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Red Admirals Vanessa atalanta (Lepidoptere: Nymphalidae) select northern winds on southward migration
Abstract
In the autumn periods of 1994-2001, the migrations of the Red Admiral Vanessa atalanta (L.) were recorded from the Porkkala Bird Tower, 35 km SW of Helsinki, Finland. By far the best year was 1998, when 1240 migrant V. atalanta were counted. Generalized to a 100-km strip, this would mean a minimum of half a million butterflies. Radar observations indicated that a large proportion may have migrated above the visible range. The migrations took place on sunny days with cool northern winds (down to +10-13°C). On warmer days with southern winds, V. atalanta individuals were stationary in the terrain. Other species observed to migrate south in the same way, but in much lower numbers, included Vanessa cardui (L.), Pieris brassicae (L.) and Autographa gamma (L.). These records help to resolve the "evolutionary puzzle" of why migrant butterflies and moths travel to northern latitudes when their offspring have such limited possibilities of returning to the south. Until now, the only butterfly for which high-elevation return migrations in northern winds have been known has been the American Monarch Danaus plexippus (L.). The mechanics of the flights, the migratory behaviour and their evolutionary significance are discussed in light of the literature.
... Srygley and Dudley, 2008). However, the vast majority of migratory insect species (including butterflies on some occasions: Mikkola, 2003;Stefanescu et al., 2012) carry out these journeys by ascending to high altitudes (typically > 100 m above the ground), where fast-moving airstreams enable considerable distances (sometimes several hundred kilometers) to be traversed in a single flight bout (Drake and Farrow, 1988;Gatehouse, 1997;Chapman et al., 2011a). In comparison to flight within the FBL, windborne migration would appear to be a rather risky and unpredictable strategy, as the distance and direction of movement will be controlled by the speed and direction of the airstreams within which the insects fly. ...
... Among the best studied insects from this perspective are nocturnally-active noctuid moth pests, and mass southward fall migrations have now been documented in, for example: Agrotis ipsilon and Helicoverpa zea in North America (Showers, 1997;Westbrook, 2008); Helicoverpa armigera, Mythimna separata and Spodoptera exigua in East Asia (Feng et al., 2003(Feng et al., , 2005(Feng et al., , 2008(Feng et al., , 2009; and Autographa gamma and Noctua pronuba in Europe (Chapman et al., 2008a(Chapman et al., , 2008bAlerstam et al., 2011). Southward windborne migrations in the fall have also been documented in other groups, including: dragonflies (Russell et al., 1998;Feng et al., 2006;Wikelski et al., 2006), leafhoppers (Taylor and Reling, 1986), pyralid moths (Riley et al., 1995) and butterflies (Mikkola, 2003;Stefanescu et al., 2012). It is thus becoming clear that many species of seasonal insect migrants use favorable tailwinds to carry out successful two-way journeys. ...
... The VLRs are operated for a 5-minute sampling period every 15 minutes throughout the daily cycle, thus giving a total of 16 sample periods within the 4-hour period of nocturnal flight activity (20:00-00:00 GMT) that we used in this study. Data for this study were collected from the 'spring' (May and June) and 'fall' (August and September) migration periods from three recent years of mass A. gamma invasions in the UK, namely 2000, 2003(Chapman et al., 2012, and also from the unusual peak of A. gamma flight activity recorded in midsummer (July) of 2006. Nightly counts of high-flying radar-detected A. gamma moths at each radar site were converted to aerial densities and migration fluxes as described elsewhere (Chapman et al., 2012). ...
The silver Y moth Autographa gamma undertakes windborne spring and fall migrations between winter breeding regions around the Mediterranean and summer breeding regions in northern Europe. Flight behaviors facilitating these migrations include: (i) selection of seasonally-favorable tailwinds; (ii) flying at the altitude of the fastest winds; (iii) adopting flight headings that partially counteract crosswind drift; and (iv) seasonal reversal of preferred directions between spring and fall. In the UK, radar measurements indicate that migratory activity is pronounced during the spring and fall, but is usually very low during midsummer (July). However, an atypically intense period of high-altitude flight was recorded during July 2006, and in this study we compare the flight behavior of A. gamma during these midsummer movements with the more typical spring and fall migrations. During July 2006, activity was most intense at significantly lower altitudes than occurred in spring or fall, and was not associated with the height of the fastest winds; consequently displacement speeds were significantly slower. The most striking difference was an absence of tailwind selectivity in July with windborne movements occurring on almost every night of the month and on tailwinds from all directions. Finally, orientation behavior was quantitatively different during July, with significantly greater dispersion of flight headings and displacements than observed in spring and fall. We discuss mechanisms which could have caused these differences, and conclude that a lack of appropriate photoperiod cues during development of the summer generation resulted in randomly-oriented 'dispersive' movements that were strikingly different from typical seasonal migrations.
... Many winged animals cover long distances during migration either flying actively or drifting with the wind, sometimes using flight only to stay aloft. Weather conditions, especially temperature and winds, and local topography have a substantial impact on their flight and orientation (e.g. Brown 1970;Alerstam 1981Alerstam , 1990aDrake & Farrow 1988;Richardson 1991;Mikkola 2003a;Å kesson & Hedenström 2007) as well as on the decision to initiate migration (Å kesson & Hedenström 2000;Å kesson et al. 2002;Wikelski et al. 2006). The displacement of small flying migrants is more or less determined by the wind, but some large insects and birds can control their track relative to the ground and avoid unwanted wind drift by adjusting their heading. ...
... There are, however, reports of monarchs, Danaus plexippus (e.g. Gibo & Pallett 1979;Gibo 1981) and red admirals (Mikkola 2003a) migrating at high altitudes and a recent study suggests that painted ladies, Vanessa cardui, on spring migration across the Mediterranean Sea are flying at altitudes around 1500 m (Stefanescu et al. 2007). ...
... During warm autumns, additional reproduction events might occur and red admirals are regularly observed as late as October in northern Europe (Henriksen & Kreutzer 1982;Eliasson et al. 2005). Each year migration in large numbers towards the south is reported in autumn throughout Europe (Williams 1951;Roer 1991;Imby 1993;Benvenuti et al. 1994Benvenuti et al. , 1996Hansen 2001;Stefanescu 2001;Mikkola 2003a), but there are also reports of large-scale migrations towards the north at this time of year (Rudebeck 1951;Radford 1975), suggesting a variable migratory pattern in autumn. In addition to all these reports on migration, there are also reports of red admirals in the middle of winter in the northern region (e.g. ...
Each autumn, large numbers of red admirals migrate throughout northern Europe, flying south, to reach areas with conditions suitable for surviving the winter. We observed the visible butterfly migration at Falsterbo peninsula, the southwesternmost point in Sweden, where red admirals are seen most autumns flying towards the Danish coast on their way to more southern parts of Europe. Weather parameters from a local weather station were used to analyse what factors are important for red admiral migration across the sea. Wind direction was among the important weather variables affecting the initiation of the migratory departure; most other studies of butterfly migration reported no large effect of wind direction. This difference is probably because the butterflies in our study were about to cross open sea for more than 20 km, whereas most previous studies were from inland locations where butterflies could avoid wind effects by flying close to the ground or on the lee side of topographical features. Other important weather variables affecting red admiral migration at Falsterbo were low wind speed and clear skies. The flight direction at Falsterbo was towards the west, which is in contrast to the southward direction generally reported during autumn migration in this species. This is probably because the red admirals followed both the local topography and the closest route to land on the other side and therefore deviated from the normally preferred direction to minimize flight over open water.
... The species' annual migration in Europe has been described based on flight directions taken at several locations (Williams 1951, Imby 1993, Benvenuti et al. 1996, Steiniger and Eitschberger 1996, Hansen 2001. Studies of winter ecology have been performed in Spain (Stefanescu 2001) and Italy (Brattström 2006), while observations of migration in relation to winds have been studied in northern Europe (Mikkola 2003a, Brattström et al. 2008a. Our knowledge about migration routes and phenology in this species, however, is still very limited. ...
... Even though the general migration in the northern parts of Europe is reported towards the south during autumn (Imby 1993, Hansen 2001, Mikkola 2003a there were butterflies in our autumn samples with dD values that suggested a more southerly origin. These individuals could be on a northward migration despite the late season, and because of this we found a mixture of individuals with different migratory origin and directions at the same location at this time of year. ...
... There was no doubt that north-south migration exists in Europe, as previous field observations have suggested (Benvenuti et al. 1996, Stefanescu 2001, Mikkola 2003a, but our data suggest that the spring migrants originated not only from the Mediterranean area, but possibly from areas further to the north or east. Most of the individuals captured in the western region and at the island of Capri in Italy, both in spring and autumn appeared to belong to another migratory population than those captured in northern Europe. ...
Tracking migratory movement of small animals with variable migration patterns is difficult with standard mark–recapture methods or genetic analysis. We used stable hydrogen isotope (δD) measurements of wings from European red admirals Vanessa atalanta to study several aspects of this species’ migration. In the central part of southern Europe we found large differences in δD values between red admirals sampled in autumn and spring supporting the hypothesis that reproduction takes place in the Mediterranean region during winter. There was also an apparent influx to southern Europe in the spring of individuals with a more southerly origin, since many samples had higher δD values and similar to those expected from coastal areas of North Africa. We found a clear seasonal difference in the δD values of red admirals sampled in northern Europe. Spring migrants arriving in northern Europe generally had high δD values that indicated a southerly origin. In autumn, δD values suggested that red admirals were mostly from regions close to the sampling sites, but throughout the sampling period there were always individuals with δD values suggesting non-local origins. The migration pattern of this species is supposedly highly variable and plastic. δD differences between individuals in the western part of Europe were generally small making migratory patterns difficult to interpret. However, butterflies from western Europe were apparently isolated from those from north-eastern Europe, since δD values in the western region rarely corresponded to those of autumn migrants from the north-east. Use of δD data for inferring butterfly migration in Europe is complex, but our study showed that this technique can be used to help uncover previously unknown aspects of red admiral migration.
... They rise on thermals up to altitudes of over 1000 m and then glide while migrating to their wintering areas (Gibo & Pallett 1979;Gibo 1981). The red admiral also uses northerly winds when migrating from the north of Europe to its breeding areas in the Mediterranean (Mikkola 2003). Although butterflies have only ever been directly observed flying at heights of 20-100 m, radar data indicate that flights may occur as high as 1000-3000 m (Mikkola 2003). ...
... The red admiral also uses northerly winds when migrating from the north of Europe to its breeding areas in the Mediterranean (Mikkola 2003). Although butterflies have only ever been directly observed flying at heights of 20-100 m, radar data indicate that flights may occur as high as 1000-3000 m (Mikkola 2003). It may well be the case, therefore, that the paucity of records of butterflies showing upper-level windborne migration is a consequence of the lack of appropriate methods for detecting this phenomenon. ...
... Taking into account the selective advantages of windborne migration (such as allowing flight to be more fuel-efficient and more rapid), it would be most surprising if V. cardui did not make use of tailwinds to complete its migrations. Although a few observations of V. cardui being carried by high-altitude winds do exist (Giuliani & Shields 1997;Mikkola 2003), it is not known if these flights are a common strategy used on migratory displacements to take advantage of wind currents. ...
