A New Distinctive Darwin Wasp Represents the First Record of the Ophion minutus Species-group (Hymenoptera: Ichneumonidae: Ophioninae) from Japan and the Far East, with an Analysis of DNA Barcode-based Species Delimitation in Ophion

A new Darwin wasp species, Ophion kobensis Shimizu sp. nov. (Hymenoptera: Ichneumonidae: Ophioninae), is described using the integrated morphological and molecular species delimitation approaches. Our results indicate that the new species is closely related to European O. ventricosus Gravenhorst, 1829 of the O. minutus species-group but can be distinguished using morphological characters, such as entirely black body colour with some light-yellow marks and not inclined epicnemial carina in lateral view. This record of the new species represents the first record of O. minutus species-group from Japan and the Far East. Phylogenetic analysis indicate that the O. minutus species-group is weakly recovered as monophyletic and sister to Ophion s. str. The analysis also indicated that two clades within the O. minutus species-group (O. minutus and O. ventricosus) diverged significantly. This suggests that the species-group, as well as the two included clades, could potentially be treated as separate species-groups or genera. The present study supports previous integrative taxonomic and phylogenetic studies of Ophion and represents a first fundamental step for studies focused on the challenging Japanese and Far Eastern Ophion.

Extinction Threat to a Previously Undescribed Species of Gall Wasp (Hymenoptera: Cynipidae) and Two Associated Parasitoid Species (Hymenoptera: Braconidae and Eulophidae) on a Threatened Rose

Diplolepis ogawai Abe and Ide sp. nov. (Hymenoptera: Cynipidae) induces galls on Rosa hirtula (Regel) Nakai (Rosales: Rosaceae), which is endemic to a restricted area of Honshu, the main island of Japan. The gall is induced mainly on the leaf of R. hirtula in spring and the mature gall falls to the ground in early summer. The gall-inducing wasp emerges from the gall on the ground in the following spring, suggesting that D. ogawai is univoltine. From spring to summer, the braconid Syntomernus flavus Samartsev and Ku and the eulophid Aprostocetus sp. are parasitic on the larva of D. ogawai in the gall, and the adult wasp of both parasitoid species emerges from the gall on the ground in summer. For S. flavus, this is the first distribution record in Japan and the first host record. Since R. hirtula is threatened with extinction by succession and deforestation, D. ogawai and its two parasitoid wasp species are considered to be at risk of coextinction with the threatened rose. In the event that the population size of this rose species is further reduced, D. ogawai and its parasitoids may -become extinct prior to the extinction of R. hirtula. To conserve these three wasp species associated with R. hirtula, protection of remnant vegetation where individuals of this threatened rose species grow is necessary.

Online citizen sciences reveal natural enemies and new occurrence data of Meteorusstellatus Fujie, Shimizu & Maeto, 2021 (Hymenoptera, Braconidae, Euphorinae)

Background

Citizen science is a research approach that involves collaboration between professional scientists and non-professional volunteers. The utilisation of recent online citizen-science platforms (e.g. social networking services) has greatly revolutionised the accessibility of biodiversity data by providing opportunities for connecting professional and citizen scientists worldwide. Meteorusstellatus Fujie, Shimizu & Maeto, 2021 (Hymenoptera, Braconidae, Euphorinae) has been recorded from the Oriental Islands of Japan and known to be a gregarious endoparasitoid of two macro-sized sphingid moths of Macroglossum, Ma.passalus (Drury) and Ma.pyrrhosticta Butler. It constructs characteristic star-shaped communal cocoons, suspended by a long cable. Although M.stellatus has been reported only from the Oriental Islands of Japan, the authors recognise its occurrence and ecological data from Taiwan and the Palaearctic Island of Japan through posts on online citizen-science groups about Taiwanese Insects on Facebook and an article on a Japanese citizen-scientist's website.

New information

Through collaboration between professional and citizen scientists via social media (Facebook groups) and websites, the following new biodiversity and ecological data associated with M.stellatus are provided: Meteorusstellatus is recorded for the first time from Taiwan and the Palaearctic Region (Yakushima Is., Japan).Cechetraminor (Butler, 1875), Hippotioncelerio (Linnaeus, 1758) and Macroglossumsitiene (Walker, 1856) (Lepidoptera, Sphingidae) are recorded for the first time as hosts of M.stellatus and two of which (C.minor and H.celerio) represent the first genus-level host records for M.stellatus.Mesochorus sp. (Hymenoptera, Ichneumonidae), indeterminate species of Pteromalidae and Trichogrammatidae (Hymenoptera), are recognised as hyperparasitoid wasps of M.stellatus.Parapolybiavaria (Fabricius, 1787) (Hymenoptera, Vespidae) is reported as a predator of pendulous communal cocoons of M.stellatus. The nature of suspended large-sized communal cocoons of M.stellatus and the importance and limitations of digital occurrence data and online citizen science are briefly discussed.

