Pesticide Contamination of Milkweeds Across the Agricultural, Urban, and Open Spaces of Low-Elevation Northern California

Halsch, Christopher A.; Code, Aimee; Hoyle, Sarah M.; Fordyce, James A.; Baert, Nicolas; Forister, Matthew L.

doi:10.3389/fevo.2020.00162

Cited by 32 publications

(30 citation statements)

References 68 publications

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“…Monarchs can be exposed to neonicotinoids in agricultural environments through drift from foliar applications or soil leaching from seed treatments at planting [32]. Neonicotinoid residues are reported in field surveys of wildflowers and milkweeds [33][34][35][36] and are found up to 48 ng/g on nectar plants and up to 56.5 ng/g on milkweed plants in field margins. Monarch caterpillars often feed on milkweed in agricultural fields and can be exposed to insecticide and herbicide foliar spraying [37].…”

Section: Introductionmentioning

confidence: 99%

Host Plant Species Mediates Impact of Neonicotinoid Exposure to Monarch Butterflies

Prouty

Barriga

Davis

et al. 2021

Insects

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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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Section: Introductionmentioning

confidence: 99%

Host Plant Species Mediates Impact of Neonicotinoid Exposure to Monarch Butterflies

Prouty

Barriga

Davis

et al. 2021

Insects

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“…The high water solubility of these insecticides (Simon-Delso et al, 2015) can often result in their movement in the environment and their rapid and significant uptake by surrounding non-crop plants (e.g. milkweed; Pecenka and Lundgren, 2015;Bargar et al, 2020;Halsch et al, 2020). Though environmental persistence varies among neonicotinoids, they can remain in the environment for years (DeCant, 2010;Goulson, 2013;Simon-Delso et al, 2015;Bonmatin et al, 2015;Wintermantel et al, 2020), exacerbating the risk of exposure for beneficial insect species that are susceptible to the chemical binding at the nicotinic acetylcholine receptors (nAchRs) in the brain (Bonmatin et al, 2015;Sánchez-Bayo et al, 2016).…”

Section: Introductionmentioning

confidence: 99%

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

Wilcox

Newman

Raine

et al. 2020

Journal of Experimental Biology

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Migratory 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.

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“…Plant protection products (PPPs, e.g., pesticides and herbicides) associated with agriculture pose a second threat. Apart from imminent mortal effect after acute exposure, the larval performance, species richness, and abundance are also affected by chronical exposure [65][66][67][68][69][70]. Therefore, butterflies often suffer collateral damage under broad-spectrum pesticides in either agroecosystems or artificial green space in urban areas [2, [71][72][73].…”

Section: China's Butterfly Diversity and Threatsmentioning

confidence: 99%

Butterfly Conservation in China: From Science to Action

Wang

Suman

Zhang

et al. 2020

Insects

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About 10% of the Earth’s butterfly species inhabit the highly diverse ecosystems of China. Important for the ecological, economic, and cultural services they provide, many butterfly species experience threats from land use shifts and climate change. China has recently adopted policies to protect the nation’s biodiversity resources. This essay examines the current management of butterflies in China and suggests various easily implementable actions that could improve these conservation efforts. Our recommendations are based on the observations of a transdisciplinary group of entomologists and environmental policy specialists. Our analysis draws on other successful examples around the world that China may wish to consider. China needs to modify its scientific methodologies behind butterfly conservation management: revising the criteria for listing protected species, focusing on umbrella species for broader protection, identifying high priority areas and refugia for conservation, among others. Rural and urban land uses that provide heterogeneous habitats, as well as butterfly host and nectar plants, must be promoted. Butterfly ranching and farming may also provide opportunities for sustainable community development. Many possibilities exist for incorporating observations of citizen scientists into butterfly data collection at broad spatial and temporal scales. Our recommendations further the ten Priority Areas of China’s National Biodiversity Conservation Strategy and Action Plan (2011–2030).

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Pesticide Contamination of Milkweeds Across the Agricultural, Urban, and Open Spaces of Low-Elevation Northern California

Cited by 32 publications

References 68 publications

Host Plant Species Mediates Impact of Neonicotinoid Exposure to Monarch Butterflies

Host Plant Species Mediates Impact of Neonicotinoid Exposure to Monarch Butterflies

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

Butterfly Conservation in China: From Science to Action

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