother neotenics possessed, indicating that the eggs were produced by automixis.

Polybia, Paraphyly, and Polistine Phylogeny

Abstract A cladistic analysis of the subgenera of the paper wasp genus Polybia Lepeletier (Hymenoptera: Vespidae; Polistinae), and the other genera that construct phragmocyttarus nests, is presented. The results clearly indicate paraphyly of Polybia in terms of the genus Synoecoides Ducke. To remove the paraphyly, Synoecoides is reduced in rank, to a subgenus of Polybia, new synonymy.

Diploid males and sex determination in a paper wasp, Polistes chinensis antennalis (Hymenoptera, Vespidae)

Summary: Beyond helping the queens reproductive function, the worker caste of Polistes wasps is expected to have an alternative reproductive strategy; to become a replacement queen, following copulation with early males that emerge along with the first brood workers. We analyzed genotypes and chromosome numbers of the early males in a natural population of P. chinensis antennalis. The frequency of early-male-producing colonies within a population was 5.2% (4/77) in 1993 through 1995. The numerical sex ratios in the 4 colonies for the 3 years and another early male-producing colony in 1999 were 1:1. For one early-male producing colony in 1995, we genotyped 31 females and all 128 males. All 31 genotyped females out of 67 emerged females showed heterozygosity and 69 out of 128 genotyped males were heterozygous; the remaining 59 males were homozygous or hemizygous. The ratio between the number of females and diploid males in this colony was 67:69, which is almost identical with one-to-one ratio. The cytological analysis of male chromosome for one early-male producing colony in 1999 revealed that the early males laid by a queen had 46 chromosomes, while worker laid males had 23. Our results revealed that the early males in this species are diploid males and eventually sterile. Secondly, the single locus complementary sex determination model is most plausible to explain the diploid male production in this species.

Cuticular hydrocarbons in workers of the slave-making ant Polyergus samurai and its slave, Formica japonica (Hymenoptera: Formicidae)

Comparisons of cuticular hydrocarbons between workers of the dulotic ant Polyergus samurai and its slave, Formica japonica, were carried out. Gas chromatography–mass spectrometry showed that the slave‐maker and its slave shared the major cuticular hydrocarbon compounds, but possessed several minor products unique to each species. No difference in hydrocarbon composition was detected between enslaved and free‐living F. japonica workers, suggesting that association with P. samurai has no qualitative effect on hydrocarbon composition in these ants. Principal component analyses of the cuticular hydrocarbon profiles (CHP) revealed that (i) CHP was species specific in a given mixed colony; and (ii) among mixed colonies, P. samurai workers had species‐colony specific CHP, while the same feature was not always found in enslaved and free‐living F. japonica workers. Therefore, a ‘uniform colony odor’ in terms of CHP is not achieved in naturally mixed colonies of P. samurai nor those of its slaves, F. japonica.

Genetical and morphological colony structure of the Australian swarm-founding polistine wasp, Ropalidia romandi (Hymenoptera, Vespidae).

Summary: Genetical colony structure of an Australian swarm-founding polistine wasp, Ropalidia romandi, was analyzed. Inseminated females with developed ovaries (egg-layers) tended to have larger body size (measured at the median cell of the forewing) than non egg-layers. Two way ANOVA revealed that the difference in body size was related to both the caste and the colony of origin. The genetic relatedness among egg-layers as detected by electrophoresis was 0.336 ± 0.114 (mean ± se), and that among non egg-layers was 0.161 ± 0.035. The inbreeding coefficient among non egg-layers was found to be significantly greater than zero, but this did not seem to play a major part in the increase in relatedness among progeny. The number of effective queens (mothers of new queens) was estimated to be 2.84 per colony. This number is much smaller than the actual counts of queens. This discrepancy is discussed in terms of possibilities that wasps practice cyclical oligogyny, matriline localization within a colony, and genotypic behavioral specialization.

