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PubMed1999

Colour vision of the foraging swallowtail butterfly papilio xuthus

This paper demonstrates that foraging summer-form females of the Japanese yellow swallowtail butterfly Papilio xuthus have colour vision. The butterflies were trained to feed on sucrose solution placed on a disk of a particular colour in a cage set in the laboratory. After a few such training runs, a butterfly was presented with the training colour randomly positioned within an array of disks of other colours, but with no sucrose solution. The results indicate that the butterflies learn rapidly to select the training colour reliably among different colours. The training colour was also correctly selected when it was covered with neutral density filters to reduce its brightness, or even when the colour was presented together with disks of a variety of shades of grey. These results demonstrate convincingly, for the first time, that a butterfly has true colour vision.

Journal Article↗

PubMedDate not supplied

Butterfly laser epithelial keratomileusis for myopia.

PURPOSE: Decreased epithelial viability is a postoperative complication of standard laser epithelial keratomileusis (LASEK) that hampers rapid recovery, and causes reduced visual acuity as well as discomfort. We present a new LASEK technique that, by increasing epithelial viability, reduces the occurrence of these complications. METHODS: In a preliminary series of patients, conventional LASEK was performed in one eye, and "Butterfly" LASEK in the fellow eye. In Butterfly LASEK, a thin paracentral epithelial line, from 8 to 11 o'clock was removed, and 20% alcohol plus BSS 'solution was placed in contact with the cornea for 5 to 30 seconds. A specially designed spatula allowed separation of epithelium from Bowman's layer, proceeding from center to periphery on both sides. A special retractor was used to move the two flaps of loose epithelium toward the limbus. After drying the surface, excimer laser ablation was performed with the Nidek EC-5000 excimer laser. Smoothing with masking solution was then carried out, followed by flap replacement and overlapping. RESULTS: We treated 70 eyes of 35 patients with Butterfly LASEK. Preoperative mean spherical equivalent refraction was -5.30 +/- 3.70 D. At 12 months after surgery, mean spherical equivalent refraction was -0.10 +/- 0.40 D, and no lines of BSCVA were lost. Ninety percent of patients preferred Butterfly LASEK to conventional LASEK because of increased comfort. At 12 months, no patient had more than trace haze, and in 96.2%, corneas were completely clear. CONCLUSIONS: Butterfly LASEK is aimed at preserving the limbal connection of epithelial stem cells and limbal vascular connections. Improved epithelial viability is thus achieved, with faster postoperative recovery.

Cell Survival↗

PubMed2001

Structure of a character and the evolution of butterfly eyespot patterns.

All butterfly eyespots appear to be formed by a similar developmental mechanism. Thus the great diversity of patterns observed across different species of butterfly has evolved through changes in the genetic modulation of this mechanism. Our descriptions of both the development of eyespots and the genetic variation for eyespot traits in an African butterfly, Bicyclus anynana, are used here to discuss the most appropriate ways of applying the character concept to the evolution of butterfly eyespot patterns. J. Exp. Zool. (Mol. Dev. Evol.) 291:93-104, 2001.

Animals↗

PubMed1997

Instar susceptibility of the monarch butterfly (Danaus plexippus) to the neogregarine parasite, Ophryocystis elektroscirrha.

The susceptibility of the monarch butterfly (Danaus plexippus) larvae to the neogregarine parasite, Ophryocystis elektroscirrha, was tested in the laboratory. Spore loads recovered from infected monarch butterflies were directly related to the inoculum level, larval stage of the host, and spore age. There was a linear relationship between spores ingested by first instar larvae and spore concentration. Larvae feeding on leaves treated with 0, 50, 500, 5000, or 50,000 spores averaged 0, 0, 193, 457, or 1,255 spores, respectively, on the abdomens of the adult butterflies. When first, third, and fifth instar larvae were given 14.5 spores/mg of body weight, there was no significant difference in the spore load of the adults resulting from the first and third instars. However, there were significant differences in the spore load from adults resulting from the first and third instars versus the fifth instar. In addition, 1-year-old spores were not as infectious as fresh spores. Our findings indicate that under field conditions, the first instar is most likely to become infected because one spore appears sufficient to produce a detectable spore load in the adult. Older instars are less susceptible and have fewer opportunities to encounter sufficient viable spores for infection to occur. Thus, vertical transmission appears to be the primary mode of parasite maintenance in natural populations of monarch butterflies.