The genus Aridelus Marshall (Hymenoptera, Braconidae, Euphorinae) from Japan, with description of a new species

Six Japanese species belonging to the genus Aridelus Marshall, 1898 (Hymenoptera, Braconidae) were recorded and photographed. Three species, A.dubius Belokobylskij, A.egregius Schmiedeknecht and A.rufotestaceus Tobias (= Aridelusrufiventris Luo & Chen syn. nov.), are new to Japan, and a new species, A.rutilipoidessp. nov. is described. An identification key to the Japanese species of Aridelus is also provided. In addition, new host records are provided, i.e., A.flavicans Chao reared from Homoeocerusunipunctatus and Riptortuspedestris (Alydidae) and A.rufotestaceus reared from Glauciassubpunctatus (Pentatomidae). The Alydidae is a newly recorded host family of Aridelus.

Genomic population structure of sympatric sexual and asexual populations in a parasitic wasp, Meteorus pulchricornis (Hymenoptera: Braconidae), inferred from six hundred single-nucleotide polymorphism loci

In spite of the two-fold reproductive advantage, asexual reproduction is not common in nature, probably due to the associated genetic deterioration or reduced genetic variation. To understand how genetic diversity is maintained in existing asexual populations, we investigated the genetic diversity and population structure of sympatric sexual and asexual populations of a parasitic wasp, Meteorus pulchricornis, using 614 genome-wide single nucleotide polymorphisms. The genetic structures of the apomictic asexual populations were distinct, showing considerable genetic differentiation among them. Most of the asexual populations were highly differentiated from the sympatric sexual population; some asexual individuals could not be distinguished from members of the sexual population. Furthermore, significantly fewer multilocus genotypes were identified in the asexual populations (1-7) compared to the sexual population (42), which is consistent with their apomictic nature. The observed patterns of fixed heterozygous sites suggest that most asexual populations had the same evolutionary origin and have long since evolved individually; the detected gene flow between the sexual population and a few asexual population may indicate independent origins of asexuality. The potential role of occasional males in apomictic wasps is also discussed.

Integrative taxonomy and analysis of species richness patterns of nocturnal Darwin wasps of the genus Enicospilus Stephens (Hymenoptera, Ichneumonidae, Ophioninae) in Japan