Apomorphy-Based Definition Also Pinpoints a Node, and PhyloCode Names Prevent Effective Communication

Acceptable methods of defining taxon (or clade) names in the draft PhyloCode, or so-called phylogenetic nomenclature, are “node based,” “stem based,” and “apomorphy based.” All of them define a clade name by pinpointing a node; whereas node-based and stem-based definitions require two or more taxon “specifiers” to define names, an apomorphy-based definition requires two specifiers of different types; namely, a single-taxon specifier and a character specifier. The taxon specifier in an apomorphy-based definition is completely different from the “type” in the Linnaean system. Taxon (or clade) names in the PhyloCode are characterized in two entirely different manners: One is a name that does not change, either in its orthography or in the contents of the taxon referred to by it (or its meaning) over time; the other is a name that is just like a pure mark and thus has no meaning. Communication through such PhyloCode names is very ineffective or impossible.

Growth and survivorship of preemergence colonies of Ropalidia fasciata in relation to foundress group size in the subtropics (Hymenoptera : Vespidae)

SummaryGrowth of preemergence colonies and colony survivorship of an independent founding polistine wasp,Ropalidia fasciata, in the subtropics are described. When a nest is founded by an association of females, foundresses originate from the same natal nest. Growth rate of preemergence nests in cells/day (nearly equivalent to oviposition rate) is a function of both stage of preemergence colony development and number of foundresses. Rate of nest development (cells/day) is positively correlated with the number of attending foundresses. Nest size increases more rapidly in the egg stage than in the larval stage. The first worker(s) develops faster than does later brood. This may be attributed to the fact that foundresses provide the first larva(e) with intensive care. Factors causing the failure of preemergence colonies are extrinsic: (1) the loss of the foundresses in single-foundress colonies, and (2) predation by large predators on colonies with multiple foundresses.ZusammenfassungFür die subtropische Polistine WespeRopalidia fasciata, die neue Nester unabhängig gründet, werden das Wachstum neugegründeter Kolonien sowie deren Überlebensrate beschrieben. Wird ein Nest von mehreren Weibchen gemeinsam gegründet, so stammen diese Weibchen vom selben Elternnest. Die Wachstumsrate neugegründeter Nester in Zellen/Tag (entspricht etwa der Eilegerate) hängt sowohl von dem Entwicklungsstadium der Kolonie wie auch von der Anzahl der Weibchen ab. Die Nestentwicklung (Zellen/Tag) ist positiv mit der Anzahl der Weibchen korreliert. Die Nestgröße nimmt im ersten Stadium, in dem nur Eier vorhanden sind, schneller zu als in dem folgenden Stadium, in dem auch Larven vorhanden sind. Die ersten Arbeiterinnen haben eine kürzere Entwicklungszeit als die später aufgezogenen Arbeiterinnen. Dieser Unterschied dürfte mit der intensiven Brutpflege der Weibchen für die ersten Larven zusammenhängen. Neugegründete Kolonien gehen vor allem durch äußere Ursachen zugrunde: (1) Durch den Verlust der Nestgründerinnen in solchen Kolonien, die von einem Weibchen allein gegründet wurden; (2) durch große Räuber, die auch Kolonien mit mehreren Nestgründerinnen vernichten.

Colony productivity of the paper wasp Polistes snelleni: Comparison between cool-temperate and warm-temperate populations

Summary: Production characteristics, including colony productivity, labor efficiency and sex ratio, in the paper wasp Polistes snelleni were compared between cool-temperate (Hokkaido, northern Japan) and warm-temperate (Nagano and Kanto, central Japan) populations, based on examination of old nests. The production schedule of P. snelleni was protandrous. Numbers of workers, males and gynes produced per colony were all larger in the warm-temperate populations. The numbers of reproductives (males plus gynes) per worker were generally greater in cool-temperate than in warm-temperate colonies, although some extraordinarily large warm-temperate nests had very high gynes/worker ratios. The number of males was not significantly correlated with the number of workers in either cool-temperate or warm-temperate populations. Differences in the production characteristics between populations are discussed in terms of climatic conditions, a major factor in differences in the length of the nesting period. The production of reproductives in very large warm-temperate nests is discussed in relation to worker reproduction.