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At least 217 records · Page 12Linked to original sources
PubMed2000

Purification and cloning of pierisin-2, an apoptosis-inducing protein from the cabbage butterfly, Pieris brassicae.

The cabbage butterfly Pieris rapae contains a strong apoptosis-inducing substance, pierisin, against human cancer cell lines, which is thought to act via ADP-ribosylation. Here we report the purification and cloning of an apoptosis-inducing substance, designated as pierisin-2, from another cabbage butterfly, Pieris brassicae. Pierisin-2 was purified from pupae by sequential chromatography and its cytotoxic and apoptosis-inducing activities to various cancer cells were similar to those of pierisin, designated as pierisin-1, from P. rapae. cDNA cloning of pierisin-2 was performed on the basis of the partial amino-acid sequence. The nucleotide sequence indicated that the cDNA encodes an 850-amino-acid protein with a calculated molecular mass of 97 986. The deduced amino-acid sequence of pierisin-2 was 91% identical with that of pierisin-1. In vitro expressed protein in the reticulocyte lysate exhibited apoptosis-inducing activities against human gastric carcinoma TMK-1 and cervical carcinoma HeLa cells, similar to the purified native pierisin-2 from the pupae. Pierisin-2 shows regional sequence similarities with certain ADP-ribosylating toxins such as the A-subunit of cholera toxin. The results from site-directed mutagenesis at Glu165, a conserved residue among ADP-ribosylating enzymes necessary for NAD binding, and from experiments with ADP-ribosylating enzyme inhibitors suggested that pierisin-2 could be considered as an ADP-ribosylating toxin like pierisin-1.

ADP Ribose Transferases↗
PubMed2001

Remotely sensed habitat diversity predicts butterfly species richness and community similarity in Canada.

Although there is no shortage of potential explanations for the large-scale patterns of biological diversity, the hypothesis that energy-related factors are the primary determinants is perhaps most extensively supported, especially in cold-temperate regions. By using unusually high-resolution biodiversity and environmental data that have not previously been available, we demonstrate that habitat heterogeneity, as measured by remotely sensed land cover variation, explains Canadian butterfly richness better than any energy-related variable we measured across spatial scales. Although species-richness predictability declines with progressively smaller quadrat sizes, as expected, we demonstrate that most variability (>90%) in butterfly richness may be explained by habitat heterogeneity with secondary contributions from climatic energy. We also find that patterns of community similarity across Canada are strongly related to patterns of habitat composition but not to differences in energy-related factors. Energy should still be considered significant but its main role may be through its effects on within-habitat diversity and perhaps, indirectly, on the sorts of habitats that may be found in a region. Effects of sampling intensity and spatial autocorrelation do not alter our findings.

Animals↗
PubMed2001

Impact of Bt corn pollen on monarch butterfly populations: a risk assessment.

A collaborative research effort by scientists in several states and in Canada has produced information to develop a formal risk assessment of the impact of Bt corn on monarch butterfly (Danaus plexippus) populations. Information was sought on the acute toxic effects of Bt corn pollen and the degree to which monarch larvae would be exposed to toxic amounts of Bt pollen on its host plant, the common milkweed, Asclepias syriaca, found in and around cornfields. Expression of Cry proteins, the active toxicant found in Bt corn tissues, differed among hybrids, and especially so in the concentrations found in pollen of different events. In most commercial hybrids, Bt expression in pollen is low, and laboratory and field studies show no acute toxic effects at any pollen density that would be encountered in the field. Other factors mitigating exposure of larvae include the variable and limited overlap between pollen shed and larval activity periods, the fact that only a portion of the monarch population utilizes milkweed stands in and near cornfields, and the current adoption rate of Bt corn at 19% of North American corn-growing areas. This 2-year study suggests that the impact of Bt corn pollen from current commercial hybrids on monarch butterfly populations is negligible.

Animals↗
PubMed2003

Modeling current and future potential wintering distributions of eastern North American monarch butterflies.

Monarch butterflies overwinter in restricted areas in montane oyamel fir forests in central Mexico with specific microclimates that allow the butterflies to survive for up to 5 months. We use ecological niche modeling (ENM) to identify areas adequate for overwintering monarch colonies under both current and future climate scenarios. The ENM approach permits testing and validation of model predictivity, and yields quantitative, testable predictions regarding likely future climate change effects. Our models predicted monarch presence with a high degree of accuracy, and indicated that precipitation and diurnal temperature range were key environmental factors in making locations suitable for monarchs. When we projected monarch distribution onto future climate scenarios (Hadley Centre climate models), we found that conditions were likely to be inadequate across the entire current winter range, particularly owing to increased cool-weather precipitation that could cause increased mortality. This study applies ENM to understanding the seasonal dynamics of a migratory species under climate change, and uses ENM to identify key limiting environmental parameters in species' responses to climate change.

