Redetermination of the crystal structure of yttrium chromium tetra-boride, YCrB4, from single-crystal X-ray diffraction data.

The structural parameters of yttrium chromium tetra-boride YCrB4 were refined based on single-crystal X-ray diffraction data. YCrB4 is ortho-rhom-bic, having a space group of type Pbam (No. 55) and with lattice parameters of a = 5.9425 (2), b = 11.4831 (4), c = 3.4643 (1) Å. The Y and Cr atoms are located at Wyckoff 4h sites (x, y, 0) and B atoms at the Wyckoff 4g sites (x, y, 1/2). The first structural investigation of YCrB4 was performed using a single crystalline sample [Kuz'ma, (1970 ▸). Kristallografiya. 15, 372-374]. The present study successfully refined all the positional and atomic displacement parameters of the Y, Cr, and B atoms.

Syntheses and structures of ammonium transition-metal dialuminium tris-(phosphate) dihydrates (NH4)MAl4(PO4)3·2H2O (M = Mn and Ni).

The structures of ammonium manganese(II) dialuminium tris-(phosphate) dihydrate, (NH4)MnAl2(PO4)3·2H2O, and ammonium nickel(II) dialuminium tris-(phosphate) dihydrate, (NH4)NiAl2(PO4)3·2H2O, were determined using single-crystal diffraction data. The structures of title compounds are isotypic to cobalt aluminophosphate, (NH4)CoAl2(PO4)3·2H2O (LMU-3) [Panz et al. (1998 ▸). Inorg. Chim. Acta, 269, 73-82], in which a three-dimensional network of vertex-sharing AlO5 and PO4 moieties delineate twelve-membered channels in which ammonium, NH4 +, and transition-metal cations (M = Mn2+ and Ni2+) reside as charge compensators for the anionic [Al2(PO4)3]3- aluminophosphate framework. In both structures, the N atom of the ammonium cation, the transition-metal ion and one of the P atoms lie on crystallographic twofold axes.

Biogeography and Ecological Differentiation of Pseudasphondylia gall midges (Diptera: Cecidomyiidae) Distributed in Taiwan and Japan, with Description of a New Species P. kiwiphila sp. nov. and the Southernmost Record of P. elaeocarpi.

Pseudasphondylia species (Diptera: Cecidomyiidae) are known to induce fruit galls on Actinidia rufa (Siebold & Zucc.) Planch. ex Miq. and finger-like leaf galls on Elaeocarpus sylvestris (Lour.) Poir. in Taiwan, but their taxonomic positions remain undetermined. Based on gall morphology and host plants, they were supposed to be the same or allied species of known Japanese congeners, i.e., P. matatabi Yuasa & Kumazawa inducing flower-bud galls on Actinidia polygama (Sieb. et Zucc.) Maxim and P. elaeocarpi Tokuda & Yukawa inducing finger-like leaf galls on E. sylvestris. Species identifications of these Taiwanese species provide us an opportunity to study biogeographical aspects and transition of ecological features in these Pseudasphondylia species distributed in East Asian Arc. Morphological comparisons and species delimitation by molecular analysis indicated that the cecidomyiid on the fruit of A. rufa is distinct from P. matatabi and thus it is described as a species new to science, P. kiwiphila sp. nov. Lin, Tokuda, & Yang. The leaf galler on E. sylvestris was identical to P. elaeocarpi, whose southernmost distribution range extended to Taiwan, a new record of its distribution. COI-based phylogenetic tree (Bayesian inference and IQ tree) of Pseudasphondylia suggested that leaf galling habitat and univoltine life history are ancestral, whereas fruit or flower-bud galling and multivoltine life history are derived. In addition, the monophyletic Actinidia-associated species lineage is sistered to the clade including the remaining Japanese fruit and flower-bud gallers, suggesting that Pseudasphondylia has colonized on the host genus Actinidia once and later speciated on different plant species of the host genus. As a biogeographical aspect of P. elaeocarpi, 2.7% of the COI distance between Japanese and Taiwanese individuals indicates that they have diverged around 1.2 mya, which corresponds to the last but second separation of Taiwan and Japan in the Pleistocene. As for Actinidia-associated Pseudasphondylia species, the two valid species are allopatric and have distinct areas of origin, suggesting they may have speciated allopatrically. Nevertheless, there is still the possibility of ecological speciation due to the following reasons: (1) Host species (and varieties) and unidentified congener of Actinidia-associated Pseudasphondylia are occurring China, revealing potential occurrence of these gall midges. (2) The divergence time (2.2-2.9 mya) of the two known species corresponds to the late Pliocene to Pleistocene, when China, Taiwan, and Japan were part of the East Asian continent. During this period, their host species were sympatric in southeast China. (3) The host of two named Actinidia-associated Pseudasphondylia species each belong to different plant groups with distinct fruit features. These presume that the speciation might have been caused via sympatric host shift.

