Takao Itino

• PhD
• Professor (Full) at Shinshu University

Whether in ant–aphid mutualism the ants exert evolutionary selection pressure on aphid morphology has not yet been fully tested. Here, we tested whether the long proboscises of Stomaphis yanonis (Aphididae Lachninae) aphids confer an advantage in preventing predation by the tending ants. Specifically, we tested the hypothesis that aphids with a sho...

Many ant-aphid interactions illustrate the concept of a mutually beneficial association between two organisms: aphids provide ants with honeydew; in return, ants defend aphids from enemies. However, ants also often prey on the aphids they attend, and we do not know if the predation pressure causes any adaptations on the side of aphids. The aphid St...

In angiosperms, intraspecific variation of flowering phenology may affect reproductive isolation and, consequently, speciation. This study focused on Impatiens noli-tangere (Balsaminaceae), which is distributed over broad latitudinal and altitudinal ranges in Japan. We aimed to reveal the phenotypic mixture of two ecotypes of I. noli-tangere with d...

Some aphid species produce a soldier caste with enlarged forelegs and horns (weapons). It has been hypothesised that the evolution of morphological specialization by soldiers in social aphids is accelerated by high predation pressure, but this possibility has not been tested. Here, we investigated the relationship between local predator abundance a...

Geographic differences in floral traits may reflect geographic differences in effective pollinator assemblages. Independent local adaptation to pollinator assemblages in multiple regions would be expected to cause parallel floral trait evolution, although sufficient evidence for this is still lacking. Knowing the intraspecific evolutionary history...

To understand the reproductive ecology of a plant species with both selfing and outcrossing reproductive systems, it is important to know how selfed individuals contribute to the maintenance of a population. Further, examination of the magnitude of inbreeding depression after pollination is essential for the accurate measurement of reproductive suc...

Geographic differences in floral traits may reflect geographic differences in effective pollinator assemblages. Independent local adaptation to pollinator assemblages in multiple regions would be expected to cause parallel floral trait evolution, although sufficient evidence for this is still lacking. In this study, we investigated the relationship...

Studying the diversification patterns of species-rich phytophagous insect taxa can help us understand the factors that cause species diversification. We conducted a molecular phylogenetic analysis of the mitochondrial COI gene of larvae of gall midges (Diptera: Cecidomyiidae) using three genetically differentiated morphs of Cimicifuga simplex plant...

The behavioural patterns of flower-visiting insects are influenced by floral display size, floral reward, etc. We tested whether insects of various taxa visiting Cimicifuga simplex would change their behaviour between hermaphroditic and female flowers. Male-phase flowers of hermaphroditic ramets provide flower visitors with nectar and pollen as rew...

Background and aims – Previous researchers have demonstrated that geographic variation in pollinator community composition can generate diversity in the floral traits of animal-pollinated plants. Our study focused on the bumblebee-pollinated white dead-nettle Lamium album var. barbatum. Geographic variation in corolla length of this species is know...

We report molecular phylogeny of Elsholtzia ciliata collected in the Japanese alps. We collected DNA samples from nine E. ciliata populations in Japanese alps and constructed phylogenetic trees based on nuclear ITS region and chloroplast DNA (trnH-psbA) sequences. As a result, the relatively large-sized E. ciliata which is widely distributed in Nag...

Background: Geographic differences in floral size sometimes reflect geographic differences in pollinator size. However, we know little about whether this floral size specialization to the regional pollinator size occurred independently at many places or occurred once and then spread across the distribution range of the plant species. Results: We...

Background Geographic differences in flower size sometimes reflect geographic differences in pollinator size. However, we know little about whether this flower size specialization to the regional pollinator size occurred independently at many places or occurred once and then spread across the distribution range of the flower species. ResultsWe inve...

Cimicifuga simplex has three genetically and ecologically distinct pollination morphs with different flowering phenology, flower sex expressions, and selfing rates. A previous study showed that strong protandry in hermaphroditic flowers of C. simplex causes there to be seasonal minority sexes; for example, unisexual female ramets are advantageous i...

Examination of the efficacy of pollinators that are not morphologically matched to a flower’s shape can deepen our understanding of the main pollinators of a plant species. In central Japan, Rhododendron japonicum is visited much more frequently by bumblebees than by butterflies although its flower shape is more suited for pollination by large butt...

