Estimated effects of climate and imidacloprid use on the abundances of woodland salamanders. Maerz, J. C., Samples, J. A., Bradke, D. R., Bassham, C., Martin, J. A., Hepinstall-Cymerman, J., Lagalante, A. F., & McCarty, E. Forest Ecology and Management, 606:123553, April, 2026. ![Estimated effects of climate and imidacloprid use on the abundances of woodland salamanders [link]](https://bibbase.org/img/filetypes/link.svg "link")
Paper doi abstract bibtex When considering the use of pesticides, forest managers need to make decisions about potential trade-offs between conserving target species and negatively affecting non-target species. To aid those decisions, estimates of non-target effects should contextualize effect sizes relative to other drivers of variation in non-target species abundance or fitness. Hemlock woolly adelgid (HWA) has decimated eastern and Carolina hemlock populations in the Southern Appalachian Mountains. Imidacloprid, a neonicotinoid insecticide, is currently used to suppress HWA populations and conserve hemlock trees and the habitats they create. Recent concerns have emerged about possible non-target impacts of imidacloprid use on amphibians including salamander populations in managed hemlock forests. Robust estimates of the impacts of imidacloprid application on salamander populations are needed to inform decisions on hemlock conservation in sensitive areas. We conducted repeated depletion samples among 15 replicate plots at each of 15 imidacloprid-treated and 9 untreated reference sites across north Georgia, western North Carolina, and eastern Tennessee. We used a hierarchical N-mixture model in a Bayesian framework to estimate any potential association between imidacloprid application and the terrestrial abundances of two direct-developing plethodontid salamander groups (Plethodon spp. and Desmognathus aeneus/D. wrighti) and a stream-breeding plethodontid salamander guild. We also estimated the relationship between hydroclimate and plethodontid salamander abundance because climate is a known driver of plethodontid salamander ecology and provides a comparative scale for any potential effect of imidacloprid use on salamander abundance. Mean Plethodon, D. aeneus/D. wrighti, and stream-breeding plethodontid abundances among all sites varied by factors of 20, 15, and 2 respectively. Mean daily vapor pressure deficit from 2011 to 2020, a measure of hydroclimate, was negatively associated with abundance of all three salamander groups. For Plethodon and D. aeneus/D. wrighti we found no evidence of an association between salamander abundance and imidacloprid dose within a 15 m radius of a plot; however, we did find evidence for a small, positive association between Plethodon abundance and imidacloprid dose within a plot. For stream-breeding species, we also found evidence for a positive association between salamander abundance and imidacloprid dose within a plot, but also a negative association between salamander abundance and imidacloprid dose within a 15 m radius. The estimated negative relationship between imidacloprid use and stream salamander abundance was comparable to the effect of climate on natural variation. Our results suggest any measurable effect of hemlock management with imidacloprid on the abundance of fully terrestrial plethodontid salamanders is trivially small compared to natural variation related to climate. However, the evidence of a negative association between imidacloprid dose and the abundance of stream-breeding plethodontids may indicate a negative effect of imidacloprid use on adjacent, aquatic larval habitats. Hemlocks are an iconic and ecologically important tree, and hemlock conservation has its own merits. None of the streambreeding species we encountered are considered rare or threatened and all occur in areas with and without hemlocks. Therefore, the continued use of imidacloprid near streams may be warranted at those sites where the salamander species present are common and widely distributed. Managers treating sites where there are rare or threatened stream-breeding salamander species should weigh potential risks to those species until more is known about imidacloprid effects on those species.