Single-crystal structure refinements and Debye temperatures of Ir2S3 kashinite and Rh2S3 bowieite.

Single crystals of Ir2S3 (diiridium trisulfide) and Rh2S3 (dirhodium trisulfide) were grown in evacuated silica-glass tubes using a chemical transport method and their crystal structures were determined by single-crystal X-ray diffraction analysis. These compounds have a unique sesquisulfide structure in which pairs of face-sharing octahedra are linked into a three-dimensional structure by further edge- and vertex-sharing. Ir2S3 and Rh2S3 had similar unit-cell parameters and bond distances. The atomic displacement parameter (MSD: mean-square displacement) of each atom in Ir2S3 was considerably smaller than that in Rh2S3. The Debye temperatures (ΘD) estimated from the observed MSDs for the Ir, S1 and S2 sites in Ir2S3 were 259, 576 and 546 K, respectively, and those for Rh, S1 and S2 in Rh2S3 were 337, 533 and 530 K, respectively. The bulk Debye temperature for Ir2S3 kashinite (576 K) was found to rank among the higher values reported for many known sulfides. The bulk Debye temperature for Rh2S3 bowieite (533 K) was lower than that for Ir2S3 kashinite, which crystallizes in the early sequences of mineral crystallization differentiation from the primitive magma in the Earth's mantle.

Crystal structure, XANES and charge distribution investigation of krennerite and sylvanite: analysis of Au-Te and Te-Te bonds in Au1-xAgxTe2 group minerals.

The structure refinement and XANES study of two gold-silver-tellurides [Au1+xAgxTe2, krennerite (x = 0.11-0.13) and sylvanite (x = 0.29-0.31)] are presented and the structures are compared with the prototype structure of calaverite (x = 0.08-0.10). Whereas the latter is well known for being incommensurately modulated at ambient conditions, neither krennerite nor sylvanite present any modulation. This is attributed to the presence of relatively strong Te-Te bonds (bond distances < 2.9 Å) in the two minerals, which are absent in calaverite (bond distances > 3.2 Å). In both tellurides, trivalent gold occurs in slightly distorted square planar coordination, whereas monovalent gold, partly substituted by monovalent silver, presents a 2+2+2 coordination, corresponding to distorted rhombic bipyramids. The differentiation between bonding and non-bonding contacts is obtained by computation of the Effective Coordination Number (ECoN). The CHARge DIstribution (CHARDI) analysis is satisfactory for both tellurides but suggests that the Te-Te bond in the [Te3]2- anion is not entirely homopolar. Both tellurides can therefore be described as Madelung-type compounds, despite the presence of Te-Te in both structures.

Transgenerational changes in pod maturation phenology and seed traits of Glycine soja infested by the bean bug Riptortus pedestris.

Land plants have diverse defenses against herbivores. In some cases, plant response to insect herbivory may be chronological and even transgenerational. Feeding by various stink bugs, such as the bean bug Riptortus pedestris (Hemiptera: Alydidae), induce physiological changes in soybean, called as green stem syndrome, which are characterized by delayed senescence in stems, leaves, and pods. To investigate the plant response to the bean bug feeding in the infested generation and its offspring, we studied the effects of R. pedestris infestation on Glycine soja, the ancestral wild species of soybean. Field surveys revealed that the occurrence of the autumn R. pedestris generation coincided with G. soja pod maturation in both lowland and mountainous sites. Following infestation by R. pedestris, pod maturation was significantly delayed in G. soja. When G. soja seeds obtained from infested and non-infested plants were cultivated, the progeny of infested plants exhibited much earlier pod maturation and larger-sized seed production than that of control plants, indicating that R. pedestris feeding induced transgenerational changes. Because earlier seed maturity results in asynchrony with occurrence of R. pedestris, the transgenerational changes in plant phenology are considered to be an adaptive transgenerational and chronological defense for the plant against feeding by the stink bug.