About 10% of aphid species show host alternation. These aphids migrate between primary and secondary host plant species in spring and autumn. Host alternation has not been observed in subfamily Lachninae, although it has been suggested on the basis of circumstantial evidence that Stomaphis japonica (Takahashi) may alternate its host between Quercus...

Geographic difference in pollinator fauna and variation in average pollinator size may lead to local adaptations of flower size that enhance pollen transfer efficiency. Here, we show that flower size (corolla tube length) of Prunella vulgaris varies both laterally and along elevational gradients, in parallel with local pollinator proboscis length....

The parasitoid wasp Protaphidius nawaii parasitizes the aphid Stomaphis japonica, which is obligatorily attended by several species of ants of genus Lasius. Subgenus Lasius or Dendrolasius ants use different defense strategies to protect the aphids that they attend (Lasius, shelter building; Dendrolasius, aggressive attack). We performed molecular...

Phytophagous insects are among the most diverse of the earth’s organisms, and their diversification patterns and the driving forces behind these have attracted considerable research interest. Host shifting to closely related plant species is thought to play an important role in phytophagous insect diversification, but the extent to which other inte...

Cimicifuga simplex (Ranunculaceae) has three genetically distinct pollination morphs. Here, we report that each of the three pollination morphs of C. simplex differs from the others with regard to sex expression and mating system: morph I consists mostly of ramets with hermaphroditic flowers and ramets with only female flowers, morph II consists of...

Most flowering plants are visited by various pollinator insects. To understand floral specialization for pollinators, the relative importance of different flower visitors to the focal plant species should be revealed. In the present study, we observed the insects that visited the orchid Platanthera hologlottis throughout the day and night using int...

Range shifts of mountain organisms toward higher elevations in response to global warming may result in spatial mismatches between plants and their pollinators. Here, we aimed to examine whether bumblebee diversity decreases in a high‐altitude zone, and whether it parallels a decrease in the altitudinal diversity of bumblebee‐visited plants. We sur...

Calystegia japonica (Convolvulaceae) and C. hederacea are perennial herbs. They are distinguished by morphological traits, such as leaf shape, but individuals which have intermediated morphological traits are often observed in the wild. These individuals are supposed to be interspecific hybrids (C. japonica × C. hederacea), because they can be cros...

Relationships between flower visitor composition and floral traits help us to understand floral evolution. Swallowtail butterflies have been assumed to be the main pollinators of Rhododendron kaempferi and R. japonicum based on their floral shapes, and R. kaempferi was reported to be pollinated by butterflies in southern Japan. In the mountains of...

Myrmecophilus crickets are well-known inquilines that live and obtain food resources in ant nests. In Japanese Myrmecophilus species various degrees of host specificity are reflected in behavioral differences among species. For example, extremely specialized species perform trophallaxis with their host ant species, whereas generalist species may st...

Japanese mountain ecosystems may face a crisis of extinction owing to habitat fragmentation and population isolation due to global warming caused by human activities. In this study, we studied highland clades of Myrmica kotokui by phylogenetic and population genetic techniques to investigate population fragmentation and isolation in mountain ecosys...

Scientific Reports 6 : Article number: srep36364 10.1038/srep36364 ; published online: 03 November 2016 ; updated: 30 March 2017 This Article contains typographical errors in Table 1. For Location E, the ?L1? value ?2 (0%)? should read ?2 (100%)?.

We undertook phylogenetic analysis of nuclear DNA to elucidate species boundaries in the symbiotic Coccus scale insects associated with mutualistic Crematogaster ants and Macaranga plants occurring in the ever-wet forests of Southeast Asia. The coccid specimens clustered into ten lineages, each corresponding to a morphospecies assignment. The linea...

Large blue butterflies, Phengaris (Maculinea), are an important focus of endangered-species conservation in Eurasia. Later-instar Phengaris caterpillars live in Myrmica ant nests and exploit the ant colony’s resources, and they are specialized to specific host-ant species. For example, local extinction of P. arion in the U. K. is thought to have be...

Studies of factors influencing spatial variation in flower size offer insights into floral evolution. We investigated altitudinal variations in five flower dimensions of two native Japanese Impatiens species (I. textori and I. noli-tangere) and their interactions with their faunal visitors. These two species have similar floral traits, including fl...

In social insects, intracaste variation suggests the existence of adaptive mechanisms such as polymorphism and polyphenism (i.e., subcastes) for maintaining the sophisticated social system. Here, we investigated intracaste variation patterns of a behavior (i.e., aggressiveness) and of morphology in the soldier caste of a eusocial aphid, Ceratovacun...

