野村 昌史

It was recently recognized that in Japan, the common yellow butterfly, Eurema hecabe, consists of two sibling species, which have been unnamed yet and tentatively called yellow (Y) type and brown (B) type. We investigated the diversity of nuclear and mitochondrial genes in Japanese populations of Y type and B type of E. hecabe. The phylogeny based on nuclear genes agreed with the distinction between Y type and B type, which had been also supported by a wide array of biological data. However, the phylogeny based on mitochondrial genes did not reflect the distinction. PCR survey of Wolbachia revealed that B-type populations were all infected while Y-type populations contained both infected and uninfected individuals. A single genotype of Wolbachia, which was inferred to be a CI-inducing strain from their wsp gene sequence, was prevalent in these populations. Notably, the mitochondrial phylogeny was in perfect agreement with the pattern of Wolbachia infection, suggesting that the Wolbachia infection had affected the mitochondrial genetic structure of the host insects. Probably, the Wolbachia strain and the associated mitochondrial genomes have been occasionally introduced from B-type populations to Y-type populations through migration and subsequent interspecific hybridization, and CI-driven population sweep has been spreading the Wolbachia strain and the particular mitochondrial haplotypes, which originated from B-type populations, into Y-type populations. On the basis of these results together with the geological and biogeographical knowledge of the Japanese Archipelago, we proposed an evolutionary hypothesis on the invasion and spread of Wolbachia infection in B-type and Y-type of E. hecabe.

The sex pheromones of four Plusiinae species in the family Noctuidae, Ctenoplusia albostriata (CA), Macdunnoughia purissinia (MP), Syngrapha ain (SA), and Diachrysia stenochtysis (DS) were identified by GC-EAD and GC-MS analyses. These were subsequently evaluated by a series of field trials in different ecological habitats. CA females produced (Z)-5-decenyl acetate (1), (Z)-7-dodecenyl acetate (11), and (Z)-7-dodecen-l-ol (111) in a ratio of 2:100:13. While the antennae of CA males responded to all three components, neither I nor III was essential to capture males. The MP females produced 11, 111, and (Z)-5-dodecenyl acetate (IV) in a ratio or 100:80:20, and this blend captured the most MP males. Compounds II and III were also identified from SA females, and mixtures ranging from 4:1 to 2:3 were equally attractive to males. DS females only produced one active compound, (Z)-7-decenyl acetate (V), and DS is the first Plusiinae species identified as using only the omega 3-compound and none of omega 5-compounds, such as 11 and III, which are common components of Plusiinae pheromones. Using previously published chemical and biosynthetic data, together with the finding from this study, we propose a classification of the Plusiinae sex pheromones.

The green lacewing, Chrysoperla carnea (Stephens), is an important natural enemy of various crop pests, especially aphids. In the Japanese fauna. there are two types of larval forms, A and B, characterized by different head capsule markings. The Type A form is distributed throughout Japan, but the Type B form has a more limited distribution. Adults use abdominal vibration as a communication signal (courtship song) during mating. We analyzed oscillograms of these songs among several Japanese populations of C carnea. The courtship songs of types A and B are distinctly different from one another. We then performed crossing tests between the two types. Copulation between same-type pairings was much more likely than between different-type pairings. We also analyzed courtship songs of European C carnea sensu stricti, introduced to Japan as a natural enemy of crop pests. The song of these introduced green lacewings appeared to differ from either type of Japanese C carnea. The two types of C carnea are likely to be different species, and also distinct from C carnea sensu stricti of Europe.

房総低山地におけるミツバツツジとキヨスミミツバツツジの種間交雑実態を把握しようと試みた。ミツバツツジ節の自生地である千葉県君津市清和県民の森で調査を行った結果,形態と開花フェノロジーにおいて両種の中間的な特徴を持つ個体が全調査個体中の約8%確認された。これら二種はポリネーターを共有し、人工的な交配は容易な事から、このグループは自然雑種由来と考えられる。一方,それらは生育立地と種子形態,葉緑体DNAにおいてミツバツツジと同様であった。よって雑種個体群の母系親はミツバツツジと推察された。それらは,ミツバツツジを子房親とした雑種個体である事が示唆された。

ミツバツツジ節自生地復元に用いられている種苗における雑種の発生について調べた。民家由来の種子から苗木を生産育成している花木センターの苗木畑において形態調査を行ったところ,様々な雑種形態を持つ個体が全調査個体中27%確認された。また,人工受粉実験を行ったところ,ミツバツツジ節内では結実率が80%近く,交配親和性は高かった。さらに,ミツバツツジが植栽された庭において,ミツバツツジとキヨスミミツバツツジがコマルハナバチをポリネーターとして共有していることが確認できた。よって導入苗木に雑種が存在する可能性は高く,自生地以外の地より導入されたミツバツツジ節苗木が存在する庭からは,自生地復元用の種子は採取しない方が望ましいと言える。

