1
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Granato C, Campera M, Bulbert M. Sensitivity of Vanessa cardui to Temperature Variations: A Cost-Effective Experiment for Environmental Education. INSECTS 2024; 15:221. [PMID: 38667351 PMCID: PMC11050276 DOI: 10.3390/insects15040221] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/26/2024] [Revised: 03/19/2024] [Accepted: 03/21/2024] [Indexed: 04/28/2024]
Abstract
Temperature increases mediated through climate change threaten the survival of species. It is of foremost importance to engage citizens and future generations in understanding the mechanisms through which temperatures impose their effects. For educators, this is not straightforward, as tools for examining the impact of temperature over the lifetime of an animal are prohibitively expensive. At the same time, environmental educators need guidance on the appropriate study systems to use with a balance between the species having an obvious response and ensuring the outcomes are ethical and sustainable. In our study, we created and tested a cost-effective experiment meant to be used for environmental education purposes. More specifically, we tested the sensitivity of the painted lady butterfly Vanessa cardui to temperature variations using a homemade incubator. We describe the design of this experiment and report findings on survival rate, morphological variations, development time of various stages and wingspan of adults across a range of biologically relevant temperatures. The information provided gives educators options for testing a variety of hypotheses with regards to the impacts of temperature using an affordable and flexible set-up. Furthermore, the findings can be used by students to develop an understanding of the ramifications of the butterflies' responses in an ecological context.
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Affiliation(s)
| | - Marco Campera
- Department of Biological and Medical Sciences, Oxford Brookes University, Oxford OX3 0BP, UK; (C.G.); (M.B.)
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2
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James DG. Monarch Butterflies in Western North America: A Holistic Review of Population Trends, Ecology, Stressors, Resilience and Adaptation. INSECTS 2024; 15:40. [PMID: 38249046 PMCID: PMC10817040 DOI: 10.3390/insects15010040] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/18/2023] [Revised: 01/04/2024] [Accepted: 01/05/2024] [Indexed: 01/23/2024]
Abstract
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.
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Affiliation(s)
- David G James
- Department of Entomology, Washington State University, Irrigated Agriculture Research and Extension Center, Prosser, WA 99350, USA
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3
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Tenger-Trolander A. Environmental and genetic effects of captivity - are there lessons for monarch butterfly conservation? CURRENT OPINION IN INSECT SCIENCE 2023; 59:101088. [PMID: 37500011 DOI: 10.1016/j.cois.2023.101088] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/26/2023] [Revised: 07/17/2023] [Accepted: 07/17/2023] [Indexed: 07/29/2023]
Abstract
Rearing monarch butterflies in captivity for later release is a popular but contentious activity due to concerns about its potential negative effects on the wild population. In this review, I discuss how captive rearing and breeding could impact monarch fitness in the wild, the current evidence for such impacts in monarchs and other captive-reared/released organisms, and how this should inform our efforts to conserve monarchs and other species.
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4
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Beetz MJ, Kraus C, El Jundi B. Neural representation of goal direction in the monarch butterfly brain. Nat Commun 2023; 14:5859. [PMID: 37730704 PMCID: PMC10511513 DOI: 10.1038/s41467-023-41526-w] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2022] [Accepted: 09/04/2023] [Indexed: 09/22/2023] Open
Abstract
Neural processing of a desired moving direction requires the continuous comparison between the current heading and the goal direction. While the neural basis underlying the current heading is well-studied, the coding of the goal direction remains unclear in insects. Here, we used tetrode recordings in tethered flying monarch butterflies to unravel how a goal direction is represented in the insect brain. While recording, the butterflies maintained robust goal directions relative to a virtual sun. By resetting their goal directions, we found neurons whose spatial tuning was tightly linked to the goal directions. Importantly, their tuning was unaffected when the butterflies changed their heading after compass perturbations, showing that these neurons specifically encode the goal direction. Overall, we here discovered invertebrate goal-direction neurons that share functional similarities to goal-direction cells reported in mammals. Our results give insights into the evolutionarily conserved principles of goal-directed spatial orientation in animals.