Three new species of the “horn-backed” phyline plant bug genus Pilophorus Hahn, namely, P. erinaceulus , P. maruyamai and P. parvolus , are described from Borneo, Malaysia and Sumatra, Indonesia. The following species are newly recorded within Southeast Asia: P. lambirensis from the Malay Peninsula; P. laticollaris from Sumatra; P. longirostris and...

Alpine plants are thought to be particularly vulnerable to extinction as a result of global warming because their habitat ranges are expected to shift upward until, eventually, no higher habitats remain into which they can escape. Moreover, even mountain plants distributing across wide altitudinal ranges are likely to experience range shifts, raisi...

Floral size is potentially influenced by local pollinators' body size. As pollinator fauna and size often change with elevation, correlation between elevational variation of pollinator size and floral size is expected. We investigated the variation of floral size in Prunella vulgaris L. (Laminaceae) and the variation of their pollinator fauna along...

Myrmecophilus crickets (Myrmecophilidae, Orthoptera) are typical ant guests. In Japan, about 10 species are recognized on the basis of morphological and molecular phylogenetic frameworks. We focused on two of these species, M. kinomurai and M. kubotai, and compared their host and habitat use. Previous work based on a limited sampling effort suggest...

The influence of locally different species interactions on trait evolution is a focus of recent evolutionary studies. However, few studies have demonstrated that geographically different pollinator-mediated selection influence geographic variation in floral traits, especially across a narrow geographic range. Here, we hypothesized that floral size...

Seed dispersal by ants, known as myrmecochory, is commonly observed among various plant taxa. The seeds of these plants have an elaiosome to attract ants. In Japan, myrmecochory has been well studied in several lowland plant species, but not in highland plant species that grow above the tree line. We investigated whether the seeds of Dicentra pereg...

Mutualism is one of the important species interactions in any ecosystems.To understand the significance of mutualism in species adaptation,we should first detect species associations in the mutualistic system.In this study,we focused on an ant-aphid mutualism composed of Lasius ants and Stomaphis aphids.Although this system is considered to be obli...

A previously reported mitochondrial DNA (mtDNA) phylogeny of Crematogaster (subgenus Decacrema) ants inhabiting Macaranga myrmecophytes indicated that the partners diversified synchronously and their specific association has been maintained for 20 million years. However, the mtDNA clades did not exactly match morphological species, probably owing t...

Plant–plant interspecific competition via pollinators occurs when the flowering seasons of two or more plant species overlap and the pollinator fauna is shared. Negative sexual interactions between species (reproductive interference) through improper heterospecific pollen transfer have recently been reported between native and invasive species demo...

Geographic trait variations are often caused by locally different selection regimes. As a steep environmental cline along altitude strongly influences adaptive traits, mountain ecosystems are ideal for exploring adaptive differentiation over short distances. We investigated altitudinal floral size variation of Campanula punctata var. hondoensis in...

Many studies have argued the importance of the flower-pollinator size matching for flower trait diversification. However, non-pollinator agents may also influence flower traits. In this study, we investigated the altitudinal variation of flower size (spur length, stamen length, petal blade length, corolla diameter, and sepal length) and flower visi...

The genetic composition of a hybrid zone can provide insight into the evolution of diversification in plants. We carried out morphological and amplified fragment length polymorphism analyses to investigate the genetic composition of a hybrid zone between two violets, Viola bissetii Hemsl. and Viola rossii Maxim. Our aim was to clarify the formation...

We observed flower-visitors of Scopolia japonica Maxim. (Solanaceae) at four wild populations. We found that at all the populations many adult individuals of dance flies, including two species Euthyneura aerea (Hybotidae) and Rhamphomyia (Pararhamphomyia) sp. (Empididae) visited S. japonica flowers, suggesting that S. japonica is myophilous.

A life-history in which an organism depends on ants is called myrmecophily. Among Lepidoptera (moths and butterflies), many species of lycaenid butterflies are known to show myrmecophily at the larval stage. Descriptions of myrmecophily among moth species, however, are very few and fragmentary. Here, we report the ant-associated behaviour of the ti...

