scholarly journals Uptake and toxicity of clothianidin to monarch butterflies from milkweed consumption

PeerJ ◽  
2020 ◽  
Vol 8 ◽  
pp. e8669 ◽  
Author(s):  
Timothy A. Bargar ◽  
Michelle L. Hladik ◽  
Jaret C. Daniels
Keyword(s):  
Larval Growth ◽  
Danaus Plexippus ◽  
Total Mortality ◽  
Monarch Butterfly ◽  
Larval Survival ◽  
Adult Size ◽  
Monarch Butterflies ◽  
Resource Managers ◽  
Natural Resource Managers ◽  
Butterfly Larvae

Recent concern for the adverse effects from neonicotinoid insecticides has centered on risk for insect pollinators in general and bees specifically. However, natural resource managers are also concerned about the risk of neonicotinoids to conservation efforts for the monarch butterfly (Danaus plexippus) and need additional data to help estimate risk for wild monarch butterflies exposed to those insecticides. In the present study, monarch butterfly larvae were exposed in the laboratory to clothianidin via contaminated milkweed plants from hatch until pupation, and the effects upon larval survival, larval growth, pupation success, and adult size were measured. Soils dosed with a granular insecticide product led to mean clothianidin concentrations of 10.8–2,193 ng/g in milkweed leaves and 5.8–58.0 ng/g in larvae. Treatment of soils also led to clothianidin concentrations of 2.6–5.1 ng/g in adult butterflies indicating potential for transfer of systemic insecticides from the soil through plants and larvae to adult butterflies. Estimated LC50s for total mortality (combined mortality of larvae and pupae) and EC50 for larval growth were variable but higher than the majority of concentrations reported in the literature for clothianidin contamination of leaves.

scholarly journals Stimulus-dependent orientation strategies in monarch butterflies

2021 ◽  
Author(s):  
Myriam Franzke ◽  
Christian Kraus ◽  
Maria Gayler ◽  
David Dreyer ◽  
Keram Pfeiffer ◽  
...  
Keyword(s):  
Visual Cues ◽  
Danaus Plexippus ◽  
Monarch Butterfly ◽  
Central Complex ◽  
Orientation Behavior ◽  
Compass Orientation ◽  
Monarch Butterflies ◽  
Sun Compass ◽  
Bright Stripe ◽  
Flight Route

Insects are well-known for their ability to keep track of their heading direction based on a combination of skylight cues and visual landmarks. This allows them to navigate back to their nest, disperse throughout unfamiliar environments, as well as migrate over large distances between their breeding and non-breeding habitats. The monarch butterfly (Danaus plexippus) for instance is known for its annual southward migration from North America to certain trees in Central Mexico. To maintain a constant flight route, these butterflies use a time-compensated sun compass for orientation which is processed in a region in the brain, termed the central complex. However, to successfully complete their journey, the butterflies' brain must generate a multitude of orientation strategies, allowing them to dynamically switch from sun-compass orientation to a tactic behavior toward a certain target. To study if monarch butterflies exhibit different orientation modes and if they can switch between them, we observed the orientation behavior of tethered flying butterflies in a flight simulator while presenting different visual cues to them. We found that the butterflies' behavior depended on the presented visual stimulus. Thus, while a dark stripe was used for flight stabilization, a bright stripe was fixated by the butterflies in their frontal visual field. If we replaced a bright stripe by a simulated sun stimulus, the butterflies switched their orientation behavior and exhibited compass orientation. Taken together, our data show that monarch butterflies rely on and switch between different orientation modes, allowing them to adjust orientation to the actual behavioral demands of the animal.

scholarly journals Differential gene expression reflects larval development and survival of monarch butterflies on different milkweed hosts

2020 ◽  
Author(s):  
Pablo M. Gonzalez-De-la-Rosa ◽  
Mariana Ramirez Loustalot-Laclette ◽  
Cei Abreu-Goodger ◽  
Therese Ann Markow
Keyword(s):  
Gene Expression ◽  
Environmental Factors ◽  
Larval Development ◽  
Larval Growth ◽  
Danaus Plexippus ◽  
Monarch Butterfly ◽  
Hippo Signaling ◽  
Asclepias Curassavica ◽  
Important Regulator ◽  
Differential Gene