1. Thousands of records of migratory butterfly species such as Vanessa cardui flying just above ground-level on fixed compass bearings have led to the common belief that these insects migrate within the so-called 'flight-boundary layer', where movements are relatively independent of the wind. 2. Given the selective advantages of windborne migration and the existence of a number of observations of flights of V. cardui from the upper levels of the atmosphere, we tested the hypothesis that migration from North Africa to southern Europe in this species is influenced by synoptic-scale wind currents. 3. Even with modern technology, it is extremely difficult to observe high-altitude flights directly, so we rely on an indirect approach that examines whether or not arrival peaks in north-eastern Spain are associated with winds blowing from Africa. 4. Arrivals of V. cardui were determined for the spring period (1 March-27 June, 1997-2006) at 79 sites in the Catalan Butterfly Monitoring Scheme. Wind patterns were described on the basis of synoptic-scale maps, transport models and back-trajectories calculated for each day of the spring period. 5. We found a strong association between migration and winds from North Africa, both for the whole data set (1997-2006; chi(2) = 4.7, P = 0.03) and for a restricted data set that excludes years in which the species was very scarce (chi(2) = 7.26, P = 0.007). 6. Episodes of massive northward migration within the species' flight-boundary layer also coincided with spells of winds from North Africa, suggesting a connection between low-altitude (observational) and high-altitude flights (inferred from wind patterns). 7. Finally, on the assumption that migration in V. cardui is windborne, a source-receptor transport model applied to spring abundance data in north-eastern Spain enables us to identify the most probable population source areas in North Africa.
... Vanessa atalanta is another migratory species that migrates between Europe and North Africa. It has latitudinal (Mikkola, 2003;Stefanescu, 2001) and possibly altitudinal migration and it may fly up to 3000 m altitude (Mikkola, 2003). As the wings of flying migratory animals are the main trait involved in movement, they are subjected to natural selection, and only those with modifications that favor migration (Outomuro and Johansson, 2019) are inherited (Alvial et al., 2019;Huang et al., 2020;Neto et al., 2013). ...
... Vanessa atalanta is another migratory species that migrates between Europe and North Africa. It has latitudinal (Mikkola, 2003;Stefanescu, 2001) and possibly altitudinal migration and it may fly up to 3000 m altitude (Mikkola, 2003). As the wings of flying migratory animals are the main trait involved in movement, they are subjected to natural selection, and only those with modifications that favor migration (Outomuro and Johansson, 2019) are inherited (Alvial et al., 2019;Huang et al., 2020;Neto et al., 2013). ...
The Western Painted Lady butterfly, Vanessa carye (Hüber, 1812), in addition to pre-senting an extensive dis�tribution in South America, has been observed flying in the Chilean Alti-plano from the coast to the highlands, from 0 to 5200 m.a.s.l. and it is suggested that could be a migratory insect. Some animal species move from one place to another by migration searching for favorable conditions. Wings of flying migratory animals are the
principal trait involved in move-ment, and their shape has been documented to change between migratory and non-migratory species or populations. In this sense, little is known about the adaptations of butterflies to ele�vational gradients, so the V. carye’s wide latitudinal and altitudinal range coupled with the different climatic conditions makes this species an interesting subject for adaptation studies. This research studies V. carye at
different elevational ranges in extreme environments at the Chilean Altiplano and Atacama Desert to determine the presence of morphotypes through geometric morphometrics associated with altitudinal patterns, and to determine the genetic diversity and population structure of this species by using COI molecular marker. Subtle morphometric changes between populations were found, so two morphometric lineages were defined: a “coastal”
lineage with more elongated wings and an “altiplano” lineage with more rounded wings. Nevertheless, low genetic diversity and no genetic structure associated to these morphological differences were found. Under�standing the processes underlying the wing shape of V. carye morphological adaptations will help to understand
its natural history. Results here may be a first approach of evidence to answer the question “Is this butterfly a
migratory species?”
... It is clear from the different studies of red admiral migration that variation in many parameters of butterfly migration (for example timing and origin of migrants) can be substantial, and likely heavily dependent on yearly differences in weather, winds and reproductive success (e.g. [14,15,28,36]). Data from reported sightings [28], standardized counts [15] and passive trap captures (this study), all result in similar time periods. It is therefore reasonable to assume that the main red admiral autumn migration in northern Europe occurs around September in most years. ...
... We may ask what is the reason for these dramatic differences in migratory intensity that we found? Studies of the effect of weather on migration of red admirals at coastal sites have shown that wind direction is important to initiate large-scale migration [15,36]. The above-mentioned studies were performed at locations where red admirals are about to cross open water and therefore may be more dependent [14] on favourable winds than at inland sites. ...
Background
Long-distance migration has evolved multiple times in different animal taxa. For insect migrants, the complete annual migration cycle covering several thousand kilometres, may be performed by several generations, each migrating part of the distance and reproducing. Different life-cycle stages and preferred orientation may thus, be found along the migration route. For migrating red admirals (Vanessa atalanta) it has been questioned if they reproduce in the most northern part of the range. Here we present migration phenology data from a two-year time series of migrating red admirals captured at Rybachy, Kaliningrad, in the northern part of Europe investigating time for migration, life-history stage (migration, reproduction) as well as site of origin in individual butterflies.
Methods
Red admirals were captured daily at a coastal site during spring, summer and autumn in 2004 and 2005. For the sampled individuals, reproductive status and fuel content were estimated by visual inspection, and hydrogen isotopes (δ²H) were analysed in wing samples. δ²H values was compared with samples from two nearby reference sites in Estonia and Poland.
Results
Analysis of hydrogen isotopes (δ²H) in red admiral wings showed that the spring cohort were of a southerly origin, while those caught in August or later in the autumn were from the local region or areas further to the north. All females caught during spring had developing eggs in their abdomen, but no eggs were found in late summer/autumn. There was a male-biased sex ratio during autumn and a difference in lipid content between years. When comparing the isotopic data with inland nearby locations, it was clear that the range of δ²H values (− 181 to − 78) was wider at Rybachy as compared to the two reference sites in Estonia and Poland (− 174 to − 100).
Conclusions
During spring, migratory female red admirals arrived from the south and were ready to reproduce, while the autumn passage mainly engaged local and more northern individuals carrying large fuel deposits in preparation for long-distance migration. The phenology data suggest that individuals select to migrate in favourable weather conditions and that numbers may differ between years. Future studies should focus on individual sampling at a wide range of sites to reveal differential migration strategies and timing of migration between sexes and populations of migrating butterflies.
Electronic supplementary material
The online version of this article (10.1186/s40462-018-0143-3) contains supplementary material, which is available to authorized users.
... Simple reliance on windborne transport would seemingly often lead to displacement in highly disadvantageous directions and could cause the progeny of spring migrants to become trapped at high latitudes at summer's end-the so-called Pied Piper phenomenon (55). However, large-scale return migrations of windborne migrants are now well documented (12,14,40,42,59,98). As wind speeds aloft are typically faster than insect airspeeds, a mechanism that ensures regular transport in seasonally beneficial directions would be highly adaptive. ...
... Initiating migratory flights only on occasions when the wind is blowing in a broadly favorable direction, and then letting the wind do the rest, appears a good strategy, especially for weak flyers, but it is dependent on a means for identifying suitable winds. In some species, return migrations in the fall are achieved by responding to particular meteorological conditions associated with winds blowing toward the equator, such as cold air temperatures (59), though this appears to be a high-risk strategy given the characteristically unpredictable weather of the temperate zone. ...
Many of the world's most serious insect pests are highly mobile. Knowledge of their movements is an essential requirement for outbreak prediction and effective pest management. This book describes how direct observations of insects in flight, using special-purpose 'entomological' radars, have contributed greatly to current understanding of insect migration and foraging. Take-off, height selection, orientation, and responses to the often complex atmospheric environment receive particular attention, while the outcomes of these behaviours, in he form of seasonal patterns of population movement, are also considered. Coverage extends to radar-based research on foraging strategies, dispersal, bee learning and the movements of beneficial insects. The essentials of radar theory are introduced and there are sections on entomological radar design, alternative remote-sensing technologies and insect echo on weather radars. This comprehensive work is an essential reference for crop-protection entomologists, aeroecologists, biologists studying animal movement, radar ornithologists and meteorologists, and biometeorologists. It will also be of great interest to the wider radar community.
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... In some cases, relatively simple decision rules seem to be employed to maximise the probability of favourable transport. For example, falling temperatures during autumn promote the initiation of migratory flights in Vanessa atalanta (red admiral butterfly; Mikkola 2003) and Anax junius (green darner dragonfly; Wikelski et al. 2006), thus increasing the probability of windborne transport on cool northerlies towards lower-latitude winter-breeding regions. In other situations, the suitability of high-altitude tailwinds cannot be assessed from simple meteorological cues such as temperature, humidity or atmospheric pressure, and migrants must somehow directly assess the direction of downwind transport during or immediately after take-off. ...
... Day-flying migration above the FBL As discussed in the previous section, butterfly migration has typically been assumed to occur exclusively within the FBL, apart from the monarch and Camberwell beauty (Nymphalis antiopa) where soaring and gliding behaviour is well documented (see Table 1). Recently, however, evidence has accumulated that butterfly migrations can occur at altitude (up to 1 km above ground) under certain circumstancespresumably the crucial factor being that high-altitude winds are blowing in seasonally beneficial directions (Mikkola 2003;Stefanescu et al. 2007Stefanescu et al. , 2013Chapman et al. 2010). For example, Stefanescu et al. (2007) found a strong association between spring arrivals of V. cardui into northeastern Spain and high-altitude winds from probable source areas in North Africa. ...
Myriad tiny insect species take to the air to engage in windborne migration, but entomology also has its 'charismatic megafauna' of butterflies, large moths, dragonflies and locusts. The spectacular migrations of large day-flying insects have long fascinated humankind, and since the advent of radar entomology much has been revealed about high-altitude night-time insect migrations. Over the last decade, there have been significant advances in insect migration research, which we review here. In particular, we highlight: (1) notable improvements in our understanding of lepidopteran navigation strategies, including the hitherto unsuspected capabilities of high-altitude migrants to select favourable winds and orientate adaptively, (2) progress in unravelling the neuronal mechanisms underlying sun compass orientation and in identifying the genetic complex underpinning key traits associated with migration behaviour and performance in the monarch butterfly, and (3) improvements in our knowledge of the multifaceted interactions between disease agents and insect migrants, in terms of direct effects on migration success and pathogen spread, and indirect effects on the evolution of migratory systems. We conclude by highlighting the progress that can be made through inter-phyla comparisons, and identify future research areas that will enhance our understanding of insect migration strategies within an eco-evolutionary perspective.
© 2015 John Wiley & Sons Ltd/CNRS.
... Simple reliance on windborne transport would seemingly often lead to displacement in highly disadvantageous directions and could cause the progeny of spring migrants to become trapped at high latitudes at summer's end-the so-called Pied Piper phenomenon (55). However, large-scale return migrations of windborne migrants are now well documented (12,14,40,42,59,98). As wind speeds aloft are typically faster than insect airspeeds, a mechanism that ensures regular transport in seasonally beneficial directions would be highly adaptive. ...
... Initiating migratory flights only on occasions when the wind is blowing in a broadly favorable direction, and then letting the wind do the rest, appears a good strategy, especially for weak flyers, but it is dependent on a means for identifying suitable winds. In some species, return migrations in the fall are achieved by responding to particular meteorological conditions associated with winds blowing toward the equator, such as cold air temperatures (59), though this appears to be a high-risk strategy given the characteristically unpredictable weather of the temperate zone. ...
Radar has been used to study insects in flight for over 40 years and has helped to establish the ubiquity of several migration phenomena: dawn, morning, and dusk takeoffs; approximate downwind transport; concentration at wind convergences; layers in stable nighttime atmospheres; and nocturnal common orientation. Two novel radar designs introduced in the late 1990s have significantly enhanced observing capabilities. Radar-based research now encompasses foraging as well as migration and is increasingly focused on flight behavior and the environmental cues influencing it. Migrant moths have been shown to employ sophisticated orientation and height-selection strategies that maximize displacements in seasonally appropriate directions; they appear to have an internal compass and to respond to turbulence features in the airflow. Tracks of foraging insects demonstrate compensation for wind drift and use of optimal search paths to locate resources. Further improvements to observing capabilities, and employment in operational as well as research roles, appear feasible.