Seven new species of the phyline plant bug genus Pilophorus Hahn, 1926, namely, P. aurifasciatus Nakatani & Komatsu, P. gracilipennis Nakatani & Komatsu, P. lambirensis Nakatani & Komatsu, P. laticollaris Nakatani & Komatsu, P. longirostris Nakatani & Komatsu, P. multivillus Nakatani & Komatsu, and P. unifasciatus Nakatani & Komatsu, are described...

Aphid-tending ants protect aphids from natural enemies and collect honeydew secreted by the aphids. However, ants also often prey on the aphids they attend. Aphids, therefore, like social parasites of ants, may well have evolved chemical mimicry as an anti-predation strategy. In this study, we aimed to determine whether the aphid Stomaphis yanonis...

Eusocial aphids produce sterile individuals (“soldiers”) that specialize behaviorally and morphologically to protect their colony from predators, while production of soldiers can negatively affect colony growth because of reproductive allocation and opportunity cost. Hence, a cost-saving soldier production strategy is expected to be favored. Here,...

Modern molecular phylogenetic techniques have revealed that some morphological species are divided into several genetically distinct cryptic species. To evaluate the biodiversity of a taxonomic group, it is essential to identify cryptic species. In addition, biogeographical studies that determine the distributions of cryptic species are of crucial...

Ecological and morphological differences were examined between two DNA clades within a myrmicine red ant, Myrmica kotokui. Twenty-four ant colonies were collected in the Japan Alps at elevations between about 1,000 and 2,200 m, and their DNA clades were determined from their mitochondrial cytochrome oxidase I gene sequences. Then, their several eco...

Eusocial aphids produce sterile individuals (soldiers) that specialize in colony protection. Killing predators is often considered the main function of soldiers. In this study, we tested the effect of harassment by soldiers of a eusocial aphid, Ceratovacuna japonica (Homoptera, Hormaphidinae), on predation by this species’ natural enemy, the larvae...

Myrmecophilus ant crickets (Orthoptera: Myrmecophilidae) are typical ant guests. In Japan, about 10 species are recognized on the basis of morphological and molecular phylogenetic frameworks. Some of these species have restricted host ranges and behave intimately toward their host ant species (i.e., they are host specialist). We focused on one spec...

We investigated the genetic diversification of the mountain ant, Myrmica kotokui, in the Japanese Alps by using molecular phylogenetic analyses. Myrmica kotokui is widely distributed in Japan, and in the central Japanese Alps it is found only between elevations of approximately 1000 to 2000 m. We hypothesized that genetically distinct clades of thi...

Rapoport’s elevational rule predicts that the number of species decreases with an increase in altitude. It is based on the assumption that the elevational distribution range of highland species should be wider than that of lowland species because the range of temperature tolerance of highland species which is adapted to cold temperature is wider th...

Some aphid species are attended by ants, which protect aphids against enemies, but ants sometimes prey on the aphids they are attending depending on the resource conditions. A previous study indicated that the ant Lasius niger preys less on the aphid individuals that experienced ant attendance than on those that did not. This observation leads to t...

Modern molecular phylogenetic techniques have revealed that some species comprise several genetically distinct species (cryp-tic species). The discovery of cryptic species is essential for evaluation of biodiversity, and the investigation of their distribution is crucial for biogeography and conservation biology. Myrmica kotokui is a common species...

In the Southeast Asian tropics, Arhopala ly-caenid butterflies feed on Macaranga ant-plants inhab-ited by Crematogaster (subgenus Decacrema) ants tending Coccus-scale insects. A recent phylogenetic study showed that (1) the plants and ants have been codiver-sifying for the past 20–16 million years (Myr), and that (2) the tripartite symbiosis was fo...

Saturation plot for the datasets. The transitions (ti: cross) and transversions (tv: triangle) ratio in 3rd codon positions was plotted against genetic distance. The substitution model of the third codon position for each dataset was based on the result of the model selections of KAKUSAN 3. Abbreviations: F81: Felsenstein, JC: Jukes-Cantor, K80: Ki...

This report elucidates the process of settlement by Coccus scale insects into Crematogaster plant-ant nests formed inside the hollow stems of a myrmecophytic species, Macaranga bancana, in a tropical rain forest. We collected wafting scale insect nymphs from the canopy using sticky traps and characterized the DNA sequence of the trapped nymphs. In...

This report elucidates the process of settlement by Coccus scale insects into Crematogaster plant-ant nests formed inside the hollow stems of a myrmecophytic species, Macaranga bancana, in a tropical rain forest. We collected wafting scale insect nymphs from the canopy using sticky traps and characterized the DNA sequence of the trapped nymphs. In...