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Affiliation(s)
- M Jerome Beetz
- Zoology II, Biocenter, University of Würzburg, Würzburg, Germany.
| | - Christian Kraus
- Zoology II, Biocenter, University of Würzburg, Würzburg, Germany
- Animal Physiology, Department of Biology, Norwegian University of Science and Technology, Trondheim, Norway
| | - Basil El Jundi
- Zoology II, Biocenter, University of Würzburg, Würzburg, Germany
- Animal Physiology, Department of Biology, Norwegian University of Science and Technology, Trondheim, Norway
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5
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Crates R, Stojanovic D, Heinsohn R. The phenotypic costs of captivity. Biol Rev Camb Philos Soc 2023; 98:434-449. [PMID: 36341701 DOI: 10.1111/brv.12913] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2022] [Revised: 10/05/2022] [Accepted: 10/07/2022] [Indexed: 11/09/2022]
Abstract
The breeding of threatened species in captivity for release is a central tool in conservation biology. Given gloomy predictions for biodiversity trends in the Anthropocene, captive breeding will play an increasingly important role in preventing future extinctions. Relative to the wild, captive environments drastically alter selection pressures on animals. Phenotypic change in captive animals in response to these altered selection pressures can incur fitness costs post-release, jeopardising their potential contribution to population recovery. We explore the ways in which captive environments can hinder the expression of wild phenotypes. We also stress that the phenotypes of captive-bred animals differ from their wild counterparts in multiple ways that remain poorly understood. We propose five new research questions relating to the impact of captive phenotypes on reintroduction biology. With better use of monitoring and experimental reintroductions, a more robust evidence base should help inform adaptive management and minimise the phenotypic costs of captivity, improving the success of animal reintroductions.
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Affiliation(s)
- Ross Crates
- Fenner School of Environment and Society, Australian National University, Linnaeus Way, Acton, Canberra, ACT, 2601, Australia
| | - Dejan Stojanovic
- Fenner School of Environment and Society, Australian National University, Linnaeus Way, Acton, Canberra, ACT, 2601, Australia
| | - Robert Heinsohn
- Fenner School of Environment and Society, Australian National University, Linnaeus Way, Acton, Canberra, ACT, 2601, Australia
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6
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Stojanovic D. Altered wing phenotypes of captive-bred migratory birds lower post-release fitness. Ecol Lett 2023; 26:789-796. [PMID: 36929598 DOI: 10.1111/ele.14200] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2022] [Revised: 01/16/2023] [Accepted: 02/20/2023] [Indexed: 03/18/2023]
Abstract
Captive breeding and release to the wild is a globally important conservation tool. However, captivity can result in phenotypic changes that incur post-release fitness costs, especially if they affect strenuous or risky behaviours. Bird wing shape is critical for migration success and suboptimal phenotypes are strongly selected against. In this study, I demonstrate surprising plasticity of bird wing phenotypes in captivity for 4/16 studied species. In a model species, captive-born juveniles with wild wing phenotypes (a 1-mm longer distal primary flight feather) survived post-release at 2.7 times the rate of those with captive phenotypes (i.e. a shorter distal feather). Subtle phenotypic changes and their fitness impacts are more common than widely realised because they are easily overlooked. To improve captive breeding for conservation, practitioners must surveil phenotypic changes and find ways to mitigate them.
