Behavioral Comparison in Males of Two Praying Mantis Species of the Same Genus, Hierodula patellifera and H. chinensis (Mantodea: Mantidae: Hierodulinae) in Japan, in Response to the Conspecific or Allospecific Species of Calling Females and Females' Headspace Crude Extract.

For many years, only one species of praying mantis in the genus Hierodula, Hierodula patellifera Serville, had been recorded in Japan. In recent years, however, Hierodula chinensis Werner, a larger species than H. patellifera Serville, has been discovered in Japan, and observations and collections in Japan have increased rapidly. There are reports that in some areas, H. patellifera became locally extinct due to the invasion of H. chinensis. Since females of H. patellifera attract conspecific males by volatile with characteristic calling behavior, a sex pheromone-mediated reproductive interference may exist between the two species. Both males of H. patellifera and males of H. chinensis were strongly attracted to conspecific females and crude headspace extract from conspecific females, while they were not attracted to females of allospecific species or crude headspace extract from allospecific females. These results indicate that sex pheromone-mediated reproductive interference may not exist between H. patellifera and H. chinensis.

Estimating plant-insect interactions under climate change with limited data.

Climate change may disrupt species-species interactions via phenological changes in one or both species. To predict and evaluate the influence of climate change on these interactions, long-term monitoring and sampling over large spatial areas are required; however, funding and labor constraints limit data collection. In this study, we predict and evaluate the plant-insect interactions with limited data sets. We examined plant-insect interaction using observational data for development of the crop plant rice (Oryza sativa) and an effective accumulated temperature (EAT) model of two mirid bugs (Stenotus rubrovittatus and Trigonotylus caelestialium). We combined 11 years of records monitoring rice phenology and the predicted phenology of mirid bugs using spatially-explicit EAT models based on both spatially and temporally high resolutions temperature data sets, then evaluated their accuracy using actual pest damage records. Our results showed that the predicted interactions between rice and mirid bugs explained rice damage to some degree. Our approach may apply predicting changes to plant-insect interactions under climate change. As such, combining plant monitoring records and theoretical predictions of insect phenology may be effective for predicting species-species interactions when available data are limited.

Intraspecific variations in life history traits of two pecky rice bug species from Japan: Mapping emergence dates and number of annual generations.

The mirid bugs Stenotus rubrovittatus and Trigonotylus caelestialium, which cause pecky rice, have become a threat to rice cultivation in Asia. Damage caused by these pests has rapidly become frequent since around 2000 in Japan. Their expansion pattern is not simple, and predicting their future spread remains challenging. Some insects with wide ranges have locally adapted variations in life-history traits. We performed laboratory rearing experiments to assess the geographical scale of intraspecific variations in life-history traits of S. rubrovittatus and T. caelestialium. The experiments were aimed at increasing the accuracy of occurrence estimates and the number of generations per year. These results were compared with previous research, and differences in development rates were observed between populations of different latitudes, but not of the same latitude. Finally, plotting the timing of adult emergence and the potential number of generations per year on maps with a 5-km grid revealed that they differed greatly locally at the same latitude. These maps can be used for developing more efficient methods of managing mirid bugs in integrated pest management.

Complete mitochondrial DNA sequence of the paper wasp Polistes riparius (Hymenoptera: Vespidae).

The paper wasp Polistes riparius is distributed in cold regions of northern East Asia to Russia. P. riparius are characterized by having longer cells than those of the closely related P. chinensis, which has a similar life history, as an adaptation to cold regions. The phylogenetic relationships of paper wasps have recently been studied; however, the genetic diversity and population structure of P. riparius has not been determined. The present study is the first to analyze the complete mitochondrial genome using next generation sequencing of P. riparius collected from Sapporo, Hokkaido Prefecture, Japan. The genome consisted of a closed loop that was 16,383 bp-long and included 13 protein coding genes (PCGs), 22 tRNA genes, two rRNA genes, and one AT-rich control region. The average AT content was 84.54%. The heavy (H)-strand was predicted to have 12 PCGs and 14 tRNA genes, while the light (L)-strand was predicted to contain one PCGs, eight tRNA genes, and two rRNA genes. All PCGs started with ATG. Stop codons were of two types: TAA for 11 genes (ND1, ND2, ND3, ND4L, ND5, ND6, COXI, COXII, COXIII, COB, ATP6 and ATP8) and TAG for two genes (ND3 and ND4). The molecular phylogenetic relationship based on the maximum likelihood method using 13 PCGs was consistent with some previous studies in which a closely relationship between P. riparius and P. jokahamae.

Reproductive interference by alien hornet Vespa velutina threatens the native populations of Vespa simillima in Japan.

The yellow-legged hornet Vespa velutina has become one of the major alien species in European and East Asian countries. As in its homeland, the invading V. velutina is reported as the major predator of honeybees and is becoming a threat to beekeeping in Europe. However, it remains unknown how V. velutina might affect native hornets when it invades Asia, where a large number of Vespa species are distributed. Thus, by analyzing the mitochondrial cytochrome c oxidase subunit I gene, we investigated whether interspecific mating occurs between V. velutina and Japanese native Vespa spp. Our results showed that the alien V. velutina causes reproductive interference in Japanese native hornet Vespa simillima. Forty-three percent of native V. simillima queens had the sperm of V. velutina males, and among the all V. simillima queens analyzed, 28% only had V. velutina sperm. We did not find evidence of V. velutina queens having the sperm of V. simillima males. These findings suggest that reproductive interference by V. velutina males poses a threat to the native V. simillima populations. A decline of V. simillima may also negatively affect other insects that interact with V. simillima.

