Migratory Butterflies Research Articles

A cold high-pressure system over North China hinders the southward migration of Mythimna separata in autumn

BackgroundIn warm regions or seasons of the year, the planetary boundary layer is occupied by a huge variety and quantity of insects, but the southward migration of insects (in East Asia) in autumn is still poorly understood.MethodsWe collated daily catches of the oriental armyworm (Mythimna separata) moth from 20 searchlight traps from 2014 to 2017 in China. In order to explore the autumn migratory connectivity of M. separata in East China, we analyzed the autumn climate and simulated the autumn migration process of moths.ResultsThe results confirmed that northward moth migration in spring and summer under the East Asian monsoon system can bring rapid population growth. However, slow southerly wind (blowing towards the north) prevailed over the major summer breeding area in North China (33°–40° N) due to a cold high-pressure system located there, and this severely disrupts the autumn ‘return’ migration of this pest. Less than 8% of moths from the summer breeding area successfully migrated back to their winter-breeding region, resulting in a sharp decline of the population abundance in autumn. As northerly winds (blowing towards the south) predominate at the eastern periphery of a high-pressure system, the westward movement of the high-pressure system leads to more northerlies over North China, increasing the numbers of moths migrating southward successfully. Therefore, an outbreak year of M. separata larvae was associated with a more westward position of the high-pressure system during the previous autumn.ConclusionThese results indicate that the southward migration in autumn is crucial for sustaining pest populations of M. separata, and the position of the cold high-pressure system in September is a key environmental driver of the population size in the next year. This study indicates that the autumn migration of insects in East China is more complex than previously recognized, and that the meteorological conditions in autumn are an important driver of migratory insects’ seasonal and interannual population dynamics.

The oriental armyworm genome yields insights into the long-distance migration of noctuid moths.

The oriental armyworm, Mythimna separata, is known for its long-distance seasonal migration and environment-dependent phase polymorphisms. Here, we present a chromosome-level genome reference and integrate multi-omics, functional genetics, and behavioral assays to explore the genetic bases of the hallmark traits of M.separata migration. Gene family comparisons show expansion of gustatory receptor genes in this cereal crop pest. Functional investigation of magnetoreception-related genes and associated flight behaviors suggest that M.separata may use the geomagnetic field to guide orientation in its nocturnal flight. Comparative transcriptome characterizes a suite of genes that may confer the observed plasticity between phases, including genes involved in protein processing, hormone regulation, and dopamine metabolism. We further report molecular signatures that underlie the dynamic regulation of a migratory syndrome coordinating reproduction and flight. Our study yields insights into environment-dependent developmental plasticity in moths and advances our understanding of long-distance migration in nocturnal insect pests.

Migration of crimson rose butterfly (Pachliopta hector) from India to Sri Lanka

Migrations of butterflies are common phenomena, yet they are one of the greatest natural events on earth. The migration of monarch butterflies, Danaus plexippus (L.) is a spectacular event that has received great attention in northern America. They travel 1,200–2,800 miles from the northeast United States and southeast Canada to the mountain forests of central Mexico, where they find suitable climatic conditions to hibernate from the beginning of November to mid-March. This swarming occurs primarily across North American land mass, so does not cross the sea. Although migration appears to be widespread among butterflies, its prevalence, and migration behaviours, are poorly understood.

The Transcription of Flight Energy Metabolism Enzymes Declined with Aging While Enzyme Activity Increased in the Long-Distance Migratory Moth, Spodoptera frugiperda.