Abies↗
PubMed1994

Rapid morphological radiation and convergence among races of the butterfly Heliconius erato inferred from patterns of mitochondrial DNA evolution.

The neotropical Heliconius butterflies are famous examples of Müllerian mimicry, due to the diverse array of shared, brightly colored wing patterns that advertise the butterflies' unpalatability. The parallel geographical variation in these patterns within several widespread species has been invoked to support the controversial Pleistocene refugium hypothesis of tropical diversification. However, in no Heliconius species have either evolutionary rates or relationships among geographical races been explicitly examined. I present a phylogenetic hypothesis based on mitochondrial DNA sequences for 14 divergent races of Heliconius erato, which reveals that similar wing patterns have evolved rapidly and convergently within the species. There is a basal split between groups of races from east and west of the Andes, reflecting a vicariant separation at the base of the Pleistocene. Within each of these clades, sequence divergence is very low, and some haplotypes are shared between allopatric races with radically different wing patterns. The topology implies a simultaneous radiation of races in these two areas within the last 200,000 years. Ages for the clades are estimated by comparing sequence divergence to a plot of mitochondrial divergence in several arthropod taxa with independently dated divergence times. This plot is linear and suggests that mitochondrial DNA in arthropods evolves in a clocklike manner, at least initially, when sequence divergence is low.

Animals↗
PubMed1999

Monarch butterflies (Danaus plexippus L.) use a magnetic compass for navigation.

Fall migratory monarch butterflies, tested for their directional responses to magnetic cues under three conditions, amagnetic, normal, and reversed magnetic fields, showed three distinct patterns. In the absence of a magnetic field, monarchs lacked directionality as a group. In the normal magnetic field, monarchs oriented to the southwest with a group pattern typical for migrants. When the horizontal component of the magnetic field was reversed, the butterflies oriented to the northeast. In contrast, nonmigratory monarchs lacked directionality in the normal magnetic field. The results are a direct demonstration of magnetic compass orientation in migratory insects.

Animals↗
PubMed2001

Taste-enhancing effects of glycine on the sweetness of glucose: a gustatory aspect of symbiosis between the ant, Camponotus japonicus, and the larvae of the lycaenid butterfly, Niphanda fusca.

The lycaenid butterfly, Niphanda fusca, has a parasitic relationship with its host ant, Camponotus japonicus: the caterpillars may use chemical mimicry to enter the ant nest where they are fed mouth-to-mouth by the adult ants until pupation. Nevertheless, larvae offer their host ants a nutritious secretion that contains 160 mM glucose and 43 mM glycine. Using glucose and glycine mixture as artificial secretions, we investigated the gustatory effect of glucose and/or glycine on the ants. Glycine induced neither feeding behavior nor gustatory response in the ants if its concentration was <500 mM. In the presence of glycine at the concentration in the secretion, however, the ants improved their preference to glucose, and the sugar receptor cell exhibited electrophysiological enhancement of response to glucose in a glycine-concentration-dependent manner. By adding glycine to glucose in their secretions, therefore, the butterfly larvae can manipulate the gustatory sense of the ants. The alluring taste of 'glycine-flavored glucose' could motivate the host ants to feed the larvae and thereby receive the secretions as a reward. The taste enhancement created by the combination of sugar and amino acid may play a role in the evolution of the parasitic relationships of these insects. The taste-enhancing effect appears to be analogous to taste enhancement by 'umami' substances in humans.

Amino Acids↗
PubMed2026

Long-read, high-coverage reference genome of the nymphalid butterfly Catonephele acontius (Nymphalidae: Biblidinae).

