Monarch Butterfly Research Articles

"Living in the time of the butterfly:" Engaging more-than-human temporalities to rethink biodiversity conservation

This article describes the ecological accounts of Jñato and Hñähñu (also known as Mazahua and Otomi) people who inhabit a territory that is today the Monarch Butterfly Biosphere Reserve in México. We draw on their narratives, documented through a multiyear historical and ethnographic study, to discuss multispecies temporalities and reciprocal relations across more-than-human entities. Analyzing local environmental knowledge through "deep time" and relational perspectives, we invite conservation and environmental studies scholars to reconsider epistemological assumptions about time and the Anthropocene. We do so by documenting the multispecies rhythms and temporalities maintained in our research sites from time immemorial. In contrast with linear notions of time, these rhythms operate cyclically through reciprocal gifting between plants, humans, and other entities such as a water spirits and witches. The "deep time" lens that such practices offer, we suggest, can enrich biodiversity conservation and more-than-human political ecologies. We conclude by stressing that this relational "world-making" is also power-laden. Political identities are embedded in, and reconstructed through, a complex political economy and uneven relations of knowledge production. Together, these constitute what we call "the time of the butterfly."

Changes in landscape and climate in Mexico and Texas reveal small effects on migratory habitat of monarch butterflies (Danaus plexippus)

The decline of the iconic monarch butterfly (Danaus plexippus) in North America has motivated research on the impacts of land use and land cover (LULC) change and climate variability on monarch habitat and population dynamics. We investigated spring and fall trends in LULC, milkweed and nectar resources over a 20-year period, and ~ 30 years of climate variables in Mexico and Texas, U.S. This region supports spring breeding, and spring and fall migration during the annual life cycle of the monarch. We estimated a − 2.9% decline in milkweed in Texas, but little to no change in Mexico. Fall and spring nectar resources declined < 1% in both study extents. Vegetation greenness increased in the fall and spring in Mexico while the other climate variables did not change in both Mexico and Texas. Monarch habitat in Mexico and Texas appears relatively more intact than in the midwestern, agricultural landscapes of the U.S. Given the relatively modest observed changes in nectar and milkweed, the relatively stable climate conditions, and increased vegetation greenness in Mexico, it seems unlikely that habitat loss (quantity or quality) in Mexico and Texas has caused large declines in population size or survival during migration.

Interactions between the Migratory Monarch Butterfly and Native Vegetation in San Luis Potosi, Mexico

Interactions between the Migratory Monarch Butterfly and Native Vegetation in San Luis Potosi, Mexico

Comparative analysis of locomotor behavior and head diurnal transcriptome regulation by PERIOD and CRY2 in the diamondback moth.

Earth's rotation shapes a 24-h cycle, governing circadian rhythms in organisms. In mammals, the core clock genes, CLOCK and BMAL1, are regulated by PERIODs (PERs) and CRYPTOCHROMEs (CRYs), but their roles remain unclear in the diamondback moth, Plutella xylostella. To explore this, we studied P.xylostella, which possesses a simplified circadian system compared to mammals. In P.xylostella, we observed rhythmic expressions of the Pxper and Pxcry2 genes in their heads, with differing phases. In vitro experiments revealed that PxCRY2 repressed monarch butterfly CLK:BMAL1 transcriptional activation, while PxPER and other CRY-like proteins did not. However, PxPER showed an inhibitory effect on PxCLK/PxCYCLE. Using CRISPR/Cas9, we individually and in combination knocked out Pxper and Pxcry2, then conducted gene function studies and circadian transcriptome sequencing. Loss of either Pxper or Pxcry2 eliminated the activity peak after lights-off in light-dark cycles, and Pxcry2 loss reduced overall activity. Pxcry2 was crucial for maintaining endogenous rhythms in constant darkness. Under light-dark conditions, 1 098 genes exhibited rhythmic expression in wild-type P.xylostella heads, with 749 relying on Pxper and Pxcry2 for their rhythms. Most core clock genes lost their rhythmicity in Pxper and Pxcry2 mutants, while Pxcry2 sustained rhythmic expression, albeit with reduced amplitude and altered phase. Additionally, rhythmic genes were linked to biological processes like the spliceosome and Toll signaling pathway, with these rhythms depending on Pxper or Pxcry2 function. In summary, our study unveils differences in circadian rhythm regulation by Pxper and Pxcry2 in P.xylostella. This provides a valuable model for understanding circadian clock regulation in nocturnal animals.