... In 2018, the German Aerospace Center (DLR) carried out a study based on a comprehensive literature research and simplified modelling of the possible interferences with flying insects by wind rotors in Germany [5]. The FlyWiP study provides comprehensive evidence from entomological literature that many insect species migrate at a higher altitude than their quotidian flight boundary layer (FBL), which usually reaches up to approximately 30 m above ground level [7][8][9][10][11][12][13][14][15][16][17][18][19]. A widespread axiom that insects are safe from wind turbine damage because the blades rotate above the FBL was proven incorrect by that analysis (Figure 1. Year When migrating insects reach maturity, and as soon as wind direction, wind speed, air temperature and season match with their intrinsic behavior patterns, they ascend above the turbulent surface layer of the atmosphere, which varies in height between 40 and 100 m above ground level [20]. ...
Wind energy is considered a pillar of the low-carbon energy system of the future. Whereas the side effects and social costs of fossil energy sources (coal, oil and gas), as well as those of nuclear energy, are well-documented and quantified, understanding of the analogous questions with respect to wind energy is far less advanced. However, such understanding is crucial in order to minimize the influence of wind energy on the environment and to compare its social costs with those of conventional energy sources. Here, we summarize the state of knowledge of three side effects of wind energy that have not been convincingly evaluated to date. We focus our analysis on three topics, namely (1) the impact of wind energy on insects; (2) the impact of wind energy on the spatiotemporal distribution of air velocity, temperature, moisture and precipitation in the vicinity of wind parks; and (3) the impact of wind energy on humans through noise emission. For each topic, we formulate open research questions that should be addressed by responsible policy incentives in order to comprehensively assess the social costs of wind energy and to develop wind farms with minimal impact on their environment.
... Migrating insects can fly at high altitudes, up to 2000 or 3000 m above the ground (Chapman & Drake, 2019;Gatehouse, 1997;Mikkola, 2003); however, most migration is below 1500 m (Drake & Reynolds, 2012). Stefanescu et al. (2013) showed that painted lady and other migrant Lepidoptera can take advantage of favourable winds and fly from the ground to altitudes over 1000 m; however, many butterfly migrants travel close to the ground where their airspeeds are higher than the wind speed, allowing them to make progress in a seasonally appropriate direction even when there is a headwind (Srygley & Dudley, 2007). ...
Several hundred butterfly species show some form of migratory behaviour. Here we identify how the methodologies available for studying butterfly migration have changed over time, and document geographic and taxonomic foci in the study of butterfly migration. We review publications on butterfly migration published in six languages (English, Simplified Chinese, Traditional Chinese, Japanese, Korean, and Spanish), summarise how migration in butterflies has been studied, explore geographic and taxonomic patterns in the knowledge base, and outline key future research directions. Using English search keywords, we found only 58 studies from Asia; however, after searching in local languages, we found an additional 98 relevant studies. Overall, butterfly migration studies are mostly from North America and Europe. Most studies focus on three species: monarch (Danaus plexippus), painted lady (Vanessa cardui) and red admiral (Vanessa atalanta). About 62% of publications are focused on the monarch, with nearly 50% of migratory butterfly species mentioned in only a single paper. Several research methods have been applied to ascribe migratory status and to study the physiology, neurobiology, and ecology of migration; however, virtually all this research is on a handful of species. There remain hundreds of species for which we do not understand the comprehensive seasonal pattern of movement, flight destinations, wintering, or breeding grounds. A better understanding of movement ecology and migratory connectivity is needed to effectively conserve migratory butterflies. It is essential that research becomes more geographically and linguistically representative since migrants frequently cross political borders and international cooperation is necessary for their conservation.
... Migrating insects can fly at high altitudes, up to 2,000 or 3,000 meters above the ground 271 (Gatehouse, 1997;Mikkola, 2003; Chapman and Drake, 2019); however, most migration is below 272 1500 meters (Drake and Reynolds, 2012). Stefanescu et al. (2013) showed that painted lady and 273 other migrant Lepidoptera can take advantage of favourable winds and fly from the ground to 274 altitudes over 1,000 meters; however, many butterfly migrants travel close to the ground where 275 their airspeeds are higher than the wind speed, allowing them to make progress in a seasonally 276 appropriate direction 277 even when there is a contrary wind (Srygley and Dudley, 2008). ...
Background
Several hundred butterfly species show some form of migratory behaviour. Here we identify how the methodologies available for studying butterfly migration have changed over time, and document geographic and taxonomic foci in the study of butterfly migration.
Method
We review publications on butterfly migration published in six languages [English, Simplified Chinese, Traditional Chinese, Japanese, Korean, and Spanish], summarise how migration in butterflies has been studied, explore geographic and taxonomic patterns in the knowledge base, and outline key future research directions.
Results
Using English search keywords, we found only 58 studies from Asia; however, after searching in local languages, we found an additional 99 relevant studies from China, Japan, and Taiwan. Overall, butterfly migration studies are mostly concentrated in North America and Europe, with only 4.6% from Africa. Most studies focus on three species: monarch [Danaus plexippus], painted lady [Vanessa cardui] and red admiral [Vanessa atalanta]. About 62% of publications are focused on the monarch, with nearly 50% of migratory butterflies mentioned in no more than a single paper.
Conclusions
Several research methods have been applied to ascribe migratory status and to study the physiology, neurobiology, and ecology of migration; however, virtually all this research is focused on a handful of species. There remain hundreds of species for which we do not understand the full seasonal pattern of movement, flight destinations, wintering, or breeding grounds. A full understanding of movement ecology and migratory connectivity is needed to effectively conserve migratory butterflies.
... Migrating insects typically fly at high in the atmosphere, up to 2,000 or 3,000 meters above the ground (Gatehouse, 1997;Mikkola, 2003;Chapman and Drake, 2010). Stefanescu et al. (2013) showed that Vanessa cardui and other migrant Lepidoptera can take advantage of favourable winds and fly from the ground to high in the atmosphere over 1,000 meters. ...
Understanding which species migrate and why is critical to elucidating their ecology and planning for their conservation yet studying migration in insects is complicated by their small size and the difficulty of tracking individuals over long distances. In my PhD, I studied the movement patterns of butterflies and assessed global progress in insect conservation.
First, I conducted a comprehensive literature review, and discovered that at least 568 butterfly species show evidence of migratory movements. This suggests migration is much more widespread among butterflies than previously realised; indeed, the rate of ‘discovery’ of migratory movements in butterflies suggests that thousands of species are migratory.
The geographic distribution of butterfly migration is poorly understood. I built ecological niche models to describe and further investigate migration in migratory butterflies. I discovered strong seasonal variation in habitat suitability for most species, and the greatest rate of apparent migration occurs in the tropics. Several species showed extreme seasonal fluctuations in their distribution, and such species may be at elevated extinction risk.
Our climate is changing, including directional changes in temperature, rainfall, and timings of seasonal transitions. We might expect to see changes in migratory behaviour as a consequence. I studied the range expansion of the tawny coster butterfly. I discovered that its climatic niche differs only slightly during its colonisation of Australasia, consistent with changing conditions driving its changed distribution. The species has expanded its range in Australia at an impressive average rate of ~ 135 km/year.
Protected areas have been established around the world to preserve samples of biodiversity from pressing threats, yet the adequacy of protected area systems in many tropical nations is poorly understood. I assessed the extent to which butterflies are covered by protected areas in a mega-populated country, Bangladesh. Using three different methods to map species distributions, I found that the current protected area distribution in Bangladesh is inadequate for conserving butterflies, with <1.5% of butterflies’ geographic range being covered by protected areas.
Most assessments of protected area performance focus on vertebrates, and the effectiveness and performance of protected areas for conserving insects is mostly unknown. There is no large-scale assessment of whether the world’s protected areas are adequate for conserving insects, nor whether these areas remain effective under climate change scenarios. I conducted the first ever assessment of the extent to which insects are represented in the global network of protected areas. Measuring geographic range in two different ways, I discovered that more than 75% of insects are inadequately conserved in protected areas.
Overall, the work has helped improve our understanding of the prevalence and characteristics of migration in insects and highlight some of the major shortfalls in global conservation efforts for insects in a changing world.
... Other well-known migrant butterfly species is the Painted lady Vanessa cardui, in early spring it has developed in Northern Africa during the winter they migrate northward and repopulate Southern Europe, and move continuously to Central and Northern Europe Western Africa and some until Central or Southern Europe, Northern-western Africa to complete the circle (Williams, 1970). Red-admiral Vanessa atalanta migrates to the north in spring and summer and towards the south in autumn (Stefanescu et al., 2001;Mikkola, 2003;Brattstrom et al., 2010). In India, many researchers were documented migration of butterflies and this phenomenon was occurred predominantly in Southern portion of India (Williams, 1927(Williams, , 1930(Williams, , 1938Evershed, 1910;French, 1943;Fisher, 1945;Briscoe, 1952;Bharos, 2000;Mathew and Biony, 2002;Kunte, 2005;Palot et al., 2002;Ramesh et al., 2010Ramesh et al., , 2013 besides, in Western Ghats and Central India (Bharos, 2002;Chaturvedi, 1993;Chaturvedi and Satheesan, 1979;Reuben, 1961Reuben, , 1962Williams, 1938). ...
Migration of Pierid butterfly, common emigrant, Catopsilia pomonawas recorded in the plains of Madurai, Tamil Nadu from north-east to south-west (~213to 223°). The migratory swarm was counted within the imaginary strip of about 10 m wide between 09.30 and 02.00 hr (IST), the total of 5,673 migratory individual of C. pomona were observed in the present investigation. Interestingly swarm individuals are unequal body size and the sex ratio of migrants of C. pomana is about 36.3% male and 63.7% female in the present exploration, it is clearly indicated that the sex ratio is biased towards female. Furthermore the migratory and non-migratory population were compared and estimated through morphometric analysis, it showed that as the thorax mass is higher than the abdominal mass of migratory individuals, and especially the abdominal mass is greater for female. Similarly the length of fore wing (FW) is more than hind wing (HW) whereas the HW breadth is more than breath of the FW of migrants. In addition, the dial variation of swarm density is reached maximum on mid-day hours (11.00 and 12.00 hr) in correspondence with the optimum temperature. The migration activity is strongly correlated with air temperature and moderately with rainfall, humidity, wind movement and wind speed.
... For example, decreased photoperiod and fluctuating temperatures can induce a reproductive diapause in the monarch butterfly (Danaus plexippus), and reduced photoperiod leads to increased lipid accumulation in bean bugs (Riptortus clavatus) (Goehring and Oberhauser, 2002;Morita et al., 1999). Similarly, reduced resource availability induces dispersal by insects to areas more suitable for nest foundation and reproduction (Benton and Bowler, 2012), and reduced temperatures induce migratory behavior in butterflies and dragonflies (Chapman et al., 2015;Mikkola, 2003;Wikelski et al., 2006), overall allowing organisms to avoid otherwise unsuitable environmental conditions and to synchronize their life history with other members of the population. ...
Insects maximize their fitness by exhibiting predictable and adaptive seasonal patterns in response to changing environmental conditions. These seasonal patterns are often expressed even when insects are kept in captivity, suggesting they are functionally and evolutionary important.
