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A number of species and taxa of Drosophilidae (Diptera) are used as model clades in various fields of biology, but our knowledge on their ecology and co-evolution (e.g. how their populations are regulated and how they interact with host organisms, enemies, and competitors) is still limited. According to studies on their host use, their primary larval resources are fruits, flowers, plant leaves and stems, tree sap, and fungal fruiting bodies, and most species are specialized to one of these resources. Among these species, those exploiting fungal fruiting bodies (i.e. mycophagous species) have been relatively well studied for their ecology, because their resources are commonly found in the field, hence their interactions with enemies and competitors can be assessed rather easily. So far, a review article has been published on their ecology in 1990. Since then, remarkable advances have been achieved on their taxonomy, phylogeny, diversity, and interactions with parasites, parasitoids, and competitors. This article reviews literature mainly published since 1990 to provide a basis for the future study of their ecology and evolution. [ABSTRACT FROM AUTHOR]

How species diversity is determined is an old question in community ecology but is not yet well understood. Island biotas offer opportunities to address this issue. Here, the ant fauna was studied in five moderately isolated islands of Japan and compared with those in reference regions on the nearby main islands to assess whether ants' ecological characteristics affect their island colonisation success. Species that were more abundant in the reference regions were more frequently found on the islands, suggesting that ant communities on these islands are likely to have a nested subset structure. Species inhabiting both forests and open lands tended to occur more frequently in the study islands at least than those exclusively inhabiting forests, but this difference was not significant. In addition, nest sites and worker body size did not have significant effects on their occurrence in these islands. These results seem to suggest that the study islands as a whole offer various environments that support a variety of ant species with different ecological characteristics. It is suggested in this study that island size affects the species richness, as has often been reported. [ABSTRACT FROM AUTHOR]

Altitudinal distribution and seasonal life cycle of drosophilid flies (Diptera) were studied on the southwestern slope of Mt. Higashi‐Kagonoto in Tomi and at Ishi‐no‐yu in Shiga Heights, Nagano, central Japan. Collections of flies were carried out from early spring to late autumn using traps baited with fermenting banana. Based on the present results and previous faunal reports from central Japan, major native drosophilid species collected in this study were classified into migratory (5 species), high‐altitude (6), mid‐altitude (14) and low‐altitude (14) species. The migratory species are assumed to perform extensive seasonal migration between low‐ and high‐altitude areas. Among these native species, Drosophila alpina (a high‐altitude species) and D. moriwakii (a mid‐altitude species) are assumed to pass only one generation in a year, while the others pass two or more generations. Five of the six high‐altitude species are assigned as the Palearctic elements, while four of the five migratory species and 12 of the 14 low‐altitude species are assigned as the Sino‐Japanese elements. The mid‐altitude species consist of approximately equal numbers of the Palearctic and Sino‐Japanese elements. Among the high‐altitude species, D. alpina and Hirtodrosophila makinoi are also distributed in high‐altitude areas in Hokkaido, northern Japan. The other high‐altitude species and most of the mid‐altitude species generally occur in low‐altitude areas in Hokkaido or the further north. The Sino‐Japanese elements occurring at high and mid altitudes in central Japan are also distributed at high altitudes in southern and southwestern China. [ABSTRACT FROM AUTHOR]

Quercus crispula and Q. dentata (Fagaceae) are dominant members of cool-temperate forests of Japan and are assumed to hybridize in nature. To characterize and discriminate these two species and their hybrids, we carried out multivariate analysis using several morphological traits and principal coordinate analysis using molecular (amplified fragment length polymorphism [AFLP]) data. Further, we examined the composition of Phyllonorycter species (leafmining insects) on individuals from a mixed forest. Morphological traits and Phyllonorycter composition differ enough in these two oak species to be useful for identification of species and hybrids. AFLP data, however, are less informative because the degree of molecular differentiation between the two species is low. Nine out of 105 individuals from a mixed stand had intermediate morphologies according to the multivariate analysis, and eight out of the nine individuals had intermediate Phyllonorycter composition in either one or both of the two study years. These eight individuals were tentatively assigned as hybrids or backcross individuals, and the remaining individual with intermediate morphologies was assigned as Q. dentata according to its Phyllonorycter composition and the AFLP analysis. Key words: AFLP; Fagaceae; hybridization; morphological traits; Phyllonorycter; Quercus crispula; Quercus dentata.