Colour image enhancement using weighted histogram equalization with improved monarch butterfly optimization

ABSTRACT Image enhancement is a technique for improving the quality of an image so that it can be viewed by both humans and machines. The primary purpose of picture contrast enhancement is to improve the image’s visual quality. Histogram equalisation (HE) is one way to increase contrast. One disadvantage of He is that it does not sustain brightness while increasing contrast since a sdden mean shift occurs during the equalisation process. A new image enhancement method is established with weighted histogram equalisation with Oppositional-based Customised Monarch Butterfly Optimisation (OCMBO), for better visual perception and improving image quality. The collected input image is in RGB format. This image is then converted into YCbCr format for contrast stretching. In digital image processing, the YCbCr colour space is often used to take advantage of the lower resolution capability of the human visual system for colour concerning luminosity. The weighted histogram equalisation with Oppositional-based Customised Monarch Butterfly Optimisation (OCMBO) is applied to the converted image’s Y component, and then the Cr, Cb and modified Y components are combined back into RGB format.

Late-instar monarch caterpillars sabotage milkweed to acquire toxins, not to disarm plant defence.

Sabotaging milkweed by monarch caterpillars (Danaus plexippus) is a famous textbook example of disarming plant defence. By severing leaf veins, monarchs are thought to prevent the flow of toxic latex to their feeding site. Here, we show that sabotaging by monarch caterpillars is not only an avoidance strategy. While young caterpillars appear to avoid latex, late-instar caterpillars actively ingest exuding latex, presumably to increase sequestration of cardenolides used for defence against predators. Comparisons with caterpillars of the related but non-sequestering common crow butterfly (Euploea core) revealed three lines of evidence supporting our hypothesis. First, monarch caterpillars sabotage inconsistently and therefore the behaviour is not obligatory to feed on milkweed, whereas sabotaging precedes each feeding event in Euploea caterpillars. Second, monarch caterpillars shift their behaviour from latex avoidance in younger to eager drinking in later stages, whereas Euploea caterpillars consistently avoid latex and spit it out during sabotaging. Third, monarchs reared on detached leaves without latex sequestered more cardenolides when caterpillars imbibed latex offered with a pipette. Thus, we conclude that monarch caterpillars have transformed the ancestral 'sabotage to avoid' strategy into a 'sabotage to consume' strategy, implying a novel behavioural adaptation to increase sequestration of cardenolides for defence.

Loss of functional cryptochrome 1 reduces robustness of 24-hour behavioral rhythms in monarch butterflies

Loss of functional cryptochrome 1 reduces robustness of 24-hour behavioral rhythms in monarch butterflies

Extreme heat reduces host and parasite performance in a butterfly-parasite interaction.

Environmental temperature fundamentally shapes insect physiology, fitness and interactions with parasites. Differential climate warming effects on host versus parasite biology could exacerbate or inhibit parasite transmission, with far-reaching implications for pollination services, biocontrol and human health. Here, we experimentally test how controlled temperatures influence multiple components of host and parasite fitness in monarch butterflies (Danaus plexippus) and their protozoan parasites Ophryocystis elektroscirrha. Using five constant-temperature treatments spanning 18-34°C, we measured monarch development, survival, size, immune function and parasite infection status and intensity. Monarch size and survival declined sharply at the hottest temperature (34°C), as did infection probability, suggesting that extreme heat decreases both host and parasite performance. The lack of infection at 34°C was not due to greater host immunity or faster host development but could instead reflect the thermal limits of parasite invasion and within-host replication. In the context of ongoing climate change, temperature increases above current thermal maxima could reduce the fitness of both monarchs and their parasites, with lower infection rates potentially balancing negative impacts of extreme heat on future monarch abundance and distribution.