In this study we examined whether workers of the eusocial bumble bee Bombus impatiens maintained a seasonal signature when kept in captivity. We used an integrative approach and compared worker egg-laying, ovarian activation, body size and mass, lipid content in the fat body, cold tolerance and expression of genes related to cold tolerance, metabolism, and stress throughout colony development.
We found that bumble bee worker physiology and gene expression patterns shift from reproductive-like to diapause-like as the colony ages. Workers eclosing early in the colony cycle had increased egg-laying and ovarian activation, and reduced cold tolerance, body size, mass, and lipid content in the fat body, in line with a reproductive-like profile, while late-eclosing workers exhibited the opposite characteristics. Furthermore, expression patterns of genes associated with reproduction and diapause differed between early- and late-eclosing workers, partially following the physiological patterns.
We suggest that a seasonal signature, innate to individual workers, the queen or the colony is used by workers as a social cue determining the phenology of the colony and discuss possible implications for understanding reproductive division of labor in bumble bee colonies and the evolutionary divergence of female castes in the genus Bombus.
... For example, decreased photoperiod and fluctuating temperatures can induce a reproductive diapause in the monarch butterfly (Danaus plexippus), and reduced photoperiod leads to increased lipid accumulation in bean bugs (Riptortus clavatus) (Goehring and Oberhauser, 2002;Morita et al., 1999). Similarly, reduced resource availability induces dispersal by insects to areas more suitable for nest foundation and reproduction (Benton and Bowler, 2012), and reduced temperatures induce migratory behavior in butterflies and dragonflies (Chapman et al., 2015;Mikkola, 2003;Wikelski et al., 2006), overall allowing organisms to avoid otherwise unsuitable environmental conditions and to synchronize their life history with other members of the population. ...
Insects maximize their fitness by exhibiting predictable and adaptive seasonal patterns in response to changing environmental conditions. These seasonal patterns are often expressed even when insects are kept in captivity, suggesting they are functionally and evolutionary important.
In this study we examined whether workers of the eusocial bumble bee Bombus impatiens maintained a seasonal signature when kept in captivity. We used an integrative approach and compared worker egg-laying, ovarian activation, body size and mass, lipid content in the fat body, cold tolerance and expression of genes related to cold tolerance, metabolism, and stress throughout colony development.
We found that bumble bee worker physiology and gene expression patterns shift from reproductive-like to diapause-like as the colony ages. Workers eclosing early in the colony cycle had increased egg-laying and ovarian activation, and reduced cold tolerance, body size, mass, and lipid content in the fat body, in line with a reproductive-like profile, while late-eclosing workers exhibited the opposite characteristics. Furthermore, expression patterns of genes associated with reproduction and diapause differed between early- and late-eclosing workers, partially following the physiological patterns.
We suggest that a seasonal signature, innate to individual workers, the queen or the colony is used by workers as a social cue determining the phenology of the colony and discuss possible implications for understanding reproductive division of labor in bumble bee colonies and the evolutionary divergence of female castes in the genus Bombus .
... Insects need warm temperatures to take-off although when flying they can tolerate somewhat lower temperatures, whereas birds are generally more tolerant to both low and high temperatures. A general pattern observed in both insects and birds is that migration is triggered by rising temperature in spring and dropping temperature in autumn (Richardson 1978a, 1990, Mikkola 2003. A consequence of solar radiation is the formation of thermal convection in the diurnal boundary layer, which is exploited by diurnally-migrating insects and birds. ...
Migratory animals are affected by various factors during their journeys, and the study of animal movement by radars has been instrumental in revealing key influences of the environment on flying migrants. Radars enable the simultaneous tracking of many individuals of almost all sizes within the radar range during day and night, and under low visibility conditions. We review how atmospheric conditions, geographic features and human development affect the behavior of migrating insects and birds as recorded by radars. We focus on flight initiation and termination, as well as in-flight behavior that includes changes in animal flight direction, speed and altitude. Several similarities and differences in the behavioral responses of different aerial migrants include an overlooked similarity in the use of thermal updrafts by very small (e.g., aphids) and very large (e.g., vultures) migrants. We propose that many aerial migrants modulate their migratory flights in relation to the interaction between atmospheric conditions and geographic features. For example, aerial migrants that encounter crosswind during flight may terminate their flight or continue their migration and may also drift or compensate for lateral displacement depending on their position (over land, near the coast or over sea). We propose several promising directions for future research, including the development and application of algorithms for tracking insects, bats and large aggregations of animals in weather radars. Additionally, an important contribution will be the spatial expansion of aeroecological radar studies to Africa, most of Asia and South America where no such studies have been undertaken. Quantifying the role of migrants in ecosystems and specifically estimating the number of departing birds from stopover sites using low-elevation radar scans is important for quantifying migrant-habitat relationships. This information, together with estimates of population demographics and migrant abundance, can help resolve the long-term dynamics of migrant populations that face large-scale environmental changes.
... 6) However, extrapolations from dust distributions have to be treated with some caution. The average dust transportation altitude is 700 mb (3,000 m) (Varga et al., 2014), which is at the upper limit of what has been reported for V. cardui (Mikkola, 2003;Stefanescu et al., 2007) and well above that so far observed for S. frugiperda (Westbrook, 2008) and other Noctuid moths (Feng et al., 2003;Drake, 2012). This means that a substantial portion of dust is being transported by air currents not available to S. frugiperda. ...
Abstract EFSA was asked for a partial risk assessment of Spodoptera frugiperda for the territory of the EU focussing on the main pathways for entry, factors affecting establishment, risk reduction options and pest management. As a polyphagous pest, five commodity pathways were examined in detail. Aggregating across these and other pathways, we estimate that tens of thousands to over a million individual larvae could enter the EU annually on host commodities. Instigating risk reduction options on sweetcorn, a principal host, reduces entry on that pathway 100‐fold. However, sweetcorn imports are a small proportion of all S. frugiperda host imports, several of which are already regulated and further regulation is estimated to reduce the median number entering over all pathways by approximately 10%. Low temperatures limit the area for establishment but small areas of Spain, Italy and Greece can provide climatic conditions suitable for establishment. If infested imported commodities are distributed across the EU in proportion to consumer population, a few hundreds to a few thousands of individuals would reach NUTS 2 regions within which suitable conditions for establishment exist. Although S. frugiperda is a known migrant, entry directly into the EU from extant populations in sub‐Saharan Africa is judged not feasible. However, if S. frugiperda were to establish in North Africa, in the range of thousands to over two million adults could seasonally migrate into the southern EU. Entry into suitable NUTS2 areas via migration will be greater than via commercial trade but is contingent on the establishment of S. frugiperda in North Africa. The likelihood of entry of the pest via natural dispersal could only be mitigated via control of the pest in Africa. If S. frugiperda were to arrive and become a pest of maize in the EU, Integrated Pest Management (IPM) or broad spectrum insecticides currently used against existing pests could be applied.
... Interestingly, no significant difference was detected in total flight duration between the offspring of migrating and resident flies. It is believed that environmental cues such as wind [49][50][51] or a change in temperature [52] are important for the departure or the continuation of migratory movement in insects [5]. Hoverflies did not receive these environmental cues in the laboratory, as temperature stayed constant throughout the experiment, and simulating wind in the laboratory was not possible, since flight mills record even the slightest movement. ...
Migration has evolved among many animal taxa and migratory species are found across all major lineages. Insects are the most abundant and diverse terrestrial migrants, with trillions of animals migrating annually. Partial migration, where populations consist of resident and migratory individuals, is ubiquitous among many taxa. However, the underlying mechanisms are relatively poorly understood and may be driven by physiological, behavioural or genetic variation within populations. We investigated the differences in migratory tendency between migratory and resident phenotypes of the hoverfly, Episyrphus balteatus, using tethered flight mills. Further, to test whether migratory flight behaviour is heritable and to disentangle the effects of environment during development, we compared the flight behaviour of laboratory-reared offspring of migrating, overwintering and summer animals. Offspring of migrants initiated more flights than those of resident individuals. Interestingly, there were no differences among wild-caught phenotypes with regard to number of flights or total flight duration. Low activity in field-collected migrants might be explained by an energy-conserving state that migrants enter into when under laboratory conditions, or a lack of suitable environmental cues for triggering migration. Our results strongly suggest that flight behaviour is heritable and that genetic factors influence migratory tendency in E. balteatus These findings support the growing evidence that genetic factors play a role in partial migration and warrant careful further investigation.
... Nymphalidae), in Helsinki (Mikkola 2003), Cnaphalocrocis medinalis Guenée (Lepidoptera: Crambidae) in eastern China (Riley et al. 1995), Agrotis ipsilon (Hufnagel) (Lepidoptera: Noctuidae) in China and North America. (Showers 1997), M. separata in Northern China (Feng et al. 2008), H. armigera in Northern China (Feng et al. 2009), and Autographa gamma (L.) (Lepidoptera: Noctuidae) in the United Kingdom (Chapman et al. 2012). ...
The spotted clover moth, Protoschinia scutosa (Denis & Schiffermüller) (Lepidoptera: Noctuidae), is an important
polyphagous pest that is widely distributed in the world. P. scutosa overwinters as pupae in agricultural soils in
Northern China. Yet, it is unclear whether P. scutosa also engages in seasonal migration over mid- to long-range
distances. In this study, we employ light trapping, field surveys, and ovarian dissection of captured adults over a
2003–2015 time period to assess P. scutosa migration in Northern China. Our work shows that P. scutosa migrates
across the Bohai Strait seasonally; the mean duration of its windborne migration period was 121.6 d, and the mean
trapping number was 1053.6 moths. Nightly catches of P. scutosa were significantly different between months,
but the differences between years were not significant. During 2009–2011 and 2013, the monthly proportion of
migrating females (65.5%) was significantly higher than that of males and showed no difference between months.
In May to June, the majority of females (May: 63.0%; June: 61.1%) were mated individuals with relatively high level
of ovarian development; however, in August and September, most females were unmated. The mean proportion
of mated females was significantly different across months but did not differ between years. The results of long-
term searchlight trapping and ovarian dissection indicate that P. scutosa exhibits a seasonal characteristic of typical
population dynamics and reproductive development of migratory insects. Our work sheds light upon key facets
of P. scutosa ecology and facilitates the future development of pest forecasting systems and pest management
schemes.
... Chapman and Drake (2010) suggested that butterflies migrations are in low-altitude. However, previous studies of migratory butterfly Vanessa atalanta (Linnaeus, 1758) indicate that flights may occur as high as 1000-3000 m (Mikkola, 2003). In agreement with the present results, Hayward (1953) reported a massive swarming of A. monuste in Argentina flying at about 1500 m or even higher. ...
The meteorological polarimetric radar RMA1 located in the city of Córdoba was used for a nonconventional phenomenon detection. Massive migrations of both Ascia monuste during early summer of 2015 and Schistocerca cancellata during late winter of 2017 were characterized by means of polarimetric variables (correlation factor ρhv and reflectivity factor ZH). The butterfly swarms show a pulsating behavior as a consequence of biological needs. The highest altitude detected was 2400 m msl. The correlation factor confirms the biological characteristic of the echo. The locust swarm migration shows a different pattern in several ways. First, it has a more uniform aspect regarding its displacement. Second, the locusts were observed to attain altitudes of 1700 m msl. Third, the correlation coefficient for the locust case showed regions with high values, which are different from the low value areas. It is concluded that radar observations of insect species may result in useful biological criteria for the government to asses areas that need to be protected for agricultural production.