Terrestrial arthropods broadly possess endogenous phytohormones auxin and cytokinins.

Some herbivorous insects possess the ability to synthesize phytohormones and are considered to use them for manipulating their host plants, but how these insects acquired the ability remains unclear. We investigated endogenous levels of auxin (IAA) and cytokinins (iP and tZ), including their ribosides (iPR and tZR), in various terrestrial arthropod taxa. Surprisingly, IAA was detected in all arthropods analysed. In contrast, tZ and/or tZR was detected only in some taxa. Endogenous levels of IAA were not significantly different among groups with different feeding habits, but gall inducers possessed significantly higher levels of iPR, tZ and tZR. Ancestral state reconstruction of the ability to synthesize tZ and tZR revealed that the trait has only been acquired in taxa containing gall inducers. Our results strongly suggest critical role of the cytokinin synthetic ability in the evolution of gall-inducing habit and IAA has some function in arthropods.

Redetermination of the crystal structures of rare-earth trirhodium diboride RERh3B2 (RE = Pr, Nd and Sm) from single-crystal X-ray data.

The crystal structures of the rare-earth (RE) trirhodium diborides praseo-dymium trirhodium diboride, PrRh3B2, neodymium trirhodium diboride, NdRh3B2, and samarium trirhodium diboride, SmRh3B2, were refined on the basis of single-crystal X-ray diffraction data. The crystal chemistry of RERh3B2 (RE: Pr, Nd, and Sm) compounds has previously been analyzed mainly on the basis of powder samples [Ku et al. (1980 ▸). Solid State Commun. 35, 91-96], and no structural investigation by single-crystal X-ray diffraction has been reported so far. The crystal structures of the three hexa-gonal RERh3B2 compounds are isotypic with that of CeRh3B2; RE, Rh and B sites are situated on special positions with site symmetry 6/mmm (Wyckoff position 1a), mmm (3g) and m2 (2c), respectively. In comparison with the previous powder X-ray study of hexa-gonal RERh3B2, the present redetermination against single-crystal X-ray data has allowed for the modeling of all atoms with anisotropic displacement parameters (ADPs). The ADPs of the Rh atom in each of the structures result in an elongated displacement ellipsoid in the direction of the stacking of the Rh kagomé-type layer. The features of obtained ADPs of atoms are discussed in relation to RERh3B2-type and analogous structures.

Comprehensive analyses of agrochemicals affecting aquatic ecosystems: A case study of Odonata communities and macrophytes in Saga Plain, northern Kyushu, Japan.

The negative influence of agrochemicals (pesticides: insecticide, fungicide, and herbicide) on biodiversity is a major ecological concern. In recent decades, many insect species are reported to have rapidly declined worldwide, and pesticides, including neonicotinoids and fipronil, are suspected to be partially responsible. In Japan, application of systemic insecticides to nursery boxes in rice paddies is considered to have caused rapid declines in Sympetrum (Odonata: Libellulidae) and other dragonfly and damselfly populations since the 1990s. In addition to the direct lethal effects of pesticides, agrochemicals indirectly affect Odonata populations through reductions in macrophytes, which provide a habitat, and prey organisms. Due to technical restrictions, most previous studies first selected target chemicals and then analyzed their influence on focal organisms at various levels, from the laboratory to the field. However, in natural and agricultural environments, various chemicals co-occur and can act synergistically. Under such circumstances, targeted analyses might lead to spurious correlations between a target chemical and the abundance of organisms. To address such problems, in this study we adopted a novel technique, "Comprehensive Target Analysis with an Automated Identification and Quantification System (CTA-AIQS)" to detect wide range of agrochemicals in water environment. The relationships between a wide range of pesticides and lentic Odonata communities were surveyed in agricultural and non-agricultural areas in Saga Plain, Kyushu, Japan. We detected significant negative relationships between several insecticides, i.e., acephate, clothianidin, dinotefuran, flubendiamide, pymetrozine, and thiametoxam (marginal for benthic odonates) and the abundance of lentic Epiprocta and benthic Odonates. In contrast, the herbicides we detected were not significantly related to the abundance of aquatic macrophytes, suggesting a lower impact of herbicides on aquatic vegetation at the field level. These results highlight the need for further assessments of the influence of non-neonicotinoid insecticides on aquatic organisms.