A study to understand how Drosophila elegans discriminates between potential mates has been carried out. Partial sexual isolation has developed between the brown and black morphs, but body coloration is not used as a sexual cue. Sexual isolation and cuticular hydrocarbons are discussed.

Molecular identification is increasingly used to speed up biodiversity surveys and laboratory experiments. However, many groups of organisms cannot be reliably identified using standard databases such as GenBank or BOLD due to lack of sequenced voucher specimens identified by experts. Sometimes a large number of sequences are available, but with too many errors to allow identification. Here, we address this problem for parasitoids of Drosophila by introducing a curated open‐access molecular reference database, DROP (Drosophila parasitoids). Identifying Drosophila parasitoids is challenging and poses a major impediment to realize the full potential of this model system in studies ranging from molecular mechanisms to food webs, and in biological control of Drosophila suzukii. In DROP, genetic data are linked to voucher specimens and, where possible, the voucher specimens are identified by taxonomists and vetted through direct comparison with primary type material. To initiate DROP, we curated 154 laboratory strains, 856 vouchers, 554 DNA sequences, 16 genomes, 14 transcriptomes, and six proteomes drawn from a total of 183 operational taxonomic units (OTUs): 114 described Drosophila parasitoid species and 69 provisional species. We found species richness of Drosophila parasitoids to be heavily underestimated and provide an updated taxonomic catalogue for the community. DROP offers accurate molecular identification and improves cross‐referencing between individual studies that we hope will catalyse research on this diverse and fascinating model system. Our effort should also serve as an example for researchers facing similar molecular identification problems in other groups of organisms. [ABSTRACT FROM AUTHOR]

For identification of insect larvae occurring in galls formed on culms of Sasa kurilensis in Shiga‐kôgen, Nagano and those of Pseudosasa japonica in Takao‐san, Tokyo, we undertook a DNA barcoding analysis using the mitochondrial cytochrome oxidase subunit 1 (CO1) gene. Seventeen operational taxonomic units (OTUs) were identified for larvae from Shiga‐kôgen and one for those from Takao‐san. Of 17 OTUs from Shiga‐kôgen, 10 were most likely assigned to Cecidomyiidae (Diptera), one to Anthomyzidae (Diptera), two to Lepidoptera and four to Hymenoptera. One OTU from Takao‐san was assigned in the Cecidomyiidae cluster. However, none of the OTUs was assigned to known species. It is unknown whether primary gall‐makers are included in the putative cecidomyiid, anthomyzid and lepidopteran species found in this study. However, hymenopteran species occurring in these galls would be parasitoids. How so many cecidomyiid species coexist on bamboo culms in Shiga‐kôgen is an interesting issue and remains to be resolved. [ABSTRACT FROM AUTHOR]

A number of insects have been suggested to perform seasonal migration between low- and high-altitude areas. In these insects, support for the occurrence of migration mainly came from observations that focal insects disappeared from a certain range of altitudes but appeared at different altitudes with short time lags. In some insects, further support was obtained by mark-recapture studies, analyses of the seasonal change of age structure or reproductive conditions in individuals from different altitudes and studies on dormancy or temperature tolerance. Other means that can be used to assess the occurrence of altitudinal migration are briefly mentioned. Two types of migration, the dormancy-associated and dormancy-independent types, are discriminated. In the former type, insects usually breed in spring, migrate to high-altitude areas in late spring or early summer, usually for aestivation, and return to low-altitude areas in autumn. In this type, the same individuals perform upward and downward migration. In the latter type, insects also perform upward migration in late spring or early summer and downward migration in autumn, but they breed both in low- and high-altitude areas. The adaptive and evolutionary aspects of altitudinal migration are briefly mentioned. [ABSTRACT FROM AUTHOR]