... As other important agriculture pests did (Wei et al. 2013(Wei et al. , 2015Cao et al. 2017;Zhang et al. 2017), A. fasciaticollis has experienced a recent population expansion. The factors giving rise to population expansion include geographical range expansion, climatic change (Rodríguez et al. 2005;Calatayud et al. 2016), ecological conditions (Mikkola 2003), anthropogenic disturbances (Xun et al. 2016;Cao et al. 2017), and host range expansion (Cullingham et al. 2011). A. fasciaticollis has long-distance dispersal ability; it can fly with a full complement of eggs, and this flight behavior allows it to readily exploit new habitants (Blackmer et al. 2004). ...
Understanding the population genetic structure and demographic dynamics of important agricultural pest insects is very important in studying insecticide resistance and control strategies. The plant bug Adelphocoris fasciaticollis (Reuter) (Hemiptera: Miridae) is one of the main insect pests on cotton in Northern China. We studied large-scale genetic structure and genetic diversity patterns and explored the demographic history. We also employed a phylogeographical approach on A. fasciaticollis samples using sequence data from mitochondrial DNA (mtDNA) and nuclear DNA (ncDNA). MtDNA showed a significant correlation between genetic and geographical distances, but ncDNA did not support this correlation. Both datasets revealed that A. fasciaticollis populations had experienced recent expansion and lacked a geographical structure. One reason for lack of a genetic structure is a high level of gene flow among the populations. We suggest that the strong flight capability of A. fasciaticollis has been aided by the East Asian monsoon and cold fronts to accelerate the rate of range expansion. In addition, decreased insecticide usage and disturbances from human activities may all have contributed to population expansion. The low effective population number was based on two datasets. It is suggested that the host crop use, local climate conditions, and the recent population expansion might be the main influencing factors.
... This weather system promoted large numbers of the offspring population, which was produced by the summer parental generation, to emigrate from the northeastern agricultural region of China southward across the sea and BH to the mainland in the south. Characteristics of the southward return migration observed in the present study were similar to the windborne migration of Empoasca fabae (Harris) [56], Nilaparvata lugens (Stål) [57], Cnaphalocrocis medinalis Guenée [58], Agrotis ipsilon (Rottemberg) [59], Vanessa atalanta (L.) [60], Mythimna separata (Walker) [61], H. armigera [43][44], and Autographa gamma (L.) [62], and it has been postulated that this behavior facilitates the return migration of these species to the southern overwintering regions. ...
The beet armyworm, Spodoptera exigua (Hübner) (Lepidoptera: Noctuidae), is a serious polyphagous insect pest worldwide. This species is known as a long-distance migrant, and previous studies on its migration have been mostly carried out in regions where it can overwinter. However, what pattern of seasonal migration this species exhibits in regions where it cannot overwinter (i.e., the ‘summer breeding region’) remains unknown. Here, we present data from 14-years of monitoring on a small remote island located in the center of the Bohai Strait, in northern China, by means of searchlight trapping and ovarian dissection. We found that the population size of this overseas migration varied significantly among years, with very large migrations in 2005, 2007, 2009, and 2014 that resulted in annual total catches of more than ten thousand individuals. In addition, nightly catches exhibited a significant inter-month variability, with the vast majority of S. exigua moths being trapped in August and September, (81.1 ± 3.6%), making S. exigua one of the most frequently encountered species in that period. The mean time from the earliest trap capture to the latest capture within a given year was 113 ± 22 d (range 57 d [2003] to 138 d [2008]). The sex ratio (females: males) was significantly less than 1:1 in each month, but the proportion of females showed an upward trend from June to October. The majority of trapped females in summer were mated (94.4 ± 10.7% in June, 80.0 ± 6.4% in July) and sexually mature (88.9 ± 11.1% in June, 61.8 ± 12.3% in July), suggesting the onset of mating and/or sexual maturation does not terminate the migration behavior in this species. These findings provide a good starting point for study of the trans-regional migration of S. exigua across different climate zones.
... However, Attisano, Tregenza, Moore, and Moore (2013) demonstrated significant physiological differences between migrant and resident female milkweed bugs, Oncopeltus fasciatus. Furthermore, the migrating flies may not have received the necessary stimuli to trigger them to make a departure decision or continue migrating (see Bauer et al., 2011;Chapman et al., 2015;Drake & Reynolds, 2012), such as temperature changes or favourable winds Chapman, Reynolds, Mouritsen, et al., 2008;Mikkola, 2003). While there is no information available on what triggers migratory behaviour in hoverflies, studies on other insects may shed some light on the mechanisms behind this. ...
Many animals differ consistently in the way they behave across time and context. This animal personality has been linked to traits such as life history strategies or dispersal. However, few studies have addressed the relationship between consistent behavioural differences and migration. This is of particular interest with respect to partial migration, in which only part of a population migrates while the other remains resident. We investigated whether two behavioural traits (activity and stress response) are consistent across time in individuals of two partially migratory hoverfly species, Episyrphus balteatus and Scaeva selenitica. We also investigated whether there were consistent behavioural differences between migratory and resident flies within species. Individual activity was consistent across time in both species. Additionally, activity of female E. balteatus differed between the phenotypes, with summer insects being more active than migrating and overwintering individuals in our assays. Furthermore, females of S. selenitica were more active and less easily stressed than E. balteatus. The results not only highlight that hoverflies behave consistently across time, but also that behavioural differences also occur between migratory and resident flies. They also provide evidence for the possible role of behavioural differences in influencing partial migration decisions within populations.
... In autumn (August-October), prevailing northerly winds, caused by the prevailing temperature gradient, blowing from east Siberia to northern China, and the updraft airflows that generally occur in the northeastern agricultural region of China, promote large number of offspring produced by summer breeders emigrating to the south. Characteristics of the backward migration observed in the present study were rather similar to those windborne migrations of Empoasca fabae (Harris) (Taylor & Reling, 1986), Nilaparvata lugens (Stål) (Riley et al., 1994), Cnaphalocrocis medinalis Guenée (Riley et al., 1995), Agrotis ipsilon (Rottemberg) (Showers, 1997), Vanessa atalanta (L.) (Mikkola, 2003), M. separata (Feng et al., 2008), H. armigera , and Autographa gamma (L.) (Chapman et al., 2012), and it has been postulated that this behavior facilitated return movements to the southern overwintering areas of these species. Understanding the seasonal migration pattern of H. viriplaca is also of economic importance, as this species becomes a major pest in many Asian crop fields during outbreak years. ...
Heliothis viriplaca
(Hüfnagel) (Lepidoptera: Noctuidae) is an important polyphagous pest of beans, cotton, maize, and alfalfa worldwide.
H. viriplaca
is a long-distance migrant, and if so, what pattern of seasonal migration this species exhibits in northern China remains unknown. In this study, in order to determine the seasonal migration of
H. viriplaca
in northern China, the combination of searchlight trapping and ovarian dissection was carried out on an isolated small island in the center of the Bohai Strait during 2003–2014. The results confirmed that
H. viriplaca
undertakes long-distance migration on the prevailing winds of the East Asian monsoon airflows. This species exhibited a regular pattern of seasonal migration across the sea from May to October, but there was considerable yearly and monthly variation in the trapped numbers, with the majority being trapped in summer (67.99 ± 6.54%). The mean period when migration was detectable at the island was 116.5 ± 5.6 days from 2003 to 2014, with the shortest time span of 74 days in 2013 and the longest of 144 days in 2005. Trapped females in May and June showed a relatively higher mating rates and some degree of ovarian development when compared with July, August and September, suggesting the migration of this species is not completely bound by the ‘oogenesis-flight syndrome’. These findings will be helpful to improve the forecasting system and managing strategies of
H. viriplaca
.
... It shows a clear bi-directional migration, heading north from the Mediterranean area in spring (Benvenuti et al. 1996) before reproducing (Henriksen & Kreutzer 1982). In late summer it returns south, as reported from field studies made at different locations in northern Europe (Williams 1951, Hansen 2001, Mikkola 2003. The numbers found in the northern parts of Europe are fluctuating, with smaller populations in cold summers, but the Red Admiral is much more regular there than most other migrating butterflies, for example the closely related Painted Lady Vanessa cardui. ...
I present data on seasonal variation in wing length and mass of Red Admirals Vanessa atalanta captured on Capri, Italy, during spring and autumn. The Red Admiral is a migratory butterfly that migrates north throughout Europe each year and then heads back south in the autumn. During the winter they are mostly found in the northern Mediterranean area where they previously were thought to hibernate, but recent data suggest that a new generation is produced before spring migration. The Red Admirals captured on Capri showed no difference in dry mass between the two seasons, when taking size in account, but had significantly longer wings in autumn. This suggests that a new generation is produced during winter.
... I.A. Bochneva. In Northern Europe, it is a seasonal vagrant species, which can successfully breed here with an autumn return migration of a new generation of adults to southern regions (Stefanescu 2001;Mikkola 2003aMikkola , 2003b. The species is usually rare in Arkhangelsk Region. ...
The Vinogradovsky District is located at the center of the Arkhangelsk Region, one of the largest federal subjects of Northern European Russia. Boreal spruce forests are the prevalent ecosystem type in this area, but large expanses of agricultural land and herb-grass meadows are also presented there. Based on the studies of 1,699 specimens collected from three meadow sites during period 2011–2013, we provide the first data on the butterfly fauna of the district, which include 56 species, belonging to 35 genera and 5 families. Our data reveal an intense northward expansion of many southern butterfly species to the Arkhangelsk Region, including migrants (Pontia edusa, Issoria lathonia, Vanessa atalanta and Vanessa cardui) and species that have established resident populations there (Pararge aegeria, Nymphalis xanthomelas, Aglais io, Lycaena dispar, Cupido alcetas). Quantitative data on species diversity and phenology of butterflies are reported, including analysis of structure of butterfly assemblages and their seasonal changes.
... region of China. Windborne migration of the leafhopper, Empoasca fabae (Harris) (Hemiptera: Cicadellidae), the brown planthopper, Nilaparvata lugens (Stål) (Hemiptera: Delphacidae), and the red admiral butterfly, Vanessa atalanta (L.) (Lepidoptera: Nymphalidae), also occur more frequently in northerly winds in autumn (Taylor and Reling 1986, Riley et al. 1994, Mikkola 2003, and it has been postulated that this behavior facilitated return movements to the southern overwintering areas of these species. The present observations provide additional evidence for this hypothesis, although further studies should be investigated in detail. ...
The common cutworm, Spodoptera litura (F.), is a serious crop pest with a strong migratory ability. Previous studies on the migration of S. litura were mostly carried out in its “year-round breeding region” (YBR) or “overwintering region” (OR). However, the pattern of seasonal movements in its “summer breeding region” (SBR; i.e., northern China where they cannot overwinter) remains unknown. Here, we present data from an 11-yr study of this species made by searchlight trapping on Beihuang (BH) Island in the center of the Bohai Strait, which provides direct evidence that S. litura regularly migrates across this sea. There was considerable yearly and monthly variation in the number of S. litura trapped on BH, with the vast majority trapped in the autumn. The mean time from the earliest trapping to the latest trapping within a year was 110 ± 12 d during 2003-2013, with the shortest time span of 40 d in 2003 and the longest of 166 d in 2012. S. litura moths had downwind displacement rather than randomly by heading toward their seasonally favorable direction (i.e. toward southwest in the four autumn migration events by prevailing northeasterly winds). Some females trapped in July showed a relatively higher proportion of having mated and a degree of ovarian development, suggesting that the migration of this species is not completely bound by the “oogenesis-flight syndrome.” These findings provide a good starting point of research on S. litura migration between its OR (or YBR) and SBR, which will help us develop more effective regional management strategies against this pest.
