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Former PMRU Scientists
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Please note: This webpage has been established to keep relevant research information conducted by PMRU researchers now retired or deceased readily available for any and all interested persons. Below are the names of former PMRU scientists with links to publications and other resources from their research efforts. 


Dr. John Gaskin

Retired - Botanist | Molecular Biologist with PMRU's Biological Control of Weeds Research Program (2002-2022


Dr. Stefan Jaronski

Retired - Insect Pathologist with PMRU's Grasshopper and Mormon Cricket Research Program (2000-2018) 

Dr. Erin Espeland

Deceased - Research Plant Ecologist with PMRU's Biological Control of Weeds Research Program (2008-2018)


Dr. John Gaskin - Botanist


The focus of Dr. Gaskin's research was the systematics and population structure of invasive plants, particularly whitetop or hoarycress (Lepidium draba, formerly Cardaria draba) and saltcedar (Tamarix spp.) Both of these invasives are present in Montana and throughout the western U.S. Saltcedar typically dominates riparian areas and whitetop is considered a pest plant in fields, rangelands and natural areas. The specific goals of this research are to find out which genotypes of these exotic plants are invading, where the genotypes originated from in Eurasia, which native and exotic species they are most closely related to, and where the invasive genotypes are distributed in the U.S. This information will be used to insure that all of the genetic diversity of these invasions will be present in tests of current and proposed biological control agents, and that all native plants closely related to the invasion will be included in host-specificity tests.

Prior to joining the USDA-Agricultural Research Service in 2002, Dr. Gaskin's dissertation at Washington University in St. Louis focused on the phylogeography of invasive Tamarix. He has done revision work on South American Smilax, and molecular systematic work in the families Campanulaceae and Tamaricaceae. 





Dr. Stefan Jaronski - Research Insect Pathologist

At Sidney ARS, Dr. Jaronski’s research centered on biocontrol of grasshoppers on U.S. rangeland, as well as continuation of older research on management of soil dwelling insect pests of various crops, including sugar beets and corn. His grasshopper work evaluated new technologies and new insect pathogenic fungi for the microbial control of grasshoppers, in close collaboration with USDA APHIS CPHST. This research included identification of baits, and chemical synergists, as well as new, better fungi and other microorganisms, and taking such technologies from the lab bench to the field.  In the process, Dr. Jaronski created small scale solid substrate mass production systems based on his industrial experience which not only allowed Kg amounts of fungus spores for testing, but also provided technical advice about such technology worldwide. As a side project he studied the population genetics of Beauveria bassiana derived from grasshoppers using molecular techniques and comparing the molecular data with other phenotypical charactersitics of the more than 400 Beauveria isolates.  His soil insect-targeted research was directed toward developing a practical mycoinsecticide, based on discovery of Metarhizium microsclerotia, that can be transferred to industry for commercialization for use against soil pest insects (sugarbeet root maggot, cabbage maggot, corn rootworm). The sugarbeet research is within the larger context of a biologically based management system for both pests and pathogens, using microorganisms, cultural practices, resistant/tolerant hybrids, and induced systemic response.

Dr. Jaronski had joined NPARL in March 2000 as an insect pathologist after a 17-year career in industry. After a Ph.D. program and two postdoctoral appointments concerning microbial control of mosquitoes, he did an abrupt left turn and (a) left the academic community for industry, (b) changed from medical entomology to agricultural pests. From 1983 to 1992, he worked at Abbott Laboratories as an insect pathologist, during which time his research involved commercial development of Beauveria bassiana and Bacillus thuringiensis for use against a wide variety of insects. In 1992 he switched to Mycotech Corp., Butte MT, a small, venture-capital biotech group commercializing Beauveria-based mycoinsecticides. There, Dr. Jaronski spent 8 years involved in all aspects of commercial development of the fungus - from the early basic research through field trials to generation of registration data, from basic mycology to formulation chemistry, from science to marketing. His last position prior to joining ARS was Manager of Biopesticide Research and Development for Mycotech.