Overcoming data gaps using integrated models to estimate migratory species' dynamics during cryptic periods of the annual cycle

Abstract Environmental and anthropogenic factors affect the population dynamics of migratory species throughout their annual cycles. However, identifying the spatiotemporal drivers of migratory species' abundances is difficult because of extensive gaps in monitoring data. The collection of unstructured opportunistic data by volunteer (citizen science) networks provides a solution to address data gaps for locations and time periods during which structured, design‐based data are difficult or impossible to collect. To estimate population abundance and distribution at broad spatiotemporal extents, we developed an integrated model that incorporates unstructured data during time periods and spatial locations when structured data are unavailable. We validated our approach through simulations and then applied the framework to the eastern North American migratory population of monarch butterflies during their spring breeding period in eastern Texas. Spring climate conditions have been identified as a key driver of monarch population sizes during subsequent summer and winter periods. However, low monarch densities during the spring combined with very few design‐based surveys in the region have limited the ability to isolate effects of spring weather variables on monarchs. Simulation results confirmed the ability of our integrated model to accurately and precisely estimate abundance indices and the effects of covariates during locations and time periods in which structured sampling are lacking. In our case study, we combined opportunistic monarch observations during the spring migration and breeding period with structured data from the summer Midwestern breeding grounds. Our model revealed a nonstationary relationship between weather conditions and local monarch abundance during the spring, driven by spatially varying vegetation and temperature conditions. Data for widespread and migratory species are often fragmented across multiple monitoring programs, potentially requiring the use of both structured and unstructured data sources to obtain complete geographic coverage. Our integrated model can estimate population abundance at broad spatiotemporal extents despite structured data gaps during the annual cycle by leveraging opportunistic data.

Monarch Butterflies in Western North America: A Holistic Review of Population Trends, Ecology, Stressors, Resilience and Adaptation.

Monarch butterfly populations in western North America suffered a substantial decline, from millions of butterflies overwintering in California in the 1980s to less than 400,000 at the beginning of the 21st century. The introduction of neonicotinoid insecticides in the mid-1990s and their subsequent widespread use appears to be the most likely major factor behind this sudden decline. Habitat loss and unfavorable climates (high temperatures, aridity, and winter storms) have also played important and ongoing roles. These factors kept overwintering populations stable but below 300,000 during 2001-2017. Late winter storm mortality and consequent poor spring reproduction drove winter populations to less than 30,000 butterflies during 2018-2019. Record high temperatures in California during the fall of 2020 appeared to prematurely terminate monarch migration, resulting in the lowest overwintering population (1899) ever recorded. Many migrants formed winter-breeding populations in urban areas. Normal seasonal temperatures in the autumns of 2021 and 2022 enabled overwintering populations to return to around the 300,000 level, characteristic of the previous two decades. Natural enemies (predators, parasitoids, parasites, and pathogens) may be important regional or local drivers at times but they are a consistent and fundamental part of monarch ecology. Human interference (capture, rearing) likely has the least impact on monarch populations. The rearing of monarch caterpillars, particularly by children, is an important human link to nature that has positive ramifications for insect conservation beyond monarch butterflies and should be encouraged.

