Nontarget impacts of neonicotinoids on nectar-inhabiting microbes

Plant-systemic neonicotinoid (NN) insecticides can exert non-target impacts on organisms like beneficial insects and soil microbes. NNs can affect plant microbiomes, but we know little about their effects on microbial communities that mediate plant-insect interactions, including nectar-inhabiting microbes (NIMs). Here we employed two approaches to assess impacts of NN exposure on several NIM taxa. First, we assayed in vitro effects of six NN compounds on NIM growth using plate assays. Second, we inoculated a standardized NIM community into nectar of NN-treated canola (Brassica napus) and assessed survival and growth after 24 hours. With few exceptions, in vitro NN exposure tended to decrease bacterial growth metrics. However, the magnitude of decrease and the NN concentrations at which effects were observed varied substantially across bacteria. Yeasts showed no consistent in vitro response to NNs. In nectar, we saw no effects of NN treatment on NIM community metrics. Rather, NIM abundan..., EXPERIMENTAL PROCEDURES 
Overview of experiments
To determine if and how exposure to NN residues affects the growth and abundance of NIMs, we conducted two separate experiments. First, we grew seven microbes as pure (single-species) cultures in artificial broths spiked to contain one of four concentrations of each of six NN compounds. We monitored microbial growth over 72 h and calculated maximum growth rate (r) and carrying capacity (K). Second, we inoculated a standardized community of four microbe taxa (a subset of those from the first experiment) into floral nectar of greenhouse-grown, potted canola plants. Plants had been treated with either low or high doses of two commercial NN formulations. Plants were also irrigated at either a low or high rate to monitor for any effect of water availability on nectar characteristics, NN translocation, or microbe community metrics.
In vitro plate reader experiment
We selected seven microbe species to assay growth in the presence of set concentr..., , # Nontarget impacts of neonicotinoids on nectar-inhabiting microbes

\[[https://doi.org/10.5061/dryad.gf1vhhmw2](https://doi.org/10.5061/dryad.gf1vhhmw2)]([https://doi.org/10.5061/dryad.gf1vhhmw2](https://doi.org/10.5061/dryad.gf1vhhmw2))

This README file was generated on 2024-03-06 by Jacob M. Cecala.

\# GENERAL INFORMATION

1\. Title of Dataset: Nontarget impacts of neonicotinoids on nectar-inhabiting microbes

2\. Author Information

A. Principal Investigator Contact Information

Name: Jacob M. Cecala

Institution: University of California, Davis

Address: Davis, CA, USA

Email: [[e-mail]](mailto:[e-mail])

B. Associate or Co-investigator Contact Information

Name: Rachel L. Vannette

Institution: University of California, Davis
Address: Davis, CA, USA
Email: [[e-mail]](mailto:[e-mail])

3\. Years of data collection: 2021-2022

4\. Geographic location of data collection: University of California, Davis, CA, USA

5\. Information about ...