@article{maerz_estimated_2026,
title = {Estimated effects of climate and imidacloprid use on the abundances of woodland salamanders},
volume = {606},
issn = {03781127},
url = {https://linkinghub.elsevier.com/retrieve/pii/S0378112726000514},
doi = {10.1016/j.foreco.2026.123553},
abstract = {When considering the use of pesticides, forest managers need to make decisions about potential trade-offs between conserving target species and negatively affecting non-target species. To aid those decisions, estimates of non-target effects should contextualize effect sizes relative to other drivers of variation in non-target species abundance or fitness. Hemlock woolly adelgid (HWA) has decimated eastern and Carolina hemlock populations in the Southern Appalachian Mountains. Imidacloprid, a neonicotinoid insecticide, is currently used to suppress HWA populations and conserve hemlock trees and the habitats they create. Recent concerns have emerged about possible non-target impacts of imidacloprid use on amphibians including salamander populations in managed hemlock forests. Robust estimates of the impacts of imidacloprid application on salamander populations are needed to inform decisions on hemlock conservation in sensitive areas. We conducted repeated depletion samples among 15 replicate plots at each of 15 imidacloprid-treated and 9 untreated reference sites across north Georgia, western North Carolina, and eastern Tennessee. We used a hierarchical N-mixture model in a Bayesian framework to estimate any potential association between imidacloprid application and the terrestrial abundances of two direct-developing plethodontid salamander groups (Plethodon spp. and Desmognathus aeneus/D. wrighti) and a stream-breeding plethodontid salamander guild. We also estimated the relationship between hydroclimate and plethodontid salamander abundance because climate is a known driver of plethodontid salamander ecology and provides a comparative scale for any potential effect of imidacloprid use on salamander abundance. Mean Plethodon, D. aeneus/D. wrighti, and stream-breeding plethodontid abundances among all sites varied by factors of 20, 15, and 2 respectively. Mean daily vapor pressure deficit from 2011 to 2020, a measure of hydroclimate, was negatively associated with abundance of all three salamander groups. For Plethodon and D. aeneus/D. wrighti we found no evidence of an association between salamander abundance and imidacloprid dose within a 15 m radius of a plot; however, we did find evidence for a small, positive association between Plethodon abundance and imidacloprid dose within a plot. For stream-breeding species, we also found evidence for a positive association between salamander abundance and imidacloprid dose within a plot, but also a negative association between salamander abundance and imidacloprid dose within a 15 m radius. The estimated negative relationship between imidacloprid use and stream salamander abundance was comparable to the effect of climate on natural variation. Our results suggest any measurable effect of hemlock management with imidacloprid on the abundance of fully terrestrial plethodontid salamanders is trivially small compared to natural variation related to climate. However, the evidence of a negative association between imidacloprid dose and the abundance of stream-breeding plethodontids may indicate a negative effect of imidacloprid use on adjacent, aquatic larval habitats. Hemlocks are an iconic and ecologically important tree, and hemlock conservation has its own merits. None of the streambreeding species we encountered are considered rare or threatened and all occur in areas with and without hemlocks. Therefore, the continued use of imidacloprid near streams may be warranted at those sites where the salamander species present are common and widely distributed. Managers treating sites where there are rare or threatened stream-breeding salamander species should weigh potential risks to those species until more is known about imidacloprid effects on those species.},
language = {en},
urldate = {2026-01-26},
journal = {Forest Ecology and Management},
author = {Maerz, John C. and Samples, Jade A. and Bradke, Danielle R. and Bassham, Cheyana and Martin, James A. and Hepinstall-Cymerman, Jeffrey and Lagalante, Anthony F. and McCarty, Elizabeth},
month = apr,
year = {2026},
pages = {123553},
}
Downloads: 0