Detecting crucial dispersal pathways using a virtual ecology approach: A case study of the mirid bug Stenotus rubrovittatus.

Detecting dispersal pathways is important both for understanding species range expansion and for managing nuisance species. However, direct detection is difficult. Here, we propose detecting these crucial pathways using a virtual ecology approach, simulating species dynamics using models, and virtual observations. As a case study, we developed a dispersal model based on cellular automata for the pest insect Stenotus rubrovittatus and simulated its expansion. We tested models for species expansion based on four landscape parameters as candidate pathways; these are river density, road density, area of paddy fields, and area of abandoned farmland, and validated their accuracy. We found that both road density and abandoned area models had prediction accuracy. The simulation requires simple data only to have predictive power, allowing for fast modeling and swift establishment of management plans.

Zingiber zerumbet CYP71BA1 catalyzes the conversion of α-humulene to 8-hydroxy-α-humulene in zerumbone biosynthesis.

Plant cytochrome P450s are involved in the biosynthesis of various classes of secondary metabolites. To elucidate the biosynthesis of zerumbone, a sesquiterpenoid with multiple potential anticancer properties, a family of P450 genes expressed in rhizomes of Zingiber zerumbet Smith, were cloned using a PCR-based cloning strategy. After functional expression in yeast, one of these P450s was found to convert α-humulene into 8-hydroxy-α-humulene, a proposed intermediate of zerumbone biosynthesis. This P450 has been designated CYP71BA1, a new member of the CYP71 family. CYP71BA1 transcripts were detected almost exclusively in rhizomes and showed a similar expression pattern to ZSS1 transcripts during rhizome development. Coexpression of a gene cluster encoding four enzymes of the mevalonate pathway with CYP71BA1 and ZSS1 in Escherichia coli leads to the production of 8-hydroxy-α-humulene in the presence of mevalonate, suggesting the possibility of microbial production of this zerumbone intermediate from a relatively simple carbon source by metabolic engineering.

Gonadotropic effects of dopamine in isolated workers of the primitively eusocial wasp, Polistes chinensis.

In social insects, biogenic amines are thought to play regulatory roles in the transition between reproductive states in females. To determine the effect of dopamine on the reproductive development of workers in primitively eusocial societies, isolated workers of the paper wasp Polistes chinensis were supplied with oral dopamine. Ovarian development was accelerated in dopamine-fed workers as compared to control workers of the same age fed only sucrose solution. Oral dopamine increased brain levels of dopamine and its metabolite (N-acetyldopamine). Brain levels of tyramine or octopamine were also increased by dopamine application in one of two colonies; levels of the tyramine metabolite N-acetyltyramine were unchanged. These results indicate that dopamine plays a gonadotropic role in isolated workers in the primitively eusocial wasp, similar to the gonadotropic role previously reported for juvenile hormone. This is the first study to report effects of dopamine on ovarian development in workers of the paper wasp.

Isolation and functional characterization of a beta-eudesmol synthase, a new sesquiterpene synthase from Zingiber zerumbet Smith.

In this paper, we have identified a new sesquiterpene synthase gene (ZSS2) from Zingiber zerumbet Smith. Functional expression of ZSS2 in Escherichia coli and in vitro enzyme assay showed that the encoded enzyme catalyzed the formation of beta-eudesmol and five additional by-products. Quantitative RT-PCR analysis revealed that ZSS2 transcript accumulation in rhizomes has strong seasonal variations. To further confirm the enzyme activity of ZSS2 and to assess the potential for metabolic engineering of beta-eudesmol production, we introduced a gene cluster encoding six enzymes of the mevalonate pathway into E. coli and coexpressed it with ZSS2. When supplemented with mevalonate, the engineered E. coli produced a similar sesquiterpene profile to that produced in the in vitro enzyme assay, and the yield of beta-eudesmol reached 100 mg/L.

Neuro-endocrine correlates of ovarian development and egg-laying behaviors in the primitively eusocial wasp (Polistes chinensis).

To explore the roles of biogenic amines in reproduction in workers in primitively eusocial societies, correlations between brain levels of biogenic amines and ovarian development or oviposition in workers of the paper wasp Polistes chinensis were investigated. Several workers in queenright colonies developed ovaries and were potential egg-layers. Maximum ovarian width was significantly correlated with brain levels of dopamine, serotonin and their metabolites (N-acetyldopamine and N-acetylserotonin). Individuals with developed ovaries proceeded with yolk formation had significantly higher levels of brain dopamine, serotonin and N-acetyldopamine compared with individuals with undeveloped ovaries. Brain dopamine levels were higher in egg-laying individuals than in other individuals with developed ovaries. Thus, the workers of the paper wasp showed quantitative differences in brain dopamine levels correlated with reproduction. These results suggest that the brain levels of biogenic amines in paper wasp workers correspond to their tasks, and that there is a mechanism for promoting reproduction by dopamine, as previously reported in the workers of eusocial bees.