Simple SummaryIn this study, we established the overall transcriptome framework of the thorax and aging-associated expression change trajectories, and constructed the possible flight energy metabolism pathways using potential energy metabolic enzymes in Spodoptera frugiperda females. Gene expression and functional prediction indicated that most genes and pathways related to energy metabolism and other biological processes (e.g., transport, longevity and signaling) were downregulated with aging, whereas the expression of enzymes of proline oxidation and genes related to immunity and repair increased with age. The increased expression of proline oxidation enzymes with age suggests that this energy metabolic pathway also is important or linked to some aging processes. Further activity assay showed that the activities of the five tested key metabolic enzymes increased with age. The transcriptional decrease but activity increase with aging imply that these enzymes are stable. A high activity of enzymes may be crucial for a long-distance migrator. The activity ratio of GAPDH/HOAD was <1 and decreased with age, indicating that lipid is the main flight fuel for this insect, particularly in aged individuals.Of all the things that can fly, the flight mechanisms of insects are possibly the least understood. By using RNAseq, we studied the aging-associated gene expression changes in the thorax of Spodoptera frugiperda females. Three possible flight energy metabolism pathways were constructed based on 32 key metabolic enzymes found in S. frugiperda. Differential expression analysis revealed up to 2000 DEGs within old females versus young ones. Expression and GO and KEGG enrichment analyses indicated that most genes and pathways related to energy metabolism and other biological processes, such as transport, redox, longevity and signaling pathway, were downregulated with aging. However, activity assay showed that the activities of all the five tested key enzymes increased with age. The age-associated transcriptional decrease and activity increase in these enzymes suggest that these enzymes are stable. S. frugiperda is a long-distance migrator, and a high activity of enzymes may be important to guarantee a high flight capacity. The activity ratio of GAPDH/HOAD ranged from 0.594 to 0.412, suggesting that lipid is the main fuel of this species, particularly in old individuals. Moreover, the expression of enzymes in the proline oxidation pathway increased with age, suggesting that this energy metabolic pathway also is important for this species or linked to some aging-specific processes. In addition, the expression of immunity- and repair-related genes also increased with age. This study established the overall transcriptome framework of the flight muscle and aging-associated expression change trajectories in an insect for the first time.

Advance in the timing of the annual migration of the brown-veined white butterfly through Johannesburg, South Africa, over the period 1914-2020.

During the mid-summer month of January each year, the migrating brown-veined white butterflies (Belenois aurota, Fabricius, 1973) move through Johannesburg, South Africa, on their path from the Karoo to Mozambique. The result is a short period of approximately 3days during which the skies of Johannesburg are filled with white butterflies, a spectacle that has been recorded in print media over the past century, and social media over the past decade. In this study, we mine these traditional and social media archives to produce the first multi-decadal phenological record of butterfly migration timing for South Africa, and explore the changes in timing and the role of climate thereof. We find a statistically significant advance in timing at a rate of 2.9days per decade (r = 0.34, p = 0.0490). The climatic drivers of shifts in migratory species arrival are difficult to detect, as they involve the role of weather at the point of departure in determining the start of flight, and the weather en route to determine the path followed. However, statistically significant relationships are found between the arrival dates and both Tmin and precipitation in the month of December, and the combination thereof (r = 0.44, p = 0.0437 and r = 0.45, p = 0.0420 respectively). The findings of this study contribute to a growing literature documenting phenological shifts in South Africa, a previously under-represented region.

Destinations of third-generation Mythimna separata (Lepidoptera: Noctuidae) moths in Jilin and its effects on population genetic diversity

Third-generation oriental armyworm larvae, Mythimna separata (Walker) (Lepidoptera: Noctuidae), have caused considerable economic losses in Jilin. Understanding the occurrence, regularity and return movement of third-generation adults is crucial for pest forecasting. The study was conducted using systemic monitoring, radar observations and molecular markers from 2015 to 2019. The main results are as follows: (1) third-generation moths were regularly captured from late August to late September. These moths have been attributed to local emergence and were identified as an “emigration population.” Wind speed and temperature were advantageous for moth migration, and advantageous northeasterly winds account for 9.6% of the total. Radar studies determined that the migrant flying height was mainly below 600 m. Moths migrated over a range of directions, including their return movements. Forward trajectories predicted that the destination regions of the Korean Peninsula, the Russian Far East, and northern China were unfavorable for survival. (2) A total of 29 haplotypes were detected. There were unique haplotypes between two sampling years. The haplotype analysis indicated similar content in the two sampling years. The haplotype diversity indices appear to have been maintained. Overall, our findings indicate that the moths did not make a successful return flight, but the genetic diversity was unaffected.

Population genetics of a recent range expansion and subsequent loss of migration in monarch butterflies.

