Our lab is employing the adverse outcome pathway (AOP) framework to estimate the risk of pesticide exposures to insects at different levels of biological organization. This is being undertaken via three research themes that incorporate in vitro, in vivo, and in silico methods:
AOP development from molecular initiating events to organismal effects
AOP development from organismal to population level effects
AOP employment to inform interspecies extrapolation
AOP development from molecular initiating events to organismal effects: Novel modes of action
We are elucidating unique low-dose effects produced by certain pesticides and other neuroactive chemicals on insect development, specifically insect pupal and adult ecdysis. These effects strongly suggest that the neuroactive compounds act through a novel mode of action. Results obtained from this project will broaden understanding of insect ecdysis and the interplay between neuroendocrine hormones and neurotransmitters. It could also lead to the development of more sustainable and targeted pest management strategies.
AOP development from organismal to population level effects: Non-target testing
We are assessing the toxicity and risk of chemical and biological pesticides on non-target insects, including insect species of conservation concern. This involves developing conceptual models to evaluate potential exposure pathways, undertaking toxicity bioassays, estimating exposure, and analyzing field and landscape-scale effects. Results obtained from this project will help determine the susceptibility of non-target insects to different pesticide use scenarios and could inform conservation practices for declining species.
AOP employment to inform interspecies extrapolation: Interspecies differences
We are elucidating differences in pesticide susceptibility within and across insect orders. This involves determining toxicokinetic and toxicodynamic factors responsible for differing susceptibilities, identifying surrogate species for toxicity testing, and extrapolating effects across species and orders. Results obtained from this project can help estimate pesticide toxicity for hard-to-rear and endangered/threatened species, and could reduce, refine, and replace insect use in toxicity bioassays.
Publications
2022
Grant TJ*, Fisher KE*, Krishnan N*, Mullin AN, Hellmich RL, Sappington TW, Adelman JS, Coats JR, Hartzler RG, Pleasants JM, Bradbury SP. Monarch butterfly ecology, behavior, and vulnerabilities in north central USA agricultural landscapes: Transdisciplinary research to support conservation decisions. BioScience. 10.1093/biosci/biac094
*Authors contributed equally.
2021
Hall MJ*, Krishnan N*, Coats JR, Bradbury SPP. Estimating screening-level risks of insecticide exposure to lepidopteran species of conservation concern in agroecosystems. American Chemical Society Symposium Series. 10.1021/bk-2021-1390.ch008
*Authors contributed equally.
Krishnan N, Jurenka RA, Bradbury SP. Neonicotinoids can cause arrested pupal ecdysis in Lepidoptera. Scientific Reports. 10.1038/s41598-021-95284-0
Krishnan N*, Hall MJ*, Hellmich RL, Coats JR, Bradbury SP. Assessing the toxicity of varroa-active dsRNA on monarch butterfly (Danaus plexippus) larvae. PLOS ONE. 10.1371/journal.pone.0251884
*Authors contributed equally.
Grant TJ, Krishnan N, Bradbury SP. Conservation risks and benefits of establishing monarch butterfly (Danaus plexippus) breeding habitat in close proximity to maize and soybean fields in the U.S. Midwest: A landscape-scale analysis of foliar insecticide effect on non-migratory monarch butterfly populations. Integrated Environmental Assessment and Management. 10.1002/ieam.4402
Krishnan N, Yang Z, Aust M, Hellmich RL, Coats JR, Bradbury SP. Monarch butterfly (Danaus plexippus) life stage risks from foliar and seed treatment insecticides. Environmental Toxicology and Chemistry. 10.1002/etc.5016
2020
Krishnan N, Yang Z, Bidne KG, Hellmich RL, Coats JR, Bradbury SP. Assessing field-scale risks of foliar insecticide applications to monarch butterfly (Danaus plexippus) larvae. Environmental Toxicology and Chemistry. 10.1002/etc.4672
2019
Krishnan N. Aquatic Toxicity Tests. Perspectives of Aquatic Toxicology Wikibook. Jovanovic B, ed. https://en.wikibooks.org/wiki/Perspectives_of_Aquatic_Toxicology
Grant TJ*, Fisher KE*, Krishnan N*, Mullin AN, Hellmich RL, Sappington TW, Adelman JS, Coats JR, Hartzler RG, Pleasants JM, Bradbury SP. Monarch butterfly ecology, behavior, and vulnerabilities in north central USA agricultural landscapes: Transdisciplinary research to support conservation decisions. BioScience. 10.1093/biosci/biac094
*Authors contributed equally.
2021
Hall MJ*, Krishnan N*, Coats JR, Bradbury SPP. Estimating screening-level risks of insecticide exposure to lepidopteran species of conservation concern in agroecosystems. American Chemical Society Symposium Series. 10.1021/bk-2021-1390.ch008
*Authors contributed equally.
Krishnan N, Jurenka RA, Bradbury SP. Neonicotinoids can cause arrested pupal ecdysis in Lepidoptera. Scientific Reports. 10.1038/s41598-021-95284-0
Krishnan N*, Hall MJ*, Hellmich RL, Coats JR, Bradbury SP. Assessing the toxicity of varroa-active dsRNA on monarch butterfly (Danaus plexippus) larvae. PLOS ONE. 10.1371/journal.pone.0251884
*Authors contributed equally.
Grant TJ, Krishnan N, Bradbury SP. Conservation risks and benefits of establishing monarch butterfly (Danaus plexippus) breeding habitat in close proximity to maize and soybean fields in the U.S. Midwest: A landscape-scale analysis of foliar insecticide effect on non-migratory monarch butterfly populations. Integrated Environmental Assessment and Management. 10.1002/ieam.4402
Krishnan N, Yang Z, Aust M, Hellmich RL, Coats JR, Bradbury SP. Monarch butterfly (Danaus plexippus) life stage risks from foliar and seed treatment insecticides. Environmental Toxicology and Chemistry. 10.1002/etc.5016
2020
Krishnan N, Yang Z, Bidne KG, Hellmich RL, Coats JR, Bradbury SP. Assessing field-scale risks of foliar insecticide applications to monarch butterfly (Danaus plexippus) larvae. Environmental Toxicology and Chemistry. 10.1002/etc.4672
2019
Krishnan N. Aquatic Toxicity Tests. Perspectives of Aquatic Toxicology Wikibook. Jovanovic B, ed. https://en.wikibooks.org/wiki/Perspectives_of_Aquatic_Toxicology