Mapping The Movement of Overwintering Western Monarch Butterflies (Danaus Plexippus) at the Pismo Beach Monarch Butterfly Grove Using ARCGIS Software

Insects are well-known for their ability to keep track of their heading direction based on a combination of skylight cues and visual landmarks. This allows them to navigate back to their nest, disperse throughout unfamiliar environments, as well as migrate over large distances between their breeding and non-breeding habitats. The monarch butterfly (Danaus plexippus) for instance is known for its annual southward migration from North America to certain trees in Central Mexico. To maintain a constant flight route, these butterflies use a time-compensated sun compass for orientation which is processed in a region in the brain, termed the central complex. However, to successfully complete their journey, the butterflies' brain must generate a multitude of orientation strategies, allowing them to dynamically switch from sun-compass orientation to a tactic behavior toward a certain target. To study if monarch butterflies exhibit different orientation modes and if they can switch between them, we observed the orientation behavior of tethered flying butterflies in a flight simulator while presenting different visual cues to them. We found that the butterflies' behavior depended on the presented visual stimulus. Thus, while a dark stripe was used for flight stabilization, a bright stripe was fixated by the butterflies in their frontal visual field. If we replaced a bright stripe by a simulated sun stimulus, the butterflies switched their orientation behavior and exhibited compass orientation. Taken together, our data show that monarch butterflies rely on and switch between different orientation modes, allowing them to adjust orientation to the actual behavioral demands of the animal.

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Contemporary loss of migration in monarch butterflies

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.1904690116 ◽

2019 ◽

Vol 116 (29) ◽

pp. 14671-14676 ◽

Cited By ~ 9

Author(s):

Ayşe Tenger-Trolander ◽

Wei Lu ◽

Michelle Noyes ◽

Marcus R. Kronforst

Keyword(s):

North American ◽

Indoor Environment ◽

Captive Breeding ◽

Danaus Plexippus ◽

Monarch Butterfly ◽

Population Recovery ◽

Monarch Butterflies ◽

Commercial Population ◽

Open Question ◽

The Impact

The annual migration of the monarch butterfly Danaus plexippus is in peril. In an effort to aid population recovery, monarch enthusiasts across North America participate in a variety of conservation efforts, including captive rearing and release of monarch butterflies throughout the summer and autumn. However, the impact of captive breeding on monarchs remains an open question. Here, we show that captive breeding, both commercially and by summertime hobbyists, causes migratory behavior to be lost. Monarchs acquired commercially failed to orient south when reared outdoors in the autumn, unlike wild-caught North American monarchs, yet they did enter reproductive diapause. The commercial population was genetically highly divergent from wild-caught North American monarchs and had rounder forewings, similar to monarchs from nonmigratory populations. Furthermore, rearing wild-caught monarchs in an indoor environment mimicking natural migration-inducing conditions failed to elicit southward flight orientation. In fact, merely eclosing indoors after an otherwise complete lifecycle outdoors was enough to disrupt southern orientation. Our results provide a window into the complexity—and remarkable fragility—of migration.

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Effects of early-life exposure to sublethal levels of a common neonicotinoid insecticide on the orientation and migration of monarch butterflies (Danaus plexippus)

Journal of Experimental Biology ◽

10.1242/jeb.230870 ◽

2020 ◽

Vol 224 (4) ◽

pp. jeb230870

Author(s):

Alana A. E. Wilcox ◽

Amy E. M. Newman ◽

Nigel E. Raine ◽

Greg W. Mitchell ◽

D. Ryan Norris

Keyword(s):

