Bumble bees being prepped for pesticide residue analysis at the USGS Organic Chemistry Research Laboratory (OCRL), California.
Michelle L Hladik, PhD
(She/her)I am an environmental organic chemist whose current research focuses on the fate and transport of current-use pesticides and other organic contaminants in aquatic and terrestrial environments.
Much of my research is focused on pesticides but also includes other organic contaminants. I direct a research laboratory that is focused on developing new methods to measure pesticides and their degradates in water, sediment, and biota. My laboratory specializes in small samples sizes, complex matrices, and non-standard procedues. Additionally, I also work on developing methods and measuring disinfection by-products in treated water (especially those that are not-currently regulated and are understudied) with a focus on wastewater discharges.
Professional Experience
Research Chemist, USGS, California Water Science Center, Sacramento, 2006 to present
Chemist, USGS, California Water Science Center, Sacramento, 2005-2006
Graduate Fellow/Research and Teaching Assistant, Deparment of Geography and Environmental Engineering, Johns Hopkins University, 1999-2005
Undergraduate Research Summer Institute, Department of Chemistry, Vassar College, 1997,1998
Undergraduate Research and Teaching Assistant, Department of Chemistry, Vassar College ,1997,1998
Education and Certifications
Ph.D. 2005, Environmental Engineering and Chemistry, Johns Hopkins University, Baltimore, Maryland
B.A. 1999, Chemistry, Vassar College, Poughkeepsie, New York
Science and Products
Organic Chemistry Research Core Technology Team
A National Assessment of Pesticide, PFAS, Microplastic, and Antibiotic Resistance Gene Exposures in White-Tailed Deer
Collaborative Science Provides Understanding of Contaminants in Bottled Water-an Increasingly Common Alternate Drinking Water Source
Wild Prairie Grouse Diet and Microbiomes Vary Between Cropland and Grassland Habitats
Pesticides Detected in Bees, Flowers, Soil, and Air within Pollinator-Attractive Row-Crop Border Plantings
Science to Understand Low-Level Exposures to Neonicotinoid Pesticides, their Metabolites, and Chlorinated Byproducts in Drinking Water
Clothianidin Exposure Associated with Changes in Tadpole Behavior
Costs and Benefits of Nitrapyrin
Dysbiosis, immunomodulation, and health effects of agricultural pesticides in wild prairie grouse
Environmental Management of Vector-borne Diseases
Water-Quality Inventory Pesticides in the Golden Gate National Recreation Area
Pesticide Fate Research Group (PFRG)
Pesticides in small volume plasma samples
Target-Chemical Concentrations for Assessment of Mixed-Organic/Inorganic Chemical and Biological Exposures in Private-Well Tapwater at Campbell, Wisconsin, 2021
Analysis of Polyphenols in Water Primrose (Ludwigia hexapetala) Plants from the Sacramento-San Joaquin Delta of California
Target-chemical concentrations and microbiological results in surface water and tapwater, Montana, 2022
Current-use pesticides in tree swallow (Tachycineta bicolor) prey
Chemical Concentrations and Microbiological Results for Assessment of Mixed-Organic/Inorganic Chemical Exposures in Tapwater in Mead, Nebraska, June 2022 and January 2023
Pesticide Concentrations Measured in Zooplankton Samples Collected from the Sacramento River and Yolo Bypass, California, 2021
Target-chemical concentrations and bioassay results for assessment of mixed-organic/inorganic chemical and biological exposures in Minneapolis/St Paul, Minnesota tapwater, August 2019
Results from U.S. Geological Survey Environmental Health Food Resources Lifecycle Integrated Science Team, Graton Pesticides (GRAPE) Study, in Graton, California, April–May 2021
Multiresidue extraction of current-use pesticides from complex solid matrices using energized dispersive extraction with analysis by gas and liquid chromatography tandem mass spectroscopy
Pesticide Concentrations in American Bullfrog (Lithobates catesbeianus) Tadpoles Collected from Ponds and Reservoirs near Mead, Nebraska
Target-Chemical Concentrations and Microbiological Results for Assessment of Mixed Contaminant and Biological Exposures in Bottled Water, 2020
Bumble bees being prepped for pesticide residue analysis at the USGS Organic Chemistry Research Laboratory (OCRL), California.