The predominantly tropical ophionine genus Enicospilus Stephens, 1835 is one of the largest genera of Darwin wasps (Hymenoptera, Ichneumonidae), with more than 700 extant species worldwide that are usually crepuscular or nocturnal and are parasitoids of Lepidoptera larvae. In the present study, the Japanese species of Enicospilus are revised using an integrative approach (combined morphology and DNA barcoding). On the basis of 3,110 specimens, 47 Enicospilus species are recognised in Japan, eight of which are new species (E.acutus Shimizu, sp. nov., E.kunigamiensis Shimizu, sp. nov., E.limnophilus Shimizu, sp. nov., E.matsumurai Shimizu, sp. nov., E.pseudopuncticulatus Shimizu, sp. nov., E.sharkeyi Shimizu, sp. nov., E.takakuwai Shimizu, sp. nov., and E.unctus Shimizu, sp. nov.), seven are new records from Japan (E.jilinensis Tang, 1990, E.laqueatus (Enderlein, 1921), E.multidens Chiu, 1954, stat. rev., E.puncticulatus Tang, 1990, E.stenophleps Cushman, 1937, E.vestigator (Smith, 1858), and E.zeugos Chiu, 1954, stat. rev.), 32 had already been recorded in Japan; three (E.biharensis Townes, Townes & Gupta, 1961, E.flavicaput (Morley, 1912), and E.merdarius (Gravenhorst, 1829)) have been erroneously recorded from Japan based on misidentifications, and four names that were previously on the Japanese list are deleted through synonymy. The following taxonomic changes are proposed: E.vacuus Gauld & Mitchell, 1981, syn. nov. (= E.formosensis (Uchida, 1928)); E.multidensstat. rev.; E.striatus Cameron, 1899, syn. nov. = E.lineolatus (Roman, 1913), syn. nov. = E.uniformis Chiu, 1954, syn. nov. = E.flatus Chiu, 1954, syn. nov. = E.gussakovskii Viktorov, 1957, syn. nov. = E.striolatus Townes, Townes & Gupta, 1961, syn. nov. = E.unicornis Rao & Nikam, 1969, syn. nov. = E.unicornis Rao & Nikam, 1970, syn. nov. (= E.pungens (Smith, 1874)); E.iracundus Chiu, 1954, syn. nov. (= E.sakaguchii (Matsumura & Uchida, 1926)); E.sigmatoides Chiu, 1954, syn. nov. (= E.shikokuensis (Uchida, 1928)); E.yamanakai (Uchida, 1930), syn. nov. (= E.shinkanus (Uchida, 1928)); E.ranunculus Chiu, 1954, syn. nov. (= E.yezoensis (Uchida, 1928)); and E.zeugosstat. rev. = E.henrytownesi Chao & Tang, 1991, syn. nov. In addition, the following new regional and country records are also provided: E.flavocephalus (Kirby, 1900), E.puncticulatus, and E.vestigator from the Eastern Palaearctic region, E.laqueatus from the Eastern Palaearctic and Oceanic regions, and E.maruyamanus (Uchida, 1928) from the Oriental region; E.abdominalis (Szépligeti, 1906) from Nepal, E.flavocephalus from Laos, E.formosensis from Laos and Malaysia, E.insinuator (Smith, 1860) from Taiwan, E.maruyamanus from India and Philippines, E.nigronotatus Cameron, 1903, E.riukiuensis (Matsumura & Uchida, 1926), and E.sakaguchii from Indonesia, E.pungens from 14 countries (Australia, Bhutan, Brunei, Indonesia, Laos, Malaysia, Nepal, New Caledonia, Papua New Guinea, Philippines, Solomon Islands, Sri Lanka, Tajikistan, and Taiwan), and E.yezoensis from South Korea. An identification key to all Japanese species of Enicospilus is proposed. Although 47 species are recognised in the present study, approximately 55 species could potentially be found in Japan based on ACE and Chao 1 estimators. The latitudinal diversity gradient of Enicospilus species richness is also tested in the Japanese archipelago based on the constructed robust taxonomic framework and extensive samples. Enicospilus species richness significantly increases towards the south, contrary to the ‘anomalous’ pattern of some other ichneumonid subfamilies.

Revalidation of Habrobracon brevicornis stat. rest. (Hymenoptera: Braconidae) Based on the CO1, 16S, and 28S Gene Fragments

Habrobracon hebetor (Say 1836) is an important biological control agent around the world. Many hundreds of papers have been published about its biology. Due to the global distribution of H. hebetor many species have been described over the years in various countries as a sister species to H. hebetor but were eventually synonymized with H. hebetor. One of which is Habrobracon brevicornis (Wesmael 1838). Here, we revalidate the status of H. brevicornis stat. rest. based on molecular data. It remains difficult to discriminate the two species based on morphology data alone, but with molecular data the differentiation is straight forward. An integrative key is provided to distinguish H. hebetor from H. brevicornis.

The changing use of the ovipositor in host shifts by ichneumonid ectoparasitoids of spiders (Hymenoptera, Ichneumonidae, Pimplinae)

Accurate egg placement into or onto a living host is an essential ability for many parasitoids, and changes in associated phenotypes, such as ovipositor morphology and behaviour, correlate with significant host shifts. Here, we report that in the ichneumonid group of koinobiont spider-ectoparasitoids (“polysphinctines”), several putatively ancestral taxa (clade I here), parasitic on ground-dwelling RTA-spiders (a group characterised by retrolateral tibial apophysis on male palpal tibiae), lay their eggs in a specific way. They tightly bend their metasoma above the spider’s cephalothorax, touching the carapace with the dorsal side of the ovipositor apically (“dorsal-press”). The egg slips out from the middle part of the ventral side of the ovipositor and moves towards its apex with the parted lower valves acting as rails. Deposition occurs as the parasitoid draws the ovipositor backwards from under the egg. Oviposition upon the tough carapace of the cephalothorax, presumably less palatable than the abdomen, is conserved in these taxa, and presumed adaptive through avoiding physical damage to the developing parasitoid. This specific way of oviposition is reversed in the putatively derived clade of polysphinctines (clade II here) parasitic on Araneoidea spiders with aerial webs, which is already known. They bend their metasoma along the spider’s abdomen, grasping the abdomen with their fore/mid legs, pressing the ventral tip of the metasoma and the lower valves of the ovipositor against the abdomen (“ventral-press”). The egg is expelled through an expansion of the lower valves, which is developed only in this clade and evident in most species, onto the softer and presumably more nutritious abdomen.