Range expansions—whether permanent or transient—strongly influence the distribution of genetic variation in space. Monarch butterflies are best known for long‐distance seasonal migration within North America but are also established as nonmigratory populations around the world, including on Pacific Islands. Previous research has highlighted stepwise expansion across the Pacific, though questions remain about expansion timing and the population genetic consequences of migration loss. Here, we present reduced‐representation sequencing data for 275 monarchs from North America (n = 85), 12 Pacific Islands (n = 136) and three locations in Australia (n = 54), with the goal of understanding (i) how the monarch's Pacific expansion has shaped patterns of population genetic variation and (ii) how loss of migration has influenced spatial patterns of differentiation. We find support for previously described stepwise dispersal across the Pacific and document an additional expansion from Hawaii into the Mariana Islands. Nonmigratory monarchs within the Mariana Islands show strong patterns of differentiation, despite their proximity; by contrast, migratory North American samples form a single genetically panmictic population across the continent. Estimates of Pacific establishment timing are highly uncertain (~100–1,000,000 years ago) but overlap with historical records that indicate a recent expansion. Our data support (i) a recent expansion across the Pacific whose timing overlaps with available historical records of establishment and (ii) a strong role for seasonal migration in determining patterns of spatial genetic variation. Our results are noteworthy because they demonstrate how the evolution of partial migration can drive population differentiation over contemporary timescales.

환경위기에서 생태적 희망찾기: 바바라 킹솔버 작품 비교 연구

The purpose of this study is to analyze Barbara Kingsolver’s Prodigal Summer and Flight Behavior based on Arne Naess’ Deep Ecology theory. Among Naess’ ‘The Eight Points of Deep Ecology,’ this study is focused on accepting life equality and recognizing diverse life forms. Barbara Kingsover, an American environmental fiction writer, expresses that no human has dominant authority on nature. She also intertwines human and non-human life with independent values and fate. In the texts Prodigal Summer and Flight Behavior, both human beings and other living things are closely interrelated. Based on Deep Ecology theory, this paper explores how Kingslover’s work offers a mode of ethical responsiveness to in an age of ecological crises. In Prodigal Summer, the character Garnett craves to revive American chestnut trees. His failure is mainly caused by his self-centered stubbornness. Through Nannie’s warm hospitality he begins to sense the value of reconciliation and co-existence with others, and finally comes to understand that American chestnut trees have survived on Nannie’s ranch regardless of reckless logging. In Flight Behavior, Dellarobia is a discontented wife, and experiences intellectual development thanks to Professor Ovid. In this text, the global climate crisis affects the migration of Monarch butterflies. The arrival of the butterflies at Zebulon Mountain totally changes Dellarobia’s life; both she and the butterflies survive torrential rain and freezing temperatures. This paper argues that through showing how her protagonists overcome environmental crisis, Kingsolver is implying that collectively the human species has agency; we can act to avert an impending environmental cataclysm.

Butterflies of Eravikulam National Park and its environs in the Western Ghats of Kerala, India

The Eravikulam National Park (ENP) holds the largest remaining pristine patches of southern montane wet temperate forests and southern montane wet temperate grasslands of peninsular India. The study shows that ENP harbours 198 species of butterflies, constituting 60.73% of the butterflies recorded from Kerala and 59.10% of butterflies observed in Western Ghats (WG). Thirty-five species of butterflies seen in ENP have some level of endemicity associated with them and 22 of them (52.38%) are strictly endemic to WG. Twenty-seven species are under the schedules of Indian Wildlife Act 1972 (WPA) and its amendments. This National Park has montane grassland-Shola dependent super-endemics like Neptis palnica and Telinga davisoni. ENP also holds Parantica nilgiriensis a Near Threatened species and another 11 Western Ghats endemics, namely, Telinga davisoni, T. oculus, Ypthima chenu, Y. ypthimoides, Arnetta mercara, Baracus hampsoni, B. subditus, Thoressa astigmata, T. evershedi, Oriens concinna, and Caltoris canaraica, which are primary grass feeders. Eravikulam, on the Anamalai–High Range–Palni landscape, lies on a major path of the return migration of butterflies to Western Ghats before the north-east monsoons. Although well-protected, the ENP has anthropogenic pressures from tea estates surrounding it, mammal-oriented management practices like controlled burning of primary grasslands, and natural forest fires, that can significantly affect the invertebrate fauna especially montane grassland shola-dependent butterflies.

