Performing Department
Entomology
Non Technical Summary
Native pollinators need healthy ecosystems, but pollinator habitats in agricultural areas can be impacted by pesticides used in neighboring farm fields. While insecticides can directly affect pollinator health, chemicals like fungicides can indirectly impact pollinators by acting on the microbes and plants on which pollinators depend. The presence of these pesticides could also alter pollinator behavior in ways that change their exposure to potentially harmful chemicals. In this collaborative project, we focus on these indirect effects, which can lead to "ecological surprises" in pollinator conservation. Our team has preliminary data from a pollinator habitat restoration experiment, where we find that regular exposure of plants and soils to insecticide and fungicide treatment changes microbial function in the soil and alters the availability of floral resources to foraging bees. In this collaborative project, we will build on this experiment in order to accomplish two overarching research objectives: 1) Determine how pesticide-altered soil and plant microbiomes affect pollinator and plant health; and 2) Investigate how pesticides affect nesting and foraging decisions of native bees. We will also identify key microbial agents of pollinator health. This project addresses two priority areas of the Pollinator Health program: Factors that influence the abundance, diversity, and health of pollinators; and Functions of the microbiome associated with pollinators and their role in promoting healthy populations.
Animal Health Component
0%
Research Effort Categories
Basic
50%
Applied
50%
Developmental
(N/A)
Goals / Objectives
The overall objective of this project is to characterize the indirect and interactive effects of fungicides and insecticides on native pollinator health in restored pollinator habitats. Our central hypothesis is that fungicides and insecticides impact pollinator health by altering the composition and function of critical soil and plant microbial associations that influence bee survival and behavior. These indirect influences of pollinator health can lead to ecological surprises that affect successful restoration and conservation efforts, and this project will address critical knowledge gaps about different pathways through which pesticides affect pollinators. Our project will generate a deeper understanding of the use and misuse of pesticides in pollinator conservation efforts, and discovery of the varied roles that plants, microbes and bee behavior play in pollinator health. We will test our central hypothesis, and thereby accomplish the overall objective of this proposal, by pursuing the following goals: (1) Quantify the effects of pesticide-altered soil microbiota on the health and survival of ground-nesting bees. We will accomplish this goal through a series of lab-based mesocosm experiments using live and sterilized soils derived from an ongoing field experiment that includes pesticide and fungicide addition. (2) Quantify the effects of pesticide-altered soil and plant microbiota on the health, survival, and population dynamics of "bee plant" species that are beneficial for pollinator health. We will accomplish this goal through greenhouse-based experiments using live and sterilized soils from our ongoing field experiment. (3) Determine how pesticide- and fungicide-mediated changes in soil microbiota affect foraging and nesting decisions of bees. We will accomplish this goal using lab-based behavior trials using soils inoculated with live microbes and insecticide and fungicide, and we will also document pollinator foraging behavior in the field using plants grown under controlled conditions to disentangle the relative effects of pesticides and microbe-mediated changes.
Project Methods
This project leverages an ongoing pollinator habitat restoration experiment that includes annual insecticide and fungicide application treatments. We will use this experiment to make field-based observations of pollinator behavior in pesticide-contaminated and pesticide-free plots. We will use this experiment to generate pesticide-impacted "legacy" soil and plant-associated microbial communities that we can use in controlled mesocosm and greenhouse-based studies. We will expose bees in their ground-nesting life stages to these soils in mesocosms that allow us to monitor bee health and survival over the course of development. Comparison of these treatments to bees exposed to sterilized soil inoculum will allow us to quantify the microbial role in bee health and survival, and comparisons among the different live soil conditions will allow us to quantify how the pesticide legacy affects bee health outcomes. Similarly, we will conduct greenhouse experiments using important "bee plants" growing in live and sterilized legacy soils to determine how pesticide legacies affect microbes that determine plant health and performance. We will characterize bee- and plant-associated microbial communities in these mesocosm and greenhouse experiments using high-throughput Illumina DNA sequencing, and we will use Bayesian inference to identify microbes that respond to pesticide legacies and microbes that are correlated to plant or bee health. Finally, we will conduct controlled foraging choice experiments using plants growing in pesticide-contaminated and pesticide-free soils to determine if pesticide presence in plant tissues or soils influences pollinator foraging behavior.