Intertidal insects associated with halophytic Suaeda (Amaranthaceae) in Japan: a case study in Saga, northern Kyushu.

In contrast to a great diversity in insects in terrestrial and freshwater ecosystems, few known species have adapted to inhabit marine environments. In this study, we surveyed insects associated with halophytic plants of Suaeda (Amaranthaceae) distributed in intertidal zones, in northern Kyushu, Japan. On four Japanese native species of Suaeda, we found insects belonging to five orders and 18 species. Amongst them, the genus Clanoneurum (Diptera: Ephydridae) and Coleophoradeviella (Lepidoptera: Coleophoridae) were newly reported from Japan; and Orthotylus (Melanotrichus) parvulus (Hemiptera: Miridae) was newly recorded from Kyushu. The seasonal occurrence of several insects on Suaeda is reported.

Life history of the endangered Japanese striped loach, Cobitis kaibarai (Cypriniformes: Cobitidae), with special reference to its reproductive ecology and the influence of creek reshapings on its population density.

In recent years, the biodiversity of freshwater fishes has been markedly decreasing worldwide because of anthropogenic activities. The Japanese striped loach, Cobitis kaibarai (Cypriniformes: Cobitidae), is a primary freshwater fish endemic to northern Kyushu, Japan. This species is designated as endangered IB class in the Red List by the Japan Ministry of the Environment. Its population is decreasing, possibly because of habitat loss and degradation. To conserve C. kaibarai populations, information on its basic ecology is necessary; nonetheless, its detailed life history and reproductive ecology have yet to be clarified. In this study, the authors conducted monthly capture-mark-recapture surveys and periodical observations to investigate the life history, spawning sites and season of C. kaibarai. They also evaluated the influence of creek reshaping (concrete revetment) on the C. kaibarai population in Saga Plain, northern Kyushu. Between 2015 and 2018, more individuals were captured during winter than summer. The average body width of females peaked in early June and small immatures were confirmed from July. Some individuals were captured across 15 or more months after their initial marking. In the survey of reproductive sites, eggs and larvae of C. kaibarai were found in shallow areas in mid-June; these were temporarily submerged following the increase in water level from early June. Therefore, C. kaibarai spawns in shallow areas during this season. Based on the capture-mark-recapture surveys, the estimated population density of C. kaibarai significantly decreased in a census site that had undergone creek reshaping, which contrasted with the results in a control site, where no significant difference was detected. The standard length of C. kaibarai increased following creek reshaping, suggesting that the proportion of C. kaibarai postponing spawning had increased, possibly because of degradation of spawning environments. The results of this study provide important ecological knowledge for the conservation of C. kaibarai and emphasize the importance of shallow waters for floodplain spawners.

A new species of Pseudasphondylia (Diptera: Cecidomyiidae) associated with Magnolia kobus DC. var. borealis Sarg. (Magnoliaceae) in Japan.

BACKGROUND: A gall midge species (Diptera: Cecidomyiidae) inducing leaf bud galls on Magnolia kobus DC. var. borealis Sarg. (Magnoliaceae) was found in Hokkaido and northern Honshu, Japan. NEW INFORMATION: Based on its morphology, the species is regarded as an undescribed species of the genus Pseudasphondylia Monzen (Cecidomyiinae, Cecidomyiidi, Asphondyliini). The species is herein described as Pseudasphondylia saohimea Matsuda, Elsayed and Tokuda sp. n. The new species is easily distinguishable from its congeners by the number of adult palpal segments and the shape of the male terminalia and larval spatula.