Catonephele acontius (Nymphalidae:Biblidinae:Epicalinii) is a butterfly species with a wide distribution across the Neotropics including the Amazon. Here, we present a long-read high-coverage reference genome for this species to serve as a genomic resource for future studies on Biblidinae butterflies, a group that is the subject of ongoing studies of seasonal adaptation under climate change. We used PacBio HiFi and IsoSeq reads to generate a highly contiguous and well-annotated reference genome. Five libraries were constructed, 4 using RNA from different tissues and 1 using high molecular weight (HMW) DNA from a wild-caught female. The DNA was sequenced using PacBio HiFi technology, and the RNA was sequenced using long read PacBio IsoSeq technology. About 20 Gb of raw HiFi data were generated and assembled to an initial size of 520.7 Mb (39 &#xd7; homozygous coverage) in 90 contigs. The assembly was then polished and decontaminated into 40 contigs with an N50 of 19.927 Mb (BUSCO completeness: 99.0%; duplication: 0.5%; fragmentation: 0.7%; and missing: 0.3%). Final assembly size was 519.2 Mb. Repeats were annotated, showing that the genome consisted of 40.4% transposable elements. IsoSeq transcriptome data from antennae, leg, ovary, and digestive tissue was then used to structurally and functionally annotate gene models for the softmasked genome, uncovering &#x223c;18,500 genes, with 70% of them given functional annotation. This reference assembly joins many published genomes in the Nymphalidae family but represents one of the first high-quality genomes from the Biblidinae subfamily. It provides a valuable resource to study the evolution of plastic and seasonal traits and will help investigate the genetic processes that may influence these species' responses to rapid climate change.

Animals↗
PubMed2004

Assessing the use of butterflies as indicators of logging in Borneo at three taxonomic levels.

Logging is an issue of major conservation concern. Less than 5% of tropical forests are currently protected, and many of these are in so-called "paper parks." Many species may therefore depend on exploited forests, and management decisions concerning these forests will be a major determinant of their survival. An important aspect of forest management will entail the use of reliable, practical, and inexpensive indicator taxa to monitor exploitation. Here, butterflies are proposed as such indicators. Species, generic, and subfamily richness was significantly higher in logged than unlogged forest and community composition differed significantly at all three taxonomic levels (species, genus, and subfamily). Richness estimators were, furthermore, highly correlated among all three taxonomic levels. Significant individual indicator taxa were found at all three taxonomic levels, but the best overall taxa (highest indicator values) were found at the generic level and included the butterfly genera Ragadia and Paralaxita as indicators of unlogged forest and the genera Ypthima, Allotinus, and Athyma as indicators of logged forest. The use of genera instead of species presents a number of practical advantages. Identification is faster, easier, and more reliable. Genera can, furthermore, usually be identified "on the wing," thereby preventing accidental mortality due to capture.

Animals↗
PubMed2005

Egg size-number trade-off and a decline in oviposition site choice quality: female Pararge aegeria butterflies pay a cost of having males present at oviposition.

Once mated, the optimal strategy for females of the monandrous butterfly, Pararge aegeria, is to avoid male contact and devote as much time as possible to ovipositing, as there is little advantage for females to engage in multiple matings. In other butterfly species the presence of males during egg laying has been shown to affect aspects of oviposition behavior and it has been suggested that repeated interference from males has the potential to reduce reproductive output. The aim of this study was to assess the effects of male presence during oviposition on reproductive output and behavior of a population of P. aegeria obtained from Madeira Island, Portugal, and maintained in the laboratory. Two experiments were performed where females were housed individually in small cages. Experiment 1 examined how social factors influenced the egg laying behavior of females. To do this the presence or absence of males was manipulated and egg size and number was measured over the first 14 days of oviposition. It was observed that when males were present during oviposition females made a trade-off between egg size and number. Experiment 2 examined how social factors affected oviposition site choice. Again, male presence/absence was manipulated, but in this experiment where the female laid her egg in relation to host quality was scored, and the size of the egg laid was measured. In the absence of males females selectively positioned their larger eggs on good quality host plants. However, selective oviposition was no longer observed when females were in the presence of males. We suggest that P. aegeria females from the Madeira Island population are adapted for a flexible oviposition strategy, governed by external cues, allowing a trade-off between egg size and number when the time available for egg laying is limiting.

Animals↗
PubMed2004

Optical properties of the scales of Morpho rhetenor butterflies: theoretical and experimental investigation of the back-scattering of light in the visible spectrum.

A study of the optical properties of the largely periodic microstructure occurring on the wings of the iridescent tropical butterfly Morpho rhetenor and responsible for its structural colouration is reported. An extensive measurement of the back-scattering of visible light from butterfly scales was performed for various angles of incidence. Efficient low-pass filter behaviour was observed for all angles of incidence and polarizations, with near-complete transmission at wavelengths above the threshold of 550 nm. The angular spread of the back-scattered light was found to be organized in lobes with total extinction of the specular reflection for all conditions of incidence. Retro-reflector behaviour was also observed for angles of incidence of 30 degrees and above. Additionally, the role of periodic geometrical features found in the microstructure for the generation of its spectral response was analysed theoretically. Using finite-difference time-domain and near-field to far-field transformation techniques, the back-scattering of visible light by models was computed numerically and the relevance of geometrical features for the production of structural colour and diffraction was demonstrated.