... Па раллельно были получены сведения о том, что зи мой в Средиземноморье периодически в массе появляются имаго V. atalanta, предположительно, прилетающие из северной и средней Европы (Ste fanescu, 2001). Позже было доказано, что особи V. atalanta нового поколения осенью действи тельно массово откочевывают на юг, а начало осенней миграции совпадает с наступлением пе риода устойчивых северных ветров (Mikkola, 2003a). Эти данные стали основой для расшиф ровки сложного жизненного цикла сезонных ми грантов, который протекает круглогодично бла годаря сезонным перемещениям бабочек между севером и югом Европы (Mikkola, 2003b V. cardui важным индикатором развития на севере может служить выраженный меланизм имаго но вого поколения. ...
... Linear model (dotted lines): (A) y ϭ 0.05x ϩ 0.25; n ϭ 5; F ϭ 2.93; P ϭ 0.185; R 2 ϭ 0.49; (B) y ϭ 0.07x Ϫ 0.35; n ϭ 5; F ϭ 13.28; P ϭ 0.036; R 2 ϭ 0.82; (C) y ϭ 0.09x Ϫ 0.30; n ϭ 5; F ϭ 11.59; P ϭ 0.042; R 2 ϭ 0.79. Nymphalidae), also occur more frequently in northerly winds in autumn (Taylor and Reling 1986, Riley et al. 1994, Mikkola 2003, and it has been postulated that this behavior facilitated return movements to the southern overwintering areas of these species. The present observations provide additional evidence for this hypothesis, although further studies should be investigated in detail. ...
During the past decade, Apolygus lucorum (Meyer-Dür) has become a key pest on cotton in northern China. Whether or not this species is a migrant, and if so, what pattern of seasonal migration this species exhibits remains unknown. The combination of searchlight trapping and radar observation on an isolated island in the center of Bohai Gulf during the past 11 yr provided direct evidence that both male and female A. lucorum adults migrate at least 40‐60 km (and probably much greater distances) across the Bohai Gulf waters. There were considerable yearly and monthly variation in the number of A. lucorum trapped on BH, and the migration period during 2009‐2013 ranged from 102 to 154 d. A. lucorum adults had downwind displacement rather than randomly by heading toward their seasonally favorable directions, which toward the east‐northeast in summer, but south‐southwest (SSW) in early autumn. The vast majority of adults flying at airspeeds 0.5‐2.5 m/s and at altitudes A. lucorum movements northward to and southward from the northeastern agricultural region of China, which will help us develop more effective management strategies against this pest species.
... In parallel, we came to know that V. atalanta imagoes periodically and massively appear in the Mediterranean in winter, presumably, flying from north and central Europe (Stefanescu, 2001). It was later demonstrated that new generation V. atalanta individuals actually massively migrated in the fall to the south and that this migration started with the period of stable northern winds (Mikkola, 2003a). These data formed the background for interpretation the complex life cycle of seasonal migrants, which continues all year round owing to seasonal migrations of butterflies between the north and the south of Europe (Mikkola, 2003b). ...
The concept that the mechanisms limiting immigration of new Lepidoptera species are analogous for islands with different ages and degrees of endemism of their biotas is discussed. Specific features of individual species play a key role in establishment of the fauna and population on small islands rather than competitive interactions between these species. It is most likely that the species stably coexisting on an island will display similar ecological characteristics and life cycles, which complies with the concepts of the neutral theory of biodiversity and biogeography.
... Occasionally, weather radars can provide information on identified insect species, for example, observations by the C-band Doppler system of the Department of Meteorology at Helsinki University (for insect migrations into Finland see http://www.helsinki.fi/*mleskine/engl/migra.html, Nieminen et al., 2000). The published work concerned pest species, but the radar has also detected the movement of nonpest Lepidoptera e.g., the Red Admiral butterfly, Vanessa atalanta (L.) (Mikkola, 2003). ...
Knowledge of flight movement is crucial to an understanding of the ecology, behaviour, genetics and evolutionary success of most insect species. However, all but the shortest flights will frequently take the insect beyond the range of both human vision and many opto-electronic devices, and thus radar technology has a valuable role to play in several distinct areas of movement research. In this review, we firstly consider the monitoring of high-altitude windborne movements of insect natural enemies, with emphasis on how novel vertical-looking radars are being employed to observe the migrations of aphid predators in the UK. Secondly, we discuss how scanning radars, with and without harmonic tags, have increased our understanding of the foraging flights of beneficial pollinators (bees), and how this technique might be applied to natural enemies. Lastly, we outline the use of harmonic direction-finders in studying the pedestrian and short flight movements of various beneficial insects, including predators. In each case we highlight the strengths and limitations of the techniques, and the prospects for future advances.
... Among the best studied insects from this perspective are nocturnally-active noctuid moth pests, and mass southward fall migrations have now been documented in, for example: Agrotis ipsilon and Helicoverpa zea in North America (Showers, 1997; Westbrook, 2008); Helicoverpa armigera, Mythimna separata and Spodoptera exigua in East Asia (Feng et al., 2003, 2005, 2008, 2009); and Autographa gamma and Noctua pronuba in Europe (Chapman et al., 2008a, 2008b, 2010; Alerstam et al., 2011). Southward windborne migrations in the fall have also been documented in other groups, including: dragonflies (Russell et al., 1998; Feng et al., 2006; Wikelski et al., 2006), leafhoppers (Taylor and Reling, 1986), pyralid moths (Riley et al., 1995) and butterflies (Mikkola, 2003; Stefanescu et al., 2012). It is thus becoming clear that many species of seasonal insect migrants use favorable tailwinds to carry out successful two-way journeys. ...
The silver Y moth Autographa gamma undertakes windborne spring and fall migrations between winter breeding regions around the Mediterranean and summer breeding regions in northern Europe. Flight behaviors facilitating these migrations include: (i) selection of seasonally-favorable tailwinds; (ii) flying at the altitude of the fastest winds; (iii) adopting flight headings that partially counteract crosswind drift; and (iv) seasonal reversal of preferred directions between spring and fall. In the UK, radar measurements indicate that migratory activity is pronounced during the spring and fall, but is usually very low during midsummer (July). However, an atypically intense period of high-altitude flight was recorded during July 2006, and in this study we compare the flight behavior of A. gamma during these midsummer movements with the more typical spring and fall migrations. During July 2006, activity was most intense at significantly lower altitudes than occurred in spring or fall, and was not associated with the height of the fastest winds; consequently displacement speeds were significantly slower. The most striking difference was an absence of tailwind selectivity in July with windborne movements occurring on almost every night of the month and on tailwinds from all directions. Finally, orientation behavior was quantitatively different during July, with significantly greater dispersion
of flight headings and displacements than observed in spring and fall. We discuss mechanisms which could have caused these differences, and conclude that a lack of appropriate photoperiod cues during development of the summer generation resulted in randomly-oriented ‘dispersive’ movements that were strikingly different from typical seasonal migrations.
... However, strong similarities in the strategies used by V. cardui and other migrant Lepidoptera, such as noctuids and hawk-moths (Chapman et al. 2010), raises the possibility that high-altitude windborne flights may be, in fact, much more widespread among migrant butterflies than has been assumed. The scarcity of records could be simply due to the difficulty of collecting data from the ground (Gibo 1981, Mikkola 2003. In this respect, radar technology is a useful complementary tool, as has been shown in our study. ...
Long-range, seasonal migration is a widespread phenomenon among insects, allowing them to track and exploit abundant but ephemeral resources over vast geographical areas. However, the basic patterns of how species shift across multiple locations and seasons are unknown in most cases, even though migrant species comprise an important component of the temperate-zone biota. The painted lady butterfly Vanessa cardui is such an example; a cosmopolitan continuously-brooded species which migrates each year between Africa and Europe, sometimes in enormous numbers. The migration of 2009 was one of the most impressive recorded, and thousands of observations were collected through citizen science programmes and systematic entomological surveys, such as high altitude insect-monitoring radar and ground-based butterfly monitoring schemes. Here we use V. cardui as a model species to better understand insect migration in the Western Palaearctic, and we capitalise on the complementary data sources available for this iconic butterfly. The migratory cycle in this species involves six generations, encompassing a latitudinal shift of thousands of kilometres (up to 60 degrees of latitude). The cycle comprises an annual poleward advance of the populations in spring followed by an equatorward return movement in autumn, with returning individuals potentially flying thousands of kilometres. We show that many long-distance migrants take advantage of favourable winds, moving downwind at high elevation (from some tens of metres from the ground to altitudes over 1000 m), pointing at strong similarities in the flight strategies used by V. cardui and other migrant Lepidoptera. Our results reveal the highly successful strategy that has evolved in these insects, and provide a useful framework for a better understanding of long-distance seasonal migration in the temperate regions worldwide.
... The patterns of genetic variation among individuals captured at our sample locations show that the migration of European red admirals is most likely to cover long distances, but not in a regular fashion as previous field observations have suggested (e.g. Williams, 1951;Benvenuti et al., 1996;Hansen, 2001;Mikkola, 2003). We see a large variation in observed frequencies of the two genotype clusters between years at our northern sites, suggesting that the origin of red admirals varies between years. ...
1. The genetic differentiation in a migratory butterfly, the red admiral (Vanessa atalanta), was investigated to discern patterns of migratory routes used across Europe. AFLP profiles showed significant differences between almost all sampled locations, but there was no clear pattern of isolation-by-distance.
2. Using the software STRUCTURE 2.2, we found two distinct genotype clusters present in different frequencies at all study sites. The frequencies of these genotypic clusters varied significantly between years within the same site. Remarkably few individuals were of mixed ancestry, indicating that some isolating mechanisms are present. Twenty-seven mtDNA haplotypes were identified but they showed no geographic structure, nor were they related to either of the two genotype clusters identified in the AFLP data.
3. Most field observations of migrating red admirals suggest a regular north–south migration pattern in Europe. Our data indicate both long-distance migration and a more variable pattern in orientation, since the composition of the two genotypic clusters shows dramatic variation between sites and years in the northern part of the distribution range.
... Two species are familiar to many people in the Holarctic region: the Painted Lady [Vanessa cardui (Linnaeus, 1758)], which has a global distribution; and the Red Admiral [Vanessa atalanta (Linnaeus, 1758)]. Both are known to be long-distance migrants and can occasionally be found moving north in large numbers during spring (Stefanescu, 1997;Stefanescu, 2001;Mikkola, 2003). Vanessa cardui is particularly well known for longdistance flights, as individuals have been recorded from the North Atlantic islands of Iceland and Svalbard, Norway, where they are unable to overwinter, representing a flight of at least 1000 km from the nearest known breeding areas. ...
Allopatric speciation is thought to occur in the absence of gene flow, thereby suggesting that widespread vagile species might be less likely to generate restricted sister taxa because of a lack of isolation. The butterfly genus Vanessa provides an ideal test of this concept, as it contains some of the most cosmopolitan and vagile species of butterflies on the planet, as well as some highly restricted taxa. Given the age of these groups, this arrangement offers a special opportunity to examine the relationship between vagility and phylogeny in generating novel taxa; specifically, does the vagility of some lineages impede allopatric speciation, leaving restricted clades more speciose? A phylogenetic hypothesis is proposed for all species belonging to the butterfly genus Vanessa based on DNA sequences from one mitochondrial and eight nuclear gene regions. The resulting topology shows very little conflict among gene regions, with five well-supported clades corresponding to morphologically consistent species groups. The data very strongly indicate a polyphyletic genus Antanartia, and thus to preserve monophyly two species previously assigned to Antanartia are transferred to Vanessa, Vanessa hippomenecomb.n. and Vanessa dimorphicacomb.n., resulting in a total of 22 species placed in Vanessa. A biogeographical analysis shows that in many cases the most geographically restricted species are sister to geographically widespread species, suggesting dispersal and allopatric speciation. Surprisingly, in almost all cases the divergences between widespread and restricted species are quite old (>5 Ma), suggesting long-term isolation and stability of both vagile and sedentary species, despite the high (even intercontinental) vagility of many extant species and, by extension, ancestral species. The biogeography of Vanessa suggests that species vagility and allopatry do not fully explain the forces governing cladogenesis in this remarkable genus.