Animals↗

PubMed2003

Thyme and isolation for the Sinai baton blue butterfly (Pseudophilotes sinaicus).

The distribution of the narrowly endemic butterfly Pseudophilotes sinaicus (Lycaenidae) was studied. Potential habitat within its range was first located and then the quality of that habitat assessed. Degree of shelter, diversity of plant species, and resource area of an individual food plant (Thymus decussatus) all affected habitat quality and together were used to develop an index of habitat suitability applicable to each site. The butterfly's distribution was then studied within the identified network of suitable habitat patches: isolated patches with a small resource area were least likely to contain butterflies. Population size in a patch (as opposed merely to patch occupancy) was affected by resource area and the quality of habitat within that patch. Metapopulation processes and variation in habitat quality therefore appear to combine to describe the distribution of patches occupied by P. sinaicus and their population sizes. This finding provides insights into some of the processes operating on an endemic species throughout its geographical range and has important implications for the conservation of this rare butterfly.

Animals↗

PubMed2003

Butterfly pollination and high-contrast visual signals in a low-density distylous plant.

In low-density butterfly-pollinated Mussaenda frondosa (Rubiaceae), flowers attract pollinators at short distances while conspicuous, non-rewarding accessory bracts are detectable at long distances by long-ranging pollinators such as the birdwing butterfly Troides minos that did not detect flower-bearing plants in the absence of these bracts. However, even in the absence of flowers, the white, ultraviolet-absorbing bracts attracted butterflies that visited flowerless plants. Although flower visits by short-ranging territorial butterflies declined significantly on removal of bracts, they did not cease completely. Nectar-robbing carpenter bees and birds did not change their behaviour following bract removal. Bract removal caused a significant decline in fruit set, indicating their importance as visual signals to pollinators.

Animals↗

PubMed2006

Landscape composition and habitat area affects butterfly species richness in semi-natural grasslands.

During the last 50 years, the distribution and abundance of many European butterfly species associated with semi-natural grasslands have declined. This may be the result of deteriorating habitat quality, but habitat loss, resulting in decreasing area and increasing isolation of remaining habitat, is also predicted to result in reduced species richness. To investigate the effects of habitat loss on species richness, we surveyed butterflies in semi-natural grasslands of similar quality and structure, but situated in landscapes of different habitat composition. Using spatially explicit habitat data, we selected one large (6-10 ha) and one small (0.5-2 ha) grassland site (pasture) in each of 24 non-overlapping 28.2 km(2) landscapes belonging to three categories differing in the proportion of the area that consisted of semi-natural grasslands. After controlling for local habitat quality, species richness was higher in grassland sites situated in landscapes consisting of a high proportion of grasslands. Species richness was also higher in larger grassland sites, and this effect was more pronounced for sedentary than for mobile species. However, the number of species for a given area did not differ between large and small grasslands. There was also a significant relationship between butterfly species richness and habitat quality in the form of vegetation height and abundance of flowers. In contrast, butterfly density was not related to landscape composition or grassland size. When species respond differently to habitat area or landscape composition this leads to effects on community structure, and nestedness analysis showed that depauperate communities were subsets of richer ones. Both grassland area and landscape composition may have contributed to this pattern, implying that small habitat fragments and landscapes with low proportions of habitat are both likely to mainly contain common generalist species. Based on these results, conservation efforts should aim at preserving landscapes with high proportions of the focal habitat.

Animals↗

PubMed2004

Polarized light helps monarch butterflies navigate.

During their spectacular migratory journey in the fall, North American monarch butterflies (Danaus plexippus) use a time-compensated sun compass to help them navigate to their overwintering sites in central Mexico. One feature of the sun compass mechanism not fully explored in monarchs is the sunlight-dependent parameters used to navigate. We now provide data suggesting that the angle of polarized skylight (the e-vector) is a relevant orientation parameter. By placing butterflies in a flight simulator outdoors and using a linear polarizing filter, we show that manipulating the e-vector alters predictably the direction of oriented flight. Butterflies studied in either the morning or afternoon showed similar responses to filter rotation. Monarch butterflies possess the anatomical structure needed for polarized skylight detection, as rhabdoms in the dorsalmost row of photoreceptor cells in monarch eye show the organization characteristic of polarized-light receptors. The existence of polarized-light detection could allow migrants to accurately navigate under a variety of atmospheric conditions and reveals a critical input pathway into the sun compass mechanism.

