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Articles 1 - 5 of 5
Full-Text Articles in Toxicology
Neonicotinoids Can Cause Arrested Pupal Ecdysis In Lepidoptera, Niranjana Krishnan, Russell A. Jurenka, Steven P. Bradbury
Neonicotinoids Can Cause Arrested Pupal Ecdysis In Lepidoptera, Niranjana Krishnan, Russell A. Jurenka, Steven P. Bradbury
Biological Sciences Faculty Research & Creative Works
Recently, we reported a novel mode of action in monarch butterfly (Danaus plexippus) larvae exposed to neonicotinoid insecticides: arrest in pupal ecdysis following successful larval ecdysis. In this paper, we explore arrested pupal ecdysis in greater detail and propose adverse outcome pathways to explain how neonicotinoids cause this effect. Using imidacloprid as a model compound, we determined that final-instar monarchs, corn earworms (Helicoverpa zea), and wax moths (Galleria mellonella) showed high susceptibility to arrested pupal ecdysis while painted ladies (Vanessa cardui) and red admirals (Vanessa atalanta) showed low susceptibility. Fall …
Evaluating Toxicity Of Varroa Mite (Varroa Destructor)-Active Dsrna To Monarch Butterfly (Danaus Plexippus) Larvae, Niranjana Krishnan, Maura J. Hall, Richard L. Hellmich, Joel R. Coats, Steven P. Bradbury
Evaluating Toxicity Of Varroa Mite (Varroa Destructor)-Active Dsrna To Monarch Butterfly (Danaus Plexippus) Larvae, Niranjana Krishnan, Maura J. Hall, Richard L. Hellmich, Joel R. Coats, Steven P. Bradbury
Biological Sciences Faculty Research & Creative Works
Varroa mites (Varroa destructor) are parasitic mites that, combined with other factors, are contributing to high levels of honey bee (Apis mellifera) colony losses. A Varroa-active dsRNA was recently developed to control Varroa mites within honey bee brood cells. This dsRNA has 372 base pairs that are homologous to a sequence region within the Varroa mite calmodulin gene (cam). The Varroa-active dsRNA also shares a 21-base pair match with monarch butterfly (Danaus plexippus) calmodulin mRNA, raising the possibility of non-target effects if there is environmental exposure. We chronically exposed the entire monarch …
Monarch Butterfly (Danaus Plexippus) Life-Stage Risks From Foliar And Seed-Treatment Insecticides, Niranjana Krishnan, Yang Zhang, Melanie E. Aust, Richard L. Hellmich, Joel R. Coats, Steven P. Bradbury
Monarch Butterfly (Danaus Plexippus) Life-Stage Risks From Foliar And Seed-Treatment Insecticides, Niranjana Krishnan, Yang Zhang, Melanie E. Aust, Richard L. Hellmich, Joel R. Coats, Steven P. Bradbury
Biological Sciences Faculty Research & Creative Works
Conservation of North America's eastern monarch butterfly (Danaus plexippus) population would require establishment of milkweed (Asclepias spp.) and nectar plants in the agricultural landscapes of the north central United States. A variety of seed-treatment and foliar insecticides are used to manage early- and late-season pests in these landscapes. Thus, there is a need to assess risks of these insecticides to monarch butterfly life stages to inform habitat conservation practices. Chronic and acute dietary toxicity studies were undertaken with larvae and adults, and acute topical bioassays were conducted with eggs, pupae, and adults using 6 representative insecticides: beta-cyfluthrin …
Conservation Risks And Benefits Of Establishing Monarch Butterfly (Danaus Plexippus) Breeding Habitats Close To Maize And Soybean Fields In The North Central United States: A Landscape-Scale Analysis Of The Impact Of Foliar Insecticide On Nonmigratory Monarch Butterfly Populations, Tyler J. Grant, Niranjana Krishnan, Steven P. Bradbury
Conservation Risks And Benefits Of Establishing Monarch Butterfly (Danaus Plexippus) Breeding Habitats Close To Maize And Soybean Fields In The North Central United States: A Landscape-Scale Analysis Of The Impact Of Foliar Insecticide On Nonmigratory Monarch Butterfly Populations, Tyler J. Grant, Niranjana Krishnan, Steven P. Bradbury
Biological Sciences Faculty Research & Creative Works
Establishing habitat in agricultural landscapes of the north central United States is critical to reversing the decline of North America's eastern monarch butterfly (Danaus plexippus) population. Insecticide use could create population sinks and threaten recovery. Discouraging habitat establishment within a 38-m zone around crop fields is a suggested risk mitigation measure. In Story County, Iowa, United States, this mitigation would discourage habitat establishment in 84% of roadsides and 38% of noncrop land. It is unclear if the conservation benefits from establishing habitat close to crop fields outweigh suppression of population growth owing to insecticide exposure. Consequently, monarch conservation …
Assessing Field-Scale Risks Of Foliar Insecticide Applications To Monarch Butterfly (Danaus Plexippus) Larvae, Niranjana Krishnan, Yang Zhang, Keith G. Bidne, Richard L. Hellmich, Joel R. Coats, Steven P. Bradbury
Assessing Field-Scale Risks Of Foliar Insecticide Applications To Monarch Butterfly (Danaus Plexippus) Larvae, Niranjana Krishnan, Yang Zhang, Keith G. Bidne, Richard L. Hellmich, Joel R. Coats, Steven P. Bradbury
Biological Sciences Faculty Research & Creative Works
Establishment and maintenance of milkweed plants (Asclepias spp.) in agricultural landscapes of the north central United States are needed to reverse the decline of North America's eastern monarch butterfly (Danaus plexippus) population. Because of a lack of toxicity data, it is unclear how insecticide use may reduce monarch productivity when milkweed habitat is placed near maize and soybean fields. To assess the potential effects of foliar insecticides, acute cuticular and dietary toxicity of 5 representative active ingredients were determined: beta-cyfluthrin (pyrethroid), chlorantraniliprole (anthranilic diamide), chlorpyrifos (organophosphate), and imidacloprid and thiamethoxam (neonicotinoids). Cuticular median lethal dose values for …