Eurema Mandarina Research Articles

Polyhydroxy Acids as Fabaceous Plant Components Induce Oviposition of the Common Grass Yellow Butterfly, Eurema Mandarina.

The common grass yellow butterfly, Eurema mandarina is a Fabaceae-feeding species, the females of which readily oviposit on Albizia julibrissin and Lespedeza cuneata in mainland Japan. We previously demonstrated that the methanolic leaf extracts of these plants, and their highly polar aqueous fractions strongly elicit female oviposition. Furthermore, the three subfractions obtained by ion-exchange chromatographic separation of the aqueous fraction have been found to be less effective alone, but synergistically stimulate female oviposition when combined. This indicates that female butterflies respond to multiple compounds with different acidity. We have previously identified d-pinitol from the neutral/amphoteric subfractions and glycine betaine from the basic subfractions as oviposition stimulants of E. mandarina. The present study aimed to identify active compounds in the remaining acidic subfractions of A. julibrissin and L. cuneata leaf extracts. GC-MS analyses of trimethylsilyl-derivatized samples revealed the presence of six compounds in the acidic subfractions. In bioassays using these authentic chemicals, erythronic acid (EA) and threonic acid (TA) were moderately active in eliciting oviposition responses in E. mandarina, with their d-isomers showing slightly higher activity than their l-isomers. Female responsiveness differed between d-EA and l-TA, the major isomers of these compounds in plants, with the response to d-EA reaching a plateau at concentrations above 0.005% and that to l-TA peaking at a concentration of 0.01%. The natural concentrations of d-EA and l-TA in fresh A. julibrissin and L. cuneata leaves were sufficient to stimulate oviposition. Furthermore, mixing 0.001% d-EA or 0.001% l-TA, to which females are mostly unresponsive, with 0.1% d-pinitol resulted in a synergistic enhancement of the oviposition response. These findings demonstrate that E. mandarina females utilize both polyhydroxy acids, EA and TA, as chemical cues for oviposition.

Sex pheromones from male forewings of the Common Grass Yellow Eurema mandarina.

The common grass yellow Eurema mandarina has a characteristic patch (sex brand) composed of specialized scales (androconia) and wing intermembranous cells on the ventral surface of its male forewing. This structure is specific to males and is thought to release compounds that induce female mate acceptance. However, no study has demonstrated that these compounds function as sex pheromones in the genus Eurema. Here we report the identification of sex pheromones in males of E. mandarina. Chemical analyses revealed that 6,10,14-trimethylpentadecan-2-one (TMP) and (E/Z)-3,7,11,15-tetramethylhexadec-2-enal [(E/Z)-phytal] were male-specific and abundant in particular regions of the male forewings. TMP was highest in the sex brand, whereas (E/Z)-phytal was concentrated in the anal cell (cell 2A), lacking androconia and intermembranous cells. The content of these compounds increases with age in males after emergence. In bioassays, virgin females displayed a posture of bending their abdomens as mating acceptance in response to stimulation by fresh male forewings. However, solvent-washed male wings did not induce such female responses, suggesting that some compounds from male wings serve as triggers. When we examined female responses to compounds applied to solvent-washed male wings, authentic TMP and (E/Z)-phytal alone showed little activity. However, the mixture elicited abdomen-bending responses in one-third of the females. Therefore, TMP and (E/Z)-phytal were found to act synergistically as aphrodisiac sex pheromones for E. mandarina females, although these activities were weak.