The database of the PREDICTS (Projecting Responses of Ecological Diversity In Changing Terrestrial Systems) project

The PREDICTS project-Projecting Responses of Ecological Diversity In Changing Terrestrial Systems (www.predicts.org.uk)-has collated from published studies a large, reasonably representative database of comparable samples of biodiversity from multiple sites that differ in the nature or intensity of human impacts relating to land use. We have used this evidence base to develop global and regional statistical models of how local biodiversity responds to these measures. We describe and make freely available this 2016 release of the database, containing more than 3.2 million records sampled at over 26,000 locations and representing over 47,000 species. We outline how the database can help in answering a range of questions in ecology and conservation biology. To our knowledge, this is the largest and most geographically and taxonomically representative database of spatial comparisons of biodiversity that has been collated to date; it will be useful to researchers and international efforts wishing to model and understand the global status of biodiversity.

Genetic Structure and Potential Environmental Determinants of Local Genetic Diversity in Japanese Honeybees (Apis cerana japonica)

Declines in honeybee populations have been a recent concern. Although causes of the declines remain unclear, environmental factors may be responsible. We focused on the potential environmental determinants of local populations of wild honeybees, Apis cerana japonica, in Japan. This subspecies has little genetic variation in terms of its mitochondrial DNA sequences, and genetic variations at nuclear loci are as yet unknown. We estimated the genetic structure and environmental determinants of local genetic diversity in nuclear microsatellite genotypes of fathers and mothers, inferred from workers collected at 139 sites. The genotypes of fathers and mothers showed weak isolation by distance and negligible genetic structure. The local genetic diversity was high in central Japan, decreasing toward the peripheries, and depended on the climate and land use characteristics of the sites. The local genetic diversity decreased as the annual precipitation increased, and increased as the proportion of urban and paddy field areas increased. Positive effects of natural forest area, which have also been observed in terms of forager abundance in farms, were not detected with respect to the local genetic diversity. The findings suggest that A. cerana japonica forms a single population connected by gene flow in its main distributional range, and that climate and landscape properties potentially affect its local genetic diversity.

Revision of the Taiwanese species of the genus Leptophion Cameron, 1901 (Hymenoptera: Ichneumonidae: Ophioninae), with a discussion of their phenology and distribution

We revise the Taiwanese species of the ophionine genus Leptophion Cameron, 1901. As a result, three species, including a new species, are recognized. Two of them were identified as L. maculipennis (Cameron, 1905) and L. radiatus (Uchida, 1956), both of which had been previously recorded in Taiwan; we redescribe them based on Taiwanese specimens. We describe a single new species as L. giganteus Shimizu & Watanabe, sp. nov. The phenology and distribution of the species are briefly discussed. A key to the Taiwanese species of Leptophion and additional couplets to the key proposed by Gauld & Mitchell (1981) are also provided.

Revision of Ishigakia Uchida (Hymenoptera: Ichneumonidae: Acaenitinae) from Japan, with a new species having a close relative in South Africa

Two Japanese species of the genus Ishigakia Uchida, 1928, i.e., the type species from Ryukyus, I. exetasea Uchida, and a new species from Honshu, I. albitarsa Ito & Maeto sp. nov., are (re-)described. Antennal tapping and oviposition behavior of female I. exetasea was observed on the stalks of Japanese silvergrass Miscanthus sinensis. The new species, I. albitarsa, has (presumably) close relatives from mainland China and, disjunctely, from South Africa. A key to the world species of Ishigakia is also provided.