Danaus Plexippus ◽

Monarch Butterfly ◽

Flight Simulator ◽

Testing Time ◽

Long Distance ◽

Monarch Butterflies ◽

Early Life Exposure ◽

Neonicotinoid Insecticide ◽

In The Wild ◽

And Migration

ABSTRACTMigratory insects use a variety of innate mechanisms to determine their orientation and maintain correct bearing. For long-distance migrants, such as the monarch butterfly (Danaus plexippus), these journeys could be affected by exposure to environmental contaminants. Neonicotinoids are synthetic insecticides that work by affecting the nervous system of insects, resulting in impairment of their mobility, cognitive performance, and other physiological and behavioural functions. To examine how neonicotinoids might affect the ability of monarch butterflies to maintain a proper directional orientation on their ∼4000 km migration, we grew swamp milkweed (Asclepias incarnata) in soil that was either untreated (0 ng g−1: control) or mixed with low (15 ng g−1 of soil) or high (25 ng g−1 of soil) levels of the neonicotinoid clothianidin. Monarch caterpillars were raised on control or clothianidin-treated milkweed and, after pupation, either tested for orientation in a static flight simulator or radio-tracked in the wild during the autumn migration period. Despite clothianidin being detectable in milkweed tissue consumed by caterpillars, there was no evidence that clothianidin influenced the orientation, vector strength (i.e. concentration of direction data around the mean) or rate of travel of adult butterflies, nor was there evidence that morphological traits (i.e. mass and forewing length), testing time, wind speed or temperature impacted directionality. Although sample sizes for both flight simulator and radio-tracking tests were limited, our preliminary results suggest that clothianidin exposure during early caterpillar development does not affect the directed flight of adult migratory monarch butterflies or influence their orientation at the beginning of migration.

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State-dependent egocentric and allocentric heading representation in the monarch butterfly brain

10.1101/2021.04.07.438824 ◽

2021 ◽

Author(s):

M. Jerome Beetz ◽

Christian Kraus ◽

Myriam Franzke ◽

David Dreyer ◽

Martin F. Strube-Bloss ◽

...

Keyword(s):

Reference Frame ◽

Reference Frames ◽

Danaus Plexippus ◽

Monarch Butterfly ◽

Central Complex ◽

Dependent Manner ◽

The Sun ◽

Monarch Butterflies ◽

State Dependent ◽

Allocentric Reference Frame

AbstractHead direction can be represented in a self-centered egocentric or a viewpoint-invariant allocentric reference frame. Using the most efficient representation is especially crucial for migrating animals, like monarch butterflies (Danaus plexippus) that use the sun for orientation. With tetrode recordings from the brain of tethered flying monarch butterflies, we examined the reference frame in which insects encode heading. We show that compass neurons switch their reference frame in a state-dependent manner. In quiescence, they encode sun-bearing angles, allowing the butterfly to map the environment within an egocentric frame. However, during flight, the same neurons encode heading within an allocentric frame. This switch converts the sun from a local to a global cue, an ideal strategy for maintaining a migratory heading over large distance.One-Sentence SummaryHeading information is encoded in different state-dependent reference frames in the monarch butterfly central complex

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An Ecological Field Lab for Tracking Monarch Butterflies & Their Parasites

The American Biology Teacher ◽

10.1525/abt.2010.72.6.5 ◽

2010 ◽

Vol 72 (6) ◽

pp. 339-344 ◽

Cited By ~ 2

Author(s):

Carrie N. Wells

Keyword(s):

Citizen Science ◽

Scientific Method ◽

Danaus Plexippus ◽

Monarch Butterfly ◽

Biological Research ◽

Research Projects ◽

Ecological Data ◽

Monarch Butterflies

The inclusion of nonscientists in biological research projects has become a useful mechanism for capturing long-term ecological data while exposing students firsthand to science and the scientific method. I have combined several existing citizen-science-based research efforts focused on Danaus plexippus, the monarch butterfly, into a comprehensive yet simple ecological lab activity that is appropriate for all ages and biological backgrounds.

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Density estimates of monarch butterflies overwintering in central Mexico

10.7287/peerj.preprints.2832 ◽

2017 ◽

Author(s):

Wayne Thogmartin ◽

Jay E Diffendorfer ◽

Laura Lopez-Hoffman ◽

Karen Oberhauser ◽

John Pleasants ◽

...