Geographic Variation in Photoperiodic Response for Induction of Pseudopupal Diapause in Epicauta gorhami (Coleoptera: Meloidae).

Geographical variations in the threshold of environmental cues for diapause induction are important in understanding the life history strategy of insects. Larvae of the bean blister beetle, Epicauta gorhami (Coleoptera: Meloidae), feed on grasshopper eggs and undergo hypermetamorphosis. They normally enter diapause as a pseudopupa (fifth instar). However, when the larvae are reared under long-day and high-temperature conditions, they do not enter pseudopupal diapause but pupate directly from the fourth instar. In addition, this insect is known to modify its photoperiodic response for induction of pseudopupal diapause depending on food availability for larvae. In this study, the larval photoperiodic responses for diapause induction were examined for three populations of E. gorhami collected from the northernmost (Morioka, 39.7°N), central (Kazo, 36.1°N), and southernmost (Takanabe, 32.1°N) parts of its distribution range, and the responses were examined under both fully fed and food-deprived (FD) conditions. Diapause incidence decreased in FD larvae for all populations in long-day conditions, and the critical day-lengths for the diapause incidence were calculated as 14.81, 13.97, and 13.99 h in the Morioka, Kazo, and Takanabe populations, respectively. The results indicate the presence of a geographical variation in larval photoperiodic response, in which diapause is induced earlier in higher latitudinal areas. From these results, together with data for developmental threshold temperature and thermal constant, the Morioka and Kazo populations were suggested to have a partial bivoltine life cycle under the conditions of extremely early oviposition season, a sufficient summer temperature, and poor larval food availability.

Oviposition by a lycaenid butterfly onto old host parts is adaptive to avoid interference by conspecific larvae.

Oviposition site selection by herbivores can depend not only on the quality of host resources, but also on the risk of predation, parasitism and interference. Females of the lycaenid butterfly Arhopala bazalus (Lepidoptera) lay eggs primarily on old host foliage away from fresh growth, where larval offspring live and feed. Resource availability of young host leaves seems not to affect the oviposition site preference by the females. To clarify the adaptive significance of A. bazalus oviposition behavior on old foliage, we tested three hypotheses: eggs on fresh foliage are (1) easily dropped during rapid leaf expansion (bottom-up hypothesis), (2) more likely to be attacked by egg parasitoids (top-down hypothesis), and (3) frequently displaced or injured by other herbivores (interference hypothesis). In field surveys, rates of egg dropping and parasitism by egg parasitoids were not significantly different between fresh and old host parts. However, the portions of fresh leaves on which A. bazalus eggs had been laid were cut from shoots on which conspecific larvae fed. Laboratory experiments demonstrated that eggs on young leaves were displaced in the presence of conspecific larvae and we observed that fifth instar larvae actively displaced conspecific eggs by feeding on the surrounding leaf tissue. These findings indicate that eggs laid on fresh leaves are at risk of being displaced by conspecific larvae, and support the interference hypothesis. Larval behavior is a likely evolutionary force for A. bazalus to lay eggs apart from larval feeding sites on the host plant.

Crystal structure refinements of stoichiometric Ni3Se2 and NiSe.

Single crystals of Ni3Se2 (trinickel diselenide) and NiSe (nickel selenide) with stoichiometric chemical compositions were grown in evacuated silica-glass tubes. The chemical compositions of the single crystals of Ni3Se2 and NiSe were determined by scanning electron microscopy and energy-dispersive X-ray spectroscopy (SEM/EDS). The crystal structures of Ni3Se2 [rhombohedral, space group R32, a = 6.02813 (13), c = 7.24883 (16) Å, Z = 3] and NiSe [hexagonal, space group P63/mmc, a = 3.66147 (10), c = 5.35766 (16) Å, Z = 2] were analyzed by single-crystal X-ray diffraction and refined to yield R values of 0.020 and 0.018 for 117 and 85 unique reflections, respectively, with Fo > 4σ(Fo). R32 is a Sohncke type of space group where enantiomeric structures can exist; the single-domain structure obtained by the refinement was confirmed to be correct by a Flack parameter of -0.05 (2). The existence of Ni-Ni bonds was confirmed in both compounds, in addition to the Ni-Se bonds. The value of the atomic displacement parameter (mean-square displacement) of each atom in NiSe was larger than that in Ni3Se2. The larger amplitude of the atoms in NiSe corresponds to longer Ni-Se and Ni-Ni bond lengths in NiSe than in Ni3Se2. The Debye temperatures, θD, estimated from observed mean-square displacements for Ni and Se in Ni3Se2, were 322 and 298 K, respectively, while those for Ni and Se in NiSe were 246 and 241 K, respectively. The existence of large cavities in the structure and the weak bonding force are likely responsible for the brittle and soft nature of the NiSe crystal.