Water samples are extracted for pesticides at the USGS Organic Chemistry Research Laboratory.
Photo credit: Elisabeth LaBarbera
Water samples are extracted for pesticides at the USGS Organic Chemistry Research Laboratory.
Photo credit: Elisabeth LaBarbera
Co-extracted matrix is removed from biosolids prior to analysis at the USGS Organic Chemistry Research Laboratory (OCRL).
Photo Credit: Gabby Black.
Co-extracted matrix is removed from biosolids prior to analysis at the USGS Organic Chemistry Research Laboratory (OCRL).
Photo Credit: Gabby Black.
Suspect screening/non-target analysis is done with LC-HRMS at the Organic Chemistry Research Laboratory (OCRL) in Sacramento, CA.
Photo credit: Michelle Hladik
Suspect screening/non-target analysis is done with LC-HRMS at the Organic Chemistry Research Laboratory (OCRL) in Sacramento, CA.
Photo credit: Michelle Hladik
Organic Chemistry Research Laboratory — Sacramento, California. Gas chromatograph-mass spectrometer - GCMS
Organic Chemistry Research Laboratory — Sacramento, California. Gas chromatograph-mass spectrometer - GCMS
Organic Chemistry Research Laboratory -- Sacramento, California. Small sample bottles with pollen inside
Organic Chemistry Research Laboratory -- Sacramento, California. Small sample bottles with pollen inside
In a field in northern California, seen here is a sunflower with several bees. Bees are drawn to sunflowers for several compelling reasons, and understanding this attraction sheds light on both the nature of bees and the characteristics of sunflowers.
In a field in northern California, seen here is a sunflower with several bees. Bees are drawn to sunflowers for several compelling reasons, and understanding this attraction sheds light on both the nature of bees and the characteristics of sunflowers.
Organic Chemistry Research Laboratory — Sacramento, California. USGS chemist working with samples in a laboratory hood
Organic Chemistry Research Laboratory — Sacramento, California. USGS chemist working with samples in a laboratory hood
Organic Chemistry Research Laboratory — Sacramento, California. USGS chemist homogenizes a tissue sample into a mortar and pestle
Organic Chemistry Research Laboratory — Sacramento, California. USGS chemist homogenizes a tissue sample into a mortar and pestle
Comparing modern identification methods for wild bees: Metabarcoding and image-based morphological taxonomic assignment
Determinants of spring migration departure dates in a New World sparrow: Weather variables reign supreme
Pesticides in small volume plasma samples: Method development and application to smallmouth bass (Micropterus dolomieu) from the Chesapeake Bay watershed, USA
Evaluating the reliability of environmental concentration data to characterize exposure in environmental risk assessments
Methods of analysis—Determination of pesticides in filtered water and suspended sediment using liquid chromatography- and gas chromatography-tandem mass spectrometry
Multigenerational, indirect exposure to pyrethroids demonstrates potential compensatory response and reduced toxicity at higher salinity in estuarine fish
Non-native Rhizophora mangle as sinks for coastal contamination on Moloka'i, Hawai'i
Conserved grasslands support similar pollinator diversity as pollinator-specific practice regardless of proximal cropland and pesticide exposure
Permethrin contamination of sawgrass marshes and potential risk for the imperiled Klot’s skipper butterfly (Euphyes pilatka klotsi)
Bifenthrin, a ubiquitous contaminant, impairs the development and behavior of the threatened Longfin Smelt during early life stages
Neonicotinoid sunflower seed treatment, while not detected in pollen and nectar, still impacts wild bees and crop yield
Comparative toxicity of two neonicotinoid insecticides at environmentally relevant concentrations to telecoprid dung beetles
Science and Products
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Organic Chemistry Research Core Technology Team
About the Research The Organic Chemistry Research Laboratory Core Technology Team (CTT) as part of the Environmental Health Program focuses on the identification and quantitation of trace level organic contaminants (with a special focus on pesticides) in a wide array of environmental media (water, sediment/soil, plants, biota, etc.).A National Assessment of Pesticide, PFAS, Microplastic, and Antibiotic Resistance Gene Exposures in White-Tailed Deer