계층분석방법(AHP)과 전문가 설문조사를 활용한 농업생태계 기후변화 지표생물 30종 선정

It is more efficient to select and monitor a few climate-sensitive organisms to assess the impacts of climate change on agroecosystems. In this study, indicator species of climate change in agroecosystem in South Korea were selected through analytical hierarchy process and an expert questionnaire survey. Climate sensitivity, agroecosystem symbolism, survey easiness, identification easiness, and public interest were selected as criteria for indicator species, with weights of 0.38 (±0.15), 0.23 (±0.13), 0.18 (±0.11), 0.14 (±0.09), and 0.07 (±0.06), respectively. According to these criteria, 30 indicator species were finally selected from six taxonomic groups of plants, aquatic invertebrates, bees, terrestrial beetles, butterflies, and spiders as follows. Seven plant species were selected: Taraxacum officinale, Capsella bursa-pastoris, Veronica persica, Hypochaeris radicata, Lamium amplexicaule, Trigonotis peduncularis, and Conyza sumatrensis. Seven aquatic invertebrate species were selected: Pomacea canaliculata, Cybister chinensis, Hydrochara affinis, Sternolophus rufipes, Hydaticus grammicus, Appasus japonicus, and Rhantus suturalis. Five butterfly species were selected: Eurema mandarina, Chilo suppressalis, Pieris rapae, Papilio xuthus, and Colias erate. Three spider species were selected: Argiope bruennichi, Larinioides cornutus, and Neoscona adianta. Four bee species were selected: Vespa velutha nigrithorax, V. simillima simillima, V. mandarinia, and V. simillima xanthoptera. Four species were selected for terrestrial beetles: Pheropsophus javanus, P. jessoensis, Platydracus brevicornis, and Chlaenius micans. The selected species are expected to be used as indicators for assessing the impacts of climate change in agroecosystems in the future.

Wolbachia have made it twice: Hybrid introgression between two sister species of Eurema butterflies.

Wolbachia, cytoplasmically inherited endosymbionts of arthropods, are known to hijack their host reproduction in various ways to increase their own vertical transmission. This may lead to the selective sweep of associated mitochondria, which can have a large impact on the evolution of mitochondrial lineages. In Japan, two different Wolbacahia strains (wCI and wFem) are found in two sister species of pierid butterflies, Eurema mandarina and Eurema hecabe. In both species, females infected with wCI (C females) produce offspring with a nearly 1:1 sex ratio, while females infected with both wCI and wFem (CF females) produce all‐female offspring. Previous studies have suggested the historical occurrence of hybrid introgression in C individuals between the two species. Furthermore, hybrid introgression in CF individuals is suggested by the distinct mitochondrial lineages between C females and CF females of E. mandarina. In this study, we performed phylogenetic analyses based on nuclear DNA and mitochondrial DNA markers of E. hecabe with previously published data on E. mandarina. We found that the nuclear DNA of this species significantly diverged from that of E. mandarina. By contrast, mitochondrial DNA haplotypes comprised two clades, mostly reflecting Wolbachia infection status rather than the individual species. Collectively, our results support the previously suggested occurrence of two independent historical events wherein the cytoplasms of CF females and C females moved between E. hecabe and E. mandarina through hybrid introgression.

Late autumn occurrence of non-diapause male adults in various geographic populations of a pierid butterfly, Eurema mandarina

ABSTRACT Adult-overwintering insects show diversity in the occurrence of reproductive diapause of males. Mating can occur both before and after winter in different species, and pre-winter mating allows males to reproduce without overwintering. In a pierid butterfly, Eurema mandarina, both diapause and non-diapause male adults emerge in the late autumn generation. Diapause females mate with non-diapause males before winter and re-mate with diapause males the following spring. Although this species is distributed from sub-tropical regions to cool-temperate regions, the geographic variation of this characteristic mating system has not been examined. A rearing experiment and a field survey were conducted to determine the geographic patterns of the mating system of the late autumn generation of E. mandarina for various populations from sub-tropical to cool temperate regions. Non-diapause males were observed in the late autumn generation in all populations examined. The frequency of pre-winter mating of females was not correlated with latitude. These results show that the mating system of the late autumn generation is similar among various populations distributed over a wider range, suggesting that the characteristic mating system may be evolutionarily stable.

A cyanogenic glucoside of Trifolium repens deters oviposition by the common grass yellow Eurema mandarina

