Development and Verification of an Interspecific Hybridization Protocol for Asclepias

Milkweed (Asclepias sp.) is an important pollinator genus across North America and is a host plant for many butterfly species, notably the monarch butterfly (Danaus plexippus). Commercial production of Asclepias is limited to a few species, because most species lack commercial traits, with minimal branching habit, excessive height, and minimal color variation. This study used a commercially viable Asclepias species, butterfly weed (Asclepias tuberosa L.), as a maternal parent and trialed three different pollination methods in an attempt to create interspecific hybrids. Pollination methods included a traditional method, a pollen–solution-based method, and a novel inverted pollinia method. The inverted pollinia method increased pollination success rates 4-fold among intraspecific crosses of A. tuberosa. When pollination methods were optimized, A. tuberosa was used as the maternal parent, and one-way crosses were made to seven other Asclepias species using the inverted pollinia method. Of the seven species used as pollen donors, four developed hybrid seed successfully: green milkweed (Asclepias hirtella Woodson), purple milkweed (Asclepias purpurascens L.), showy milkweed (Asclepias speciosa Torr.), and common milkweed (Asclepias syriaca L.). As germination methods vary significantly among Asclepias species, three methods of germination were trialed on seed developed via interspecific hybridizations: direct seeded, cold–moist stratification, and embryo rescue. Of the three methods, cold–moist stratification was superior to direct seeding and embryo rescue. This research is the first documented case of a controlled interspecific hybridization event among these species.

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Monarch butterfly and milkweed declines substantially predate the use of genetically modified crops

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.1811437116 ◽

2019 ◽

Vol 116 (8) ◽

pp. 3006-3011 ◽

Cited By ~ 20

Author(s):

J. H. Boyle ◽

H. J. Dalgleish ◽

J. R. Puzey

Keyword(s):

Genetically Modified ◽

Danaus Plexippus ◽

Genetically Modified Crops ◽

Monarch Butterfly ◽

The United States ◽

Gm Crops ◽

Herbicide Resistant ◽

The Past ◽

Scientific Attention ◽

Herbicide Use

Monarch butterfly (Danaus plexippus) decline over the past 25 years has received considerable public and scientific attention, in large part because its decline, and that of its milkweed (Asclepias spp.) host plant, have been linked to genetically modified (GM) crops and associated herbicide use. Here, we use museum and herbaria specimens to extend our knowledge of the dynamics of both monarchs and milkweeds in the United States to more than a century, from 1900 to 2016. We show that both monarchs and milkweeds increased during the early 20th century and that recent declines are actually part of a much longer-term decline in both monarchs and milkweed beginning around 1950. Herbicide-resistant crops, therefore, are clearly not the only culprit and, likely, not even the primary culprit: Not only did monarch and milkweed declines begin decades before GM crops were introduced, but other variables, particularly a decline in the number of farms, predict common milkweed trends more strongly over the period studied here.

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High Survivorship of First-Generation Monarch Butterfly Eggs to Third Instar Associated with a Diverse Arthropod Community

Insects ◽

10.3390/insects12060567 ◽

2021 ◽

Vol 12 (6) ◽

pp. 567

Author(s):

Misty Stevenson ◽

Kalynn L. Hudman ◽

Alyx Scott ◽

Kelsey Contreras ◽

Jeffrey G. Kopachena

Keyword(s):