Animals↗
PubMed2000

Sex-ratio-distorting Wolbachia causes sex-role reversal in its butterfly host.

Sex-role-reversed mating systems in which females compete for males and males may be choosy are usually associated with males investing more than females in offspring. We report that sex-role reversal may also be caused by selfish genetic elements which distort the sex ratio towards females. Some populations of the butterflies Acraea encedon and Acraea encedana are extremely female biased because over 90% of females are infected with a Wolbachia bacterium that is maternally inherited and kills male embryos. Many females in these populations are virgins suggesting that their reproductive success may be limited by access to males. These females form lekking swarms at landmarks in which females exhibit behaviours which we interpret as functioning to solicit matings from males. The hypothesis that female A. encedon swarm in order to mate is supported by the finding that, in release recapture experiments, mated females tend to leave the swarm while unmated females remained. This behaviour is a sex-role-reversed form of a common mating system in insects in which males form lekking swarms at landmarks and compete for females. Female lekking swarms are absent from less female-biased populations and here the butterflies are instead associated with resources in the form of the larval food plant.

Animals↗
PubMed2000

Nuptial gifts and the use of body resources for reproduction in the green-veined white butterfly Pieris napi.

Reproduction in butterflies, as in many holometabolous insects, is usually constrained by the amount of nutrients the animals can collect as juveniles. In polyandric species the females can also supplement their larval-derived reserves with protein-rich donations, so-called nuptial gifts, delivered by the males at mating. Recent findings also indicate that females have access to nitrogen from the histolysis of flight muscles in the thorax. This field study examined how butterflies of the polyandric gift-giving species Pieris napi (Lepidoptera: Pieridae) use body resources in their reproduction and how the male donations affect the females use of stored reserves. The results support earlier studies, indicating that females use resources from the breakdown of thorax muscles to increase their reproductive potential and the results also indicate that males also use thorax material in their reproduction. The study also supports recent findings that the male donation increases the breakdown of body resources and thereby boosts the reproductive output of the female.

Animals↗
PubMed2000

Does the presence of ant nests matter for oviposition to a specialized myrmecophilous Maculinea butterfly?

More than 50% of the lycaenid butterflies have an ant-associated lifestyle (myrmecophily) which may vary from coexistence to specific mutualistic or even parasitic interactions. Ant-related host-plant selection and oviposition has been observed in some myrmecophilous lycaenids. Therefore, it is remarkable that there is no evidence for this behaviour in the highly specialized, obligate myrmecophilous butterflies of the genus Maculinea. In contrast with previous findings, our results provide evidence for ant-related oviposition patterns in Maculinea alcon in relation to the distribution of specific host-ant nests (i.e. Myrmica ruginodis) based on repeated egg counts during the flight period in two populations. We also show that ant-related oviposition can be counterbalanced by intraspecific competition and oviposition deterrency when host plants already carry several eggs. Therefore, the absence of a correlation between egg load and the presence of host-ant nests at the end of the flight period should be interpreted carefully Whether ovipositional cues are obtained either directly (from ants or their nests) or indirectly (from vegetation structure), and whether alternative explanations based on the phenology and growth form of host plants are possible, is discussed.

Animals↗
PubMed2000

Day-flying butterflies remain day-flying in a Polynesian, bat-free habitat.

To test the theory that insectivorous bats have selected for diurnality in earless butterflies I compared the nocturnal flight patterns of three species of nymphalid butterflies on the bat-free Pacific island of Moorea with those of three nymphalids in the bat-inhabited habitat of Queensland, Australia. Nocturnal flight, measured as the ratio of deep night (1 h following sunset to 1 h preceding sunrise) to twilight night (1 h before sunset to 30 min after sunrise) activity did not differ significantly between the two locations, nor did the percentage of individuals active and I conclude that living in a bat-released habitat has not produced nocturnal flight in these insects. This result is surprising considering the potential advantages of escaping diurnally active predators and suggests that physiological adaptations (e.g. thermoregulation and/or vision) currently constrain these insects to diurnal flight. Since taxonomic records suggest that gene flow does not exist with bat-exposed conspecifics, I suggest that insufficient time has elapsed since these species migrated to Moorea to have resulted in major phenotypic changes such as diel flight preferences.