Host plants and pollination regions for the long-distance migratory noctuid moth, Hadula trifolii Hufnagel in China.

Nocturnal moths are important pollinators of plants. The clover cutworm, Hadula trifolii, is a long‐distance migratory nocturnal moth. Although the larvae of H. trifolii are polyphagous pests of many cultivated crops in Asia and Europe, the plant species pollinated by the adult are unclear. Pollen species that were attached to individual migrating moths of H. trifolii were identified based on pollen morphology and DNA to determine their host plants, geographic origin, and pollination areas. The moths were collected on their seasonal migration pathway at a small island, namely Beihuang, in the center of the Bohai Sea of China during 2014 to 2018. Pollen was detected on 28.60% of the female moths and 29.02% of the male, mainly on the proboscis, rarely on compound eyes and antennae. At least 92 species of pollen from 42 plant families, mainly from Asteraceae, Amaranthaceae, and Pinaceae, distributed throughout China were found on the test moths. Migratory H. trifolii moths visited herbaceous plants more than woody plants. Pollen of Macadamina integrifolia or M. tetraphylla was found on moths early in the migratory season. These two species are distributed in Guangdong, Yunnan, and Taiwan provinces in China, indicating that migratory moths probably traveled about 2000 km from southern China to the Beihuang Island in northern China. Here, by identifying plant species using pollen, we gained a better understanding of the interactions between H. trifolii moths and a wide range of host plants in China. This work provides valuable and unique information on the geographical origin and pollination regions for H. trifolii moths.

Genetic studies of fall armyworm indicate a new introduction into Africa and identify limits to its migratory behavior

The fall armyworm, Spodoptera frugiperda (J.E. Smith) is native to the Americas and a major pest of corn and several other crops of economic importance. The species has characteristics that make it of particular concern as an invasive pest, including broad host range, long-distance migration behavior, and a propensity for field-evolved pesticide resistance. The discovery of fall armyworm in western Africa in 2016 was followed by what was apparently a remarkably rapid spread throughout sub-Saharan Africa by 2018, causing economic damage estimated in the tens of billions USD and threatening the food security of the continent. Understanding the history of the fall armyworm invasion of Africa and the genetic composition of the African populations is critical to assessing the risk posed to different crop types, the development of effective mitigation strategies, and to make Africa less vulnerable to future invasions of migratory moth pests. This paper tested and expanded on previous studies by combining data from 22 sub-Saharan nations during the period from 2016 to 2019. The results support initial descriptions of the fall armyworm invasion, including the near absence of the strain that prefers rice, millet, and pasture grasses, while providing additional evidence that the magnitude and extent of FAW natural migration on the continent is more limited than expected. The results also show that a second entry of fall armyworm likely occurred in western Africa from a source different than that of the original introduction. These findings indicate that western Africa continues to be at high risk of future introductions of FAW, which could complicate mitigation efforts.

Areawide management of fall armyworm, Spodoptera frugiperda (Lepidoptera: Noctuidae), using selected cover crop plants

