Evidence for a Growing Population of Eastern Migratory Monarch Butterflies Is Currently Insufficient

Thogmartin, Wayne E.; Szymanski, Jennifer A.; Weiser, Emily L.

doi:10.3389/fevo.2020.00043

Cited by 8 publications

(15 citation statements)

References 17 publications

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“…The first addition was to evaluate the assumption of a constant population change rate and to report TYC values derived from models that accommodate variable change rates if the assumption was not supported. Previous work (Thogmartin et al, 2020) and this analysis both demonstrate that a constant rate assumption is not appropriate for this time series. increased from nearly 0% to 90% (Thogmartin, Wiederholt, et al, 2017).…”

Section: Discussionmentioning

confidence: 74%

“…Previous work (Thogmartin et al, 2020) and this analysis both demonstrate that a constant rate assumption is not appropriate for this time series. increased from nearly 0% to 90% (Thogmartin, Wiederholt, et al, 2017). As herbicide use and habitat loss stabilised, Thogmartin, Wiederholt, et al (2017) concluded that further herbicide-associated declines in monarchs were not expected, and that monarchs would likely level off at a new stationary population size.…”

Section: Discussionmentioning

confidence: 74%

“…increased from nearly 0% to 90% (Thogmartin, Wiederholt, et al, 2017). As herbicide use and habitat loss stabilised, Thogmartin, Wiederholt, et al (2017) concluded that further herbicide-associated declines in monarchs were not expected, and that monarchs would likely level off at a new stationary population size. This prediction seems well supported by results from both Thogmartin et al (2020) and this analysis (Figure 2) and underscores the conclusion that constant change models may not be the best choice for modelling monarch butterfly populations.…”

Section: Discussionmentioning

confidence: 99%

“…Log-transformed abundance and modelling techniques using normal distributions were employed instead of untransformed abundance and modelling techniques using Poisson or negative binomial distributions to be consistent with the monarch literature (Schultz et al, 2017;Semmens et al, 2016;Thogmartin et al, 2020;Walker et al, 2022) -Méthé et al, 2021;Dennis et al, 2006). A state space model was included in the model set because first-order time series models are increasingly used for trend estimation for breeding birds in North America (Link et al, 2017;Link et al, 2020).…”

Section: Methodsmentioning

confidence: 99%

“…If the proportional rate of change has been constant, then a simple exponential change model may suffice (Akçakaya et al, 2021; IUCN, 2022). However, when the rate of change has not been constant, more complex models are preferred, including those with logistic functional forms (Akçakaya et al, 2021), segmented regressions (Akçakaya et al, 2021; Thogmartin et al, 2020), or smooth models such as generalised‐additive models (Fewster et al, 2000; Smith & Edwards, 2021) or state‐space models (Auger‐Méthé et al, 2021; Semmens et al, 2016). Well‐established model comparison techniques (Hooten & Hobbs, 2015) are recommended to determine the best, or best set of, candidate models from which to derive TYC estimates (Akçakaya et al, 2021).…”

Section: Introductionmentioning

confidence: 99%

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Change in monarch winter abundance over the past decade: A Red List perspective

Meehan

Crossley

2023

Insect Conserv Diversity

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Assessing invertebrate species for the IUCN Red List under Criterion A frequently involves fitting an appropriate statistical model to available abundance data and calculating a 10‐year change (TYC) estimate from predicted abundances. When the rate of change has not been constant across the entire time series, models that accommodate variable change rates are recommended. The monarch butterfly (Danaus plexippus) was recently added to the IUCN Red List (A2ab Endangered) based on analysis of data on winter abundances in Mexico and the western USA between 1993 and 2020. TYC estimates in the monarch assessment came from models that assumed constant change rates. We conducted a Bayesian analysis of the same data using models that accommodated variable change rates and used those models to compute TYC estimates. Our results suggested that monarch population change rates have not been constant over the study period. The analysis yielded a model‐averaged TYC estimate of +5.23%, which was not statistically distinguishable from 0% and was considerably different from values of −46% and −72% in the assessment. The Bayesian posterior probability of a TYC value below −30% (A2ab Vulnerable) was 0.15 and that of a TYC value below −50% (A2ab Endangered) was 0.03. We recommend that researchers evaluating monarch conservation status consider using abundance models with variable change rates, as models with constant change rates may not accurately predict the trajectory of monarch abundances into the future.