Animals↗
PubMed2001

Sexual conflict and cooperation in butterfly reproduction: a comparative study of polyandry and female fitness.

Most butterfly species can be characterized as capital breeders, meaning that reproductive output is strongly coupled to the amount of resources they have procured during the larval stage. Accordingly, female fecundity is generally correlated with female mass, both within and across species. However, the females of some species can be partly characterized as income breeders, in the sense that their reproductive output is dependent not only on larval-derived capital but also on resources acquired during the adult stage. These adult resources can be derived from female feeding or from male-transferred nuptial gifts. Recent studies on the within-species effects of multiple matings on female fitness show that females generally gain directly from multiple matings in terms of increased lifetime offspring production. Here, we test whether the positive effects of multiple mating on female fitness also hold at a comparative level, by conducting a laboratory study of female reproductive output in eight pierid species that differ in life-time female mating frequency. Female reproductive output, measured as cumulative egg mass divided by female mass, increased significantly with polyandry (r = 0.942, p < 0.001), demonstrating that the positive effect of mating rate on female reproductive fitness also holds between species. The positive effect of male nutrient contribution is substantial, and the per capita reproductive output is more than twice as high in the most polyandrous species as in the most monandrous ones. Hence, the positive net effect of the ejaculates is highly substantial, although males and females can have sexual interests that run counter to each other, setting the stage for sexually antagonistic coevolution, so that the various component parts of the male ejaculate-sperm, nutrients, anti-aphrodisiacs, and gonadotrophic hormones-may each correspond to a separate conflict-cooperation balance between the sexes. Two scenarios for the evolution of nuptial gifts in butterflies are discussed, one arguing that variation in larval food is the underlying factor and the other arguing that sexually antagonistic coevolution is the driving force. The two views are complementary rather than mutually exclusive, although the former hypothesis predicts that variation in female mating rate depends on variation in larval food availability, whereas the latter suggests that variation in female mating rate between species results from species-specific idiosyncrasies.

Animals↗
PubMed2002

Limited-view iridescence in the butterfly Ancyluris meliboeus.

Few mechanisms exist in nature that effect colour reflectivity, simultaneously high in spectral purity and in intensity, over a strictly limited portion of solid angle above a surface. Fewer still bring about such colour reflectivity with an angle dependence that is distinct from the colour transition associated with conventional multilayer interference. We have discovered that the ventral wings of the butterfly Ancyluris meliboeus exhibit these optical effects, and that they result from remarkable nano-scale architecture on the wing scales of the butterfly. This nano-structure is in the form of high-tilt multilayering that, as a result of abrupt termination of the multilayers, brings about diffraction concurrently with interference. The product is bright structural colour in a limited angular region over the ventral wing surface that enables remarkably strong flicker and colour contrast through minimal wing movement. The visibility effects associated with its colour, in terms of bright and dark zones of the observation hemisphere over the wing surface, are described. We suggest the purpose of the high-contrast ventral wing visibility associated with A. meliboeus is at-rest signalling; this is distinct from the dorsal wing visibility of other species such as those of the genus Morpho, the function of which is largely for in-flight signalling.

Animals↗
PubMed2002

Short-term studies underestimate 30-generation changes in a butterfly metapopulation.

Most studies of rare and endangered species are based on work carried out within one generation, or over one to a few generations of the study organism. We report the results of a study that spans 30 generations (years) of the entire natural range of a butterfly race that is endemic to 35 km(2) of north Wales, UK. Short-term studies (surveys in single years and dynamics over 4 years) of this system led to the prediction that the regional distribution would be quite stable, and that colonization and extinction dynamics would be relatively unimportant. However, a longer-term study revealed unexpectedly high levels of population turnover (local extinction and colonization), affecting 18 out of the 20 patches that were occupied at any time during the period. Modelling the system (using the 'incidence function model' (IFM) for metapopulations) also showed higher levels of colonization and extinction with increasing duration of the study. The longer-term dynamics observed in this system can be compared, at a metapopulation level, with the increased levels of variation observed with increasing time that have been observed in single populations. Long-term changes may arise from local changes in the environment that make individual patches more or less suitable for the butterfly, or from unusual colonization or extinction events that take metapopulations into alternative states. One implication is that metapopulation and population viability analyses based on studies that cover only a few animal or plant generations may underestimate extinction threats.

Animals↗