... This strategy, which minimizes energy consumption and travelling time and would be expected to evolve in an organism whose life history is shaped by long-distance migration, has indeed been confirmed in some other related species (e.g. Vanessa atalanta (Linnaeus) (Nymphalidae: Nymphalinae) and Danaus plexippus (Linnaeus) (Nymphalidae: Danainae); Gibo & Pallett 1979;Mikkola 2003;Brower et al. 2006;Brattström et al. 2008). ...
Each spring, Vanessa cardui (Linnaeus) migrates into Europe, sometimes in huge numbers. Although it is widely accepted that migrants come from North Africa, there is currently a dearth of information on the source areas they originate from. However, in a recent study, a strong association between V cardui arriving in spring in Catalonia (NE Spain) and synoptic-scale winds originating in North Africa was found, which allowed us to predict the most likely location for the source areas in the Maghreb. In March 2009 we organized an expedition to confirm in situ the occurrence of immature stages and/or emerging adults at one of the hypothetical breeding areas in Morocco. Immatures were found at virtually all the sampled sites, with the maximum abundance being recorded in the Souss valley. Breeding habitats with plenty of thistles and mallows were sufficiently common to permit populations of great density to build up. We found a massive emergence site of 1.8 ha with an estimated population of 170,000 larvae, of which 155,000 had successfully pupated, the rest having been parasitised by the wasp Cotesia vanessae. Bird prédation of adults was also recorded at this site. Our observations, together with the typical patchy distribution of the ruderal habitats used for breeding, suggest that source populations most frequently originate in small habitat pockets with favourable conditions that allow for high patch occupancy and levels of oviposition.
... During the current study, it was found that H. armigera moths oriented toward the downwind direction during high-altitude migration over the sea in all seasons, which is consistent with the orientation behavior exhibited by this species during migration over the continent in previous studies (Feng et al. 2004a(Feng et al. , 2005a(Feng et al. , 2005b. As expected, the H. armigera moths did not initiate windborne migration (or migrated less frequently) during spells of southerly winds during fall (Drake and Farrow 1988), as documented for other Northern Hemisphere species such as the leafhopper Empoasca fabae (Harris) (Hemiptera: Cicadellidae) (Taylor and Reling 1986) and red admiral butterßies, Vanessa atalanta (L.) (Lepidoptera: Nymphalidae) (Mikkola 2003). Multiple collection of samples in the searchlight trap indicated that the H. armigera moths did took off during the early evening on unfavorable winds but rarely commenced highaltitude migration. ...
The seasonal migration of the Helicoverpa armigera (Hübner) (Lepidoptera: Noctuidae) over the Bohai Sea was observed with a searchlight trap and an entomological radar located on a small island in the center of the sea, and through a network of light-traps around the Bohai region. The H. armigera moths were observed to migrate over the sea at least as early as May and light trapping through a network suggested migration might start as early as April, as soon as the moths had emerged from overwintering pupae. H. armigera moths migrated toward the north in southerly winds during spring and summer, and returned south on nights with northerly winds, or at altitudes where the wind was northerly, during fall. The passage of a weather front (cold or warm) or trough at approximately 1700 hours provokes migration of H. armigera over the sea. The H. armigera generally flew at altitudes of below 1,500 m above sea level (asl) with layer concentrations at 200-500 m asl, where the wind direction, wind speed, and temperature were optimum. During fall migration, H. armigera tended to orient toward the southwest and was able to compensate for the wind drift by turning clockwise when the downwind direction was < 225 degrees but counterclockwise when it was > 225 degrees. The displacement speed measured with the radar was 24-41 km/h, the duration of flight was 8-11 h and the maximum migration rate was 1,894 moths per km per h.
The extent of aerial flows of insects circulating around the planet and their impact on ecosystems and biogeography remain enigmatic because of methodological challenges. Here we report a transatlantic crossing by Vanessa cardui butterflies spanning at least 4200 km, from West Africa to South America (French Guiana) and lasting between 5 and 8 days. Even more, we infer a likely natal origin for these individuals in Western Europe, and the journey Europe-Africa-South America could expand to 7000 km or more. This discovery was possible through an integrative approach, including coastal field surveys, wind trajectory modelling, genomics, pollen metabarcoding, ecological niche modelling, and multi-isotope geolocation of natal origins. The overall journey, which was energetically feasible only if assisted by winds, is among the longest documented for individual insects, and potentially the first verified transatlantic crossing. Our findings suggest that we may be underestimating transoceanic dispersal in insects and highlight the importance of aerial highways connecting continents by trade winds.
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.
Although migrant butterflies are rare (or sporadically seen) guests on the Arctic Ocean islands, there is a slowly growing dataset on repeated occurrences of these insects in insular tundra and polar deserts. Altogether six long-distance migrant butterfly species were found to cross wide marine barriers north of the Arctic Circle (66.56°N), i.e. Vanessa atalanta, V. cardui, Nymphalis antiopa, N. xanthomelas, Aporia crataegi, and Pieris napi. Migrant individuals of V. cardui discovered on Svalbard (up to 78.27°N in 1978) reflect the farthest dispersal event of butterflies to the Arctic ever reported. Our record of N. xanthomelas at the northern margin of Novaya Zemlya (76.95°N) represents the northernmost finding of this species globally, reflecting the world's second farthest record of northern poleward immigration of butterflies. This occurrence coincides with an exceptionally warm summer season, when the third highest July and second highest August air temperature occurred (since global records began in 1880). Furthermore, the immigration into Novaya Zemlya coincides with a population explosion and massive expansion of N. xanthomelas in Siberia in 2019-2020. Our air current reconstructions indicate that this species most likely immigrated into Novaya Zemlya from mainland regions situated south-southeast (Polar Urals, Yugorsky Peninsula, and western Yamal) and east (Taymyr) of the archipelago. Overall, our findings reveal that long-distance dispersal events of butterflies to the Arctic islands are always linked to massive expansions of the corresponding species in mainland areas.
A number of insects have been suggested to perform seasonal migration between low‐ and high‐altitude areas. In these insects, support for the occurrence of migration mainly came from observations that focal insects disappeared from a certain range of altitudes but appeared at different altitudes with short time lags. In some insects, further support was obtained by mark–recapture studies, analyses of the seasonal change of age structure or reproductive conditions in individuals from different altitudes and studies on dormancy or temperature tolerance. Other means that can be used to assess the occurrence of altitudinal migration are briefly mentioned. Two types of migration, the dormancy‐associated and dormancy‐independent types, are discriminated. In the former type, insects usually breed in spring, migrate to high‐altitude areas in late spring or early summer, usually for aestivation, and return to low‐altitude areas in autumn. In this type, the same individuals perform upward and downward migration. In the latter type, insects also perform upward migration in late spring or early summer and downward migration in autumn, but they breed both in low‐ and high‐altitude areas. The adaptive and evolutionary aspects of altitudinal migration are briefly mentioned.
Säätutkilla kartoitetaan sadealueita. Ilmassa lentävät hyönteiset aiheuttavat sateiden ja satavien pilvien ohella merkittävimmän kaiun kesäaikaan säätutkissa. Koska tutkan mittauksessa käytännöllinen alin korkeus on sadan metrin luokkaa, hyönteiset ovat tällöin niin korkealla että niitä voidaan yleensä pitää vaeltajina. Vaeltavat hyönteiset nousevat tarkoituksellisesti tällaisille korkeuksille, kun taas muusta syystä liikkeellä olevat yksilöt pysyttäytyvät alhaalla, jossa ne voivat omalla lentonopeudellaan ylittää ilmanvirtausnopeuden ja pystyvät pääsemään kohteeseensa. Säätutkilla hyönteisten aiheuttama kaiku-kerros ulottuu tavallisesti noin +5 asteen lämpötilaan saakka, jolloin noin +25 asteen pintalämpötilassa kauniina kesäpäivänä kaikukerros voi olla noin kahden kilometrin paksuinen.Hyönteismigraatiolla voidaan tarkoittaa hyvin erilaisia yksilöiden liikkeitä, joilla on merkitystä lajin populaatioille. Suomessa migraatioihin liittyviä tutkimuksia on tehty paljon toisaalta perhosten ja toisaalta tuhohyönteisten osalta. Metapopulaatioiden tutkimuksessa migraatio on myös keskeinen tekijä. Hyönteisten vaellusten tarkkailussa kiinnostuksen kohteena ovat olleet erityisesti immigraatiot, jotka tuovat tarkastellulle alueelle yksilöitä. Immigraation merkitys korostuu tuhohyönteisten vaikutusten arvioinnissa, koska yleensä ennustusmenetelmät populaatioiden kehittymisestä perustuvat havaintoihin paikallisesta populaatiosta.Erityisesti Helsingin yliopiston säätutkan mittauksia on viime kahdenkymmenen vuoden kuluessa käytetty lähinnä kirvojen ja perhosten immigraatioiden tutkimuksessa. Tämän tutkan sijainti Suomenlahden rannikon tuntumassa onkin tehnyt mahdolliseksi erottaa meren yli tulevat immigraatiot lyhytkestoisemmista paikallisista vaelluksista. Toisaalta taas Ilmatieteen laitoksen säätutkaverkosto kattaa varsinkin Etelä-Suomen kesäisten sateiden osalta varsin hyvin, jolloin myös hyönteisvaellusten seurantaa voidaan tehdä koko alueella. Vuoden 2004 lopulla Helsingin yliopiston rakennuksen katolle Kumpulan yliopistoalueella asennettiin uuden säätutkan antenni. Tämä Vaisala Oyj:n rakentama tutka on Suomen ensimmäinen polarimetrinen säätutka.Polarisaatiosäätutkalla kyetään aikaisempaa paremmin erottamaan hyönteiset muista kaiun aiheuttajista ja lisäksi on mahdollista saada lisää tietoa havaittavien hyönteisten lajistosta ja käyttäytymisestä ilmavirtauksissa. Tämän tutkan käyttömahdollisuuksia ja yleensä vastaavanlaisten järjestelmien hyödyntämistä tutkitaan hankkeessa "Polarisaatiotutkan monitieteelliset sovellukset". Yksi alue tässä tutkimuksessa on kehittää tuhohyönteisten vaellusten ennustusmalli. Tässä osuudessa ovat mukana Helsingin yliopisto, Ilmatieteen laitos ja Maa- ja elintarviketalouden tutkimuskeskus. Säätutkilla ja erityisesti käytössä olevalla uudella polarisaatiotutkalla hyönteisvaelluksia pyritään seuraamaan tämän ennustusmallin toiminnan varmistamiseksi. Samaan aikaan tehostetulla hyönteisten pyydystyksellä selvitetään vaellusten saapumista maastoon.
Ornithologists in Finland recorded the autumn migration of the Red Admiral butterfly, Vanessa atalanta (L.). In the best year, 1998, 1240 migrants were counted from a bird tower in September. That is, half a million butterflies migrated over a 100-km front. The butterflies were flying above forests riding on cool northerly winds. Radar indicated that a large proportion migrated at high elevations outside the visible range. These records help to resolve an "evolutionary puzzle" of why migrant butterflies and moths travel to northern latitudes when their offspring have limited possibilities of returning south. Until now, the only butterfly for which a high-elevation return migration on northerly winds is known is the American Monarch Danaus plexippus (L.).