BackgroundFall armyworm, Spodoptera frugiperda (J. E. Smith) is a migratory moth that annually migrates northward each spring from sites in southern Florida and southern Texas. This caterpillar pest feeds on and damages row, turf and vegetable crops in the eastern and central U.S. Before migrating in spring, it feeds on cover crops in central and eastern Florida and expands its populations. Our objective was to use multi-year studies to compare fall armyworm populations that develop in cover crop plants.MethodsA series of field experiments and a laboratory feeding study were conducted to compare infestation and feeding and of fall armyworm on different cover crop plants. Field experiments had plots planted with corn (Zea mays L.), sorghum-sudangrass [Sorghum bicolor (L.) Moench], a standard cover crop in Florida, and two alternative cover crops, sunn hemp (Crotalaria juncea L.) and cowpea [Vigna unguiculata (L.) Walpers spp. unguiculata]. Another trial compared populations in sorghum-sudangrass and in mixtures of sorghum-sudangrass with buckwheat (Fagopyrum esculentum Moench) or pearl millet (Cenchrus americanus (L.) Morrone). Fall armyworm larvae were fed and allowed to develop on different sunn hemp germplasm in a laboratory trial.ResultsField populations of fall armyworm were highest on corn, followed by sorghum-sudangrass. Sunn hemp and cowpea had larval populations 70–96% less than on sorghum-sudangrass, suggesting replacement of this cover crop with either plant species might help reduce areawide populations of resident or migratory fall armyworm. Larvae collected from cover crop plots had parasitism levels that averaged 30%, with Chelonus insularis (Hymenoptera: Braconidae) emerging as the most commonly-collected species. Larval feeding on different sunn hemp germplasm lines resulted in no difference in weight gain.ConclusionsReplacing sorghum-sudangrass with sunn hemp varieties or germplasm should be acceptable as a replacement cover crop for areawide management of fall armyworm.

The genome of the black cutworm Agrotis ipsilon

The black cutworm (BCW), Agrotis ipsilon, is a worldwide polyphagous and underground pest that causes a high level of economic loss to a wide range of crops through the damage of roots. This species performs non-directed migration throughout East and Southeast Asia seasonally. Lack of a genome information has limited further studies on its unique biology and the development of novel management approaches. In this study, we present a 476 Mb de novo assembly of BCW, along with a consensus gene set of 14,801 protein-coding gene models. Quality controls show that both genome assembly and annotations are high-quality and mostly complete. We focus manual annotation and comparative genomics on gene families that related to the unique attributes of this species, such as nocturnality, long-distance migration, and host adaptation. We find that the BCW genome encodes a similar gene repertoire in various migration-related gene families to the diural migratory butterfly Danaus plexiipus, with additional copies of long wavelength opsin and two eye development-related genes. On the other hand, we find that the genomes of BCW and many other polyphagous lepidopterans encode many more gustatory receptor genes, particularly the lineage-specific expanded bitter receptor genes, than the mono- or oligo-phagous species, suggesting a common role of gustatory receptors (GRs) expansion in host range expansion. The availability of a BCW genome provides valuable resources to study the molecular mechanisms of non-directed migration in lepidopteran pests and to develop novel strategies to control migratory nocturnal pests.

Exploring the Role of Cognition in the Annual Fall Migration of the Monarch Butterfly (Danaus plexippus).

Simple SummaryEach year, millions of monarch butterflies in eastern North America undergo a spectacular fall migration to overwintering sites in central Mexico, where they remain until returning northward in the spring. In addition to the navigational challenges faced during the southward flight, migratory individuals are also challenged with the foraging task of locating high-quality nectar sources for overwinter survival in the face of unfamiliar floral landscapes that change in complex and unpredictable ways. In the research reported here, a proboscis extension paradigm is used to investigate learning and long-term memory abilities that might help fall migrants meet these unique foraging demands. Male and female migratory and captive-reared individuals were consecutively trained to perform color and odor cue discriminations and then tested for their ability to simultaneously retain reward information associated with each cue in memory without reinforcement over a period of 7 days. Results showed that male and female fall migrants can learn the reward properties of color and odor cues with over 75% accuracy after less than 40 s of exposure and can simultaneously retain visual and olfactory information predicting the availability of floral rewards in memory without reinforcement for at least 7 days. Captive-reared male butterflies also showed the ability to retain visual and olfactory information in long-term memory for 7 days; however, 80% of captive-reared females could not retain color cues in long-term memory for more than 24 h. These novel findings are consistent with the view that monarch butterflies have enhancements to long-term memory that enable them to minimize the amount of time and energy wasted searching for suitable nectar sources during their annual fall migration, thereby optimizing migratory performance and increasing the chance of overwinter survival. The possibility that female monarchs undergo a seasonal change in visual long-term memory warrants further empirical investigation.Each fall, monarch butterflies in eastern North America undergo an extraordinary long-distance migration to wintering areas in central Mexico, where they remain until returning northward in the spring. Migrants survive the overwintering period by metabolizing lipid reserves accumulated exclusively though floral nectar; however, there is little known about how individuals maximize foraging efficiency in the face of floral environments that constantly change in complex and unpredictable ways along their migratory route. Here, a proboscis extension paradigm is used to investigate the role of cognition during the foraging phase of monarch migration. Male and female migratory butterflies were consecutively trained to discriminate between two color and odor cues and then tested for their ability to simultaneously retain the information on the reward value of each cue in memory without reinforcement over a period of 7 days. To gain further insight into cognitive abilities of monarchs as a migratory species, a second set of captive-reared males and females were tested under harnessed conditions at the same time as wild-caught fall migrants. Results showed that male and female migrants can learn the reward properties of color and odor cues with over 75% accuracy after less than 40 s of exposure and can simultaneously retain visual and olfactory information predicting the availability of floral rewards in memory without reinforcement for at least 7 days. Captive-reared male butterflies also showed the ability to retain visual and olfactory information in long-term memory for 7 days; however, 80% of captive-reared females could not retain color cues in long-term memory for more than 24 h. These novel findings are consistent with the view that monarch butterflies, as a migratory species, have enhancements to long-term memory that enable them to minimize the amount of time and energy wasted searching for suitable nectar sources during their annual fall migration, thereby optimizing migratory performance and increasing the chance of overwinter survival. The possibility that female monarchs undergo a seasonal change in visual long-term memory warrants further empirical investigation.