AbstractThe common grass yellow Eurema mandarina (Pieridae, Coliadinae) widely inhabits Japan, feeds on various fabaceous plants such as silktree (Albizia julibrissin) and uses d‐pinitol, a cyclitol omnipresent in Fabaceae, as a primary oviposition stimulant. However, E. mandarina has a clear host preference within the Fabaceae; for example, white clover (Trifolium repens) is a nonhost despite containing d‐pinitol. The present study aims to identify plant chemicals in white clover that inhibit oviposition of E. mandarina. Females lay very few eggs on T. repens foliage and plastic plant models treated with a methanolic extract of the foliage. The foliage extract is fractionated by successive extraction with chloroform, isobutanol and water. None of these fractions induce egg‐laying responses. The aqueous fraction is further separated into four subfractions (Tr‐3‐1 to Tr‐3‐4) by column chromatography. Among these subfractions, females show high egg‐laying responses to Tr‐3‐1, which is known to contain d‐pinitol. Interestingly, Tr‐3‐2, when mixed with Tr‐3‐1, significantly decreases egg‐laying responses, indicating that it contains oviposition deterrents. Chemical analyses reveal that two cyanogenic glucosides, linamarin and lotaustralin, are the major constituents of Tr‐3‐2. Authentic linamarin does not elicit egg‐laying responses and significantly inhibits female oviposition when mixed with Tr‐3‐1 at the natural concentration. Although these cyanogenic glucosides are reported to synergistically induce oviposition of a coliadine species Colias erate on white clover, we conclude that linamarin acts as an oviposition deterrent for E. mandarina, restricts its host range and regulates their differential host acceptance.

The Role of N,N,N-Trimethylglycine in Oviposition of Eurema mandarina on Albizia julibrissin.

The common grass yellow Eurema mandarina (Lepidoptera: Pieridae) uses the silk tree Albizia julibrissin (Fabaceae) as a primary host in Japan. We previously reported that D-pinitol, a cyclitol found in fresh leaves of A. julibrissin, solely elicits moderate oviposition responses from females. However, the aqueous neutral/amphoteric fraction of the fresh leaf extract containing D-pinitol weakly induces oviposition. Moreover, the aqueous neutral/amphoteric/basic fraction was significantly more active than the neutral/amphoteric fraction in eliciting responses, indicating that some basic compounds are involved in stimulating oviposition. High-resolution mass spectrometry and proton nuclear magnetic resonance measurements revealed that the aqueous basic faction contains N,N,N-trimethylglycine (trivial name: glycine betaine) in alkali metal salt form. The average concentration of this quaternary ammonium compound in fresh leaves was estimated to be 0.012% w/w in high performance liquid chromatography analyses. The authentic N,N,N-trimethylglycine induced oviposition at concentrations greater than 0.001% (w/v) and slightly enhanced female responses to the aqueous neutral fraction and authentic D-pinitol. However, its analogues, N,N-dimethylglycine, N-methylglycine, and glycine as well as its precursor choline were inactive. These results demonstrate that N,N,N-trimethylglycine, together with D-pinitol, serves as an stimulant of E. mandarina for oviposition on the leaves of A. julibrissin.

Effect of mating on survival at low temperature in females of the Japanese common grass yellow, Eurema mandarina

1. In some insects that overwinter as adults, mating occurs both before and after overwintering. Two hypotheses have been proposed to explain the adaptive significance of pre‐overwintering copulation of females. One is the bet‐hedging hypothesis, which explains pre‐overwintering copulation as a preparation for less chance of mating in the following spring. The other is the nuptial gift hypothesis, which states that secretions derived from males increase overwintering success of females.2. In Eurema mandarina, both diapause autumn‐ and non‐diapause summer‐form male adults emerge with autumn‐form female adults in the last generation in a year. Most autumn‐form females mate with summer‐form males before winter, and re‐mate with autumn‐form males in the following spring. Because autumn‐form females have sufficient chances for mating after overwintering, the nuptial gift hypothesis has been regarded as the more probable hypothesis.3. To test the nuptial gift hypothesis, the survival period was compared under short‐day conditions at 10 °C between mated and unmated females that had been reared on sucrose solution at 25 °C for 15–21 days. The mated females had significantly greater longevity than the unmated females, supporting the nuptial gift hypothesis. Body size also affected the survival period.4. The results suggest that the nuptial gift is an important factor for the evolution of pre‐overwintering copulation in species in which females mate both before and after overwintering.