Host Plants ◽

First Generation ◽

Danaus Plexippus ◽

Monarch Butterfly ◽

Conservation Strategies ◽

North Texas ◽

Ecological Processes ◽

Area Of Occupancy ◽

Predator Abundance ◽

A Site

Based on surveys of winter roost sites, the eastern migratory population of the monarch butterfly (Danaus plexippus) in North America appears to have declined in the last 20 years and this has prompted the implementation of numerous conservation strategies. However, there is little information on the survivorship of first-generation monarchs in the core area of occupancy in Texas, Oklahoma, and Louisiana where overwinter population recovery begins. The purpose of this study was to determine the survivorship of first-generation eggs to third instars at a site in north Texas and to evaluate host plant arthropods for their effect on survivorship. Survivorship to third instar averaged 13.4% and varied from 11.7% to 15.6% over three years. The host plants harbored 77 arthropod taxa, including 27 predatory taxa. Despite their abundance, neither predator abundance nor predator richness predicted monarch survival. However, host plants upon which monarchs survived often harbored higher numbers of non-predatory arthropod taxa and more individuals of non-predatory taxa. These results suggest that ecological processes may have buffered the effects of predators and improved monarch survival in our study. The creation of diverse functional arthropod communities should be considered for effective monarch conservation, particularly in southern latitudes.

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Pretty Picky for a Generalist: Impacts of Toxicity and Nutritional Quality on Mantid Prey Processing

Environmental Entomology ◽

10.1093/ee/nvx038 ◽

2017 ◽

Vol 46 (3) ◽

pp. 626-632 ◽

Cited By ~ 2

Author(s):

Jamie L. Rafter ◽

Justin F. Vendettuoli ◽

Liahna Gonda-King ◽

Daniel Niesen ◽

Navindra P. Seeram ◽

...

Keyword(s):

C:N Ratio ◽

Danaus Plexippus ◽

Monarch Butterfly ◽

The Body ◽

Gut Contents ◽

Corn Borers ◽

Body Tissues ◽

Heterogeneous Quality ◽

Behavioral Trials

Abstract Prey have evolved a number of defenses against predation, and predators have developed means of countering these protective measures. Although caterpillars of the monarch butterfly,Danaus plexippus L., are defended by cardenolides sequestered from their host plants, the Chinese mantidTenodera sinensis Saussure guts the caterpillar before consuming the rest of the body. We hypothesized that this gutting behavior might be driven by the heterogeneous quality of prey tissue with respect to toxicity and/or nutrients. We conducted behavioral trials in which mantids were offered cardenolide-containing and cardenolide-freeD. plexippus caterpillars and butterflies. In addition, we fed mantids starved and unstarvedD. plexippus caterpillars from each cardenolide treatment and nontoxicOstrinia nubilalis Hübner caterpillars. These trials were coupled with elemental analysis of the gut and body tissues of bothD. plexippus caterpillars and corn borers. Cardenolides did not affect mantid behavior: mantids gutted both cardenolide-containing and cardenolide-free caterpillars. In contrast, mantids consumed bothO. nubilalis and starvedD. plexippus caterpillars entirely.Danaus plexippus body tissue has a lower C:N ratio than their gut contents, whileO. nubilalis have similar ratios; gutting may reflect the mantid’s ability to regulate nutrient uptake. Our results suggest that post-capture prey processing by mantids is likely driven by a sophisticated assessment of resource quality.

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Interspecific Hybridization Of Red Clover (Trifolium Pratense L.) With Alsike Clover (Trifolium Hybndum L.) Using In Vitro Embryo Rescue

Genetic Manipulation in Plant Breeding ◽

10.1515/9783110871944-081 ◽

1986 ◽

pp. 469-472

Keyword(s):

Interspecific Hybridization ◽

Trifolium Pratense ◽

Embryo Rescue ◽

Red Clover ◽

Trifolium Pratense L

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Cardenolides, toxicity, and the costs of sequestration in the coevolutionary interaction between monarchs and milkweeds

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.2024463118 ◽

2021 ◽

Vol 118 (16) ◽

pp. e2024463118

Author(s):

Anurag A. Agrawal ◽

Katalin Böröczky ◽

Meena Haribal ◽

Amy P. Hastings ◽

Ronald A. White ◽

...