Experimental investigation on flow structures of steadily translating low-aspect-ratio wings in low Reynolds number flow

In recent decades, Micro Air Vehicles (MAVs) have been a hot topic for their promising future. But the promotions of MAVs are hindered by their short endurances. To solve this problem, inspirations are brought from migratory butterflies who utilize the ‘flapping-gliding’ skill during long-distance migration to improve the flight efficiency. The butterfly’s gliding flights, which can be simplified by considering the steadily translating fixed wings, have drawn high attentions. Previous studies mainly focus on the aerodynamics of the low-aspect-ratio fixed wings at Re ≈ 105 via force measurements. However, few experimental studies have measured the 3D flow fields. Consequently, the underlying high lift-to-drag ratio mechanisms in the steadily translating butterfly-shaped wings are still not clear. To shed new light on this problem, the 3D flow structures around butterfly-shaped wings were captured and investigated in detail.

Seasonal spatial dynamics of butterfly migration

AbstractUnderstanding the seasonal movements of migratory species underpins ecological studies. Several hundred butterfly species show migratory behaviour, yet the spatial pattern of these migrations is poorly understood. We developed climatic niche models for 405 migratory butterfly species globally to estimate patterns of seasonal movement and the distribution of seasonal habitat suitability. We found strong seasonal variation in habitat suitability for most migratory butterflies with &gt;75% of pixels within their distributions showing seasonal switching in predicted occupancy for 85% of species. The greatest rate of seasonal switching occurred in the tropics. Several species showed extreme range fluctuations between seasons, exceeding 10‐fold for 53 species (13%) and more than 100‐fold for nine species (2%), suggesting that such species may be at elevated extinction risk. Our results can be used to search for the ecological processes that underpin migration in insects, as well as to design conservation interventions for declining migratory insects.

Monarch Butterfly Migration as an Integrative Model of Complex Trait Evolution.

AbstractUnderstanding the genetic architecture of complex trait adaptation in natural populations requires the continued development of tractable models that explicitly confront organismal and environmental complexity. A decade of high-throughput sequencing-based investigations into the genomic basis of migration points to an integrative framework that incorporates quantitative genetics, evolutionary developmental biology, phenotypic plasticity, and epigenetics to explain migration evolution. In this perspective, I argue that the transcontinental migration of the monarch butterfly (Danaus plexippus) can serve as a compelling system to study the mechanism of evolutionary lability of a complex trait. Monarchs show significant phenotypic and genotypic diversity across their global range, with phenotypic switching that allows for explicit study of evolutionary lability. A developmental approach for elucidating how migratory traits are generated and functionally integrated will be important for understanding the evolution of monarch migration traits. I propose a plasticity threshold model to describe migration lability, and I describe novel functional techniques that will help resolve open questions and model assumptions. I conclude by considering the relationships between adaptive genetic architecture, anthropogenic climate change, and conservation management practice and the timeliness of the monarch migration model to illuminate these connections given the rapid decline of the North American migration.