Animal Migration↗

PubMed2003

Feeding responses of adult butterflies, Nymphalis xanthomelas, Kaniska canace and Vanessa indica, to components in tree sap and rotting fruits: synergistic effects of ethanol and acetic acid on sugar responsiveness.

Exuded tree sap and rotting fruits are important feeding sources for adults of many butterfly species. However, the chemical composition of such rotting foods and the effects of these constituents on butterfly feeding behaviour have rarely been investigated. Chemical analyses revealed that these food sources contain several major components, including fructose, glucose, ethanol and acetic acid. Moreover, 15 amino acids were identified from the exuded tree sap. The gustatory responsiveness to these components was examined in the proboscis of nymphalid adults of three species (Nymphalis xanthomelas, Kaniska canace and Vanessa indica). The first two species primarily feed on sap and rotting fruits, while V. indica frequently visits flowers. Fructose elicited larger feeding responses from these saprophagous butterflies than glucose, which had a feeding-stimulatory effect only on N. xanthomelas at a concentration equivalent to that of the food. Ethanol, acetic acid and the five major amino acids identified in tree sap did not elicit feeding responses by themselves. However, ethanol and/or acetic acid, when mixed with these sugars at equivalent concentrations, evoked feeding and enhanced probing responses in K. canace and V. indica. These results suggest that ethanol and acetic acid, together with sugars at low concentrations, synergistically stimulate butterfly feeding behaviour.

Acetic Acid↗

PubMed2006

Evidence of protease in the saliva of the butterfly Heliconius melpomene (L.) (Nymphalidae, Lepidoptera).

Butterflies of the genus Heliconius are well known for their peculiar habits of utilizing pollen as a source of amino acids. Saliva plays a major role in the process of extracting amino acids and proteins from the pollen grains. In this investigation, we obtained samples of saliva from adult Heliconius melpomene by placing pumpkin pollen or fine glass-beads on the proboscis, which stimulates the butterflies to release saliva. Proteolytic activity was determined in the saliva by an insoluble protein-dye that turns blue when cleaved by proteases. Its extinction value was measured with a spectrophotometer at 595 nm. Both the saliva sampled with pollen and the saliva obtained from inert glass-beads exhibit proteolytic activity demonstrating that the saliva contains proteases. The proteolytic activity of the pollen/saliva samples was higher than that of the glass-bead/saliva samples, which we attribute to the stimulating effects of pollen, such as taste, smell, and texture, and not to proteases which might have been liberated from the pollen. This is indicated by the fact that pollen samples without saliva showed only a negligible indication for proteolytic activity. In general, females exhibit higher proteolytic activities than males, presumably due to their greater amino acid investment in reproduction. We present here first evidence for the existence of proteases in the saliva of a butterfly species and suggest that these enzymes are crucial for the use of amino acids and proteins from pollen in Heliconius butterflies.

Animals↗

PubMed2003

Effect of habitat fragmentation on dispersal in the butterfly Proclossiana eunomia.

Comparison of dispersal rates of the bog fritillary butterfly between continuous and fragmented landscapes indicates that between patch dispersal is significantly lower in the fragmented landscape, while population densities are of the same order of magnitude. Analyses of the dynamics of the suitable habitat for the butterfly in the fragmented landscape reveal a severe, non linear increase in spatial isolation of patches over a time period of 30 years (i.e. 30 butterfly generations), but simulations of the butterfly metapopulation dynamics using a structured population model show that the lower dispersal rates in the fragmented landscape are far above the critical threshold leading to metapopulation extinction. These results indicate that changes in individual behaviour leading to the decrease of dispersal rates in the fragmented landscape were rapidly selected for when patch spatial isolation increased. The evidence of such an adaptive answer to habitat fragmentation suggests that dispersal mortality is a key factor for metapopulation persistence in fragmented landscapes. We emphasise that landscape spatial configuration and patch isolation have to be taken into account in the debate about large-scale conservation strategies.

Animals↗

PubMed2006

An ecological risk assessment of Cry1F maize pollen impact to pale grass blue butterfly.