The Drosophila parasitoid system is an excellent model for the study of biological and ecological interactions. In Japan, extensive studies have been carried out on Drosophila parasitoids since the early 2000s. Here we provide up-to-date information on their diversity, distributions, host use and reproductive mode. Until now, 45 wasp species have been recorded. In addition, four genetically distinct groups (tentatively assigned as "races") have been found in Ganaspis brasiliensis (Figitidae). Most of them are larvo-pupal parasitoids belonging to the families Figitidae and Braconidae, and some are pupal parasitoids of the families Pteromalidae and Diapriidae. A species of Encyrtidae was also recorded. Their major hosts are indicated with information on the host's breeding sites. Except Ganaspis xanthopoda and two races of G. brasiliensis that are distributed both in tropical and temperate regions, they are divided into tropical and temperate species. The tropical species are mainly distributed in Southeast Asia, and their distributions in Japan are restricted to the Ryukyu islands, particularly Iriomote-jima. The temperate species have been recorded from the main islands of Japan and surrounding islands but not from the Ryukyu islands, except two braconid species, Asobara japonica and Phaenocarpa sp. TK1. Some of the temperate species have also been recorded from Korea, China, Europe and/or North America. Among the 45 Japanese parasitoid spe- cies, at least seven are assumed to be thelytokous. [ABSTRACT FROM AUTHOR]

To understand how ectomycorrhizal (ECM), wood-decomposing (WDC) and litter-decomposing (LDC) fungi differ in abundance and fruiting season, fruiting-body production was monitored by counting their number and/or measuring their biomass in deciduous broad-leaved and coniferous forests in Ishikawa (central Japan) and Hokkaido (northern Japan). ECM fungi were dominant in forests of both types in Ishikawa and a Larix kaempheri forest in Tomakomai (Hokkaido), whereas WDC fungi were dominant in a deciduous broad-leaved forest in Sapporo (Hokkaido). ECM and WDC fungi usually showed two abundance peaks in Kanazawa (Ishikawa), mid-summer and autumn for ECM fungi and spring or summer and autumn for WDC fungi, whereas LDC fungi usually showed one peak in autumn. In Tomakomai, the abundance peak appeared later in ECM fungi but earlier in LDC and WDC fungi in comparison with Kanazawa. The mode of resource acquisition is assumed as one of factors that affect the seasonal timing of fruiting-body production. On the other hand, highly positive correlations were often observed between precipitation in Jun or Aug and the fruiting-body production in summer and/or autumn in the survey in Kanazawa, suggesting that precipitation could affect the fruiting-body production a few months later. • Ectomycorrhizal fungi (ECM) showed two production peaks in mid-summer and autumn. • Wood-decomposing fungi (WDC) showed two peaks in spring and mid- or late-autumn. • Litter-decomposing fungi (LDC) showed a peak in autumn. • ECM showed more extensive yearly variation in fruiting phenology than WDC. • Precipitation is assumed to affect the fruiting-body production. [ABSTRACT FROM AUTHOR]

Leptopilina heterotoma is a Drosophila parasitoid mainly occurring in temperate regions, and females of this species are pro-ovigenic (i.e. all or nearly all of their lifetime eggs are already mature at emergence). Here I investigated how L. heterotoma overwinters in Sapporo, Japan, a cool temperate region, by outdoor and laboratory experiments. Females of this species had mature eggs at emergence as expected, and they did not resorb eggs even if they were exposed to cold or starvation. Nevertheless, females were able to overwinter, and post-overwintering females retained parasitization capacity. In this species, thus, adult overwintering is not associated with reproductive diapause. However, females grown in late autumn or at low temperatures (e.g. 5°C) had a fewer number of mature eggs and higher winter survival. At low temperatures, female larvae could save energy by reducing egg production and allocate the saved energy to expenditure for overwintering. In contrast to females, males and pre-adult individuals were not able to overwinter. [ABSTRACT FROM AUTHOR]

The distribution pattern and competition of insects exploiting Camellia japonica flowers were studied in Tokyo, central Japan, to understand how their distributions are determined. Dasiops sp. of Lonchaeidae (Diptera) exploited flower buds and showed random distribution, whereas Drosophila unipectinata, D. oshimai and D. lutescens of Drosophilidae (Diptera) and Epuraea commutata of Nitidulidae (Coleoptera) exploited fully opened, late and fallen flowers and showed aggregated distribution. From the distribution pattern, it is assumed that Dasiops sp. has clutches of single egg whereas drosophilid and nitidulid species have clutches of more than one egg. In resource supplementary experiments, body size of drosophilid flies increased if resources were supplemented, although their survival is assumed to be unaffected. However, their body size did not decrease with increase of larval density in resource patches. It is therefore unclear whether resource competition occurs among drosophilid flies in Camellia flowers in nature. From the present and previous studies, it is assumed that aggregation (or production of clutches of more than one egg) is related to the use of fermenting or decayed resources; aggregation might increase larval survival and/or performance under the presence of molds or microorganisms. Dasiops sp. exploited flower buds and showed random distribution, whereas Drosophila unipectinata, D. oshimai, D. lutescens and Epuraea commutata of Nitidulidae (Coleoptera) exploited fully‐opened, late and fallen flowers and showed aggregated distribution. Aggregated distribution seems to arise by production of clutches containing more than one egg and may be an adaptation to use fermenting or decayed resources. [ABSTRACT FROM AUTHOR]