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Affiliation(s)
- Dejan Stojanovic
- Fenner School of Environment and Society, Australian National University, Canberra, Australia
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7
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Aldridge DC, Ollard IS, Bespalaya YV, Bolotov IN, Douda K, Geist J, Haag WR, Klunzinger MW, Lopes‐Lima M, Mlambo MC, Riccardi N, Sousa R, Strayer DL, Torres SH, Vaughn CC, Zając T, Zieritz A. Freshwater mussel conservation: A global horizon scan of emerging threats and opportunities. GLOBAL CHANGE BIOLOGY 2023; 29:575-589. [PMID: 36444494 PMCID: PMC10100069 DOI: 10.1111/gcb.16510] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/07/2022] [Revised: 09/27/2022] [Accepted: 10/15/2022] [Indexed: 06/16/2023]
Abstract
We identified 14 emerging and poorly understood threats and opportunities for addressing the global conservation of freshwater mussels over the next decade. A panel of 17 researchers and stakeholders from six continents submitted a total of 56 topics that were ranked and prioritized using a consensus-building Delphi technique. Our 14 priority topics fell into five broad themes (autecology, population dynamics, global stressors, global diversity, and ecosystem services) and included understanding diets throughout mussel life history; identifying the drivers of population declines; defining metrics for quantifying mussel health; assessing the role of predators, parasites, and disease; informed guidance on the risks and opportunities for captive breeding and translocations; the loss of mussel-fish co-evolutionary relationships; assessing the effects of increasing surface water changes; understanding the effects of sand and aggregate mining; understanding the effects of drug pollution and other emerging contaminants such as nanomaterials; appreciating the threats and opportunities arising from river restoration; conserving understudied hotspots by building local capacity through the principles of decolonization; identifying appropriate taxonomic units for conservation; improved quantification of the ecosystem services provided by mussels; and understanding how many mussels are enough to provide these services. Solutions for addressing the topics ranged from ecological studies to technological advances and socio-political engagement. Prioritization of our topics can help to drive a proactive approach to the conservation of this declining group which provides a multitude of important ecosystem services.
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Affiliation(s)
- David C. Aldridge
- Aquatic Ecology Group, Department of ZoologyUniversity of CambridgeCambridgeUK
| | - Isobel S. Ollard
- Aquatic Ecology Group, Department of ZoologyUniversity of CambridgeCambridgeUK
| | - Yulia V. Bespalaya
- N. Laverov Federal Center for Integrated Arctic Research of the Ural Branch of the Russian Academy of SciencesArkhangelskRussia
| | - Ivan N. Bolotov
- N. Laverov Federal Center for Integrated Arctic Research of the Ural Branch of the Russian Academy of SciencesArkhangelskRussia
- Northern Arctic Federal UniversityArkhangelskRussia
| | - Karel Douda
- Department of Zoology and FisheriesCzech University of Life Sciences PraguePragueCzech Republic
| | - Juergen Geist
- Aquatic Systems Biology UnitTechnical University of MunichFreisingGermany
| | - Wendell R. Haag
- Southern Research Station, Center for Bottomland Hardwoods ResearchU.S. Forest ServiceFrankfortKentuckyUSA
| | - Michael W. Klunzinger
- Australian Rivers InstituteGriffith UniversityNathanQueenslandAustralia
- Department of Aquatic ZoologyWestern Australian MuseumWelshpoolWestern AustralianAustralia
| | - Manuel Lopes‐Lima
- CIBIO/InBIO/BIOPOLIS—Research Center in Biodiversity and Genetic ResourcesUniversity of PortoVairãoPortugal
| | - Musa C. Mlambo
- Department of Freshwater InvertebratesAlbany MuseumMakhandaSouth Africa
- Department of Zoology and EntomologyRhodes UniversityMakhandaSouth Africa
| | | | - Ronaldo Sousa
- CBMA—Centre of Molecular and Environmental Biology, Department of BiologyUniversity of MinhoBragaPortugal
| | - David L. Strayer
- Cary Institute of Ecosystem StudiesMillbrookNew YorkUSA
- Graham Sustainability InstituteUniversity of MichiganAnn ArborMichiganUSA
| | - Santiago H. Torres
- Centro de Investigaciones y Transferencia Santa Cruz (CONICET, UNPA, UTN), Unidad Académica San JuliánUniversidad Nacional de la Patagonia AustralSanta CruzArgentina
| | - Caryn C. Vaughn
- Oklahoma Biological Survey and Department of BiologyUniversity of OklahomaNormanOklahomaUSA
| | - Tadeusz Zając
- Institute of Nature ConservationPolish Academy of SciencesKrakówPoland
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8
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Tenger-Trolander A, Julick CR, Lu W, Green DA, Montooth KL, Kronforst MR. Seasonal plasticity in morphology and metabolism differs between migratory North American and resident Costa Rican monarch butterflies. Ecol Evol 2023; 13:e9796. [PMID: 36844673 PMCID: PMC9943933 DOI: 10.1002/ece3.9796] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2022] [Revised: 01/16/2023] [Accepted: 01/18/2023] [Indexed: 02/24/2023] Open
Abstract