Reproductive isolation was studied in four syntopic species of Petunia sensu Jussieu (Solanaceae) at a site in Rio Grande do Sul State, Brazil. Reciprocal artificial crossing experiments confirmed that a genetic barrier exists between Petunia (P. axillaris and P. integrifolia) and Calibrachoa (C. parviflora and C. heterophylla), and also between C. parviflora and C. heterophylla. Petunia axillaris (white, nocturnally scented flower) is genetically compatible with the syntopic and allotopic P. integrifolia (coloured, unscented flower). Reproductive isolation appears to be maintained by the two species having different pollinators: nocturnally active hawkmoths (Manduca contracta and M. diffissa subsp. petuniae) pollinate P. axillaris while a diurnally active bee (Hexantheda sp.) pollinates P. integrifolia. Flowers of P. integrifolia exhibit diurnal opening and closing movements synchronous with the activity period of the bee. Other than a probable nectar robber (a carpenter bee, Xylocopa augusti), no insect visited flowers of P. axillaris in the day. Amounts of floral nectar in P. axillaris and P. integrifolia were within the range of hawkmoth- and bee-pollinated flowers, respectively. Reproductive isolating mechanisms in the genus Petunia sensu Jussieu are discussed. © 2001 Annals of Botany Company.

The geographical distribution and habitat characteristics of 11 arboreal land snails, subgenus Luchuhadra, including four vulnerable species, was investigated on the Amami, Okinawa and Miyako Islands. Most of the species except for Satsuma omoro (due to lack of sufficient observation) occurred more abundantly on Ficus virgata in natural woodlands. However, the vulnerable species, S. hemihelvus, was found not only within the woodland, but also in a public garden woodland maintained artificially. S. hemihelvus was mainly found on the underside of leaves, while S. sororcula was on the trunk of the tree. S. sooi, S. erabuensis, S. amanoi, S. iheyaensis, and S. hemihelvus showed limited geographical distributions, with less abundance, except for S. hemihelvus, which numbered more than 200 individuals at any observation site. On the other hand, S. largillierti and S. sororcula had many populations with high abundance.

Anadevidia peponis and Macdunnoughia confusa are defoliators of plants in the family Cucurbitaceae and Compositae, respectively, in Japan. GC-MS analyses of crude pheromone gland extracts treated with or without dimethyl disulfide indicated that females of A. peponis produced six monoene acetates and two monoene alcohols and that M. confusa females produced five monoene acetates. These components include (Z)-7-dodecenyl acetate as a major common constituent and three other acetates as minor common constituents. The minor constituents are quite different in blend composition. In addition, with (Z)-7-dodecenyl acetate, an indispensable component for male attraction is (Z)-5-decenyl acetate for A. peponis and (Z)-9-tetradecenyl acetate is essential for M. confusa. Field tests with synthetic lures showed synergistic effects of some other minor components and male attraction of three additional Plusiinae species, Macdunnoughia purissima, Ctenoplusia albostriata, and Chrysodeixis eriosoma, suggesting their reproductive isolation is based in part on pheromonal communication.

An allozyme survey of 30 species of Japanese plusiine moths was made by means of polyacrylamide gel electrophoresis. Comparison of zymograms of several enzymes, and genetic identity and distance measures were calculated from allele frequencies of 4 electrophoretical loci from 3 enzymes (esterases, hexokinase and phosphoglucomutase), and then UPGMA phenograms and Wagner procedure distance phenograms of plusiine moths were made from the measures. In the phylogenetic analyses, the 30 plusiine species were divided into three groups. These three groups mainly coincided with tribes that were prescribed by previous classifications based on external morphological characters. The obtained phenograms, however, appear to suggest that Ctenoplusia albostriata and other members of the genus Ctenoplusia have separate identities, although they are related species based on morphological characters. The phenograms may also indicate that (1) there is a close association of the genus Anadevidia and the "Autographa group," whereas their morphological characters did not support this association, and. (2) the genera Diachrysia and Plusia should be separated from other genera belonging to the tribe Plusiini, although external morphological characters indicate that these two genera belong to the tribe Plusiini.

Thysanoplusia intermixta, which inhabits the temperate zone in Japan, is a defoliator of plants in the family Compositae, Apiaceae, and others. By CC-MS analysis, (Z)-7-dodecenyl acetate, (Z)-7-dodecen-1-ol, (5E, 7Z)-5,7-dodecadienyl acetate and (5E,7Z)-5,7-dodecadien-1-ol were identified from a pheromone gland extract of the virgin females in a ratio of 18:3:100: 13. A lure baited only with the major diene acetate could attract male moths of T. intermixta in the field. Other minor components had a synergistic effect on the attraction of the diene acetate. The same four components were included in a very different ratio of 100:6:11:1 in the gland extract of Thysanoplusia orichalcea, a closely related subtropical species. The monoene and diene acetates are essential for field attraction, and a 100:11 mixture is an optimum lure for T. orichalcea males. However, this mixture, including the diene acetate as a minor component, captured very few T intermixta males, suggesting the possibility that these two Thysanoplusia species are reproductively isolated from each other by pheromonal communication.