Abstract: Lipid synthesis can have a major effect on survival and reproduction, yet most insect parasitoids fail to synthesize lipids. For parasitic wasps in the genus Leptopilina, however, studies have suggested that there is intraspecific variation in the ability for lipid synthesis. These studies were performed on only few populations, and a large‐scale investigation of both lipogenic ability and population genetic structure is now needed. Here, we first examined lipogenic ability of nine Leptopilina heterotoma populations collected in 2013 and found that five of nine populations synthesized lipids. The 2013 populations could not be used to determine genetic structure; hence, we obtained another 20 populations in 2016 that were tested for lipogenic ability. Thirteen of 20 populations (all Leptopilina heterotoma) were then used to determine the level of genetic differentiation (i.e., haplotype and nucleotide diversity) by sequencing neutral mitochondrial (COI) and nuclear (ITS2) markers. None of the 2016 populations synthesized lipids, and no genetic differentiation was found. Our results did reveal a nearly twofold increase in mean wasp lipid content at emergence in populations obtained in 2016 compared to 2013. We propose that our results can be explained by plasticity in lipid synthesis, where lipogenic ability is determined by environmental factors, such as developmental temperature and/or the amount of lipids carried over from the host. [ABSTRACT FROM AUTHOR]

Distributions and oviposition sites of Drosophila suzukii (Matsumura) and its parasitoids on wild cherry tree were studied in early summer in a suburb of Tokyo, central Japan. Adults of D. suzukii occurred in the foliage layer as well as in the undergrowth layer. The number of D. suzukii that emerged did not significantly differ between wild cherry fruit collected from the foliage layer and those from the undergrowth layer. In addition, the number of D. suzukii that emerged per fruit decreased when fruit were left on the ground longer. It is therefore assumed that D. suzukii females rarely oviposit eggs in fallen wild cherry fruit. The suzukii-associated type of Ganaspis brasiliensis (Ihering) was the major parasitoid that emerged from D. suzukii in the study area. The rate of parasitism by this parasitoid did not significantly differ between larvae in fresh fruit from the foliage layer and those in fallen fruit from the undergrowth layer. This may also suggest that this wasp rarely attacks D. suzukii larvae in fallen fruit. Adults of the suzukii-associated type of G. brasiliensis, Asobara sp. TK1, and Leptopilina japonica that attack D. suzukii were mainly collected from the foliage layer. On the basis of the present results, some proposals for the control of D. suzukii were discussed. [ABSTRACT FROM AUTHOR]

1. Generalist koinobiont parasitoids often exhibit high flexibility in their development; their larvae shorten or prolong the developmental period depending on the host quality at parasitisation. However, flexibility of the growth rate of parasitoid larvae has rarely been investigated so far. 2. This study investigated how the koinobiont parasitoid wasps Asobara japonica and Leptopilina ryukyuensis regulate their larval growth when they parasitise host Drosophila larvae with varying larval periods. 3. In both parasitoid species, the preimaginal period was longer when they parasitised 1-day-old larvae of Drosophila rufa than when they parasitised older larvae of D. rufa or when they parasitised larvae of Drosophila simulans, a species with a shorter larval period than D. rufa. After host pupariation, A. japonica accelerated its growth, thereby showing a biphasic growth curve. On the other hand, L. ryukyuensis did not accelerate its growth after host pupariation. 4. Growth retardation of parasitoid larvae in 1-day-old D. rufa larvae would contribute to avoiding excess growth before host pupariation, because the excess growth of parasitoid larvae would have negative effects on host growth. The growth rate acceleration of A. japonica after host pupariation suggests that they enhance resource utilisation in a host that has reached maximum body mass. It remains uncertain as to why L. ryukuensis does not show clear accelerated growth after host pupariation . Nonetheless, these results suggest that parasitoid larvae have the ability to detect the developmental stage of hosts in a species-specific manner. [ABSTRACT FROM AUTHOR]