The intrinsic toxicity of lepidopteran-active Bt proteins necessitates assessment of non-target risks associated with environmental release of transgenic crops expressing these proteins. Principles of ecological risk assessment provide a means for assessing non-target risks when information regarding exposure to the toxin and species-specific effects are lacking. This is shown for the case of Bt Cry1F maize release in Japan, where off-field pollen dissemination and effect on butterfly species is of concern. The specific ecological entity of concern for the assessment of the non-target impact of Cry1F maize pollen was Yamato-shijimi (pale grass blue butterfly), Pseudozizeeria maha (Kollar), a commonly occurring, susceptible species. Yamato-shijimi is widely adapted in Japan where it occurs in both rural and metropolitan settings, corresponding to the distribution and habitat of katabami (Oxalis corniculata (L.)), the larval host plant. The northern extent of Yamato-shijimi habitat lies to the south of major maize production regions in Japan, but exposure may occur elsewhere where maize and Yamato-shijimi co-occur. Screening level assessment of potential adverse effects to Yamato-shijimi in the field environment considered the probability for spatial-temporal co-occurrence of the life stages of concern (1st and 2nd instars) and the stressor (Cry1F protein expressed in maize pollen) at environmentally relevant concentrations. In the event of exposure to maize pollen, early instars of Yamato-shijimi feed exclusively on the underside of katabami leaves, which further limits the portion of the butterfly population that would be exposed. Projected levels of exposure to Cry1F pollen are below the toxicity level of concern and, thus, indicate negligible risk. Most sensitive species characterization (intergenera sensitivity) similarly shows negligible risk to other Japanese butterfly species of concern when distributed beyond the maize field or field margin.

Animals↗

PubMed2000

Non-random dispersal in the butterfly Maniola jurtina: implications for metapopulation models.

The dispersal patterns of animals are important in metapopulation ecology because they affect the dynamics and survival of populations. Theoretical models assume random dispersal but little is known in practice about the dispersal behaviour of individual animals or the strategy by which dispersers locate distant habitat patches. In the present study, we released individual meadow brown butterflies (Maniola jurtina) in a non-habitat and investigated their ability to return to a suitable habitat. The results provided three reasons for supposing that meadow brown butterflies do not seek habitat by means of random flight. First, when released within the range of their normal dispersal distances, the butterflies orientated towards suitable habitat at a higher rate than expected at random. Second, when released at larger distances from their habitat, they used a non-random, systematic, search strategy in which they flew in loops around the release point and returned periodically to it. Third, butterflies returned to a familiar habitat patch rather than a non-familiar one when given a choice. If dispersers actively orientate towards or search systematically for distant habitat, this may be problematic for existing metapopulation models, including models of the evolution of dispersal rates in metapopulations.

Animals↗

PubMed2001

Juvenile hormone regulation of longevity in the migratory monarch butterfly.

Monarch butterflies (Danaus plexippus) of eastern North America are well known for their long-range migration to overwintering roosts in south-central Mexico. An essential feature of this migration involves the exceptional longevity of the migrant adults; individuals persist from August/September to March while their summer counterparts are likely to live less than two months as adults. Migrant adults persist during a state of reproductive diapause in which both male and female reproductive development is arrested as a consequence of suppressed synthesis of juvenile hormone. Here, we describe survival in monarch butterflies as a function of the migrant syndrome. We show that migrant adults are longer lived than summer adults when each are maintained under standard laboratory conditions, that the longevity of migrant adults is curtailed by treatment with juvenile hormone and that the longevity of summer adults is increased by 100% when juvenile hormone synthesis is prevented by surgical removal of its source, the corpora allatum. Thus, monarch butterfly persistence through a long winter season is ensured in part by reduced ageing that is under endocrine regulation, as well as by the unique environmental properties of their winter roost sites. Phenotypic plasticity for ageing is an integral component of the monarch butterflies' migration-diapause syndrome.

Animal Migration↗

PubMed2005

Tracking butterfly flight paths across the landscape with harmonic radar.

For the first time, the flight paths of five butterfly species were successfully tracked using harmonic radar within an agricultural landscape. Until now, butterfly mobility has been predominantly studied using visual observations and mark-recapture experiments. Attachment of a light-weight radar transponder to the butterfly's thorax did not significantly affect behaviour or mobility. Tracks were analysed for straightness, duration, displacement, ground speed, foraging and the influence of linear landscape features on flight direction. Two main styles of track were identified: (A) fast linear flight and (B) slower nonlinear flights involving a period of foraging and/or looped sections of flight. These loops potentially perform an orientation function, and were often associated with areas of forage. In the absence of forage, linear features did not provide a guiding effect on flight direction, and only dense treelines were perceived as barriers. The results provide tentative support for non-random dispersal and a perceptual range of 100-200 m for these species. This study has demonstrated a methodology of significant value for future investigation of butterfly mobility and dispersal.