ABSTRACTSecond instar larvae of the monarch butterfly, Danaus plexippus, from a nonmigratory population in Irapuato, Mexico, were reared for twenty-four hours on three species of milkweed hosts: Asclepias curassavica, A. linaria, and Gomphocarpus physocarpus. We then measured larval growth and differential expression of coding genes and of microRNAs. Larval growth was similar on the two Asclepias species, while little growth was observed on G. physocarpus. The greatest differences in coding gene expression occurred in genes controlling growth and detoxification and were most extreme in comparisons between G. physocarpus and the two Asclepias. MicroRNAs are predicted to be involved as regulators of many of these processes, in particular miR-278, differentially expressed here, could be an important regulator of growth through Hippo signaling. The implications for survival of the monarch, especially in the context of environmental factors altering the availability of their favored milkweed species, are discussed.

scholarly journals Contemporary loss of migration in monarch butterflies

2019 ◽  
Vol 116 (29) ◽  
pp. 14671-14676 ◽  
Author(s):  
Ayşe Tenger-Trolander ◽  
Wei Lu ◽  
Michelle Noyes ◽  
Marcus R. Kronforst
Keyword(s):  
North American ◽  
Indoor Environment ◽  
Captive Breeding ◽  
Danaus Plexippus ◽  
Monarch Butterfly ◽  
Population Recovery ◽  
Monarch Butterflies ◽  
Commercial Population ◽  
Open Question ◽  
The Impact

The annual migration of the monarch butterfly Danaus plexippus is in peril. In an effort to aid population recovery, monarch enthusiasts across North America participate in a variety of conservation efforts, including captive rearing and release of monarch butterflies throughout the summer and autumn. However, the impact of captive breeding on monarchs remains an open question. Here, we show that captive breeding, both commercially and by summertime hobbyists, causes migratory behavior to be lost. Monarchs acquired commercially failed to orient south when reared outdoors in the autumn, unlike wild-caught North American monarchs, yet they did enter reproductive diapause. The commercial population was genetically highly divergent from wild-caught North American monarchs and had rounder forewings, similar to monarchs from nonmigratory populations. Furthermore, rearing wild-caught monarchs in an indoor environment mimicking natural migration-inducing conditions failed to elicit southward flight orientation. In fact, merely eclosing indoors after an otherwise complete lifecycle outdoors was enough to disrupt southern orientation. Our results provide a window into the complexity—and remarkable fragility—of migration.

scholarly journals Effects of early-life exposure to sublethal levels of a common neonicotinoid insecticide on the orientation and migration of monarch butterflies (Danaus plexippus)

2020 ◽  
Vol 224 (4) ◽  
pp. jeb230870
Author(s):  
Alana A. E. Wilcox ◽  
Amy E. M. Newman ◽  
Nigel E. Raine ◽  
Greg W. Mitchell ◽  
D. Ryan Norris
Keyword(s):  
Danaus Plexippus ◽  
Monarch Butterfly ◽  
Flight Simulator ◽  
Testing Time ◽  
Long Distance ◽  
Monarch Butterflies ◽  
Early Life Exposure ◽  
Neonicotinoid Insecticide ◽  
In The Wild ◽  
And Migration