Day‐Flying Lepidopteran Species Abundance, Diversity, and Distribution in Wolaita Sodo University, Ethiopia

Lepidoptera account for the second largest, most diverse, widespread, and widely recognized insect order in the class Insecta. At four microhabitats at Wolaita Sodo University (WSU) in Ethiopia, lepidopteran diversity and abundance were studied for the first time using transects between January 2022 and December 2023. Data were analyzed using analysis of variance, correlation analysis, diversity indices, and ordination and cluster analysis. Altogether 50 species of 367 individuals were collected throughout the study period distributed in 6 families. The Nymphalidae family contained the highest species abundance 20 (34%). In comparison to other ecosystems, open forest regions (35%) included more species, followed by shrub forest (30%). Species such as Danaus plexippus, Tirumala septentrionis, and Melanargia lachesis were abundant in open forest habitat. Idea leuconoe and Eurema brigitta were also abundant, regardless of location. About 36% of species were recorded only in dry season and 36% of total were recorded only in wet season. Spearman’s rho correlation analysis showed that butterfly families had strong positive relationships with flying habitat and flight seasons. Therefore, adequate conservation measures should be taken to ensure their survival, as well as the preservation of their habitats for the benefit of the ecosystem as a whole.

Insecticides, more than herbicides, land use, and climate, are associated with declines in butterfly species richness and abundance in the American Midwest.

Mounting evidence shows overall insect abundances are in decline globally. Habitat loss, climate change, and pesticides have all been implicated, but their relative effects have never been evaluated in a comprehensive large-scale study. We harmonized 17 years of land use, climate, multiple classes of pesticides, and butterfly survey data across 81 counties in five states in the US Midwest. We find community-wide declines in total butterfly abundance and species richness to be most strongly associated with insecticides in general, and for butterfly species richness the use of neonicotinoid-treated seeds in particular. This included the abundance of the migratory monarch (Danaus plexippus), whose decline is the focus of intensive debate and public concern. Insect declines cannot be understood without comprehensive data on all putative drivers, and the 2015 cessation of neonicotinoid data releases in the US will impede future research.

Divergent impacts of the neonicotinoid insecticide, clothianidin, on flight performance metrics in two species of migratory butterflies.

Long-distance flight is crucial for the survival of migratory insects, and disruptions to their flight capacity can have significant consequences for conservation. In this study, we examined how a widely used insecticide, clothianidin (class: neonicotinoid), impacted the flight performance of two species of migratory butterflies, monarchs (Danaus plexippus) and painted ladies (Vanessa cardui). To do this, we quantified the free-flight energetics and tethered-flight velocity and distance of the two species using flow-through respirometry and flight mill assays. Our findings show differential effects of the pesticide on the two species. For painted ladies, we found that clothianidin exposure reduced average free-flight metabolic rates, but did not affect either average velocity or total distance during tethered flight. Other studies have linked low flight metabolic rates with reduced dispersal capacity, indicating that clothianidin exposure may hinder painted lady flight performance in the wild. Conversely, for monarchs, we saw no significant effect of clothianidin exposure on average free-flight metabolic rates but did observe increases in the average velocity, and for large individuals, total distance achieved by clothianidin-exposed monarchs in tethered flight. This suggests a potential stimulatory response of monarchs to low-dose exposures to clothianidin. These findings indicate that clothianidin exposure has the potential to influence the flight performance of butterflies, but that not all species are impacted in the same way. This highlights the need to be thoughtful when selecting performance assays, as different assays can evaluate fundamentally distinct aspects of physiology, and as such may yield divergent results.

Monarch butterflies memorize the spatial location of a food source.

Spatial memory helps animals to navigate familiar environments. In insects, spatial memory has extensively been studied in central place foragers such as ants and bees. However, if butterflies memorize a spatial location remains unclear. Here, we conducted behavioural experiments to test whether monarch butterflies (Danaus plexippus) can remember and retrieve the spatial location of a food source. We placed several visually identical feeders in a flight cage, with only one feeder providing sucrose solution. Across multiple days, individual butterflies predominantly visited the rewarding feeder. Next, we displaced a salient landmark close to the feeders to test which visual cue the butterflies used to relocate the rewarding feeder. While occasional landmark displacements were ignored by the butterflies and did not affect their decisions, systematic displacement of both the landmark and the rewarding feeder demonstrated that the butterflies associated the salient landmark with the feeder's position. Altogether, we show that butterflies consolidate and retrieve spatial memory in the context of foraging.