Host manipulation by an ichneumonid spider ectoparasitoid that takes advantage of preprogrammed web-building behaviour for its cocoon protection

Host manipulation by parasites and parasitoids is a fascinating phenomenon within evolutionary ecology, representing an example of extended phenotypes. To elucidate the mechanism of host manipulation, revealing the origin and function of the invoked actions is essential. Our study focused on the ichneumonid spider ectoparasitoid Reclinervellus nielseni, which turns its host spider (Cyclosa argenteoalba) into a drugged navvy, to modify the web structure into a more persistent cocoon web so that the wasp can pupate safely on this web after the spider's death. We focused on whether the cocoon web originated from the resting web that an unparasitized spider builds before moulting, by comparing web structures, building behaviour and silk spectral/tensile properties. We found that both resting and cocoon webs have reduced numbers of radii decorated by numerous fibrous threads and specific decorating behaviour was identical, suggesting that the cocoon web in this system has roots in the innate resting web and ecdysteroid-related components may be responsible for the manipulation. We also show that these decorations reflect UV light, possibly to prevent damage by flying web-destroyers such as birds or large insects. Furthermore, the tensile test revealed that the spider is induced to repeat certain behavioural steps in addition to resting web construction so that many more threads are laid down for web reinforcement.

Revision of the genus Jezarotes Uchida (Hymenoptera: Ichneumonidae: Acaenitinae), with the description of a new species from Laos

Two Japanese species of Jezarotes, J. tamanukii Uchida, 1928, and J. yamatonis Uchida, 1928, are synonymized based on the results of a morphological examination and DNA sequence analysis of the mitochondrial COI gene. Jezarotes tetragonis Lee & Lee, 2009, from Korea is also synonymized with J. tamanukii. The key to the world's species of Jezarotes proposed by Lee & Lee (2009) is updated, including a new species J. mitai sp. nov. from Laos.

Revision of the genus Arotes Gravenhorst (Hymenoptera: Ichneumonidae: Acaenitinae) from Japan

Three Japanese species of the genus Arotes Gravenhorst, 1829 are revised. A new species, A. japonicus Ito & Watanabe, sp. nov., is described from the four main islands of Japan. This species can easily be distinguished from congeneric species by the black body without yellow markings and the entirely black hind tibia. Arotes sugiharai Uchida, 1934 is newly recorded from the islands of Kyushu and Tsushima, and the males of this species are described for the first time. The synonymy of A. moiwanus (Matsumura, 1912) and its color variant alboannulatus Uchida, 1928 are confirmed by DNA sequence analysis of the mitochondrial COI gene. The key to the world's species of Arotes proposed by Castillo et al. (2011) is updated and a key to the Japanese species is provided.

The PREDICTS database: a global database of how local terrestrial biodiversity responds to human impacts

Biodiversity continues to decline in the face of increasing anthropogenic pressures such as habitat destruction, exploitation, pollution and introduction of alien species. Existing global databases of species’ threat status or population time series are dominated by charismatic species. The collation of datasets with broad taxonomic and biogeographic extents, and that support computation of a range of biodiversity indicators, is necessary to enable better understanding of historical declines and to project – and avert – future declines. We describe and assess a new database of more than 1.6 million samples from 78 countries representing over 28,000 species, collated from existing spatial comparisons of local-scale biodiversity exposed to different intensities and types of anthropogenic pressures, from terrestrial sites around the world. The database contains measurements taken in 208 (of 814) ecoregions, 13 (of 14) biomes, 25 (of 35) biodiversity hotspots and 16 (of 17) megadiverse countries. The database contains more than 1% of the total number of all species described, and more than 1% of the described species within many taxonomic groups – including flowering plants, gymnosperms, birds, mammals, reptiles, amphibians, beetles, lepidopterans and hymenopterans. The dataset, which is still being added to, is therefore already considerably larger and more representative than those used by previous quantitative models of biodiversity trends and responses. The database is being assembled as part of the PREDICTS project (Projecting Responses of Ecological Diversity In Changing Terrestrial Systems – http://www.predicts.org.uk). We make site-level summary data available alongside this article. The full database will be publicly available in 2015.

Apomictic parthenogenesis in a parasitoid wasp Meteorus pulchricornis, uncommon in the haplodiploid order Hymenoptera

Although apomixis is the most common form of parthenogenesis in diplodiploid arthropods, it is uncommon in the haplodiploid insect order Hymenoptera. We found a new type of spontaneous apomixis in the Hymenoptera, completely lacking meiosis and the expulsion of polar bodies in egg maturation division, on the thelytokous strain of a parasitoid wasp Meteorus pulchricornis (Wesmael) (Braconidae, Euphorinae) on pest lepidopteran larvae Spodoptera litura (Fabricius) (Noctuidae). The absence of the meiotic process was consistent with a non-segregation pattern in the offspring of heterozygous females, and no positive evidence was obtained for the induction of thelytoky by any bacterial symbionts. We discuss the conditions that enable the occurrence of such rare cases of apomictic thelytoky in the Hymenoptera, suggesting the significance of fixed heterosis caused by hybridization or polyploidization, symbiosis with bacterial agents, and occasional sex. Our finding will encourage further genetic studies on parasitoid wasps to use asexual lines more wisely for biological control.