Research has documented exposures and consequential environmental health effects of pesticides, PFAS, microplastics, and antibiotic resistance genes in environmental biota. Little is known, however, regarding such effects in white-tailed deer ( Odocoileus virginianus ).Collaborative Science Provides Understanding of Contaminants in Bottled Water-an Increasingly Common Alternate Drinking Water Source
U.S. Geological Survey researchers and public health experts collaborated to determine what contaminants occur in bottled water, which is an increasingly common alternate drinking water source, to broaden their understanding of human exposure to contaminants in drinking water supply chains. Bottled water, like public-supply and private-well tap water supply chains, contained multiple organic...Wild Prairie Grouse Diet and Microbiomes Vary Between Cropland and Grassland Habitats
Wild prairie grouse residing in croplands had altered diets and gut microbiome imbalances characterized by a greater abundance of pathogenic bacteria and antibiotic-resistance genes in comparison to those residing in grasslands. Similar gut microbiome imbalances are rarely associated with lethal outcomes, but rather linked to sublethal health effects including growth, development, behavior, immune...Pesticides Detected in Bees, Flowers, Soil, and Air within Pollinator-Attractive Row-Crop Border Plantings
Field study in California describes the potential for pollinator-attractive field borders in agricultural areas to become a pesticide exposure pathway to bees through soil, air, and plants.Science to Understand Low-Level Exposures to Neonicotinoid Pesticides, their Metabolites, and Chlorinated Byproducts in Drinking Water
Scientists reported the discovery of three neonicotinoid pesticides in drinking water and their potential for transformation and removal during water treatment. The research provides new insights into the persistence of neonicotinoids and their potential for transformation during water treatment and distribution, while also identifying granulated activated carbon as a potentially effective...Clothianidin Exposure Associated with Changes in Tadpole Behavior
During a laboratory exposure study, tadpole movement decreased with increased concentrations of clothianidin, a neonicotinoid pesticide. Decreased movement could affect a tadpole’s ability to forage, escape predation, and metamorphose before ponds dry.Costs and Benefits of Nitrapyrin
In December 2020, our research group (as part of the Food Integrated Science Team) published a review of nitrapyrin costs and benefits in the journal Environmental Science & Technology .Dysbiosis, immunomodulation, and health effects of agricultural pesticides in wild prairie grouse
Agrochemical pollution poses a severe threat to biodiversity. Agrochemicals can detrimentally affect wildlife growth, development, survival, reproduction, and immune responses, which facilitates emergence and spread of infectious diseases that may cause unusually high mortality. Animal microbiota plays a fundamental role in host’s food detoxification and defense against pathogens, regulates...Environmental Management of Vector-borne Diseases
Effective management programs for vector-borne pathogens, such as West Nile Virus and the Lyme disease spirochete, are necessary to protect public health. However, some vector control methods, such as landscape manipulations and pesticide applications, can also adversely affect nontarget species and environmentally sensitive natural systems. Efficient targeting and integration of vector control...Water-Quality Inventory Pesticides in the Golden Gate National Recreation Area
In 1998, all urban creeks in the San Francisco Bay Area were added to the Clean Water Act Section 303d list due to known or suspected diazinon impairment. Diazinon is an organophosphorus insecticide used on lawns, and fruit and vegetables. This pesticide has since been "phased out" and has not been available for purchase since late 2004. Diazinon use is declining and is being replaced by other...Pesticide Fate Research Group (PFRG)
Pesticides are used in both agricultural and urban settings to manage unwanted plants, insects, fungi, and other pests. However, these substances and their breakdown products can move beyond their intended application sites through various means, ending up in areas where they weren't meant to be. This movement can happen via the air, through water (both surface and groundwater), and by sticking to... - Data