Keyword(s):

Population Size ◽

Population Decline ◽

Danaus Plexippus ◽

Mixture Distribution ◽

Monarch Butterfly ◽

Accurate Estimate ◽

Monarch Butterflies ◽

Density Estimates ◽

Considerable Uncertainty ◽

Log Normal

Given the rapid population decline and recent petition for listing of the monarch butterfly (Danaus plexippus L.) under the Endangered Species Act, an accurate estimate of the Eastern, migratory population size is needed. Because of difficulty in counting individual monarchs, the number of hectares occupied by monarchs in the overwintering area is commonly used as a proxy for population size, which is then multiplied by the density of individuals per hectare to estimate population size. There is, however, considerable variation in published estimates of overwintering density, ranging from 6.9–60.9 million ha-1. We develop a probability distribution for overwinter density of monarch butterflies from six published density estimates. The mean density among the mixture of the six published estimates was ~27.9 million butterflies ha-1 (95% CI: 2.4–80.7 million ha-1); the mixture distribution is approximately log-normal, and as such is better represented by the median (21.1 million butterflies ha-1). Based upon assumptions regarding the number of milkweed needed to support monarchs, the amount of milkweed (Asclepias spp.) lost (0.86 billion stems) in the northern U.S. plus the amount of milkweed remaining (1.34 billion stems), we estimate >1.8 billion stems is needed to return monarchs to an average population size of 6 ha. Considerable uncertainty exists in this required amount of milkweed because of the considerable uncertainty occurring in overwinter density estimates. Nevertheless, the estimate is on the same order as other published estimates. The studies included in our synthesis differ substantially by year, location, method, and measures of precision. A better understanding of the factors influencing overwintering density across space and time would be valuable for increasing the precision of conservation recommendations.

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Changes in the geomagnetic field has little effect on the overwintering range of Eastern North American fall migratory monarch butterflies (Danaus plexippus), indicating a lack of an innate magnetic map sense for navigation

10.21203/rs.2.22446/v1 ◽

2020 ◽

Author(s):

Patrick Anthony Guerra ◽

Stephen Matter

Keyword(s):

Magnetic Field ◽

North American ◽

Geomagnetic Field ◽

Danaus Plexippus ◽

Monarch Butterfly ◽

Central Mexico ◽

Earth’S Magnetic Field ◽

Long Distance ◽

Monarch Butterflies ◽

Earth's Magnetic Field

Abstract BackgroundIndividuals of many species that perform annual long-distance migrations are capable of stopping at specific overwintering destinations, despite having not been there before. The iconic monarch butterfly (Danaus plexippus) and its annual long-distance fall migration is a famous example of this phenomenon. During the fall, Eastern North American monarch butterflies use various compass mechanisms to properly orient their flight southwards, in order to leave their summer breeding grounds in Southern Canada and the Northern United States, and reach their overwintering sites in Central Mexico. It remains a mystery, however, how monarchs locate and stop at these specific, consistent overwintering sites, especially since these individuals are on their maiden voyage. MethodsWe test the hypothesis that fall migrant monarchs locate these overwintering sites by using an innate, inherited map sense based on sensing and responding to specific geomagnetic signatures that are correlated with the overwintering sites. Using a natural displacement approach, we examined if the locations of overwintering sites and the abundance of monarchs at them, changes with the natural shift of the Earth’s magnetic field over time (2004-2018).ResultsWe found that despite the natural displacement of the geomagnetic field over the years, the locations of the overwintering sites and monarch abundance were unaffected. For example, fall monarchs continued to overwinter at the most southern sites in Mexico, even when the geomagnetic coordinates associated with these sites would have shifted north due to the natural shift of the Earth’s magnetic field, placing these sites significantly outside the range of the overwintering area.ConclusionsOur results suggest that monarchs do not employ a map sense based on geomagnetic cues for finding their overwintering sites, and might instead use other mechanisms or strategies for locating them (potentially using localized sensory cues) once they are near or have arrived in Central Mexico. We suggest that future work should now focus on understanding what these cue parameters are, in order to inform conservation efforts that are aimed at protecting the threatened monarch butterfly and preserving its annual long-distance migration.