Environmental heterogeneity in temperate latitudes is expected to maintain seasonally plastic life-history strategies that include the tuning of morphologies and metabolism that support overwintering. For species that have expanded their ranges into tropical latitudes, it is unclear the extent to which the capacity for plasticity will be maintained or will erode with disuse. The migratory generations of the North American (NA) monarch butterfly Danaus plexippus lead distinctly different lives from their summer generation NA parents and their tropical descendants living in Costa Rica (CR). NA migratory monarchs postpone reproduction, travel thousands of kilometers south to overwinter in Mexico, and subsist on little food for months. Whether recently dispersed populations of monarchs such as those in Costa Rica, which are no longer subject to selection imposed by migration, retain ancestral seasonal plasticity is unclear. To investigate the differences in seasonal plasticity, we reared the NA and CR monarchs in summer and autumn in Illinois, USA, and measured the seasonal reaction norms for aspects of morphology and metabolism related to flight. NA monarchs were seasonally plastic in forewing and thorax size, increasing wing area and thorax to body mass ratio in autumn. While CR monarchs increased thorax mass in autumn, they did not increase the area of the forewing. NA monarchs maintained similar resting and maximal flight metabolic rates across seasons. However, CR monarchs had elevated metabolic rates in autumn. Our findings suggest that the recent expansion of monarchs into habitats that support year-round breeding may be accompanied by (1) the loss of some aspects of morphological plasticity as well as (2) the underlying physiological mechanisms that maintain metabolic homeostasis in the face of temperature heterogeneity.
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Affiliation(s)
- Ayşe Tenger-Trolander
- Department of Ecology and Evolution University of Chicago Chicago Illinois USA.,Ecology and Evolutionary Biology University of Michigan Ann Arbor Michigan USA
| | - Cole R Julick
- School of Biological Sciences University of Nebraska-Lincoln Lincoln Nebraska USA
| | - Wei Lu
- Department of Ecology and Evolution University of Chicago Chicago Illinois USA
| | - Delbert André Green
- Ecology and Evolutionary Biology University of Michigan Ann Arbor Michigan USA
| | - Kristi L Montooth
- School of Biological Sciences University of Nebraska-Lincoln Lincoln Nebraska USA
| | - Marcus R Kronforst
- Department of Ecology and Evolution University of Chicago Chicago Illinois USA
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9
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Solis-Sosa R, Semeniuk CAD, Larrivée M, Cox S. Investing in monarch conservation: understanding private funding dynamics. FRONTIERS IN CONSERVATION SCIENCE 2022. [DOI: 10.3389/fcosc.2022.903132] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Non-profit environmental organizations (NGOs) rely heavily on external donors to fulfill their mandates. However, forecasting donations for long-term planning is an elusive task at best. The non-compulsory nature of donation requires NGOs to understand how donors’ attention and funding allocations change over time as conservation scenarios change and incorporate these insights into their budgeting plans. We hypothesize that an NGO can hinder its capacity to reach its conservation goals by neglecting its donor-NGO-natural system (DNNS), which is reactive to the socio-ecological context. To test our hypothesis, we compared the ecological outcomes derived from a budgeting strategy assuming donors have a fixed willingness to pay throughout the program (open-loop) against the reality that donor preferences change over time (closed-loop) based on the evolving ecological context, partly driven by the program’s actions. Our analysis was performed using two different willingness to pay (WTP) behavioural models, one representing donors informed about the success of the program supported (GPI), and another without such information (GPI), evidencing how the underlying assumptions about the target donors can radically change the organization’s fundraising strategy. Next, we used our closed-loop approach to estimate NGO’s optimal yearly donation requests to achieve a conservation target. Finally, we tested the consequences of presuming an incorrect WTP behavioural model while estimating optimal yearly donation requests by applying the optimization results from the previous step into a model parameterized with a different behavioural model. Our model was created by coupling a discrete choice experiment (DCE) and a systems dynamics model, developing a coupled social-ecological model of the eastern Monarch butterfly (Danaus plexippus), a charismatic long-distant migrant butterfly that has dwindled in numbers across North America mainly due to the increases in GMO agriculture. Our results showed a significant difference in donations received and ecological outcome forecasted by an open-loop model and the actual numbers obtained by the more real-life, closed-loop model, highlighting the importance of accounting for human behaviour during the planning phase of a long-term conservation strategy. Next, when we used our closed-loop to estimate optimal donation requests, the conservation objectives and funds raised were consistently and efficiently achieved, regardless of the underlying behavioural WTP model. We also designed novel visual tools from the behaviour WTP model exploration to bridge the gap between science insights obtained from DCEs and decision-making. However, when we used closed-loop optimal donation requests obtained from one WTP behaviour model into a simulation parameterized with different WTP behavioural models, considerable ecological and financial targets deviations arose. These deviations highlight the importance of acknowledging the dynamic nature of donor’s behaviour and the need to thoroughly characterize such behaviour. Finally, we introduce a novel forecasting tool that conservation managers will have at their disposal to improve the accuracy of their budget forecasting and, ultimately, increase the program’s success rate.