A Hybrid Extreme Gradient Boosting and Long Short-Term Memory Algorithm for Cyber Threats Detection

The vast amounts of data, lack of scalability, and low detection rates of traditional intrusion detection technologies make it impossible to keep up with evolving and increasingly sophisticated cyber threats. Therefore, there is an urgent need to detect and stop cyber threats early. Deep Learning has greatly improved intrusion detection due to its ability to self-learn and extract highly accurate features. In this paper, a Hybrid XG Boosted and Long Short-Term Memory algorithm (HXGBLSTM) is proposed. A comparative analysis is conducted between the computational performance of six established evolutionary computation algorithms and the recently developed bio-inspired metaheuristic algorithm called Zebra Optimisation Algorithm. These algorithms include the Particle Swarm Optimisation Algorithm, the Bio-inspired Algorithms, Bat Optimisation Algorithm, Firefly Optimisation Algorithm, and Monarch Butterfly Optimisation Algorithm, as well as the Genetic Algorithm as an Evolutionary Algorithm. The dimensionality curse has been mitigated by using these metaheuristic methods for feature selection, and the results are compared with the wrapper-based feature selection XGBoost algorithm. The proposed algorithm uses the CSE-CIC -IDS2018 dataset, which contains the latest network attacks. XGBoost outperformed the other FS algorithms and was used as the feature selection algorithm. In evaluating the effectiveness of the newly proposed HXGBLSTM, binary and multi-class classifications are considered. When comparing the performance of the proposed HXGBLSTM for cyber threat detection, it outperforms seven innovative deep learning algorithms for binary classification and four of them for multi-class classification. Other evaluation criteria such as recall, F1 score, and precision have been also used for comparison. The results showed that the best accuracy for binary classification is 99.8\%, with F1-score of 99.83\%, precision of 99.85\%, and recall of 99.82\%, in extensive and detailed experiments conducted on a real dataset. The best accuracy, F1-score, precision, and recall for multi-class classification were all around 100\%, which does give the proposed algorithm an advantage over the compared ones.

A silk-floss tree (Ceiba speciosa) provides an oasis for floral visitors in an otherwise hostile suburban-farmland environment

ABSTRACT Keystone components in green urban spaces can make a big difference in supporting either impoverished or rich animal communities. Trees that produce thousands of flowers at densities higher than that of herbs and produce much more nectar than the latter can be such keystone structures. However, there is a lack of specific information on trees, both native and alien, and their flower visitors in urban/suburban contexts, which blurs the conservation role that such species can perform. In 2019 and 2020, we thoroughly recorded the flower visitors to a silk-floss tree in suburban Guadalajara, Mexico. To our knowledge, this is the first comprehensive inventory of silk-floss tree flower visitors. We documented 79 species/morphospecies of insects; eight of birds, and one of mammals visiting the flowers. All, except two, are native to the region; three are endemic/quasi-endemic to Mexico. Besides direct and indirect floral resources, the silk-floss tree offered perches, resting/hiding cover, nesting substrate, and seed fibres used by several birds, and feeding substrate for gleaning insectivorous birds. Four species are on one or more conservation listings: monarch butterfly (endangered), pink-spotted swallowtail (vulnerable), sparkling-tailed hummingbird (threatened), and lesser long-nosed bat (near-threatened). Our data supports that small patches can enhance the quality of urban green spaces, and that rather than geographic origin, flower output drives visitation. Alien trees can be pollination enhancement ‘devices’ for imperilled pollination networks. Silk-floss trees are a potential option for conservation-oriented urban greening, as well as to contribute to enhancing human enjoyment of nature, and provide opportunities for public outreach.