Filter Total Items: 39
Pesticides in small volume plasma samples
Pesticides are widely applied and can enter the environment, potentially effecting non-target organisms. To better evaluate pesticide exposure using non-lethal techniques, a method was developed for the extraction of pesticides and their degradates from small (100 µL) volume plasma samples. Solid phase extraction was used for lipid removal after plasma samples were protein precipitated. Samples weTarget-Chemical Concentrations for Assessment of Mixed-Organic/Inorganic Chemical and Biological Exposures in Private-Well Tapwater at Campbell, Wisconsin, 2021
Tapwater samples were obtained from groundwater sources on French Island, in the town of Campbell, Wisconsin. Samples from three locations were collected multiple times over a period of three days to assess temporal variations in water quality. Samples from an additional eight locations, were collected one time, spatially distributed around Campbell. Due to privacy concerns, the exact location ofAnalysis of Polyphenols in Water Primrose (Ludwigia hexapetala) Plants from the Sacramento-San Joaquin Delta of California
Water primrose (Ludwigia hexapetala) is an invasive aquatic plant that has rapidly increased in coverage throughout the Sacramento-San Joaquin Delta. Water primrose has invaded wetlands and may contribute towards mortality of tules (Schoenoplectus spp.) and cattails (Typha spp.). Little research has been completed on the mechanisms responsible for marsh loss, but previous studies have suggested thTarget-chemical concentrations and microbiological results in surface water and tapwater, Montana, 2022
This data release contains the concentration and quality-assurance results for inorganic constituents, as well as organic compounds (volatile organic compounds [VOC], per- and polyfluoroalkyl substances [PFAS], pesticides and disinfection byproducts [DBP]) and microbiological results collected in the Little Big Horn River and residential or commercial tapwater locations in Montana. Twenty-two tapwCurrent-use pesticides in tree swallow (Tachycineta bicolor) prey
Analysis of biological tissues or direct sources of food may better characterize exposure of non-target organisms to current-use pesticides. Food boluses were collected from tree swallow (Tachycineta bicolor) nestlings using a non-lethal, ligature method and were composited based on nest. The ligatures, which prevented the bolus from being swallowed, were placed on nestlings for 1 h until samplesChemical Concentrations and Microbiological Results for Assessment of Mixed-Organic/Inorganic Chemical Exposures in Tapwater in Mead, Nebraska, June 2022 and January 2023
In the United States and globally, the lack of data on contaminant exposure from unregulated private-well point-of-use (POU) tapwater (TW) is a recognized public health data gap and an obstacle to risk management and homeowner decision making. Mead, Nebraska, is an agricultural community about 30 miles west of Omaha. To help address the lack of data on broad contaminant exposures in TW sourced froPesticide Concentrations Measured in Zooplankton Samples Collected from the Sacramento River and Yolo Bypass, California, 2021
Zooplankton samples were collected at one site upstream of the Yolo Bypass in Northern California, three sites within the Bypass, and at a comparison site on the Sacramento River below the city of Sacramento and analyzed for a large suite of current-use pesticides and degradates. Samples were collected every two weeks from early August 2021 to mid-October 2021. Samples were collected by towing a 1Target-chemical concentrations and bioassay results for assessment of mixed-organic/inorganic chemical and biological exposures in Minneapolis/St Paul, Minnesota tapwater, August 2019
This dataset contains the concentration and quality assurance results for inorganic and organic analytes collected for the U.S. Geological Survey (USGS), Ecosystems Mission Area, Environmental Health Infrastructure Program, Tapwater Exposure Project conducted in Minnesota, in August of 2019. Samples were obtained from multiple publicly distributed water sources in Minnesota in 2019. Due to privacyResults from U.S. Geological Survey Environmental Health Food Resources Lifecycle Integrated Science Team, Graton Pesticides (GRAPE) Study, in Graton, California, April–May 2021