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10
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Losey JE, Chen C, Davis AE, Deitsch JF, Gertin JG, Gorneau JA, Hallock EM, Jordán JP, Kim ZJ, Kubinski EG, Laurenz N, Li SB, Mullen EK, O’Brien A, Richardson LI, Vincent S, Wang SY, Yarhouse EL, Schydlowsky A, Curtis PD. Insects and Spiders on the Web: Monitoring and Mitigating Online Exploitation of Species and Services. Glob Ecol Conserv 2022. [DOI: 10.1016/j.gecco.2022.e02098] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022] Open
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11
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Pocius VM, Majewska AA, Freedman MG. The Role of Experiments in Monarch Butterfly Conservation: A Review of Recent Studies and Approaches. ANNALS OF THE ENTOMOLOGICAL SOCIETY OF AMERICA 2022; 115:10-24. [PMID: 35069967 PMCID: PMC8764570 DOI: 10.1093/aesa/saab036] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/07/2021] [Indexed: 06/14/2023]
Abstract
Monarch butterflies (Danaus plexippus) (Lepidoptera Danaidae Danaus plexippus (Linnaeus)) are an iconic species of conservation concern due to declines in the overwintering colonies over the past twenty years. Because of this downward trend in overwintering numbers in both California and Mexico, monarchs are currently considered 'warranted-but-precluded' for listing under the Endangered Species Act. Monarchs have a fascinating life history and have become a model system in chemical ecology, migration biology, and host-parasite interactions, but many aspects of monarch biology important for informing conservation practices remain unresolved. In this review, we focus on recent advances using experimental and genetic approaches that inform monarch conservation. In particular, we emphasize three areas of broad importance, which could have an immediate impact on monarch conservation efforts: 1) breeding habitat and host plant use, 2) natural enemies and exotic caterpillar food plants, and 3) the utility of genetic and genomic approaches for understanding monarch biology and informing ongoing conservation efforts. We also suggest future studies in these areas that could improve our understanding of monarch behavior and conservation.
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Affiliation(s)
- Victoria M Pocius
- Department of Biological Sciences, University of Alabama, Tuscaloosa, AL, USA
| | | | - Micah G Freedman
- Department of Ecology and Evolution, University of Chicago, Chicago, IL, USA
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12
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Prouty C, Barriga P, Davis AK, Krischik V, Altizer S. Host Plant Species Mediates Impact of Neonicotinoid Exposure to Monarch Butterflies. INSECTS 2021; 12:insects12110999. [PMID: 34821799 PMCID: PMC8623494 DOI: 10.3390/insects12110999] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/12/2021] [Revised: 10/27/2021] [Accepted: 11/02/2021] [Indexed: 11/16/2022]
Abstract
Simple Summary Neonicotinoids are the most widely used insecticides in North America and many studies document the negative effects of neonicotinoids on bees. Monarch butterflies are famous for their long-distance migrations, and for their ability to sequester toxins from their milkweed host plants. The neonicotinoids imidacloprid and clothianidin were suggested to correlate with declines in North American monarchs. We examined how monarch development, survival, and flight were affected by exposure to neonicotinoids, and how these effects depend on milkweed host plant species that differ in their cardenolide toxins. Monarch survival and flight were unaffected by low and intermediate neonicotinoid doses. At the highest dose, neonicotinoids negatively affected monarch pupation and survival, for caterpillars that fed on the least toxic milkweed. Monarchs fed milkweed of intermediate toxicity experienced moderate negative effects of high insecticide doses. Monarchs fed the most toxic