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Uptake and toxicity of clothianidin to monarch butterflies from milkweed consumption

PeerJ ◽

10.7717/peerj.8669 ◽

2020 ◽

Vol 8 ◽

pp. e8669 ◽

Cited By ~ 1

Author(s):

Timothy A. Bargar ◽

Michelle L. Hladik ◽

Jaret C. Daniels

Keyword(s):

Larval Growth ◽

Danaus Plexippus ◽

Total Mortality ◽

Monarch Butterfly ◽

Larval Survival ◽

Adult Size ◽

Monarch Butterflies ◽

Resource Managers ◽

Natural Resource Managers ◽

Butterfly Larvae

Recent concern for the adverse effects from neonicotinoid insecticides has centered on risk for insect pollinators in general and bees specifically. However, natural resource managers are also concerned about the risk of neonicotinoids to conservation efforts for the monarch butterfly (Danaus plexippus) and need additional data to help estimate risk for wild monarch butterflies exposed to those insecticides. In the present study, monarch butterfly larvae were exposed in the laboratory to clothianidin via contaminated milkweed plants from hatch until pupation, and the effects upon larval survival, larval growth, pupation success, and adult size were measured. Soils dosed with a granular insecticide product led to mean clothianidin concentrations of 10.8–2,193 ng/g in milkweed leaves and 5.8–58.0 ng/g in larvae. Treatment of soils also led to clothianidin concentrations of 2.6–5.1 ng/g in adult butterflies indicating potential for transfer of systemic insecticides from the soil through plants and larvae to adult butterflies. Estimated LC50s for total mortality (combined mortality of larvae and pupae) and EC50 for larval growth were variable but higher than the majority of concentrations reported in the literature for clothianidin contamination of leaves.

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Density estimates of monarch butterflies overwintering in central Mexico

PeerJ ◽

10.7717/peerj.3221 ◽

2017 ◽

Vol 5 ◽

pp. e3221 ◽

Cited By ~ 17

Author(s):

Wayne E. Thogmartin ◽

Jay E. Diffendorfer ◽

Laura López-Hoffman ◽

Karen Oberhauser ◽

John Pleasants ◽

...

Keyword(s):

Population Size ◽

Population Decline ◽

Danaus Plexippus ◽

Mixture Distribution ◽

Monarch Butterfly ◽

Accurate Estimate ◽

Monarch Butterflies ◽

Density Estimates ◽

Considerable Uncertainty ◽

Log Normal

Given the rapid population decline and recent petition for listing of the monarch butterfly (Danaus plexippus L.) under the Endangered Species Act, an accurate estimate of the Eastern, migratory population size is needed. Because of difficulty in counting individual monarchs, the number of hectares occupied by monarchs in the overwintering area is commonly used as a proxy for population size, which is then multiplied by the density of individuals per hectare to estimate population size. There is, however, considerable variation in published estimates of overwintering density, ranging from 6.9–60.9 million ha−1. We develop a probability distribution for overwinter density of monarch butterflies from six published density estimates. The mean density among the mixture of the six published estimates was ∼27.9 million butterflies ha−1 (95% CI [2.4–80.7] million ha−1); the mixture distribution is approximately log-normal, and as such is better represented by the median (21.1 million butterflies ha−1). Based upon assumptions regarding the number of milkweed needed to support monarchs, the amount of milkweed (Asclepias spp.) lost (0.86 billion stems) in the northern US plus the amount of milkweed remaining (1.34 billion stems), we estimate >1.8 billion stems is needed to return monarchs to an average population size of 6 ha. Considerable uncertainty exists in this required amount of milkweed because of the considerable uncertainty occurring in overwinter density estimates. Nevertheless, the estimate is on the same order as other published estimates. The studies included in our synthesis differ substantially by year, location, method, and measures of precision. A better understanding of the factors influencing overwintering density across space and time would be valuable for increasing the precision of conservation recommendations.

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A PROPOSED METHOD FOR MARKING MIGRANT BUTTERFLIES

The Canadian Entomologist ◽

10.4039/ent7321-2 ◽

1941 ◽

Vol 73 (2) ◽

pp. 21-22 ◽

Cited By ~ 2

Author(s):

F. A. Urquhart

Keyword(s):

Danaus Plexippus ◽

Late Summer ◽

Lake Ontario ◽

Monarch Butterfly ◽

Species Trees ◽

Monarch Butterflies ◽

Royal Ontario Museum ◽

North Shore ◽

The North

In the late summer of 1940, there was a decided peak in the abundance of the monarch butterfly, Danaus plexippus L. Numerous reports were received by the Royal Ontario Museum of Zoology, and a personal investigation proved the abundance of the species; trees bordering the north shore of Lake Ontario in the vicinity of Toronto were literally covered with monarch butterflies.

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