Insects typically spend the winter in a species-specific diapause stage. The speckled wood butterfly, Pararge aegeria, is unique in having two alternative diapause stages, hibernating as larvae or pupae. In southern Sweden this creates a seasonal flight pattern with four annual adult flight periods: the first in May (pupal diapause), the second in June (larval diapause), and the third and fourth directly developing offspring generations in July and August, respectively. We address the raison d'être of the two diapause pathways by (1) outdoor rearing of cohorts, and (2) performing transect censuses throughout the season for 20 years. We contend that an early start of next season provides a benefit accruing to pupal diapause; conversely, a large proportion of the offspring from adults of the fourth flight peak are unable to reach the pupal stage before winter, providing a benefit accruing to larval winter diapause. The results obtained show that the two hibernation pathways are unlikely to be genetically distinct because of a strong overlap between the two offspring generations, and because sibling offspring from the third and fourth flight periods are likely to choose either of the two hibernation pathways, thereby resulting in a genetic mixing of the pathways. © 2011 The Linnean Society of London, Biological Journal of the Linnean Society, 2011, 102, 635–649.
Many insects undertake long-distance migrations to exploit seasonally variable conditions at high latitudes, but the mechanisms used by migrants to select and maintain beneficial flight headings are poorly understood. Using computerized flight simulators, we performed controlled experiments to test the ability of an obligate migrant butterfly (Vanessa cardui) to orient in seasonally advantageous directions (i.e. northwards in spring and southwards in autumn). We also investigated the compass mechanism used to select and maintain these headings. Laboratory-reared autumn-generation butterflies flown in the U.K. displayed a highly significant mean orientation towards the south-southwest, consistent with return migration to winter breeding sites. However, seasonally adaptive flight headings were not observed in wild-caught adults flown at the same time. Spring-generation adults caught in Gibraltar (presumed to be migrating from winter breeding sites in North Africa into Europe) showed no evidence of northward flight headings, but produced a wide scatter of flight headings with a mean direction towards the west. Butterflies flown in the simulators when the sky was not visible produced a random scatter of flight headings and less-directed flight tracks, providing evidence that migrating V. cardui use a sun compass to select and maintain their flight headings. However, when butterflies were subjected to a 6 h clock shift, no change in orientation was observed relative to the control group. Field evidence for a return migration in autumn by V. cardui is surprisingly scarce in the literature, but we conclude that the species does attempt such southward movements and that individuals use a sun compass to select their migratory heading.
Not at the Mercy of the Wind
How can insects that migrate at high altitudes on fast-moving winds influence their direction of migration, when wind speeds typically exceed their self-propelled air speeds by a factor of three or four? Using automated vertical-looking entomological radar systems, Chapman et al. (p. 682 ) show that compass-mediated selection of favorable tailwinds, and partial correction for crosswind drift, are widespread phenomena in migrant insect species. Specialized flight behaviors have decisive influence on the migration pathways achieved by insects. Thus, contrary to popular belief, migrant insects are not at the mercy of the wind.
The autumn migration of Helicoverpa armigera (Hübner) was observed with radar and two types of light-trap at Langfang, Hebei province, China in 2001 and 2002. The sudden increase in the proportion of H. armigera moths in the searchlight trap indicated migration into the area and catches increased 10-fold during the second half of the night due to the landing of migrants before dawn. The moths' migratory flights took place at up to 2000 m above the ground, and moths flew differentially at times, and heights, when favourable (i.e. northerly) winds occurred. This facilitated the maximum displacement of moths towards the south during these 'return' migrations. The moths flew over the radar site at consistently high densities through the night, and the resulting flight durations of c. 10 h, at displacement speeds of 30-33 km h-1, would allow moths emerging in the far northeast of China (i.e. Liaoning and Jilin provinces and the Inner Mongolia autonomous region) to migrate into northern China (Hebei, Shandong and Henan provinces). The association of the seasonal migratory movements of H. armigera with crops in northern China is briefly discussed.
A new theory of migration in butterflies is outlined and present concepts are examined. During the course of evolution many butterflies have become adapted in the larval stage to foodplants that occur in small and scattered localities, the distribution of which changes constantly. It is argued that whenever this happens selection might be expected to produce a butterfly which flies from one foodplant site to another. Further it is argued that while they were crossing areas devoid of foodplants selection would have favoured those individuals that flew at a constant angle to the sun. At first all angles to the sun would be represented equally in the population but each individual would pass on to its offspring a bias towards its own particular angle. It is suggested that the temperature gradient experienced by a butterfly dispersing in this way would constitute a marked selective pressure. This selective pressure would cause an increase in the number of individuals flying at certain angles and a decrease in the number flying at others. The effects of temperature on rate of development and fecundity were demonstrated for Pieris rapae and P. brassicae in the laboratory. The effects of seasonal and geographical temperature variations on these two species in the field were also demonstrated. Based on these results the relative selective advantage of each flight direction was calculated for different times of the year. As a result of these calculations it was predicted that P. rapae should fly at 159^circ to the sun until 27 August, when it should fly at 0^circ. For P. brassicae it was predicted that the first brood should fly at 159^circ and the second brood at 339^circ. Observations of flight direction of these two species from August of one year to October of the following year agreed well with these predictions. The observations of flight direction also showed that P. rapae, and probably also P. brassicae and Vanessa atalanta, were using the sun as the environmental clue by which they were orientating themselves. There was no compensation for the sun's movement during the day or season. Experiments showed that P. rapae is sensitive to photoperiod during the adult stage. It is by this means that the same individuals can change their flight direction from 159^circ to 0^circ at the most selectively advantageous time. A calculation based on the results of this investigation suggested that a return flight would be a selective disadvantage to both P. rapae and P. brassicae. Observation of these two species suggested that in neither does the southward movement function as a return flight, i.e. is equal in distance to the northward movement.
The substance of this paper deals with one striking feature of insect migration — common orientation at night by larger-sized (30–2000 mg), high-flying insects. This phenomenon was unsuspected before it was made dramatically obvious by the fortuitous sensitivity of simple scanning radars to non-random orientation in populations of airborne insects (Schaefer 1969). Since then, common orientation has been widely observed in many radar studies (J. Roffey, personal communication 1972; Riley 1975; Schaefer 1976; Reid et al. 1979; Riley and Reynolds 1979,1983; W.W. Wolf, personal communication 1980; Greenbank et al. 1980; Drake et al. 1981; Drake 1983, 1984) and it appears to be a very common feature of nocturnal migratory flight. All authors agree that orientation occurs in both the presence and absence of moonlight.
Describes the planetary boundary layer and the role of its structure in insect migration, then examines various atmospheric motions that migrants encounter. -P.J.Jarvis
Vanishing bearings of individual, autumn-migrating Danaus plexippus were recorded at various inland locations of the E USA and at coastlines parallel and nonparalllel to the direction of migration. At the coast in unfavorable winds, including strong tailwinds, monarchs avoided heading out over the ocean. Inland, across the Piedmont Plain as well as in the Appalachian Mountains, monarchs even migrated in strong tailwinds, flying very rapidly at high altitudes. Monarchs can probably keep track of and compensate for displacements by wind. Mean directions at two representative multi-sample inland locations agreed with the directions predicted by Kiepenheuer's (1984) model of the magnetoclinic compass. -from Author
(1) The problem of the long-distance, return migration to their overwintering region by weakly flying aeroplankton was investigated. Aircraft-mounted nets were used to sample for migrant potato leafhoppers at an altitude of 152 m above ground level along a transect in Central Pennsylvania during the summers of 1981 and 1982. (2) The wind most frequently associated with the potato leafhopper, Empoasca fabae, migratory flight during June-September was from the north-northeast; the prevailing wind during the summer months is from the west. (3) The distribution of windspeed and direction during the sampling period was similar to the 30-year averages at c. 1500 m (850 mB) at Buffalo, New York. (4) In both years the peak leafhopper densities were associated with the passage of cold fronts from west to east. (5) It is postulated that the meteorological conditions associated with these frontal systems stimulate exodus flights of migrant leafhoppers at a moment most likely to facilitate a return to their southern overwintering sites.
(1) Fifteen-point profiles of aerial density in relation to height up to 32 m were measured for twenty-four insect taxa. (2) All profiles showed a discontinuity. (3) This discontinuity occurred at a height of 30 cm for total insects, where mean-wind speed matched mean flight-speed. (4) Flight behaviour above the discontinuity was much more consistent than below. (5) Above the discontinuity, log density X log height regression coefficients conformed with expectation based on known behaviour, size, and upward atmospheric transport. (6) The discontinuity thus agrees with expectation from the boundary layer hypothesis. (7) The proportion of small insects above the boundary layer is significantly correlated with the diurnal flight periodicity of the taxon.
Systematic observations on seasonal incidence of the red admiral (Vanessa atalanta L.) in central‐northern Italy were made in the course of four successive years. Our data show that our region is characterized by regular bidirectional migration which is particularly remarkable in October, during autumn migration to the overwintering sites. Red admirals’ migration is highly directional: individuals fly along straight lines at the mean speed of 14 km/h, and produce highly oriented distributions of their vanishing bearings. This directional preference is not the result of passive displacement caused by winds, but is the expression of an internal tendency based on the use of a compass mechanism. Red admirals’ seasonal incidence in our area significantly differs from that reported for the northern range of this butterfly species. This study constitutes the base of a long‐term investigation aimed at clarifying the phenology and other aspects of migration of this butterfly species (origin and destination of migrants, mechanism of orientation) which, despite the amount of literature on this subject, are as yet not entirely understood.
Stochastic effects of climate and weather have a pervasive influence on the induction, performance and evolution of migration.
In wing-dimorphic species, their influence on habitat quality, and on rates of development of the migrant itself, maintains
variation in responses to environmental cues determining wing-form and migratory behaviour. Migrants flying above their flight
boundary layer rely on winds to disperse them across landscapes in which their habitats are distributed. Patterns of distribution
of habitat patches, and the influence of changing windspeeds and direction on the displacements of migrants, result in selection
for variation in migratory potential at each migration. In subsequent migrations, this variation and stochastic effects of
the winds on groundtracks of individual migrants ensure that their destinations ‘sample’ the landscapes they travel over.
The extent and resolution of this sampling, by which migrants reach favourable habitats, depend on the components of migratory
potential, their mode of inheritance, and genetic correlations between them, as well as on the characteristics of the winds
on which they travel.
Mitogenic and inhibitory growth factors and steroid ovarian hormones play important roles as selective modulators of normal mammary development and in the onset and the progression of human breast cancer. The focus of this article is to review past and current research on the interactions of these two classes of effectors in mammary gland development and neoplasia. Steroid hormones regulate synthesis of growth stimulatory and inhibitory growth factors, growth factor receptors, and growth factor binding proteins. In turn, growth factor pathways may modulate phosphorylation and function of steroid receptors and potentiate or inhibit the mitogenic actions of steroids. Ultimately, during the progression of the malignant mammary epithelial cell to hormonal autonomy, overexpression, mutation, or disregulation of key elements of growth factor signal transduction pathways all may play critical roles.
The long-range migration of insects in general is briefly discussed here and serves as an introduction for in-depth inquiry into the migratory ecology of Agrotis ipsilon, the black cutworm. Zoogeography, pest status and injury, and seasonal occurrence of the species are reviewed. Circumstantial evidence of long-range movement of A. ipsilon moths within both hemispheres is presented, followed by experimental evidence of long-range movement of A. ipsilon moths in China and North America. Based upon experimental evidence published by several investigators, a theory is proposed of the existence of a thermal range (0-36 degrees C) for A. ipsilon pupae that acts as the precursor for adult (moth) migration. This theory should help explain the circumstantial and empirical evidence gathered upon the annual appearance and disappearance of this species over large geographic areas.