milkweed species had no negative consequences associated with neonicotinoid treatment. Our work shows that monarchs tolerate low neonicotinoid doses, but experience detrimental effects at higher doses, depending on milkweed species. To our knowledge, this is the first study to show that host plant species potentially reduce the residue of neonicotinoid insecticides on the leaf surface, and this phenomenon warrants further investigation. Abstract Neonicotinoids are the most widely used insecticides in North America. Numerous studies document the negative effects of neonicotinoids on bees, and it remains crucial to demonstrate if neonicotinoids affect other non-target insects, such as butterflies. Here we examine how two neonicotinoids (imidacloprid and clothianidin) affect the development, survival, and flight of monarch butterflies, and how these chemicals interact with the monarch’s milkweed host plant. We first fed caterpillars field-relevant low doses (0.075 and 0.225 ng/g) of neonicotinoids applied to milkweed leaves (Asclepias incarnata), and found no significant reductions in larval development rate, pre-adult survival, or adult flight performance. We next fed larvae higher neonicotinoid doses (4–70 ng/g) and reared them on milkweed species known to produce low, moderate, or high levels of secondary toxins (cardenolides). Monarchs exposed to the highest dose of clothianidin (51–70 ng/g) experienced pupal deformity, low survival to eclosion, smaller body size, and weaker adult grip strength. This effect was most evident for monarchs reared on the lowest cardenolide milkweed (A. incarnata), whereas monarchs reared on the high-cardenolide A. curassavica showed no significant reductions in any variable measured. Our results indicate that monarchs are tolerant to low doses of neonicotinoid, and that negative impacts of neonicotinoids depend on host plant type. Plant toxins may confer protective effects or leaf physical properties may affect chemical retention. Although neonicotinoid residues are ubiquitous on milkweeds in agricultural and ornamental settings, commonly encountered doses below 50 ng/g are unlikely to cause substantial declines in monarch survival or migratory performance.
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Affiliation(s)
- Cody Prouty
- Odum School of Ecology, University of Georgia, Athens, GA 30602, USA; (P.B.); (A.K.D.); (S.A.)
- Correspondence:
| | - Paola Barriga
- Odum School of Ecology, University of Georgia, Athens, GA 30602, USA; (P.B.); (A.K.D.); (S.A.)
| | - Andrew K. Davis
- Odum School of Ecology, University of Georgia, Athens, GA 30602, USA; (P.B.); (A.K.D.); (S.A.)
| | - Vera Krischik
- Department of Entomology, University of Minnesota, St. Paul, MN 55108, USA;
| | - Sonia Altizer
- Odum School of Ecology, University of Georgia, Athens, GA 30602, USA; (P.B.); (A.K.D.); (S.A.)
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13
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Davis AK. Captive-reared migratory monarchs fly in the wrong direction: a critique of Wilcox et al. CONSERVATION PHYSIOLOGY 2021; 9:coab063. [PMID: 34413978 PMCID: PMC8372217 DOI: 10.1093/conphys/coab063] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/11/2021] [Revised: 06/30/2021] [Accepted: 07/31/2021] [Indexed: 06/13/2023]
Affiliation(s)
- Andrew K Davis
- Odum School of Ecology, University of Georgia, Athens, GA 30602, USA
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14
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James DG, Kappen L. Further Insights on the Migration Biology of Monarch Butterflies, Danaus plexippus (Lepidoptera: Nymphalidae) from the Pacific Northwest. INSECTS 2021; 12:161. [PMID: 33672834 PMCID: PMC7917764 DOI: 10.3390/insects12020161] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/30/2020] [Revised: 02/05/2021] [Accepted: 02/10/2021] [Indexed: 02/06/2023]
Abstract