ABSTRACTMigratory insects use a variety of innate mechanisms to determine their orientation and maintain correct bearing. For long-distance migrants, such as the monarch butterfly (Danaus plexippus), these journeys could be affected by exposure to environmental contaminants. Neonicotinoids are synthetic insecticides that work by affecting the nervous system of insects, resulting in impairment of their mobility, cognitive performance, and other physiological and behavioural functions. To examine how neonicotinoids might affect the ability of monarch butterflies to maintain a proper directional orientation on their ∼4000 km migration, we grew swamp milkweed (Asclepias incarnata) in soil that was either untreated (0 ng g−1: control) or mixed with low (15 ng g−1 of soil) or high (25 ng g−1 of soil) levels of the neonicotinoid clothianidin. Monarch caterpillars were raised on control or clothianidin-treated milkweed and, after pupation, either tested for orientation in a static flight simulator or radio-tracked in the wild during the autumn migration period. Despite clothianidin being detectable in milkweed tissue consumed by caterpillars, there was no evidence that clothianidin influenced the orientation, vector strength (i.e. concentration of direction data around the mean) or rate of travel of adult butterflies, nor was there evidence that morphological traits (i.e. mass and forewing length), testing time, wind speed or temperature impacted directionality. Although sample sizes for both flight simulator and radio-tracking tests were limited, our preliminary results suggest that clothianidin exposure during early caterpillar development does not affect the directed flight of adult migratory monarch butterflies or influence their orientation at the beginning of migration.

scholarly journals State-dependent egocentric and allocentric heading representation in the monarch butterfly brain

2021 ◽  
Author(s):  
M. Jerome Beetz ◽  
Christian Kraus ◽  
Myriam Franzke ◽  
David Dreyer ◽  
Martin F. Strube-Bloss ◽  
...  
Keyword(s):  
Reference Frame ◽  
Reference Frames ◽  
Danaus Plexippus ◽  
Monarch Butterfly ◽  
Central Complex ◽  
Dependent Manner ◽  
The Sun ◽  
Monarch Butterflies ◽  
State Dependent ◽  
Allocentric Reference Frame

AbstractHead direction can be represented in a self-centered egocentric or a viewpoint-invariant allocentric reference frame. Using the most efficient representation is especially crucial for migrating animals, like monarch butterflies (Danaus plexippus) that use the sun for orientation. With tetrode recordings from the brain of tethered flying monarch butterflies, we examined the reference frame in which insects encode heading. We show that compass neurons switch their reference frame in a state-dependent manner. In quiescence, they encode sun-bearing angles, allowing the butterfly to map the environment within an egocentric frame. However, during flight, the same neurons encode heading within an allocentric frame. This switch converts the sun from a local to a global cue, an ideal strategy for maintaining a migratory heading over large distance.One-Sentence SummaryHeading information is encoded in different state-dependent reference frames in the monarch butterfly central complex

scholarly journals Disrupting butterfly caterpillar microbiomes does not impact their survival and development

2019 ◽  
Vol 286 (1917) ◽  
pp. 20192438 ◽  
Author(s):  
Kruttika Phalnikar ◽  
Krushnamegh Kunte ◽  
Deepa Agashe
Keyword(s):  
Larval Growth ◽  
Biomass Accumulation ◽  
Larval Survival ◽  
Gut Bacteria ◽  
Growth And Survival ◽  
Gut Microbes ◽  
Survival And Development ◽  
Similar Survival ◽  
And Control ◽  
Butterfly Larvae

Associations with gut microbes are believed to play crucial roles in the physiology, immune function, development and behaviour of insects. However, microbiome sequencing has recently suggested that butterflies are an anomaly, because their microbiomes do not show strong host- and developmental stage-specific associations. We experimentally manipulated butterfly larval gut microbiota and found that disrupting gut microbes had little influence on larval survival and development. Larvae of the butterflies Danaus chrysippus and Ariadne merione that fed on chemically sterilized or antibiotic-treated host plant leaves had significantly reduced bacterial loads, and their gut bacterial communities were disrupted substantially. However, neither host species treated this way suffered a significant fitness cost: across multiple experimental blocks, treated and control larvae had similar survival, growth and development. Furthermore, re-introducing microbes from the excreta of control larvae did not improve larval growth and survival. Thus, these butterfly larvae did not appear to rely on specialized gut bacteria for digestion, detoxification, biomass accumulation and metamorphosis. Our experiments thus show that dependence on gut bacteria for growth and survival is not a universal phenomenon across insects. Our findings also caution that strategies which target gut microbiomes may not always succeed in controlling Lepidopteran pests.

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