DEPARTMENT OF ENTOMOLOGY
DEPARTMENT DIRECTORY

George Heimpel

Associate Professor 1997 – present.

Ph.D. University of California, Davis 1995

Born in: Göttingen, Germany

Grew up in: El Cerrito, California, USA

Research in our lab focuses on biological control and natural enemy ecology.  The main subjects of most projects are parasitoids, but predators and reproductive parasites are represented as well.  Current projects include:

• Soybean aphid biological control
• Sex determination in parasitoid wasps
• Conservation biological control using flowering and overwintering cover crops
• Life-history evolution in parasitoid wasps
• Natural enemies and resistance evolution in pests of transgenic crops

Mark Asplen

Post-doc 

Ph.D. University of Arizona 2007

Research projects/interests:

I am broadly interested in the empirical study of invertebrate organismal biology, with special emphasis on insects. During the course of my Ph.D. research at the University of Arizona, I investigated life history correlates in whitefly parasitoids in an attempt to test specific hypotheses in parasitoid life history evolution. During the course of my post-doctoral appointment in the Heimpel lab, I have taken on two separate research projects: (1) the overwintering and migratory strategies of Binodoxys communis, a classical biological agent of the soybean aphid in the US, and (2) tracing the evolutionary patterns of sex determination mechanisms in the Hymenoptera (bees, wasps, ants, and sawflies). During the course of these endeavors, I have attempted to utilize a wide variety of methods, including behavioral, morphological, and phylogenetic approaches. In addition to scholarly pursuits, I have a strong interest in biology education, and relish in the opportunity to bring the life sciences to future generations.

Research projects/interests:

My work focuses on the potential for resident species to interfere with introduced biological control agent's ability to control a target pest. This biotic interference (which is analogous to the invasion biology term 'biotic resistance') can occur in a number of ways including predation, negative interactions with symbiotes of the target pest (which could be internal, as in the case of symbiotic bacteria in aphids that reduce the success of parasitoids; or external, as in the case of ants that protect aphids from attack), and detrimental behavioral interactions.

Specifically, my dissertation research asks the question, "Will biotic interference occur against a parasitoid classical biological control agent of the soybean aphid, and if it does, how?" To answer this question, my research has been mainly divided into three steps. First, I tried to predict the strength of biotic interference using a surrogate parasitoid in the field releases prior to releasing the actual biological control agent. I found that biotic interference is likely, but that adding a parasitoid to the system should still improve biological control of the soybean aphid. Next, after permits to release Binodoxys communis (the actual biological control agent) were obtained, I tried to determine whether my pre-release test using a surrogate parasitoid were realistic by doing simultaneous releases of the surrogate parasitoid and B. communis into different field plots. I found that both parasitoids performed similarly, proving that the surrogate study was successful, and also found that biotic interference against B. communis was context-dependent. Finally, the last major part of my dissertation deals with the mechanisms that cause biotic interference against B. communis and in what context. This part is still on-going, but so far I've found that intraguild predation is the most likely cause of biotic interference, and that it may be stronger when more aphids are on plants with developing B. communis, because aggregation to these plants by resident predators will cause stronger predation on B. communis. Also, B. communis may avoid using aphid patches where a ladybeetle has recently been foraging due to a chemical scent left by the ladybeetle. This could cause reductions in B. communis populations when ladybeetles are so ubiquitous that no "clean" aphid patches can be found.

Publications/presentations

Other interests:

Guitar-playing, reading fiction (often sci-fi), racquetball, games (video and board)

Christine Dieckhoff

Ph.D. Student

M.S. University of Bremen, Germany

Hometown: Nurenberg, Germany

Research Projects/Interests:

My research is part of a classical biological control program against the soybean aphid, Aphis glycines that is a serious pest in the North America. The focus of my research are the host specificity and ovarian dynamics of the aphid parasitoid Binodoxys communis (Gahan) (Hymenoptera: Braconidae) with respect to changes in various state variables.

Jonathan Dregni

Lab technician

B.S. University of California, Berkeley 1986

Hometown: Minnetonka, MN

I bring a long-time passion for gardening to our lab; I grow the plants that are used to keep our aphids thriving. I'm interested in native plants and ecological communities, and am also determining the host range of various aphid parasitoids. Much of my work is done within the University of Minnesota/Minnesota Dept. of Ag. Quarantine laboratory.