{"_id":"fjgAhjaspL86Zx5Ro","bibbaseid":"maerz-samples-bradke-bassham-martin-hepinstallcymerman-lagalante-mccarty-estimatedeffectsofclimateandimidaclopriduseontheabundancesofwoodlandsalamanders-2026","author_short":["Maerz, J. C.","Samples, J. A.","Bradke, D. R.","Bassham, C.","Martin, J. A.","Hepinstall-Cymerman, J.","Lagalante, A. F.","McCarty, E."],"bibdata":{"bibtype":"article","type":"article","title":"Estimated effects of climate and imidacloprid use on the abundances of woodland salamanders","volume":"606","issn":"03781127","url":"https://linkinghub.elsevier.com/retrieve/pii/S0378112726000514","doi":"10.1016/j.foreco.2026.123553","abstract":"When considering the use of pesticides, forest managers need to make decisions about potential trade-offs between conserving target species and negatively affecting non-target species. To aid those decisions, estimates of non-target effects should contextualize effect sizes relative to other drivers of variation in non-target species abundance or fitness. Hemlock woolly adelgid (HWA) has decimated eastern and Carolina hemlock populations in the Southern Appalachian Mountains. Imidacloprid, a neonicotinoid insecticide, is currently used to suppress HWA populations and conserve hemlock trees and the habitats they create. Recent concerns have emerged about possible non-target impacts of imidacloprid use on amphibians including salamander populations in managed hemlock forests. Robust estimates of the impacts of imidacloprid application on salamander populations are needed to inform decisions on hemlock conservation in sensitive areas. We conducted repeated depletion samples among 15 replicate plots at each of 15 imidacloprid-treated and 9 untreated reference sites across north Georgia, western North Carolina, and eastern Tennessee. We used a hierarchical N-mixture model in a Bayesian framework to estimate any potential association between imidacloprid application and the terrestrial abundances of two direct-developing plethodontid salamander groups (Plethodon spp. and Desmognathus aeneus/D. wrighti) and a stream-breeding plethodontid salamander guild. We also estimated the relationship between hydroclimate and plethodontid salamander abundance because climate is a known driver of plethodontid salamander ecology and provides a comparative scale for any potential effect of imidacloprid use on salamander abundance. Mean Plethodon, D. aeneus/D. wrighti, and stream-breeding plethodontid abundances among all sites varied by factors of 20, 15, and 2 respectively. Mean daily vapor pressure deficit from 2011 to 2020, a measure of hydroclimate, was negatively associated with abundance of all three salamander groups. For Plethodon and D. aeneus/D. wrighti we found no evidence of an association between salamander abundance and imidacloprid dose within a 15 m radius of a plot; however, we did find evidence for a small, positive association between Plethodon abundance and imidacloprid dose within a plot. For stream-breeding species, we also found evidence for a positive association between salamander abundance and imidacloprid dose within a plot, but also a negative association between salamander abundance and imidacloprid dose within a 15 m radius. The estimated negative relationship between imidacloprid use and stream salamander abundance was comparable to the effect of climate on natural variation. Our results suggest any measurable effect of hemlock management with imidacloprid on the abundance of fully terrestrial plethodontid salamanders is trivially small compared to natural variation related to climate. However, the evidence of a negative association between imidacloprid dose and the abundance of stream-breeding plethodontids may indicate a negative effect of imidacloprid use on adjacent, aquatic larval habitats. Hemlocks are an iconic and ecologically important tree, and hemlock conservation has its own merits. None of the streambreeding species we encountered are considered rare or threatened and all occur in areas with and without hemlocks. Therefore, the continued use of imidacloprid near streams may be warranted at those sites where the salamander species present are common and widely distributed. Managers treating sites where there are rare or threatened stream-breeding salamander species should weigh potential risks to those species until more is known about imidacloprid effects on those species.","language":"en","urldate":"2026-01-26","journal":"Forest Ecology and Management","author":[{"propositions":[],"lastnames":["Maerz"],"firstnames":["John","C."],"suffixes":[]},{"propositions":[],"lastnames":["Samples"],"firstnames":["Jade","A."],"suffixes":[]},{"propositions":[],"lastnames":["Bradke"],"firstnames":["Danielle","R."],"suffixes":[]},{"propositions":[],"lastnames":["Bassham"],"firstnames":["Cheyana"],"suffixes":[]},{"propositions":[],"lastnames":["Martin"],"firstnames":["James","A."],"suffixes":[]},{"propositions":[],"lastnames":["Hepinstall-Cymerman"],"firstnames":["Jeffrey"],"suffixes":[]},{"propositions":[],"lastnames":["Lagalante"],"firstnames":["Anthony","F."],"suffixes":[]},{"propositions":[],"lastnames":["McCarty"],"firstnames":["Elizabeth"],"suffixes":[]}],"month":"April","year":"2026","pages":"123553","bibtex":"@article{maerz_estimated_2026,\n\ttitle = {Estimated effects of climate and imidacloprid use on the abundances of woodland salamanders},\n\tvolume = {606},\n\tissn = {03781127},\n\turl = {https://linkinghub.elsevier.com/retrieve/pii/S0378112726000514},\n\tdoi = {10.1016/j.foreco.2026.123553},\n\tabstract = {When considering the use of pesticides, forest managers need to make