Deciphering invasion routes from molecular data is crucial to understanding biological invasions, including identifying bottlenecks in population size and admixture among distinct populations. Here, we unravel the invasion routes of the invasive pest Drosophila suzukii using a multi-locus microsatellite dataset (25 loci on 23 worldwide sampling locations). To do this, we use approximate Bayesian computation (ABC), which has improved the reconstruction of invasion routes, but can be computationally expensive. We use our study to illustrate the use of a new, more efficient, ABC method, ABC random forest (ABC-RF) and compare it to a standard ABC method (ABC-LDA). We find that Japan emerges as the most probable source of the earliest recorded invasion into Hawaii. Southeast China and Hawaii together are the most probable sources of populations in western North America, which then in turn served as sources for those in eastern North America. European populations are genetically more homogeneous than North American populations, and their most probable source is northeast China, with evidence of limited gene flow from the eastern US as well. All introduced populations passed through bottlenecks, and analyses reveal five distinct admixture events. These findings can inform hypotheses concerning how this species evolved between different and independent source and invasive populations. Methodological comparisons indicate that ABC-RF and ABC-LDA show concordant results if ABC-LDA is based on a large number of simulated datasets but that ABC-RF out-performs ABC-LDA when using a comparable and more manageable number of simulated datasets, especially when analyzing complex introduction scenarios. [ABSTRACT FROM AUTHOR]

The Drosophila parasitoid Asobara japonica Belokobylskij (Hymenoptera: Braconidae) has highly toxic venom that kills host larvae if its injection is not followed by an injection of lateral oviduct components along with egg-laying. In the present study, the venoms of seven other Drosophila parasitoids (Asobara rossica, Asobara rufescens, Asobara pleuralis, Leptopilina heterotoma, Leptopilina japonica, Leptopilina ryukyuensis, and Leptopilina victoriae) are tested against three kinds of Drosophila species (i.e. Drosophila species that are suitable as host for focal parasitoids, those that are resistant to the parasitoids, and a cosmopolitan species, Drosophila simulans). Venoms of the three Asobara species are not toxic to any of Drosophila species, whereas those of the four Leptopilina species are toxic to some Drosophila species. The toxicity of venom varies among Leptopilina species, and the susceptibility to venom also varies among host Drosophila species. Furthermore, toxicity and paralytic effects of venom are not correlated. Because the toxicity of venom is not adaptive for parasitoids, it may be an inevitable side effect of some components that play an essential role in parasitism. [ABSTRACT FROM AUTHOR]

The Asian vinegar fly Drosophila suzukii (spotted wing Drosophila [SWD]) has emerged as a major invasive insect pest of small and stone fruits in both the Americas and Europe since the late 2000s. While research efforts have rapidly progressed in Asia, North America, and Europe over the past 5 years, important new insights may be gained in comparing and contrasting findings across the regions affected by SWD. In this review, we explore common themes in the invasion biology of SWD by examining (1) its biology and current pest status in endemic and recently invaded regions; (2) current efforts and future research needs for the development of predictive models for its geographic expansion; and (3) prospects for both natural and classical (=importation) biological control of SWD in invaded habitats, with emphasis on the role of hymenopteran parasitoids. We conclude that particularly fruitful areas of research should include fundamental studies of its overwintering, host-use, and dispersal capabilities; as well as applied studies of alternative, cost-effective management techniques to complement insecticide use within the integrated pest management framework. Finally, we emphasize that outreach efforts are critical to effective SWD management by highlighting successful strategies and insights gained from various geographic regions. [ABSTRACT FROM AUTHOR]

Abundances and parasitism rates of frugivorous drosophilid flies were studied in three localities at altitudes of 250–1350 m in and near Bogor, Indonesia. The drosophilid and parasitoid species were classified into four groups: low-altitude species, high-altitude species, species abundant at a mid-altitude location and species occurring rather evenly from low to high locations. Theananassaeandimmigransspecies groups were major drosophilids collected. All species of theananassaespecies group were more abundant at lower altitudes, and the parasitism rate in this species group decreased with increasing altitude. Thus, the host abundance seems to affect the parasitism rate. On the other hand, the rate of parasitism in theimmigransspecies group showed no apparent relation with altitude or density, possibly due to the fact that species of this species group varied in altitudinal distribution. It is also suggested that the diversity of drosophilid species affects the composition of parasitoid species. [ABSTRACT FROM PUBLISHER]