The fall migration of monarch butterflies, Danaus plexippus (L.), in the Pacific Northwest was studied during 2017-2019 by tagging 14,040 captive-reared and 450 wild monarchs. One hundred and twenty-two captive-reared monarchs (0.87%) were recovered at distances averaging 899.9 ± 98.6 km for Washington-released and 630.5 ± 19.9 km for Oregon-released monarchs. The greatest straight-line release to recovery distance was 1392.1 km. A mean travel rate of 20.7 ± 2.2 km/day and maximum travel of 46.1 km/day were recorded. Recovery rates were greater for Oregon-released monarchs (0.92%) than Washington-released (0.34%) or Idaho-released monarchs (0.30%). Most monarchs (106/122) were recovered SSW-S-SSE in California, with 82 at 18 coastal overwintering sites. Two migrants from Oregon were recovered just weeks after release ovipositing in Santa Barbara and Palo Alto, CA. Two migrants released in central Washington recovered up to 360.0 km to the SE, and recoveries from Idaho releases to the S and SE suggests that some Pacific Northwest migrants fly to an alternative overwintering destination. Monarchs released in southern Oregon into smoky, poor quality air appeared to be as successful at reaching overwintering sites and apparently lived just as long as monarchs released into non-smoky, good quality air. Migration and lifespan for monarchs infected with the protozoan parasite, Ophryocystis elektroscirrha (McLaughlin and Myers), appeared to be similar to the migration and survival of uninfected monarchs, although data are limited. Our data improve our understanding of western monarch migration, serving as a basis for further studies and providing information for conservation planning.
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Affiliation(s)
- David G. James
- Irrigated Agriculture Research and Extension Center, Department of Entomology, Washington State University, Prosser, WA 99350, USA;
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15
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Wilcox AAE, Newman AEM, Raine NE, Mitchell GW, Norris DR. Captive-reared migratory monarch butterflies show natural orientation when released in the wild. CONSERVATION PHYSIOLOGY 2021; 9:coab032. [PMID: 34386237 PMCID: PMC8355447 DOI: 10.1093/conphys/coab032] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/19/2020] [Revised: 01/27/2021] [Accepted: 04/14/2021] [Indexed: 05/08/2023]
Abstract
Eastern North American migratory monarch butterflies (Danaus plexippus) have faced sharp declines over the past two decades. Captive rearing of monarch butterflies is a popular and widely used approach for both public education and conservation. However, recent evidence suggests that captive-reared monarchs may lose their capacity to orient southward during fall migration to their Mexican overwintering sites, raising questions about the value and ethics of this activity undertaken by tens of thousands of North American citizens, educators, volunteers and conservationists each year. We raised offspring of wild-caught monarchs on swamp milkweed (Asclepias incarnata) indoors at 29°C during the day and 23°C at night (~77% RH, 18L:6D), and after eclosion, individuals were either tested in a flight simulator or radio tracked in the wild using an array of automated telemetry towers. While 26% (10/39) of monarchs tested in the flight simulator showed a weakly concentrated southward orientation, 97% (28/29) of the radio-tracked individuals that could be reliably detected by automated towers flew in a south to southeast direction from the release site and were detected at distances of up to 200 km away. Our results suggest that, although captive rearing of monarch butterflies may cause temporary disorientation, proper orientation is likely established after exposure to natural skylight cues.
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Affiliation(s)
- Alana A E Wilcox
- Department of Integrative Biology, University of Guelph, Guelph, Ontario, N1G 2W1, Canada
- Corresponding author: Department of Integrative Biology, University of Guelph, Guelph, Ontario, N1G 2W1, Canada.