decisions about potential trade-offs between conserving target species and negatively affecting non-target species. To aid those decisions, estimates of non-target effects should contextualize effect sizes relative to other drivers of variation in non-target species abundance or fitness. Hemlock woolly adelgid (HWA) has decimated eastern and Carolina hemlock populations in the Southern Appalachian Mountains. Imidacloprid, a neonicotinoid insecticide, is currently used to suppress HWA populations and conserve hemlock trees and the habitats they create. Recent concerns have emerged about possible non-target impacts of imidacloprid use on amphibians including salamander populations in managed hemlock forests. Robust estimates of the impacts of imidacloprid application on salamander populations are needed to inform decisions on hemlock conservation in sensitive areas. We conducted repeated depletion samples among 15 replicate plots at each of 15 imidacloprid-treated and 9 untreated reference sites across north Georgia, western North Carolina, and eastern Tennessee. We used a hierarchical N-mixture model in a Bayesian framework to estimate any potential association between imidacloprid application and the terrestrial abundances of two direct-developing plethodontid salamander groups (Plethodon spp. and Desmognathus aeneus/D. wrighti) and a stream-breeding plethodontid salamander guild. We also estimated the relationship between hydroclimate and plethodontid salamander abundance because climate is a known driver of plethodontid salamander ecology and provides a comparative scale for any potential effect of imidacloprid use on salamander abundance. Mean Plethodon, D. aeneus/D. wrighti, and stream-breeding plethodontid abundances among all sites varied by factors of 20, 15, and 2 respectively. Mean daily vapor pressure deficit from 2011 to 2020, a measure of hydroclimate, was negatively associated with abundance of all three salamander groups. For Plethodon and D. aeneus/D. wrighti we found no evidence of an association between salamander abundance and imidacloprid dose within a 15 m radius of a plot; however, we did find evidence for a small, positive association between Plethodon abundance and imidacloprid dose within a plot. For stream-breeding species, we also found evidence for a positive association between salamander abundance and imidacloprid dose within a plot, but also a negative association between salamander abundance and imidacloprid dose within a 15 m radius. The estimated negative relationship between imidacloprid use and stream salamander abundance was comparable to the effect of climate on natural variation. Our results suggest any measurable effect of hemlock management with imidacloprid on the abundance of fully terrestrial plethodontid salamanders is trivially small compared to natural variation related to climate. However, the evidence of a negative association between imidacloprid dose and the abundance of stream-breeding plethodontids may indicate a negative effect of imidacloprid use on adjacent, aquatic larval habitats. Hemlocks are an iconic and ecologically important tree, and hemlock conservation has its own merits. None of the streambreeding species we encountered are considered rare or threatened and all occur in areas with and without hemlocks. Therefore, the continued use of imidacloprid near streams may be warranted at those sites where the salamander species present are common and widely distributed. Managers treating sites where there are rare or threatened stream-breeding salamander species should weigh potential risks to those species until more is known about imidacloprid effects on those species.},\n\tlanguage = {en},\n\turldate = {2026-01-26},\n\tjournal = {Forest Ecology and Management},\n\tauthor = {Maerz, John C. and Samples, Jade A. and Bradke, Danielle R. and Bassham, Cheyana and Martin, James A. and Hepinstall-Cymerman, Jeffrey and Lagalante, Anthony F. and McCarty, Elizabeth},\n\tmonth = apr,\n\tyear = {2026},\n\tpages = {123553},\n}\n\n\n\n","author_short":["Maerz, J. C.","Samples, J. A.","Bradke, D. R.","Bassham, C.","Martin, J. A.","Hepinstall-Cymerman, J.","Lagalante, A. F.","McCarty, E."],"key":"maerz_estimated_2026","id":"maerz_estimated_2026","bibbaseid":"maerz-samples-bradke-bassham-martin-hepinstallcymerman-lagalante-mccarty-estimatedeffectsofclimateandimidaclopriduseontheabundancesofwoodlandsalamanders-2026","role":"author","urls":{"Paper":"https://linkinghub.elsevier.com/retrieve/pii/S0378112726000514"},"metadata":{"authorlinks":{}},"html":""},"bibtype":"article","biburl":"https://bibbase.org/zotero-group/jcmaerz/6026147","dataSources":["FuXGdg8RaL9fWCJW7"],"keywords":[],"search_terms":["estimated","effects","climate","imidacloprid","use","abundances","woodland","salamanders","maerz","samples","bradke","bassham","martin","hepinstall-cymerman","lagalante","mccarty"],"title":"Estimated effects of climate and imidacloprid use on the abundances of woodland salamanders","year":2026}