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Section: Discussionmentioning

confidence: 74%

Section: Discussionmentioning

confidence: 74%

Section: Discussionmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Change in monarch winter abundance over the past decade: A Red List perspective

Meehan

Crossley

2023

Insect Conserv Diversity

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Responding to the US national pollinator plan: a case study in Michigan

Bloom

Graham

Haan

et al. 2021

Frontiers in Ecol & Environ

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P ollinating insects are essential to life on Earth, supporting the sustainability and resilience of natural habitats and agroecosystems (Williams et al. 2019;van Klink et al. 2020). Despite their importance, populations of insect pollinators face numerous challenges due to a combination of diseases, parasites, pesticides, climate change, and habitat loss (Goulson et al. 2015). As the international plight of pollinators has become more apparent, 16 nations have enacted pollinator supportive policies (FAO 2020). In the US, a 2014 Presidential Memorandum directed the US Department of Agriculture (USDA) and the Environmental Protection Agency (EPA) to co-lead a task force to create a strategy to promote the health of honey bees (Apis mellifera) and other pollinators (PHTF 2015). This task force released a national pollinator strategy in 2015 that included three key goals with timelines: (1) reduce honey bee overwintering losses in the US to no more than 15% by 2025, (2) increase the overwintering monarch butterfly (Danaus plexippus) population in Mexico to 6 ha by 2020 (as it is not feasible to count individuals, the area covered by overwintering monarchs is measured as a proxy for abundance), and (3) restore or enhance 7 million acres of habitat for pollinators in the US by 2020 (PHTF 2015). A Pollinator Research Action Plan (hereafter, "national plan") that highlighted the priorities for addressing the three goals was also developed (PHTF 2015). Michigan as a case studyFunding to address the national plan was made available through various routes, including the USDA. The USDA's National Institute of Food and Agriculture (NIFA) supported our research and extension team to address the goals in Michigan, a state reliant on wild bees and managed honey bees for crop pollination (Huang and Pett 2010) and containing summer breeding grounds of the eastern monarch butterfly (Flockhart et al. 2013). Because regional solutions to pollinator challenges are important, we highlight how our efforts in Michigan contribute to the national goals. We also draw on public databases to assess progress toward the national goals and show where further focus is needed. The year 2020 was a milestone year to achieve two of the three goals, providing an opportunity to revisit the strategy that inspired 5 years of work. Herein, we evaluate local and national progress and identify future needs for honey bees, monarch butterflies, and pollinator habitat to support wild bees.

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Change‐point analysis of lambda‐cyhalothrin efficacy against soybean aphid (Aphis glycines Matsumura): identifying practical resistance from field efficacy trials

Menger

Ribeiro

Potter

et al. 2022

Pest Management Science

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Background Soybean aphid (Aphis glycines Matsumura) remains the most economically important arthropod pest of soybean in the Upper Midwest Region of the USA. Soybean aphid resistance to the pyrethroid insecticides emerged in 2015; however, the reduction in the efficacy of field applications of pyrethroid insecticides has not been quantified. Based on time‐series data from insecticide efficacy trials at two locations, a novel approach of continuous two‐phase change point‐regression models was used to indicate whether a change in percent control had occurred, and to provide an indication of when and to what degree the percent control had changed. Results At both locations examined in this study, a significant change point for percent control of λ‐cyhalothrin was detected in 2014, thus marking the onset of practical resistance in the soybean aphid. Percent control decreased at a rate of 4.30% and 19.90% per year at these locations. By contrast, percent control for chlorpyrifos remained high over time with no significant change point. Conclusion This research demonstrates that retrospective time‐series analysis of insecticide efficacy data can identify the onset and magnitude of practical resistance in the field. This further validates and compliments the other lines of evidence related to pyrethroid resistance in soybean aphid. © 2022 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

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Evidence for a Growing Population of Eastern Migratory Monarch Butterflies Is Currently Insufficient

Cited by 8 publications

References 17 publications

Change in monarch winter abundance over the past decade: A Red List perspective

Change in monarch winter abundance over the past decade: A Red List perspective

Responding to the US national pollinator plan: a case study in Michigan

Change‐point analysis of lambda‐cyhalothrin efficacy against soybean aphid (Aphis glycines Matsumura): identifying practical resistance from field efficacy trials

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