Keyword(s):

Danaus Plexippus ◽

Monarch Butterfly ◽

Chemical Defenses ◽

Trade Off ◽

Asclepias Curassavica ◽

Plant Chemical ◽

Whole Plants ◽

Benefits And Costs

For highly specialized insect herbivores, plant chemical defenses are often co-opted as cues for oviposition and sequestration. In such interactions, can plants evolve novel defenses, pushing herbivores to trade off benefits of specialization with costs of coping with toxins? We tested how variation in milkweed toxins (cardenolides) impacted monarch butterfly (Danaus plexippus) growth, sequestration, and oviposition when consuming tropical milkweed (Asclepias curassavica), one of two critical host plants worldwide. The most abundant leaf toxin, highly apolar and thiazolidine ring–containing voruscharin, accounted for 40% of leaf cardenolides, negatively predicted caterpillar growth, and was not sequestered. Using whole plants and purified voruscharin, we show that monarch caterpillars convert voruscharin to calotropin and calactin in vivo, imposing a burden on growth. As shown by in vitro experiments, this conversion is facilitated by temperature and alkaline pH. We next employed toxin-target site experiments with isolated cardenolides and the monarch’s neural Na+/K+-ATPase, revealing that voruscharin is highly inhibitory compared with several standards and sequestered cardenolides. The monarch’s typical >50-fold enhanced resistance to cardenolides compared with sensitive animals was absent for voruscharin, suggesting highly specific plant defense. Finally, oviposition was greatest on intermediate cardenolide plants, supporting the notion of a trade-off between benefits and costs of sequestration for this highly specialized herbivore. There is apparently ample opportunity for continued coevolution between monarchs and milkweeds, although the diffuse nature of the interaction, due to migration and interaction with multiple milkweeds, may limit the ability of monarchs to counteradapt.

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Strengths and limitations of Bacillus thuringiensis galleriae for managing Japanese beetle ( Popillia japonica ) adults and grubs with caveats for cross‐order activity to monarch butterfly ( Danaus plexippus ) larvae

Pest Management Science ◽

10.1002/ps.5532 ◽

2019 ◽

Vol 76 (2) ◽

pp. 472-479 ◽

Cited By ~ 1

Author(s):

Carl T Redmond ◽

Lindsey Wallis ◽

Matthew Geis ◽

R Chris Williamson ◽

Daniel A Potter

Keyword(s):

Bacillus Thuringiensis ◽

Danaus Plexippus ◽

Monarch Butterfly ◽

Popillia Japonica ◽

Japanese Beetle ◽

Monarch Butterfly Danaus Plexippus

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Predators of monarch butterfly eggs and neonate larvae are more diverse than previously recognised

Scientific Reports ◽

10.1038/s41598-019-50737-5 ◽

2019 ◽

Vol 9 (1) ◽

Cited By ~ 5

Author(s):

Sara L. Hermann ◽

Carissa Blackledge ◽

Nathan L. Haan ◽

Andrew T. Myers ◽

Douglas A. Landis

Keyword(s):

Danaus Plexippus ◽

Monarch Butterfly ◽

The United States ◽

Field Observations ◽

Primary Host ◽

The Past ◽

Conservation Concern ◽

Neonate Larvae ◽

Choice Feeding ◽

Predator Community

Abstract Conserving threatened organisms requires knowledge of the factors impacting their populations. The Eastern monarch butterfly (Danaus plexippus L.) has declined by as much as 80% in the past two decades and conservation biologists are actively seeking to understand and reverse this decline. While it is well known that most monarchs die as eggs and young larvae, few studies have focused on identifying what arthropod taxa contribute to these losses. The aim of our study was to identify previously undocumented predators of immature monarchs in their summer breeding range in the United States. Using no-choice feeding assays augmented with field observations, we evaluated 75 arthropod taxa commonly found on the primary host plant for their propensity to consume immature monarchs. Here we report 36 previously unreported monarch predators, including representatives from 4 new orders (Orthoptera, Dermaptera, Lepidoptera and Opiliones) and 11 taxa (Acrididae, Gryllidae, Tettigoniidae, Forficulidae, Anthocoridae, Geocoridae, Lygaeidae, Miridae, Nabidae, Erebidae and Opilliones). Surprisingly, several putative herbivores were found to readily consume immature monarchs, both in a targeted fashion or incidentally as a result of herbivory. This work expands our understanding of the monarch predator community and highlights the importance of unrecognized predation on insects of conservation concern.

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