| | - Amy E M Newman
- Department of Integrative Biology, University of Guelph, Guelph, Ontario, N1G 2W1, Canada
| | - Nigel E Raine
- School of Environmental Sciences, University of Guelph, Guelph, Ontario, N1G 2W1, Canada
| | - Greg W Mitchell
- Wildlife Research Division, Environment and Climate Change Canada, National Wildlife Research Centre, 1125 Colonel By Drive, Ottawa, Ontario, K1S 5B6, Canada
- Department of Biology, Carleton University, 1125 Colonel By Drive, Ottawa, Ontario, K1S 5B6, Canada
| | - D Ryan Norris
- Department of Integrative Biology, University of Guelph, Guelph, Ontario, N1G 2W1, Canada
- Nature Conservancy of Canada, 245 Eglington Avenue East, Toronto, Ontario, M4P 3J1, Canada
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Guerra PA. The Monarch Butterfly as a Model for Understanding the Role of Environmental Sensory Cues in Long-Distance Migratory Phenomena. Front Behav Neurosci 2020; 14:600737. [PMID: 33343312 PMCID: PMC7744611 DOI: 10.3389/fnbeh.2020.600737] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2020] [Accepted: 11/12/2020] [Indexed: 11/13/2022] Open
Abstract
The awe-inspiring annual migration of monarch butterflies (Danaus plexippus) is an iconic example of long-distance migratory phenomena in which environmental sensory cues help drive successful migration. In this mini-review article, I begin by describing how studies on monarch migration can provide us with generalizable information on how sensory cues can mediate key aspects of animal movement. I describe how environmental sensory cues can trigger the development and progression of the monarch migration, as well as inform sensory-based movement mechanisms in order to travel to and reach their goal destination, despite monarchs being on their maiden voyage. I also describe how sensory cues can trigger season-appropriate changes in migratory direction during the annual cycle. I conclude this mini-review article by discussing how contemporary environmental challenges threaten the persistence of the monarch migration. Environmental challenges such as climate change and shifting land use can significantly alter the sensory environments that monarchs migrate through, as well as degrade or eliminate the sources of sensory cues that are necessary for successful migration.
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Affiliation(s)
- Patrick A. Guerra
- Department of Biological Sciences, College of Arts and Sciences, University of Cincinnati, Cincinnati, OH, United States
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Abstract
Insect wings are living, flexible structures composed of tubular veins and thin wing membrane. Wing veins can contain hemolymph (insect blood), tracheae, and nerves. Continuous flow of hemolymph within insect wings ensures that sensory hairs, structural elements such as resilin, and other living tissue within the wings remain functional. While it is well known that hemolymph circulates through insect wings, the extent of wing circulation (e.g., whether flow is present in every vein, and whether it is confined to the veins alone) is not well understood, especially for wings with complex wing venation. Over the last 100 years, scientists have developed experimental methods including microscopy, fluorescence, and thermography to observe flow in the wings. Recognizing and evaluating the importance of hemolymph movement in insect wings is critical in evaluating how the wings function both as flight appendages, as active sensors, and as thermoregulatory organs. In this review, we discuss the history of circulation in wings, past and present experimental techniques for measuring hemolymph, and broad implications for the field of hemodynamics in insect wings.
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Affiliation(s)
- Mary K Salcedo
- Department of Biomedical and Mechanical Engineering Virginia Tech, Blacksburg, VA, USA
| | - John J Socha
- Department of Biomedical and Mechanical Engineering Virginia Tech, Blacksburg, VA, USA
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18
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Tenger-Trolander A, Kronforst MR. Migration behaviour of commercial monarchs reared outdoors and wild-derived monarchs reared indoors. Proc Biol Sci 2020; 287:20201326. [PMID: 32752991 DOI: 10.1098/rspb.2020.1326] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
Captive rearing of monarch butterflies is a commercial and personal pursuit enjoyed by many different groups and individuals. However, the practice remains controversial, especially after new evidence showed that both a group of commercially derived monarchs reared outdoors and a group of wild-derived but indoor-reared monarchs failed to orient south, unlike wild-derived monarchs reared outdoors. To more fully characterize the mechanisms responsible for the loss of orientation in both commercial and indoor-reared monarchs, we performed flight simulator experiments to determine (i) whether any fraction of commercial monarchs maintains a southern heading over multiple tests, and (ii) whether indoor conditions with the addition of sunlight can induce southern flight in wild-derived monarchs. Commercial monarchs changed their flight direction more often over the course of multiple tests than wild-derived monarchs. While as a group the commercial monarchs did not fly south on average, a subset of individuals did orient south over multiple tests, potentially explaining the discordance between flight simulator assays and the recovery of tagged commercial monarchs at overwintering locations. We also show that even when raised indoors with sunlight, wild-derived monarchs did not consistently orient south in the flight simulator, though wild-derived monarchs reared outdoors did orient south.
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Affiliation(s)
| | - Marcus R Kronforst
- Department of Ecology and Evolution, University of Chicago, Chicago, IL 60637, USA
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