Predators generally have traits that enable them to efficiently capture their prey and thus improve their survival. Natural selection should also favor traits of predators that improve the survival rate of their eggs, which are immobile and incapable of active resistance. We hypothesized that eggs of Atkinsonia ignipicta, a specialist predator of t...

Seed dispersal by ants (myrmecochory) is an important life phase in flowering herbs of temperate deciduous forests, and long dispersal is basically preferable in terms of plant fitness. Although it is known that larger ants transport seeds farther, previous studies conflicted whether larger seeds are preferred by large ants. We examine how seed siz...

Comparative historical biogeography of multiple symbionts occurring on a common host taxa can shed light on the processes of symbiont diversification. Myrmecophytic Macaranga plants are associated with the obligate mutualistic symbionts: Crematogaster (subgenus Decacrema) ants and Coccus scale insects. We conduct phylogeographic analyses based on m...

The ant-loving crickets (Orthoptera: Myrmecophilidae) are obligate inquilines within ant colonies that obtain nourishment from ants in their nests. Recently, new morphological and genetic approaches have revealed more ant cricket species than had previously been recognized and have provided insights into their host specificity. In this study, we co...

Myrmecophytism, a type of mutualistic symbiosis, occurs between certain species of Macaranga trees and Crematogasterants in the tropics of Southeast Asia. Several recent studies have revealed that myrmecophytism in Macaranga- Crematogaster involves a highly species-specific partnership, but there is less specificity at the beginning of the symbiosi...

Ant crickets (Orthoptera, Myrmecophilidae) are typical ant guests that obtain nourishment from the ants in their nests. Some ant crickets are host-specific, whereas other species are host-generalists. We investigated the behavioral polarization between the specialist cricket Myrmecophilus albicinctus and generalist Myrmecophilus formosanus. In the...

In the Asian tropics, a conspicuous radiation of Macaranga plants is inhabited by obligately associated Crematogaster ants tending Coccus (Coccidae) scale insects, forming a tripartite symbiosis. Recent phylogenetic studies have shown that the plants and the ants have been codiversifying over the past 16-20 million years (Myr). The prevalence of co...

Ant crickets (Myrmecophilidae, Orthoptera) are typical ant guests. Although ten species (all belonging to genus Myrmecophilus) have recently been described from Japan, their phylogeny and the extent of host specificity are not known. Here, we reconstruct mtDNA phylogeny of 48 individuals from six species to examine their host specificity, habitat u...

Size-frequency distribution of social insect castes has been reported to change temporally and spatially, and be influenced by external factors such as colony size. Here, we show for the first time that the sterile soldiers of eusocial aphids change the size and shape of their armatures, seasonally and locally. Evidence is presented that, in non-so...

We investigate the geographical and historical context of diversification in a complex of mutualistic Crematogaster ants living in Macaranga trees in the equatorial rain forests of Southeast Asia. Using mitochondrial DNA from 433 ant colonies collected from 32 locations spanning Borneo, Malaya and Sumatra, we infer branching relationships, patterns...

Molecular phylogenetic study indicated that Luehdorfia chinensis huashanensis is genetically distinct from L. c. chinensis. Phylogenetic trees based on the COI and ND5+COI genes indicated that L. c. huashanensis is phylogenetically even more closely related to L. longicaudata than to L. c. chinensis. The present molecular phylogenetic study contrib...

We investigate the evolution of host association in a cryptic complex of mutualistic Crematogaster (Decacrema) ants that inhabits and defends Macaranga trees in Southeast Asia. Previous phylogenetic studies based on limited samplings of Decacrema present conflicting reconstructions of the evolutionary history of the association, inferring both cosp...

The present study was conducted to determine the duration of developmental stages of Callosobruchus chinensis and to identify the susceptible stages of azuki bean weevil to neem and sesame oils. The results of the study showed that the duration for the 1st to 4th instar larva and pupal stages of C. chinensis were 7-12, 12-16, 16-19, 19-22 and 22-27...

In Macaranga myrmecophytes, differences in the production of the food bodies (FBs), on which symbiont ants feed, may relate to the intensity of antiherbivore defense by the ants. Interspecific comparisons among Macaranga species on such a mutualistic cost give important information on their strategies and evolution of antiherbivore defense. In this...