Three new species of the genus Scaphicoma Motschulsky, 1863 (Coleoptera, Staphylinidae, Scaphidiinae) from Northern Sulawesi, Indonesia

Three new species of the genus Scaphicoma Motschulsky, 1863 from Sulawesi, Indonesia are illustrated and described: Scaphicoma subflava Ogawa & Löbl, sp. n., S. bidentia Ogawa & Löbl, sp. n., and S. quadrifasciata Ogawa & Löbl, sp. n.Lepteroscapha pallens Achard, 1921 is designated as the type species of the genus Lepteroscapha Achard, 1921.

Revision of the genus Apophua Morley, 1913, from Japan (Hymenoptera, Ichneumonidae, Banchinae)

Japanese species of the genus Apophua Morley, 1913, are revised. Eleven species are found from Japan and two of them, A. elegans sp. nov. and A. yamato sp. nov., are newly described. Distribution data and an updated key to Japanese species are provided.

Taxonomic status of the subgenus Conoblasta Förster 1869 of the genus Glypta Gravenhorst 1829 with revision of Japanese species (Hymenoptera, Ichneumonidae, Banchinae)

The Japanese species of subgenus Conoblasta Förster 1869 sensu Aubert (1978) and Kuslitzky (1974, 2007) of the genus Glypta Gravenhorst 1829 are reviewed. No reliable synapomorphies are found for the species of Conoblasta after all and thus we conclude that they should be treated as a tentative species group. Eighteen species of the Conoblasta species group, including 11 new species (G. cognata sp. nov., G. daisetsuzana sp. nov., G. densepunctata sp. nov., G. flavitarsus sp. nov., G. ichitai sp. nov., G. karasawensis sp. nov., G. nipponica sp. nov., G. shigaensis sp. nov., G. suwai sp. nov., G. touyaensis sp. nov., G. zenibakoensis sp. nov.) and two newly recorded species (G. chinensis (Uchida 1956) and G. extincta Ratzeberg 1852), are recognized from Japan. A key to the Japanese species is provided.

A new species of the genus Himertosoma from the Ryukyus, Japan, with a key to species from the Palaearctic and Oriental Regions (Hymenoptera, Ichneumonidae, Banchinae)

A new species of the genus Himertosoma Schmiedeknecht, Himertosoma kuslitzkiisp. n., was discovered in Amamioshima Island, the Ryukyus. This new species resembles two Oriental species, Himertosoma philippense Chandra & Gupta and Himertosoma townesi Chandra & Gupta, in the colour pattern of the head and metasoma, number of flagellomeres, and the relatively slender first metasomal tergite, but can easily be distinguished from them by the nearly evenly punctate propodeum, different length/width ratio of the first metasomal tergite, different length of the ovipositor sheath, tricoloured mesosoma, and the whitish band along the posterior margin of the second and following metasomal tergites. A key to the Palaearctic and Oriental species of Himertosoma is also provided.

Prolonged diapause of specialist seed-feeders makes predator satiation unstable in masting of Quercus crispula

Quercus crispula (= Q. mongolica var. grosseserrata) is the predominant tree species in cool temperate, mixed broadleaf/conifer forests in northern Japan. We compared 11 years of data on acorn production in a population of Q. crispula, with data on seed-insect populations, to try to answer the following questions: (1) Does Q. crispula show a regular pattern of masting? (2) How long do principal seed predators remain in diapause? (3) How do the seed predators affect the pattern of predator satiation? Q. crispula showed a tendency to alternate bearing, with significant synchrony between individual trees. The principal acorn-feeding insects ( Curculio spp. weevils), which infested 25%-70% of matured acorns, generally exhibited a prolonged diapause of 2 years. No significant negative relationship was found between the rate of injury by the weevils and the density of mature acorns, indicating that simple predator satiation fails due to the synchrony of the life-cycle of acorn-feeding insects and the periodical production of acorns. However, the rate of injury by the weevils was negatively correlated with the relative abundance of mature acorns to the number of weevil larvae that had matured 2 years previously. Thus, the proportion of sound acorns notably increased in a rich crop after a disturbance in alternate bearing. Prolonged diapause of specific seed predators is critical in determining the peak year of sound-seed production.