Development of Grasshopper Biocontrol Agents a Lengthy Process 
(PDF; 315KB)   The Roundup ( By Lois Kerr, June 2010, p. 17-18


NPARL Research Entomologist Stefan Jaronski and Biological Science Technician Julie Grace hosted a Solid Substrate Fermentation Workshop for ARS scientists from related programs Feb. 16 - 18, 2005 at the Sidney ARS facility.  In addition to the workshop, Grace developed a short how-to manual illustrating the techniques discussed during the workshop.  Click here to download The Art of Fermentation. (PDF; 1.39 MB)


Homing in on Hopper Hordes

Grasshoppers: Their Biology, Identification and Management

Microbes for Sugar Beet Maggots (PDF; 24 KB)



Patents, Proceedings and Miscellaneous Publications:



Dr. Erin Espeland - Research  (Plant) Ecologist

Dr. Espeland’s research with NPARL’s Pest Management Unit focused on establishment, genetic identity and evolutionary potential of restored native populations in the face of biological invasions. This research includes the role of competition on restoration success, the role of genetic identity and maternal effects on the establishment of restoration materials. Additional research was established to track whole-ecosystem recovery after weed removal and restoration; this includes bird, insect and plant populations as well as soil conditions.  

Below is a list of projects Dr. Espeland participated in before joining the USDA:

Post-doctoral Scholar, Univ. of Nevada-Reno. Field and greenhouse research testing the heritable interrelationship of weeds and native species to the environment. Field testing suitability of a variety of restoration species and crops in Nevada agricultural practice. With Dr. Elizabeth Leger, Dept. of Natural Resources and Environmental Science.

Doctoral Research, UC Davis. Field and greenhouse research testing the effects of density dependence and local productivity on natural selection and genetic drift in California annual plants. With Dr. Kevin J. Rice, Dept. of Plant Sciences.

Research Assistant, UC Davis. Greenhouse research on adaptive potential of Aegilops triuncialis (goatgrass), comparing native-range and introduced populations' ability to adapt to serpentine soil. With Dr. Kevin J. Rice, Dept. of Plant Sciences.

Plant Ecologist, BMP Ecosciences, San Francisco CA. Library and field research to develop reference document for use by the City of Santa Cruz to develop an adaptive management plan for the endangered species Holocarpha macradenia. With Dr. Bruce Pavlik, BMP Ecosciences.

Research Fellow, Lawrence Livermore National Laboratory. Demographic monitoring of rare plant populations: Eschscholzia rhombipetala, Amsinckia grandiflora, Erodium macrophyllum (alias California macrophyllum), and Blepharizonia plumosa. Design and conduct experiments on effects of burning and other manipulations on granivory, germination, survivorship, and long-term population viability of several plant species. With Dr. Tina M. Carlsen, Environmental Restoration Dept.

Research Assistant, UC Davis. Isolate PCR primer to distinguish Aegilops caudataand Ae. Umbellulata from each other for the purpose of determining maternal parent of Ae. Triuncialis (goatgrass) in invasive populations. With Dr. John McKay, currently at Colorado State University.

Masters Research, San Jose State University. Field and common garden experiments to determine interpopulation differences in Eschscholzia californica. Developed and optimized primers for conducting RAPD analysis of genetic differences among populations. With Dr. Rodney G. Myatt, Dept. of Biological Sciences.

Research Assistant, Univ. of Western Ontario. Population restoration of Cirsium pitcherii, an endangered sand dune plant. Dr. M. Anwar Maun, Dept. of Biology (deceased).

Environmental Technician, Lawrence Livermore National Laboratory. Greenhouse research on effects of intraspecific competition and self-compatibility on Amsinckia grandiflora, a federally-listed endangered plant. Field research on ecophysiological effects of competitive environment on A. grandiflora. Dr. Tina M. Carlsen, Environmental Restoration Dept.

Research Assistant, Mills College. Demography and population restoration of state-listed endangered plant Acanthomintha duttonii. Common garden experiment to determine if and congenerics are serpentinite endemics or tolerators. Dr. Bruce M. Pavlik, Dept. of Biology.  



Peer-Reviewed Publications:

Other Publications:

Invited Talks:

Contributed Papers:

Technical Papers: