DEPARTMENT OF ENTOMOLOGY
DEPARTMENT DIRECTORY

Advisor:

George Heimpel

Mailing address:

University of Minnesota
Department of Entomology
219 Hodson Hall, 1980 Folwell Avenue
St. Paul, MN 55108

Fax:

612-625-5299

E-mail

Education:

Ph.D. Student and EPA Star Fellow

B.S. in Zoology, B.S. in Conservation Biology, UW - Madison 2003

Degree sought:

Ph.D. Entomology

Research:

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:

Chacón JM and GE Heimpel. in prep. "Density-dependent apparent competition between an aphid and its parasitoid."

Chacón JM, Landis D, Heimpel GE. 2008. "Potential biotic interference of a classical biological control agent of soybean aphid." Biological Control 46: 216-225.

Gardiner M.M., D.A. Landis, C. Gratton, C.D. Difonzo, M. O'Neal, J. Chacón, M. Wayo, N. Schmidt, E. Mueller, and G.E. Heimpel. 2008. Landscape structure impacts biocontrol services in north-central U.S. soybean fields. Ecological Applications in press.

Presentations

Dept. of Ecology, Evolution and Behavior (University of Minnesota), 2008; Invited seminar: Chacón JM, Heimpel GE. Biotic interference of a classical biological control agent of soybean aphid.

Entomological Society of America - National (Reno, NV), 2008; Oral presentation: Chacón JM, Heimpel GE. The effect of aphid density on intraguild predation of a soybean aphid parasitoid.

Entomological Society of America - National (San Diego, CA), 2007; Oral presentation: Chacón JM, Heimpel GE. Biotic interference of a classical biological control agent of soybean aphid.

Aphidophaga 11 (Athens, Greece), 2007; Oral presentation: Chacon JM, Heimpel GE. Biotic interference of a classical biological control agent of soybean aphid.

EPA-STAR Fellows Conference (Washington, D.C) 2006; Poster presentation: Classical biological control of the soybean aphid.

Entomological Society of America - North Central Branch (Urbana, IL), 2006; Oral presentation: Chacon JM, Heimpel GE. Potential biotic interference of a classical biological control agent of soybean aphid: a pre-release assessment.

Invasive Species Workshop (St. Paul, MN), 2005; Oral presentation: Chacon JM, Heimpel GE. Intraguild predation affects the efficacy of a parasitoid of soybean aphid.

Entomological Society of America - National (Ft. Lauderdale, FL), 2005; Oral presentation: Chacon JM, Heimpel GE. Intraguild predation of a parasitoid biological control agent of the soybean aphid.