Overwintering success in adults of the Japanese common grass yellow Eurema mandarina

AbstractThe evolution of reproductive diapause is controversial in males as compared to females that must overwinter to leave offspring, because late‐autumn males can obtain offspring by pre‐overwintering copulation. The Japanese common grass yellow Eurema mandarina is suitable to examine the evolution of male reproductive diapause, because direct comparisons are possible between males that do and do not exhibit reproductive diapause. Approximately one‐half of males are insensitive to diapause‐inducing conditions, and emerge as non‐diapause summer‐form. Most autumn‐form females mate with summer‐form males in late autumn. Females that have overwintered re‐mate with autumn‐form males before the onset of oviposition. Because last‐male‐precedence is general in sperm competition in Lepidoptera, it is unclear why half of males emerge as summer‐form in late autumn. A potential adaptive benefit for emerging as summer‐form is increased sperm overwintering success, if autumn‐form females have a higher overwintering success than autumn‐form males. In the present study, overwintering success was estimated for both sexes of autumn‐form adults by rearing under seminatural conditions and a mark–release–recapture technique. Both approaches estimated an overwintering success of approximately 5% for both sexes. The absence of difference in overwintering success between the sexes suggests that pre‐overwintering copulation does not increase sperm overwintering success. However, a considerably low overwintering success may explain, at least partly, the presence of summer‐form males in late autumn. The degree of overwintering success might be more important than the sexual differences of overwintering success in the evolution of male reproductive diapause.

Feminizing Wolbachia endosymbiont disrupts maternal sex chromosome inheritance in a butterfly species.

Wolbachia is a maternally inherited ubiquitous endosymbiotic bacterium of arthropods that displays a diverse repertoire of host reproductive manipulations. For the first time, we demonstrate that Wolbachia manipulates sex chromosome inheritance in a sexually reproducing insect. Eurema mandarina butterfly females on Tanegashima Island, Japan, are infected with the wFem Wolbachia strain and produce all‐female offspring, while antibiotic treatment results in male offspring. Fluorescence in situ hybridization (FISH) revealed that wFem‐positive and wFem‐negative females have Z0 and WZ sex chromosome sets, respectively, demonstrating the predicted absence of the W chromosome in wFem‐infected lineages. Genomic quantitative polymerase chain reaction (qPCR) analysis showed that wFem‐positive females lay only Z0 eggs that carry a paternal Z, whereas females from lineages that are naturally wFem‐negative lay both WZ and ZZ eggs. In contrast, antibiotic treatment of adult wFem females resulted in the production of Z0 and ZZ eggs, suggesting that this Wolbachia strain can disrupt the maternal inheritance of Z chromosomes. Moreover, most male offspring produced by antibiotic‐treated wFem females had a ZZ karyotype, implying reduced survival of Z0 individuals in the absence of feminizing effects of Wolbachia. Antibiotic treatment of wFem‐infected larvae induced male‐specific splicing of the doublesex (dsx) gene transcript, causing an intersex phenotype. Thus, the absence of the female‐determining W chromosome in Z0 individuals is functionally compensated by Wolbachia‐mediated conversion of sex determination. We discuss how Wolbachia may manipulate the host chromosome inheritance and that Wolbachia may have acquired this coordinated dual mode of reproductive manipulation first by the evolution of female‐determining function and then cytoplasmically induced disruption of sex chromosome inheritance.

Wolbachia infections of the butterfly Eurema mandarina interfere with embryonic development of the sawfly Athalia rosae

Although maternally transmitted microorganisms such as Wolbachia are well known to have a variety of effects on the reproduction of diverse insect species, little is known about the underlying mechanisms of actions. Artificial transfer of Wolbachia between taxonomically distant host species may provide insights into Wolbachia-induced manipulations of hosts. Here we performed a cross-order transfer of feminizing Wolbachia derived from a butterfly, Eurema mandarina. The Wolbachia were propagated in the Eurema hecabe cell line, called NTU-YB, and then used to inject prepupal/pupal females of a Wolbachia-free hymenopteran sawfly, Athalia rosae. The 14 females that emerged as adults looked morphologically and behaviorally healthy, and ovarian development appeared normal on dissection. However, in contrast to the control, none of the 333 eggs harbored by the seven Wolbachia-injected females developed successfully. Similarly, none of the 140 eggs laid on host plant by the four Wolbachia-injected females, which were mated with males, showed any signs of development. Wolbachia infection was detected from whole-body samples of the inoculated individuals, but not from the eggs they produced. Disruption of embryonic development despite the absence of Wolbachia in the egg cytoplasm may represent a new phenotype involving maternal effects that result in female sterility.