In the spring of 2021, six households with private wells were selected throughout Graton, California, based on proximity to agriculture (within one mile of agriculture), well depth (i.e., less than 150 feet in depth), and well type (i.e., dug versus drilled). Silicone bands were deployed for 30 days at outdoor locations at each household to passively sample pesticides in ambient air. On May 3, 202Multiresidue extraction of current-use pesticides from complex solid matrices using energized dispersive extraction with analysis by gas and liquid chromatography tandem mass spectroscopy
A multiresidue method for solids (i.e., soil, sediment, sludge) was developed and evaluated for the analysis of pesticides and pesticide degradates. Initially, a well characterized soil was used to determine the recovery of target compounds using an Energized Dispersive Guided Extraction (EDGE) system with two extraction solvents, acetonitrile and 1:1 (v/v) hexane:acetone. Extracts were cleaned usPesticide Concentrations in American Bullfrog (Lithobates catesbeianus) Tadpoles Collected from Ponds and Reservoirs near Mead, Nebraska
To evaluate the potential uptake and accumulation of pesticides in amphibians, American bullfrog (Lithobates catesbeianus) tadpoles were collected from surface water sites (four ponds and one reservoir) in 2021 near Mead, Nebraska. Sites were located in the landscape surrounding the AltEn ethanol plant, a plant which had previously received pesticide treated (coated) seeds. Tadpoles were collectedTarget-Chemical Concentrations and Microbiological Results for Assessment of Mixed Contaminant and Biological Exposures in Bottled Water, 2020
This data release contains concentration and quality-assurance results for inorganic, organic analytes and microbiological pathogens collected from 30 different commercial bottled water sources. Samples were processed on July 20 and August 17, 2020 at the New Jersey Water Science Center and analyzed at various U.S. Geological Survey laboratories. Samples were analyzed for nutrients, cations and an - Multimedia
Bumble bees being prepped for pesticide residue analysis.Bumble bees being prepped for pesticide residue analysis.
Bumble bees being prepped for pesticide residue analysis at the USGS Organic Chemistry Research Laboratory (OCRL), California.
Bumble bees being prepped for pesticide residue analysis at the USGS Organic Chemistry Research Laboratory (OCRL), California.
Water samples are extracted for pesticides.Water samples are extracted for pesticides at the USGS Organic Chemistry Research Laboratory.
Photo credit: Elisabeth LaBarbera
Water samples are extracted for pesticides at the USGS Organic Chemistry Research Laboratory.
Photo credit: Elisabeth LaBarbera
Biosolids Analysis.Co-extracted matrix is removed from biosolids prior to analysis at the USGS Organic Chemistry Research Laboratory (OCRL).
Photo Credit: Gabby Black.
Co-extracted matrix is removed from biosolids prior to analysis at the USGS Organic Chemistry Research Laboratory (OCRL).
Photo Credit: Gabby Black.
Liquid Chromatography-High Resolution Mass Spectrometry (LC-HRMS).Liquid Chromatography-High Resolution Mass Spectrometry (LC-HRMS).Suspect screening/non-target analysis is done with LC-HRMS at the Organic Chemistry Research Laboratory (OCRL) in Sacramento, CA.
Photo credit: Michelle Hladik
Suspect screening/non-target analysis is done with LC-HRMS at the Organic Chemistry Research Laboratory (OCRL) in Sacramento, CA.
Photo credit: Michelle Hladik
Gas chromatograph-mass spectrometer (GCMS) used for pesticide analysisGas chromatograph-mass spectrometer (GCMS) used for pesticide analysisOrganic Chemistry Research Laboratory — Sacramento, California. Gas chromatograph-mass spectrometer - GCMS
Organic Chemistry Research Laboratory — Sacramento, California. Gas chromatograph-mass spectrometer - GCMS
Pollen samples from various plants collected from hedgerowsPollen samples from various plants collected from hedgerowsOrganic Chemistry Research Laboratory -- Sacramento, California. Small sample bottles with pollen inside
Organic Chemistry Research Laboratory -- Sacramento, California. Small sample bottles with pollen inside
Sunflower with BeesIn a field in northern California, seen here is a sunflower with several bees. Bees are drawn to sunflowers for several compelling reasons, and understanding this attraction sheds light on both the nature of bees and the characteristics of sunflowers.
