scholarly journals Distribution, phenology, and land cover preference risk assessments of four South-Central US milkweeds (Asclepias spp.) important for monarch butterflies

2021 ◽  
Author(s):  
James L Tracy ◽  
Tuula Kantola ◽  
Kristen A Baum ◽  
Robert N Coulson
Keyword(s):  
Land Cover ◽  
Open Space ◽  
Danaus Plexippus ◽  
Bias Reduction ◽  
Risk Assessments ◽  
Larval Food ◽  
Science Data ◽  
Monarch Butterflies ◽  
Late Season ◽  
South Central

Abstract South-Central US milkweeds (Asclepias spp.) are critical adult nectar and larval food resources for producing the first spring and last summer/fall generations of declining eastern migratory monarch butterflies (Danaus plexippus). MaxEnt niche models were developed for North American ranges of four important South-Central US milkweeds: Asclepias asperula ssp. capricornu, A. viridis, A. oenotheroides, and A. latifolia. Twelve models per species utilized subsets of six to eight of 95 edapho-topo-climatic variables chosen by a random subset feature selection algorithm. Milkweed weekly phenology was compared between early and late season periods of monarch activity. Novel land cover preference risk assessments were developed for milkweeds through land cover utilization-availability analyses, incorporating a novel sample bias reduction method for citizen science data before calculation of relativized electivity index (E*) land cover preference. Asclepias a. ssp. capricornu and A. viridis occurred more frequently during early season monarch activity, while A. oenotheroides and A. latifolia occurred more frequently during late season monarch activity. Milkweed utilization of roadsides varied from 6–31%. Developed-Open Space and Grassland Herbaceous land classes generally had highest benefit among milkweeds. Cultivated Crops and Shrub/Scrub had high risk. Combined milkweed high Ei* kernel density estimation surfaces resolved interior and coastal corridors of milkweed land cover preference providing functional connectivity for the monarch spring and fall migrations. A potentially critical gap in milkweed land cover benefit connectivity was identified in South Texas. Milkweed land cover preference risk assessments can be used to prioritize milkweed habitat conservation for enhancing monarch migration connectivity across the South-Central US.

scholarly journals Estimating the annual distribution of monarch butterflies in Canada over 16 years using citizen science data

FACETS ◽  
2019 ◽  
Vol 4 (1) ◽  
pp. 238-253
Author(s):  
D. T. Tyler Flockhart ◽  
Maxim Larrivée ◽  
Kathleen L. Prudic ◽  
D. Ryan Norris
Keyword(s):  
North America ◽  
Citizen Science ◽  
Habitat Restoration ◽  
Danaus Plexippus ◽  
The United States ◽  
Science Data ◽  
Eastern Canada ◽  
Long Distance ◽  
Monarch Butterflies ◽  
Breeding Distribution

Monarch butterflies ( Danaus plexippus, Linnaeus, 1758) are comprised of two migratory populations separated by the Rocky Mountains and are renowned for their long-distance movements among the United States, Canada, and Mexico. Both populations have declined over several decades across North America prompting all three countries to evaluate conservation efforts. Monitoring monarch distribution and abundance is a necessary aspect of ongoing management in Canada where they are a species at risk. We used presence-only data from two citizen science data sets to estimate the annual breeding distribution of monarch butterflies in Canada between 2000 and 2015. Monarch breeding distribution in Canada varied widely among years owing to natural variation, and when considering the upper 95% of the probability of occurrence, the annual mean breeding distribution in Canada was 484 943 km2 (min: 173 449 km2; max: 1 425 835 km2). The area of occurrence was approximately an order of magnitude larger in eastern Canada than in western Canada. Habitat restoration for monarch butterflies in Canada should prioritize productive habitats in southern Ontario where monarchs occur annually and, therefore, likely contribute most to the long-term viability of monarchs in eastern North America. Overall, our assessment sets the geographic context to develop successful management strategies for monarchs in Canada.

scholarly journals Distribution and phenology of monarch butterfly larvae and their milkweed hosts in the South Central US

2022 ◽  
Author(s):  
James L Tracy ◽  
Tuula Kantola ◽  
Kristen A. Baum ◽  
Robert N. Coulson
Keyword(s):  
Land Cover ◽  
Spatial Density ◽  
Conservation Priorities ◽  
The South ◽  
Conservation Assessment ◽  
Early Season ◽  
Late Season ◽  
South Central ◽  
Larval Host ◽  
Host Selectivity