D-Pinitol in Fabaceae: an Oviposition Stimulant for the Common Grass Yellow Butterfly, Eurema mandarina

The common grass yellow butterfly, Eurema mandarina (formerly Eurema hecabe mandarina) (Lepidoptera, Pieridae), recently has been separated taxonomically from a subtropical population of Eurema hecabe in Japan. This species is widely distributed in the temperate region of Japan, and feeds mainly on various ligneous plants within the Fabaceae. We attempted to identify an oviposition stimulant for E. mandarina from its primary hosts, Albizia julibrissin and Lespedeza cuneata. In both hosts, crude extract and an aqueous fraction elicited oviposition responses from gravid females. A polar subfraction of the aqueous fraction also stimulated high oviposition-stimulatory activity, comparable to the original aqueous fraction, suggesting that E. mandarina females use water-soluble compounds for host recognition. Subsequent activity-directed fractionation by ion exchange chromatography indicated that one of the key substances was contained in the neutral/amphoteric fraction. Chemical analyses revealed that the active fractions of both hosts contained D-(+)-pinitol as the major component. We examined female responses to authentic D-pinitol and found that it induced oviposition responses at concentrations greater than 0.1%. Since this cyclitol is omnipresent in Fabaceae, we conclude that D-pinitol plays a role in mediating oviposition of E. mandarina on fabaceous plants.

Adaptive significance of the mating of autumn-morph females with non-overwintering summer-morph males in the Japanese Common Grass Yellow, Eurema mandarina (Lepidoptera: Pieridae)

Autumn-morph adults of the Japanese Common Grass Yellow, Eurema mandarina (de l’Orza), overwinter with reproductive diapause, while the summer-morph adults do not. A low temperature and short photoperiod induce autumn-morph adults. Because of different critical photoperiods between the sexes, the summer-morph males coexist with the autumn-morph adults in late autumn. While autumn-morph males show little mating activity, mating between summer-morph males and autumn-morph females frequently occurs. Thereafter, mated autumn-morph females re-mate with autumn-morph males the following spring. Two hypotheses, a nuptial gift hypothesis and a risk-hedge hypothesis, explaining the adaptive significance of pre-overwinter copulation by autumn-morph females were examined. Wild autumn-morph females were collected in November, late March, April and early May. The decrease in the number of eggs contained in autumn-morph females indicated that they started oviposition in mid-April. The shape of the spermatophore suggested that autumn-morph females could re-mate with autumn-morph males before mid-April. Although the eupyrene sperm of the summer-morph males remained in the spermatheca just after overwintering, the nuptial gift hypothesis is more plausible than the risk-hedge hypothesis because most females re-mated in the spring before the onset of oviposition. A counter-adaptation of summer-morph males acting as a strategy for mating with autumn-morph females was also discussed.

キタキチョウの夏型雄の精子生産と注入精子数

キタキチョウの夏型雄の精子生産と注入精子数

Wolbachia-induced feminisation newly found in Eurema hecabe, a sibling species of Eurema mandarina (Lepidoptera: Pieridae)

1. Complete feminisation of genetic males into functional females, a unique case among insects, is known in Eurema mandarina (former Eurema hecabe Y type) that are infected with two strains of Wolbachia, wCIEm and wFemEm. 2. Here, we newly found that a proportion of wild-caught E. hecabe (former E. hecabe B type) produced only female offspring. Cytogenetic observations indicated that individuals of E. hecabe displaying the all-female trait were genetically male (i.e. feminisation). 3. Multilocus sequence typing analyses demonstrated that the feminised individuals of E. hecabe were infected with two Wolbachia strains, wCIEh and wFemEh, that were indistinguishable from wCIEm and wFemEm, respectively. 4. Even identical strains of Wolbachia can be regulated differently depending on the host genetic background. Therefore, we compared the infection densities and vertical transmission efficiencies of Wolbachia between feminised E. mandarina and E. hecabe, but detected no significant differences in these traits. 5. The possible routes by which the two Wolbachia strains have transferred between E. mandarina and E. hecabe are discussed.