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To clarify the life history of the Japanese spider wasp Dipogon sperconsus, bionomical studies using bamboo-cane trap nests were carried out in Japan. Based on weekly and consecutive daily surveys of trap nests and rearing of broods from collected nests, we evaluated the production of cells and eggs per day, prey spiders, and seasonal patterns of nesting activities. We found a relatively short critical period of switching from the summer generation into the overwintering generation. We also found that the voltinism is affected by the timing of egg production of the second generation in relation to this critical period. The developmental period for each generation and sex, voltinism and cell production per day were determined based on data for a large number of individuals for the first time.

Accurate morphological ant mimicry by Myrmarachne jumping spiders confers strong protective benefits against predators. However, it has been hypothesized that the slender and constricted ant-like appearance imposes costs on the hunting ability because their jumping power to capture prey is obtained from hydraulic pressure in their bodies. This hypothesis remains to be sufficiently investigated. We compared the jumping and prey-capture abilities of seven Myrmarachne species and non-myrmecomorphic salticids collected from tropical forests in Malaysian Borneo and northeastern Thailand. We found that the mimics had significantly reduced abilities compared with the non-mimics. The analysis using geometric morphometric techniques revealed that the reduced abilities were strongly associated with the morphological traits for ant mimicry and relatively lower abilities were found in Myrmarachne species with a more narrowed form. These results support the hypothesis that the jumping ability to capture prey is constrained by the morphological mimicry and provide a new insight into understanding the evolutionary costs of accurate mimicry.

The systematics of the subgenus Stigmatodipogon Ishikawa of the genus Dipogon Fox is revised. Six species are listed. Two new species, Dipogon (Stigmatodipogon) kurokawai Shimizu, sp. nov. (Honshu, Japan) and D. (S.) lao Loktionov & Lelej, sp. nov. (Laos) are described and illustrated and other four species from Japan, the Russian Far East and Eastern Siberia are redescribed. A new combination is proposed for D. (S.) budrisi (Loktionov & Lelej, 2014), comb. nov. Nesting records of D. (S.) kurokawai and prey records of D. (S.) macrostigmatus Ishikawa, 1959 and D. (S.) petiolatus Lelej, 1986 are presented. These are the first records of biology for this subgenus. A key to species is provided.

In tropical rain forests, high canopy trees have diverse and abundant populations of ants and spiders. However, accessing high trees and their fauna remains difficult; thus, how ants and spiders interact in the canopy remains unclear. To better understand the interspecific interactions between these two dominant arthropod groups, we investigated their spatial distributions at the canopy surface in a tropical rain forest in Borneo. We sampled ants and spiders six times between 2009 and 2011 by sweeping with an insect net at the tree crown surfaces of 190 emergent or tall (≥20 m in height) trees. We collected 438 ant individuals belonging to 94 species and 1850 spider individuals (1630 juveniles and 220 adults) belonging to 142 morphospecies (adults only) from a total of 976 samples. The fact that we collected four times more spider individuals than ant individuals suggests that fewer ants forage at the tree crown surface than previously thought. The number of spider individuals negatively correlated with the number of ant individuals and the number of ant species, indicating significant exclusivity between ant and spider spatial distributions at the tree crown surface. Niche-overlap between the two taxa confirmed this observation. Although our data do not address the causes of these spatial distributions, antagonistic interspecific interactions such as interference behaviors and intra-guild predation are ecological mechanisms that give rise to exclusive spatial distributions.

A new species of the genus Castoponera Deeleman-Reinhold, 2001, Castoponera christae sp. n., is described here. The species is closely related to Castoponera lecythus Deeleman-Reinhold, 2001, but can be distinguished by the structures of the male palp and the female genitalia.

A trap-nesting study provided the first documentation of brood parasitism in Dipogon nagasei and in D. iwatai. Dipogon nagasei was found to brood parasitize D. sperconsus, D. conspersus, D. inconspersus, and D. bifasciatus. Dipogon iwatai brood parasitized D. sperconsus, D. conspersus, D. romankovae, and Auplopus carbonarius. Both brood parasitic species are with the subgenus Nipponodipogon, whereas all five Dipogon hosts are in the subgenus Deuteragenia. Comparison of their ecological features revealed that brood parasitism in D. nagasei is considerably more derived than in D. iwatai. Of particular note is the fact that in D. nagasei the female routinely lays up to five eggs on a single host spider, all of which develop into adult wasps without larval cannibalism; almost all Pompilidae previously studied lay only one egg on a host spider.

Phoretic deutonymphs of Sennertia alfkeni and S. japonica, both associated with the Japanese large carpenter bee, Xylocopa appendiculata, were distinguished by Fain (1974) by body size and the presence or absence of a spine proximal to the pretarsal claw. Despite these morphological differences, rearing of iso‐female lines yielded both morphological forms, thus revealing that both were the same species but functionally different during phoresy. Adults also expressed variation in the form of the dorsal setae, ranging from narrow to broad. We hypothesized that deutonymphal morphology was controlled environmentally, but that the adult setal morphology was at least partially controlled genetically. Both types of deutonymphs disembarked from a female bee during the host tunnelling through provisioning of nests in spring, but there seemed to be no behavioural difference between the two morphs at the time of disembarkation.