In a field in northern California, seen here is a sunflower with several bees. Bees are drawn to sunflowers for several compelling reasons, and understanding this attraction sheds light on both the nature of bees and the characteristics of sunflowers.
A U.S. Geological Survey chemist evaporating sample extractsA U.S. Geological Survey chemist evaporating sample extractsOrganic Chemistry Research Laboratory — Sacramento, California. USGS chemist working with samples in a laboratory hood
Organic Chemistry Research Laboratory — Sacramento, California. USGS chemist working with samples in a laboratory hood
U.S. Geological Survey chemist homogenizes a tissue sampleU.S. Geological Survey chemist homogenizes a tissue sampleOrganic Chemistry Research Laboratory — Sacramento, California. USGS chemist homogenizes a tissue sample into a mortar and pestle
Organic Chemistry Research Laboratory — Sacramento, California. USGS chemist homogenizes a tissue sample into a mortar and pestle
- Publications
Filter Total Items: 113
Comparing modern identification methods for wild bees: Metabarcoding and image-based morphological taxonomic assignment
With the decline of bee populations worldwide, studies determining current wild bee distributions and diversity are increasingly important. Wild bee identification is often completed by experienced taxonomists or by genetic analysis. The current study was designed to compare two methods of identification including: (1) morphological identification by experienced taxonomists using images of field-cAuthorsCassandra Smith, Robert S. Cornman, Jennifer A. Fike, Johanna M. Kraus, Sara J. Oyler-McCance, Carrie E Givens, Michelle Hladik, Mark W. Vandever, Dana W. Kolpin, Kelly SmallingDeterminants of spring migration departure dates in a New World sparrow: Weather variables reign supreme
Numerous factors influence the timing of spring migration in birds, yet the relative importance of intrinsic and extrinsic variables on migration initiation remains unclear. To test for interactions among weather, migration distance, parasitism, and physiology in determining spring departure date, we used the Dark-eyed Junco (Junco hyemalis) as a model migratory species known to harbor diverse andAuthorsAllison J. Byrd, Katherine M. Talbott, Tara M. Smiley, Taylor B. Verrett, Michael S. Gross, Michelle Hladik, Ellen D. Ketterson, Daniel J. BeckerPesticides in small volume plasma samples: Method development and application to smallmouth bass (Micropterus dolomieu) from the Chesapeake Bay watershed, USA
Nontarget organisms are exposed to pesticides following applications in agricultural and urban settings, potentially resulting in deleterious effects. Direct measurements of pesticides in biological tissues may aid in characterizing exposure, accumulation, and potential toxicity versus analyses in environmental media alone (e.g., water, soil, and air). Plasma represents a nonlethal sampling mediumAuthorsMichael S. Gross, Vicki S. Blazer, Michelle HladikEvaluating the reliability of environmental concentration data to characterize exposure in environmental risk assessments
Environmental risk assessments often rely on measured concentrations in environmental matrices to characterize exposure of the population of interest—typically, humans, aquatic biota, or other wildlife. Yet, there is limited guidance available on how to report and evaluate exposure datasets for reliability and relevance, despite their importance to regulatory decision-making. This paper is the secAuthorsMichelle Hladik, Arjen Markus, Dennis R. Helsel, Lisa H. Nowell, Stefano Polesello, Heinz Rudel, Drew Szabo, Iain WilsonMethods of analysis—Determination of pesticides in filtered water and suspended sediment using liquid chromatography- and gas chromatography-tandem mass spectrometry
The widespread application of pesticides in agricultural and urban areas leads to their presence in surface waters. Presence of these biologically active chemicals in environmental waters potentially has adverse effects on nontarget organisms. To better understand the environmental fate of these contaminants, a robust method to capture chemicals with wide-ranging physicochemical properties has beeAuthorsMichael S. Gross, Corey J. Sanders, Matthew D. De Parsia, Michelle L. HladikMultigenerational, indirect exposure to pyrethroids demonstrates potential compensatory response and reduced toxicity at higher salinity in estuarine fish