Using community science to map western monarch butterflies (Danaus plexippus) in spring.

Migratory animals follow seasonal cycles comprising linked phases often with different habitat requirements and demographic processes. Conservation of migratory species therefore must consider the full seasonal cycle to identify points limiting population viability. For western monarch butterflies, which have experienced significant declines, early spring is considered a critical period in the annual population cycle. However, records of western monarchs in early spring, when overall abundance is lowest, have historically been extremely limited. We used a community science initiative, the Western Monarch Mystery Challenge, to collect data on monarch distribution throughout the western United States between February 14th and April 22nd over 3 years. Using data from the Western Monarch Mystery Challenge and iNaturalist, we identified potential breeding habitat for western monarchs in early spring that spanned a large geographic area and several ecoregions. We observed monarchs in early spring that likely eclosed in the current year, suggesting that population expansion from overwintering sites reflects both movement and population growth. The number of records of western monarchs from early spring was higher during the Mystery Challenge (33.0/year) than earlier years (5.1/year). This study demonstrates the potential for and limitations of community science to increase our understanding of species at points in the life cycle when they are rare.

Cryopreservation as a method of conservation for the threatened monarch butterfly

Cryopreservation as a method of conservation for the threatened monarch butterfly

Testing the selective sequestration hypothesis: Monarch butterflies preferentially sequester plant defences that are less toxic to themselves while maintaining potency to others.

Herbivores that sequester toxins are thought to have cracked the code of plant defences. Nonetheless, coevolutionary theory predicts that plants should evolve toxic variants that also negatively impact specialists. We propose and test the selective sequestration hypothesis, that specialists preferentially sequester compounds that are less toxic to themselves while maintaining toxicity to enemies. Using chemically distinct plants, we show that monarch butterflies sequester only a subset of cardenolides from milkweed leaves that are less potent against their target enzyme (Na+ /K+ -ATPase) compared to several dominant cardenolides from leaves. However, sequestered compounds remain highly potent against sensitive Na+ /K+ -ATPases found in most predators. We confirmed this differential toxicity with mixtures of purified cardenolides from leaves and butterflies. The genetic basis of monarch adaptation to sequestered cardenolides was also confirmed with transgenic Drosophila that were CRISPR-edited with the monarch's Na+ /K+ -ATPase. Thus, the monarch's selective sequestration appears to reduce self-harm while maintaining protection from enemies.

Got milkweed? Genetic assimilation as potential source for the evolution of nonmigratory monarch butterfly wing shape.

Monarch butterflies (Danaus plexippus) are well studied for their annual long-distance migration from as far north as Canada to their overwintering grounds in Central Mexico. At the end of the cold season, monarchs start to repopulate North America through short-distance migration over the course of multiple generations. Interestingly, some populations in various tropical and subtropical islands do not migrate and exhibit heritable differences in wing shape and size, most likely an adaptation to island life. Less is known about forewing differences between long- and short-distance migrants in relation to island populations. Given their different migratory behaviors, we hypothesized that these differences would be reflected in wing morphology. To test this, we analyzed forewing shape and size of three different groups: nonmigratory, lesser migratory (migrate short-distances), and migratory (migrate long-distances) individuals. Significant differences in shape appear in all groups using geometric morphometrics. As variation found between migratory and lesser migrants has been shown to be caused by phenotypic plasticity, and lesser migrants develop intermediate forewing shapes between migratory and nonmigratory individuals, we suggest that genetic assimilation might be an important mechanism to explain the heritable variation found between migratory and nonmigratory populations. Additionally, our research confirms previous studies which show that forewing size is significantly smaller in nonmigratory populations when compared to both migratory phenotypes. Finally, we found sexual dimorphism in forewing shape in all three groups, but for size in nonmigratory populations only. This might have been caused by reduced constraints on forewing size in nonmigratory populations.