Scoliid wasps are ectoparasitoids that attack soil-dwelling scarabaeid larvae, and little is known about their host-searching behavior. In this study we investigated the cues used in host location by Campsomeriella annulata (Fabricius) and examined whether or not these wasps can detect hosts in the soil from the surface. In a dual-choice test with a Y-tube, female wasps were attracted to sand with host odor, sand with host feces, and sand used for rearing the host, the larvae of Anomala rufocuprea Motschulsky (Coleoptera: Scarabaeidae). In a dual-choice test for cues presented at a distance, the wasps did not discriminate between the Y-tube arms with and without cues. In an experimental arena in which host products and a host grub were buried 0.5 cm below the surface the wasps did not respond to the cues from the surface in terms of the burrowing frequencies and antennal tapping rates. Our results indicate that C. annulata searches for the host grubs by using kairomones, residual cuticular substances, or feces deposited in the soil as the grubs move through it, and that wasps cannot perceive the host in the soil from the surface. We discuss how scoliid wasps search for soil-dwelling hosts using cues that are reliable but not highly detectable.

The spatial and temporal distributions of scoliid wasps in the coastal sand dunes at Hakoishi, Kyoto Prefecture, Japan, were investigated using three different sampling methods in 2002 and 2003. Of eight scoliid species collected in the present study, five species, Scolia historionica, Campsomeriella annulata, Scolia decorata, Scolia oculata, and Megacampsomeris schulthessi, were dominant. The flying insects caught by Malaise traps and flower-visiting insects caught by insect nets were mostly males, and this biased pattern was due to the active mate-searching behavior of male wasps and their frequent visits to flowers to supplement energy consumed by such behavior. Given that the ground traps caught females exclusively, female wasps seemed to actively engage in host-searching behavior on and below the ground. Of the wasps caught by Malaise traps and flower-visit sampling, five dominant species showed spatially different habitat use: S. historionica and C. annulata mainly occupied the grassland zone on the plain (Gp), S. decorata occupied the grassland zone on the terrace (Gt) and the forest zone (Fp), S. oculata occupied the small scrub zone on the plain (Sp), and M. schulthessi occupied the small scrub zone on the terrace (St). Ground trap samples also indicated that S. historionica and C. annulata shared habitats. On the basis of the observed seasonal changes in wasp abundance and the degree of wing wear as an index of wasp age, S. historionica and C. annulata are thought to be bivoltine species, whereas S. decorata, S. oculata, and M. schulthessi are thought to be univoltine species. These scoliid wasp species may play an important role in pollinating coastal plants in the grassland zone.

Prey selection by a spider wasp,Batozonellus lacerticida, was investigated at the riverside of the Toyohira River in Misumai, Sapporo, Hokkaido over 7 years from 1981 to 1987. Seventeen species of araneid spiders were found in the study area and six of them were hunted by the wasps. Most (97.3%) of the 223 prey records obtained were of three species,Araneus macacus, A. marmoreus andA. pinguis. Nesting activity of the wasps continued until mid-August in 1981, 1982 and 1986, but stopped in July in 1984, 1985 and 1987. The length of nesting period was related to whether the wasps successfully switched prey species fromA. macacus toA. marmoreus andA. pinguis andA. pinguis or not Switching seemed to occur at the phase when density ofA. macacus remained high, depending on the density of largerA. marmorus andA. pinguis. This switching had large effects on species composition and size distribution of actual prey. Chesson's index α calculated at every 10 day period revealed that the wasps preferredA. macacus to the two other species and large prey to medium and small ones. The effect of prey density on preference depended on whetherA. macacus was present or absent. In the presence of it there were only slight differences in preference among various conditions of prey density. However, whenA. macacus was absent, densities of bothA. marmoreus andA. pinguis had some complementary effects on preference. The importance of prey size selection by pompilid wasps, and implications of density effects on preference are discussed.

Insects flying into the web of an orb-weaving spiderAraneus pinguis (Karsch) and their avoidance of (pre-hitting process) and escapes from (post-hitting process) the web were examined by direct observation under natural and semi-natural conditions. In the pre-hitting process, mobile insects such as Brachycera, Lepidoptera and Hymenoptera showed a low hitting ratio (number of insects hitting/number of insects flying within 1 m3 space around the web-site) because of active web avoidance and flying activity in layers lower or higher than those in which the webs are usually laid. In contrast, less mobile insects like Heteroptera, Coleoptera and Homoptera showed a high hitting ratio. In the post-hitting process, Brachycera, Lepidoptera and some Nematocera frequently escaped without being detained by the web. Many Orthoptera and Hymenoptera escaped without any sign of detection by the spider. Coleoptera frequently escaped during the spider's attack. Small insects from the Homoptera, Nematocera and Hymenoptera rarely escaped from the web, but were not immediately attacked. Mean escape time of insects was correlated significantly with capture success of the spider. Overall most of the escapes occurred in the early phases of the predation process. This indicates that escapes are unlikely to result in heavy loss of time and energy expenditure due to unsuccessful predation. Escape patterns of insects seem to be related to their mobility.

The pattern of prey utilization of the orb-weaving spiderAraneus pinguis was studies by comparing between arthropods restrained in the empty webs (spiders were removed) and those unattacked in the intact webs (spiders were not removed). The number of arthropods was larger in the empty webs than in the intact webs. In the empty webs, web area, mesh width, number of radii, and signal thread length were presumed to affect the number of arthropods left in a single web. As for the intact webs, web area, mesh width, and web-exposure time were important factors. In the empty webs, the density of arthropods decreased away from the hub. On the other hand, the density of unattacked arthropods in the intact webs was the same throughout the web.