Animals↗

PubMed2005

New insights into butterfly-environment relationships using partitioning methods.

Variation partitioning and hierarchical partitioning are novel statistical approaches that provide deeper understanding of the importance of different explanatory variables for biodiversity patterns than traditional regression methods. Using these methods, the variation in occupancy and abundance of the clouded apollo butterfly (Parnassius mnemosyne L.) was decomposed into independent and joint effects of larval and adult food resources, microclimate and habitat quantity. The independent effect of habitat quantity variables (habitat area and connectivity) captured the largest fraction of the variation in the clouded apollo patterns, but habitat connectivity had a major contribution only for occupancy data. The independent effects of resources and microclimate were higher on butterfly abundance than on occupancy. However, a considerable amount of variation in the butterfly patterns was accounted for by the joint effects of predictors and may thus be causally related to two or all three groups of variables. Abundance of the butterfly in the surroundings of the focal grid cell had a significant effect in all analyses, independently of the effects of other predictors. Our results encourage wider applications of partitioning methods in biodiversity studies.

Animals↗

PubMed2006

Light on the moth-eye corneal nipple array of butterflies.

The outer surface of the facet lenses in the compound eyes of moths consists of an array of excessive cuticular protuberances, termed corneal nipples. We have investigated the moth-eye corneal nipple array of the facet lenses of 19 diurnal butterfly species by scanning electron microscopy, transmission electron microscopy and atomic force microscope, as well as by optical modelling. The nipples appeared to be arranged in domains with almost crystalline, hexagonal packing. The nipple distances were found to vary only slightly, ranging from about 180 to 240 nm, but the nipple heights varied between 0 (papilionids) and 230 nm (a nymphalid), in good agreement with previous work. The nipples create an interface with a gradient refractive index between that of air and the facet lens material, because their distance is distinctly smaller than the wavelength of light. The gradient in the refractive index was deduced from effective medium theory. By dividing the height of the nipple layer into 100 thin slices, an optical multilayer model could be applied to calculate the reflectance of the facet lenses as a function of height, polarization and angle of incidence. The reflectance progressively diminished with increased nipple height. Nipples with a paraboloid shape and height 250 nm, touching each other at the base, virtually completely reduced the reflectance for normally incident light. The calculated dependence of the reflectance on polarization and angle of incidence agreed well with experimental data, underscoring the validity of the modelling. The corneal nipples presumably mainly function to reduce the eye glare of moths that are inactive during the day, so to make them less visible for predators. Moths are probably ancestral to the diurnal butterflies, suggesting that the reduced size of the nipples of most butterfly species indicates a vanishing trait. This effect is extreme in papilionids, which have virtually absent nipples, in line with their highly developed status. A similar evolutionary development can be noticed for the tapetum of the ommatidia of lepidopteran eyes. It is most elaborate in moth-eyes, but strongly reduced in most diurnal butterflies and absent in papilionids.

Animals↗

PubMedDate not supplied

A simulation study of the genetic regulatory hierarchy for butterfly eyespot focus determination.

The color patterns on the wings of butterflies have been an important model system in evolutionary developmental biology. Two types of models have been used to study these patterns. The first type of model employs computational techniques and generalized mechanisms of pattern formation to make predictions about how color patterns will vary as parameters of the model are changed. These generalized mechanisms include diffusion gradient, reaction-diffusion, lateral inhibition, and threshold responses. The second type of model uses known genetic interactions from Drosophila melanogaster and patterns of candidate gene expression in one of several butterfly species (most often Junonia (Precis) coenia or Bicyclus anynana) to propose specific genetic regulatory hierarchies that appear to be involved in color pattern formation. This study combines these two approaches using computational techniques to test proposed genetic regulatory hierarchies for the determination of butterfly eyespot foci (also known as border ocelli foci). Two computer programs, STELLA 8.1 and Delphi 2.0, were used to simulate the determination of eyespot foci. Both programs revealed weaknesses in a genetic model previously proposed for eyespot focus determination. On the basis of these simulations, we propose two revised models for eyespot focus determination and identify components of the genetic regulatory hierarchy that are particularly sensitive to changes in model parameter values. These components may play a key role in the evolution of butterfly eyespots. Simulations like these may be useful tools for the study of other evolutionary developmental model systems and reveal similar sensitive components of the relevant genetic regulatory hierarchies.

Animals↗