Abstract South Central US milkweeds (Asclepias) are critical adult nectar and larval food resources for producing the first spring and last summer/fall generations of declining eastern migratory monarch butterflies (Danaus plexippus). This study addresses multiple gaps in assessment of monarch conservation priorities for the South Central US through analyses of monarch larval host selectivity, phenology, and spatial density, as well as the phenology, niche modeled distribution, and land cover selectivity of important milkweed hosts. Results are synthesized to estimate seasonal milkweed resource areas. About 70% of monarch larval activity occurred from mid-March to mid-July (early season) and 30% from mid-August to late November (late season). Twenty-six wild milkweed (Apocynaceae) hosts were mapped, including four new records for North America. Important hosts included Asclepias a. ssp. capricornu, A. viridis, and A. oenotheroides, that were utilized more frequently during early season, and Asclepias latifolia, utilized more frequently during late season. Landscape host selectivity was positive for A. viridis and A. a. ssp. capricornu in late and early seasons, respectively, and negative for A. oenotheroides in late season. Milkweed land cover selectivity was positive for Developed-Open Space and Grassland Herbaceous, and negative for Cultivated Crops and Shrub/Scrub. Seasonal milkweed resource areas and larval spatial densities resolved interior and coastal corridors providing functional connectivity for monarch spring and fall migrations. A potential gap in milkweed land cover benefit was identified in South Texas. The novel merging of milkweed niche models with larval phenology, host selectivity, milkweed phenology, and land cover selectivity informs conservation assessment.

scholarly journals Mapping the premigration distribution of eastern Monarch butterflies using community science data

2021 ◽  
Author(s):  
Iman Momeni‐Dehaghi ◽  
Joseph R. Bennett ◽  
Greg W. Mitchell ◽  
Trina Rytwinski ◽  
Lenore Fahrig
Keyword(s):  
Science Data ◽  
Monarch Butterflies ◽  
Community Science

scholarly journals Tracking multi-generational colonization of the breeding grounds by monarch butterflies in eastern North America

2013 ◽  
Vol 280 (1768) ◽  
pp. 20131087 ◽  
Author(s):  
D. T. Tyler Flockhart ◽  
Leonard I. Wassenaar ◽  
Tara G. Martin ◽  
Keith A. Hobson ◽  
Michael B. Wunder ◽  
...  
Keyword(s):  
North America ◽  
Danaus Plexippus ◽  
Late Summer ◽  
Breeding Habitat ◽  
Eastern North America ◽  
Distribution Models ◽  
Monarch Butterflies ◽  
Breeding Distribution ◽  
Breeding Grounds ◽  
Isotope Measurements

Insect migration may involve movements over multiple breeding generations at continental scales, resulting in formidable challenges to their conservation and management. Using distribution models generated from citizen scientist occurrence data and stable-carbon and -hydrogen isotope measurements, we tracked multi-generational colonization of the breeding grounds of monarch butterflies ( Danaus plexippus ) in eastern North America. We found that monarch breeding occurrence was best modelled with geographical and climatic variables resulting in an annual breeding distribution of greater than 12 million km 2 that encompassed 99% occurrence probability. Combining occurrence models with stable isotope measurements to estimate natal origin, we show that butterflies which overwintered in Mexico came from a wide breeding distribution, including southern portions of the range. There was a clear northward progression of monarchs over successive generations from May until August when reproductive butterflies began to change direction and moved south. Fifth-generation individuals breeding in Texas in the late summer/autumn tended to originate from northern breeding areas rather than regions further south. Although the Midwest was the most productive area during the breeding season, monarchs that re-colonized the Midwest were produced largely in Texas, suggesting that conserving breeding habitat in the Midwest alone is insufficient to ensure long-term persistence of the monarch butterfly population in eastern North America.

Developmental and reproductive effects of clothianidin exposure in monarch butterflies (Lepidoptera: Nymphalidae)

2021 ◽  
pp. 1-16
Author(s):  
Alana A.E. Wilcox ◽  
Amy E.M. Newman ◽  
D. Ryan Norris
Keyword(s):  
Egg Size ◽  
Insect Pests ◽  
Danaus Plexippus ◽  
Crop Damage ◽  
High Dose ◽  
Monarch Butterflies ◽  
Insecticide Treatment ◽  
Late Instar ◽  
Length Width ◽  
The Impact

Abstract Neonicotinoid insecticides are used to reduce crop damage caused by insect pests, but sublethal levels could affect development and reproduction in nontarget insects, such as monarch butterflies (Danaus plexippus) (Lepidoptera: Nymphalidae). To investigate the impact of field-realistic concentrations of the neonicotinoid clothianidin on monarch butterflies, we grew swamp milkweed (Asclepias incarnata) (Apocynaceae) in either low (15 ng/g of soil) or high (25 ng/g of soil) levels of clothianidin, or in a control (0 ng/g), then raised monarchs on the milkweed. Morphological traits of monarch caterpillars were measured during development and, once they eclosed, were mated as adults to quantify egg size and mass and the number of eggs laid. Although the effects of the treatment had complex effects on caterpillar length, width and volume of late-instar caterpillars were negatively affected. Fifth-instar caterpillars from the high-dose insecticide treatment had lower mass than other groups. Adult monarch butterflies raised on treated milkweed were larger than controls, but clothianidin exposure did not affect the number of eggs laid or egg size. Although the magnitude of the effect depends on clothianidin concentration, our results suggest that exposure to clothianidin during early life can impact monarch caterpillar development but is unlikely to reduce female reproductive output.

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