Abstract
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 armyworms (Spodoptera frugiperda) and European corn borers (Ostrinia nubilalis) were recalcitrant. All larvae with arrested ecdysis developed pupal cuticle, but with incomplete shedding of larval cuticle and unexpanded pupal appendages; corn earworm larvae successfully developed into adults with unexpanded appendages. Delayed initiation of pupal ecdysis was also observed with treated larvae. Imidacloprid exposure was required at least 26 h prior to pupal ecdysis to disrupt the molt. These observations suggest neonicotinoids may disrupt the function of crustacean cardioactive peptide (CCAP) neurons, either by directly acting on their nicotinic acetylcholine receptors or by acting on receptors of inhibitory neurons that regulate CCAP activity.
Recommended Citation
N. Krishnan et al., "Neonicotinoids Can Cause Arrested Pupal Ecdysis in Lepidoptera," Scientific Reports, vol. 11, article no. 15787, Nature Research, Aug 2021.
The definitive version is available at https://doi.org/10.1038/s41598-021-95284-0
Department(s)
Biological Sciences
International Standard Serial Number (ISSN)
2045-2322
Document Type
Article - Journal
Document Version
Final Version
File Type
text
Language(s)
English
Rights
© 2021 The Authors, All rights reserved.
Creative Commons Licensing
This work is licensed under a Creative Commons Attribution 4.0 License.
Publication Date
04 Aug 2021
Comments
This research was funded by the Henry and Sylvia Richardson Research Incentive Grant obtained from the entomology department at Iowa State University (ISU) ($1000 student grant). It was also supported in part by the Agriculture and Food Research Initiative Pollinator Health Program (Grant No. 2018-67013-27541) from the U.S. Department of Agriculture (USDA) National Institute of Food and Agriculture and State of Iowa funds.