Outbreak of Catopsilia pyranthe L. on Senna (Cassia angustifolia Vahl) and Migration in Western Arid Region of India

Background: Cassia angustifolia Vahl, senna, known for medicinal properties belongs to family fabacea is a hardy plant, suitable for saline and rainfed conditions serving as a host for caterpillars of Catopsilia pyranthe L. butterflies suffering up to 90 per cent defoliation. An attempt was made to record butterfly migrations due to an outbreak of the lepidopteron pest on senna which is the first report on butterfly migration in western arid region.Methods: Surveys made in different districts for accurate quantification of butterflies passing within 5 minute through a 10 meter wide strip. For diurnal pattern, observations were taken on hourly basis. Correlation of butterfly density with weather parameters was worked out.Result: Migration was mainly in South West direction in a steady line connecting Jaisalmer, Jodhpur, Pali, Sirohi and Ajmer. The highest density (1360 butterflies/10m/5 minute) accounting for 16,320.0 butterflies/10m/hour and 97,920.0 butterflies/10m/day recorded in Keru (Jodhpur) representing bell shape curve of diurnal movement with a maximum activity between 12.00 noon and 1.00 PM.

Migration in butterflies: a global overview.

Insect populations including butterflies are declining worldwide, and they are becoming an urgent conservation priority in many regions. Understanding which butterfly species migrate is critical to planning for their conservation, because management actions for migrants need to be coordinated across time and space. Yet, while migration appears to be widespread among butterflies, its prevalence, as well as its taxonomic and geographic distribution are poorly understood. The study of insect migration is hampered by their small size and the difficulty of tracking individuals over long distances. Here we review the literature on migration in butterflies, one of the best-known insect groups. We find that nearly 600 butterfly species show evidence of migratory movements. Indeed, the rate of 'discovery' of migratory movements in butterflies suggests that many more species might in fact be migratory. Butterfly migration occurs across all families, in tropical as well as temperate taxa; Nymphalidae has more migratory species than any other family (275 species), and Pieridae has the highest proportion of migrants (13%; 133 species). Some 13 lines of evidence have been used to ascribe migration status in the literature, but only a single line of evidence is available for 92% of the migratory species identified, with four or more lines of evidence available for only 10 species - all from the Pieridae and Nymphalidae. Migratory butterflies occur worldwide, although the geographic distribution of migration in butterflies is poorly resolved, with most data so far coming from Europe, USA, and Australia. Migration is much more widespread in butterflies than previously realised - extending far beyond the well-known examples of the monarch Danaus plexippus and the painted lady Vanessa cardui - and actions to conserve butterflies and insects in general must account for the spatial dependencies introduced by migratory movements.

Effects of flight altitude on the lift generation of monarch butterflies: from sea level to overwintering mountain

Aerodynamic efficiency behind the annual migration of monarch butterflies, the longest among insects, is an unsolved mystery. Monarchs migrate 4000 km at high-altitudes to their overwintering mountains in Central Mexico. The air is thinner at higher altitudes, yielding reduced aerodynamic drag and enhanced range. However, the lift is also expected to reduce in lower density conditions. To investigate the ability of monarchs to produce sufficient lift to fly in thinner air, we measured the climbing motion of freely flying monarchs in high-altitude conditions. An optical method was used to track the flapping wing and body motions inside a large pressure chamber. The air density inside the chamber was reduced to recreate the higher altitude densities. The lift coefficient generated by monarchs increased from 1.7 at the sea-level to 9.4 at 3000 m. The correlation between this increase and the flapping amplitude and frequency was insignificant. However, it strongly correlated to the effective angle of attack, which measures the wing to body velocity ratio. These results support the hypothesis that monarchs produce sufficiently high lift coefficients at high altitudes despite a lower dynamic pressure.