Estuarine environments are critical to fish species and serve as nurseries for developing embryos and larvae. They also undergo daily fluctuations in salinity and act as filters for pollutants. Additionally, global climate change (GCC) is altering salinity regimes within estuarine systems through changes in precipitation and sea level rise. GCC is also likely to lead to an increased use of insectiAuthorsSara Hutton, Samreen Siddiqui, Emily Pedersen, Christopher Markgraf, Amelie Segarra, Michelle Hladik, Richard E Connon, Susanne M. BranderNon-native Rhizophora mangle as sinks for coastal contamination on Moloka'i, Hawai'i
Coastal mangrove forests provide a suite of environmental services, including sequestration of anthropogenic contamination. Yet, research lags on the environmental fate and potential human health risks of mangrove-sequestered contaminants in the context of mangrove removal for development and range shifts due to climate change. To address this, we conducted a study on Moloka'i, Hawai'i, comparingAuthorsGeoffrey Szafranski, Elise F. Granek, Michelle Hladik, Mia HackettConserved grasslands support similar pollinator diversity as pollinator-specific practice regardless of proximal cropland and pesticide exposure
Pollinator diversity and abundance are declining globally. Cropland agriculture and the corresponding use of agricultural pesticides may contribute to these declines, while increased pollinator habitat (flowering plants) can help mitigate them. Here we tested whether the relative effect of wildflower plantings on pollinator diversity and counts were modified by proportion of nearby agricultural laAuthorsJohanna M. Kraus, Kelly Smalling, Mark W. Vandever, Carrie E Givens, Cassandra Smith, Dana W. Kolpin, Michelle HladikPermethrin contamination of sawgrass marshes and potential risk for the imperiled Klot’s skipper butterfly (Euphyes pilatka klotsi)
Nontarget effects from mosquito control operations are possible in habitats adjacent to areas targeted by ultra-low-volume (ULV) sprays of permethrin for adult mosquito control. We assessed the risks of permethrin exposure to butterflies, particularly the imperiled Klot's skipper, when exposed to ground-based ULV sprays. Samples of larval host plant leaves (sawgrass) were collected in June (in mosAuthorsTimothy Bargar, Michelle HladikBifenthrin, a ubiquitous contaminant, impairs the development and behavior of the threatened Longfin Smelt during early life stages
The Longfin Smelt (Spirinchus thaleichthys) population in the San Franscisco Bay/Sacramento-San Joaquin Delta (Bay-Delta) has declined to ∼1% of its pre-1980s abundance and, as a result, is listed as threatened under the California Endangered Species Act. The reasons for this decline are multiple and complex, including the impacts of contaminants. Because the spawning and rearing seasons of LongfiAuthorsFlorian Mauduit, Amelie Segarra, Julia Sherman, Michelle Hladik, Luann Wong, Thomas M Young, Levi Lewis, Tien-Chieh Hung, Nann A. Fangue, Richard E ConnonNeonicotinoid sunflower seed treatment, while not detected in pollen and nectar, still impacts wild bees and crop yield
Neonicotinoid seed treatments are commonly used in agricultural production even though their benefit to crop yield and their impact on pollinators, particularly wild bees, remains unclear. Using an on-farm matched pair design in which half of each field was sown with thiamethoxam treated seed and half without, we assessed honey bee and wild bee exposure to pesticides in sunflower fields by analyziAuthorsLaura T. Ward, Michelle Hladik, Aidee Guzman, Ariana Bautista, Nicholas MillsComparative toxicity of two neonicotinoid insecticides at environmentally relevant concentrations to telecoprid dung beetles
Dung beetles (Coleoptera: Scarabaeinae) frequently traverse agricultural matrices in search of ephemeral dung resources and spend extended periods of time burrowing in soil. Neonicotinoids are among the most heavily applied and widely detected insecticides used in conventional agriculture with formulated products designed for row crop and livestock pest suppression. Here, we determined the comparaAuthorsMichael C. Cavallaro, Michelle Hladik, Samantha Hittson, Greg Middleton, W. Wyatt Hoback - News