Research Projects/Interests:

My research is focused on understanding the population dynamics of the predators of soybean aphid (SBA), Aphis glycines. Since its invasion of North America in 2000 the SBA has notably changed the arthropod community of the soybean agroecosystem. Several predators rapidly responded to the expanding range and increasing populations of SBA. The first objective of this study is to characterize the species composition of the foliar and ground predatory fauna associate with SBA. Surveys of beneficial organisms have been done to document their nature, abundance and potential role on the pest. This survey was done in seven fields in Québec, Canada. We used pitfall traps to estimate population levels of ground beetles and the foliar predators were collected with sweep nets and characterized with visual examination. Coccinellids are the most important aphidophagous predators found on the soybean crop in Canada. The second objective of this study is to determine the impact of intraguild predation between coccinellid species. Intraguild predation (IGP) is an antagonist interaction between natural enemies wherein one predator consumes another from the same guild. It may explain why natural enemy communities sometimes fail to reduce pest populations. To test the presence of IGP, we are using a PCR-based method to detect DNA of intraguild prey in the guts of coccinellid predators, using primers that amplify the ITS-1 or COI regions. Primers will be developed for five species of coccinellids: Harmonia axyridis, Hippodamia convergens, Coleomegilla maculata, Coccinella septempunctata and Propylea quatuordecimpunctata. We will use this method to analyze gut contents of field-collected individuals. This study will give us a better understanding of the predator's role of SBA regulation and the impact of IGP between coccinellid species.

Ph.D student, 2006-present (Ecology, Evolution and Behavior, U of MN)

M.S. 2005 (Ecology, Evolution and Behavior, U of MN) Thesis presentation pdf

B.S. Zoology, 2003, University of Panama

Hometown: David, Chiriqui. Panama.

Research projects/interests

During the last six years I have worked with many different organisms, but always focusing on the same topic: evolution. My main fields of interest are molecular systematics, phylogeography, and historical biography of neotropical taxa using DNA sequence data. Also I am interested in several topics of molecular evolution at the level of genes and genomes. I have been very fortunate in being able to work at great places and most importantly with great people since my years as a college senior. See my webpage for more details.

For my PhD, I am studying the evolution of a gene related to sexual development in several species of insects. A recent report by Beye et al. (2003) found evidence of the existence of a gene called csd ('complementary sex determiner') that plays an important role in the sex determination of honey bees and is likely to be involved in sex determination of many other hymenopteran species. The main objective of my PhD research is to identify the csd gene in members of the parasitoid families Ichneumonidae and Braconidae in order to follow the evolution of this gene within the superfamily Ichneumonoidea. The Ichneumonoidea is a large superfamily within the Hymenoptera that contains species that range widely in their mating systems and that also contains many species that are economically important from the standpoint of biological pest control. The outcome of this research will provide important information regarding the evolution of the csd gene in the Hymenoptera as well as providing clues for the understanding of the evolution of mating systems in parasitoids. It will also be of practical use in the improving our understanding of how parasitoids can be used as biological control agents.

Publications/Presentations

Other interests: Mostly cooking.

Emily Mohl

Ph.D. Student (on rotation) Dept. of Ecology, Evolution & Behavior

B.S. Grinnell College, Iowa

Hometown: St. Louis, MO

Research projects/interests:

My interests involve the evolution and ecology of species interactions. I am working on a short project in the Heimpel lab to investigate limits to the host range of the parasitoid Binodoxys communis. For my thesis work, I am interested in developing a project to understand the bottom-up and top-down factors affecting the population dynamics of the introduced aphid Aphis nerii.

Post-doc

Ph.D. Penn State University, 2007

Hometown: Ankara, Turkey

Research projects/interests:

My primary research interests are ecology of insect ­ plant interactions and control and management of invasive species. I enjoy working in applied systems as this allows for gaining insight into ecological problems while studying basic ecological concepts. My research in the Heimpel lab revolves around soybean aphid suppression through conservation biological control and classical biological control. I am working on two main projects, one of which aims to identify the mechanisms through which suppression of the soybean aphid may be achieved in a rye cover crop system. The other involves the release and establishment of the parasitoid Binodoxys communis for biological control of the soybean aphid. My broader research interests also include dispersal, metapopulation ecology and conservation biology.