Three new species of Ametrodiplosis (Diptera: Cecidomyiidae) from Japan, with a key to the Japanese species and a molecular phylogenetic analysis.

Ametrodiplosis Rübsaamen (Diptera: Cecidomyiidae: Clinodiplosini) is a mostly Holarctic gall midge genus whose species are associated with a wide range of seed plant families, either as gall-inducers or inquilines. In this study, we describe three species of Ametrodiplosis from Japan: A. adetos n. sp. feeding in the flowers of Tylophora aristolochioides Miq. (Apocynaceae); A. aeroradicis n. sp. inducing aerial root galls on Trachelospermum asiaticum (Sieb. et Zucc.) Nakai and T. gracilipes var. liukiuense (Apocynaceae); and A. stellariae n. sp. forming leaf bud galls on Stellaria uliginosa Murray var. undulata (Thunb.) Ohwi (Caryophyllaceae). A molecular phylogenetic analysis using mitochondrial COI and ribosomal 16S genes and nuclear ribosomal 28S gene were conducted for the three new Ametrodiplisis species and other clinodiplosine taxa sequences available in GenBank. The analysis supported the monophyly of Ametrodiplosis despite the variable life history of the three species. In addition, it indicated very low intraspecific genetic divergence among the individuals from different localities and/or host plants. A taxonomic key to the three new Japanese species of Ametrodiplosis is provided.

Silence of the killers: discovery of male-killing suppression in a rearing strain of the small brown planthopper, Laodelphax striatellus.

According to evolutionary theory, sex ratio distortions caused by reproductive parasites such as Wolbachia and Spiroplasma are predicted to be rapidly normalized by the emergence of host nuclear suppressors. However, such processes in the evolutionary arms race are difficult to observe because sex ratio biases will be promptly hidden and become superficially unrecognizable. The evolution of genetic suppressors has been reported in just two insect species so far. In the small brown planthopper, Laodelphax striatellus, female-biases caused by Spiroplasma, which is a 'late' male-killer, have been found in some populations. During the continuous rearing of L. striatellus, we noted that a rearing strain had a 1 : 1 sex ratio even though it harboured Spiroplasma. Through introgression crossing experiments with a strain lacking suppressors, we revealed that the L. striatellus strain had the zygotic male-killing suppressor acting as a dominant trait. The male-killing phenotype was hidden by the suppressor even though Spiroplasma retained its male-killing ability. This is the first study to demonstrate the existence of a late male-killing suppressor and its mode of inheritance. Our results, together with those of previous studies, suggest that the inheritance modes of male-killing suppressors are similar regardless of insect order or early or late male killing.

Revision of the birch-associated genus Massalongia (Diptera, Cecidomyiidae), with description of a new species from Japan and a taxonomic key to worldwide species.

Betula (Betulaceae), or birch, is a Holarctic genus of trees and shrubs whose species have ornamental, industrial, and medical importance. Gall midges of the genus Massalongia (Diptera: Cecidomyiidae: Cecidomyiidi) are exclusively associated with birches in the Palearctic region. In 2018, an undescribed Massalongia species was discovered forming leaf galls on the midveins of B. grossa on Mount Tara, Saga Prefecture, Kyushu, Japan. In this study the species is described as M. nakamuratetsui Elsayed & Tokuda, sp. nov., and a DNA barcode provided for it. The other known species of Massalongia are redescribed because the original descriptions are outdated and insufficient. A lectotype is designated for M. bachmaieri. In addition, the monotypic genus Apagodiplosis, containing A. papyriferae associated with B. papyrifera in the Nearctic region, is synonymized here under Massalongia, resulting in M. papyriferae comb. nov., rendering Massalongia a Holarctic genus with six species. Comparing the sequence data of M. nakamuratetsui with all sequences available in The Barcode of Life Data (BOLD) system supports the occurrence of Massalongia in the Nearctic region and suggest that more species could be discovered there. Massalongia species form leaf or bud galls, and their mature larvae drop to the ground in autumn and overwinter in characteristic waterproof bottle-like cocoons, which is possibly a protective adaptation for pupation in wet and snowy lands. A taxonomic key to all Massalongia species is provided.

Orange Leafhopper Cicadulina bipunctata Feeding Induces Gall Formation Nitrogen Dependently and Regulates Gibberellin Signaling.

Orange leafhopper Cicadulina bipunctata feeding induces wallaby ear symptoms, namely growth suppression and gall formation characterized by severe swelling of leaf veins, on various Poaceae, thereby leading to low crop yields. Here, we investigated the development of wallaby ear symptoms on rice seedlings due to C. bipunctata feeding. After confirming that C. bipunctata feeding induces growth suppression and gall formation on rice seedlings, we further demonstrated that gall formation score decreased with decreasing levels of nitrogen in the medium and that C. bipunctata feeding induces the expression levels of nitrogen transporter genes. These gene expression changes may participate in the nutrient accumulation observed in galled tissues and in gall formation. In addition, these expression changes should induce growth promotion but the inhibition of gibberellin signaling by C. bipunctata feeding might be the reason why growth is suppressed. Treatment with plant growth regulators did not affect gall formation, suggesting the existence of a complex gall formation mechanism by C. bipunctata feeding.

Dispersal of the Common Cutworm, Spodoptera litura, Monitored by Searchlight Trap and Relationship with Occurrence of Soybean Leaf Damage.

The common cutworm, Spodoptera litura Fabricius (Lepidoptera: Noctuidae) is a major pest of soybean. Pheromone traps are used to monitor male adults, but the catch peaks do not always predict leaf damage in soybean fields. Thus, there is no accurate means of forecasting soybean damage, and insecticide is applied on the basis of farmers' observations of actual damage in fields. To understand the occurrence of soybean leaf damage, the dispersal of S. litura in a soybean field in southwestern Japan was preliminarily investigated using a searchlight trap in comparison to a pheromone trap at one location, from August to mid-October in 2016-2018. To determine the relationship between pest arrival and crop damage, trap catch numbers and the number of soybean leaves damaged by 1st-instar larvae were examined by separately comparing raw numbers and cumulative numbers. The raw catch numbers of the two trap types in August and September 2016 and 2018 preceded subsequent damage peaks by an average of 5.3 days. This temporal difference coincided with the estimated duration of the egg stage plus an assumed mating period. Furthermore, the cumulative catch numbers of the two traps in August and September were linearly associated with cumulative damaged leaves in the same period in each year and in the three-year period. The coefficient of determination (R2) of linear regression between the cumulative catch numbers of the searchlight trap and the cumulative damaged leaves for the three-year period was much higher than that between the cumulative catch of the pheromone trap and cumulative damage. This suggests that soybean leaf damage is closely linked to the number of S. litura arrivals at the survey site. Thus, the searchlight trap captured S. litura arrivals better than the pheromone trap. As the linear regression function of the cumulative catch of the searchlight trap for the three-year period was tentatively correlated with a prefectural economic injury level for soybean fields, it might be feasible to predict S. litura-induced soybean damage using searchlight traps. The cumulative female catch number of the searchlight trap was also linearly associated with damaged leaves, but the coefficient of determination was generally lower than that with the cumulative total catch. The female ratio of searchlight trap catches in September was <0.5 in contrast to S. litura migrating overseas (>0.5). The advantages and disadvantages of the two trapping methods, as well as necessary further studies are discussed. Our findings provide a foundation for S. litura monitoring with searchlight traps.