Research Accomplishment Reports 2009

Biological Control in Pest Management Systems of Plants

J.D. Harwood
Department of Entomology

 

Non-Technical Summary

Outputs: The results of the proposed research activities will consist of:

• new or improved natural enemy species or biotypes for biological control of major arthropod and weed pests in the U.S.;
• improved methods for incorporating biological control into IPM programs for key agricultural resources in the U.S. data addressing the ecological basis of success and failure of biological control; and
• data addressing the environmental and economic impacts of biological control.

The publications, presentations and website will continue to provide the state and federal agencies, and grower industry clientele with both technical and practical information on a timely basis.

Outcomes or projected Impacts: The availability of new or improved biological control options for major pest species in the U.S. will result in

• reduced pesticide usage,
• increased sustainability of agricultural production systems, and
• economic benefits to both agricultural producers (in the form of reduced pest management costs) and consumers (in the form of reduced food costs).

The attendant benefits of reducing pesticide usage include reduced food, soil and water contamination, reduced impacts on nontarget species including wildlife, and reduced human exposure to potentially harmful chemicals. Enhanced knowledge of the ecological mechanisms underlying biological control will increase success rates. Enhanced knowledge of the environmental and economic impacts of biological control will improve the environmental safety of biological control and foster its adoption in current and new pest management programs.

2009 Project Description

Ongoing field research throughout the United States and in select overseas locations is seeking to identify the role of generalist predators in biological control of crop pests, paying particular attention to the role of prey biodiversity on predation dynamics. As such, direct output to growers, extension agents, etc., can be obtained from this research as we seek to address pertinent questions to agriculture in the state.

These experiments are currently being conducted in alfalfa, corn and winter wheat and include graduate student and postdoctoral scientist training in the agricultural sciences. Mechanisms of foraging by generalist predators are being examined with a view to identifying their role in biological control. This is being achieved through the integration of molecular techniques, behavioral studies in the laboratory and field experiments. These approaches are being used in parallel to delineate trophic connectivity and measure the intensity of specific predator-prey interactions.

Understanding the forces that regulate the abundance of these important natural enemies can ultimately provide information that discerns the role of prey biodiversity and habitat management on predation dynamics. Thus, outputs are relevant across states due to the nature of the experimental approach and utility of the findings. Specific impacts are given in the Impacts section.

2009 Impact

(1). Role of Coccinellidae in aphid biological control. Coccinellids and aphids interact in a wide range of agricultural and forest habitats and the value of coccinellid predation for aphid suppression in these systems varies from a minor role to significant reductions leading to within-season control. In a major review, a comparative discussion of the management of the cotton aphid (Aphis gossypii Glover) and the soybean aphid (Aphis glycines Matsumura) highlighted the importance of documenting levels of pest mortality by coccinellids.

(2). Effect of biodiversity of biological control. Experiments showed that a diverse diet significantly enhanced predator fecundity and survival. Experiments were conducted using common generalist predators found in arable fields in Europe, the carabid beetle Pterostichus melanarius (Coleoptera: Carabidae) and the linyphiid spider Erigone atra (Araneae: Linyphiidae). In conclusion, predators offered only pests (slugs or aphids) had lowest growth rates and fecundity and diversity significantly increased such parameters.

(3). Biological control of coffee berry borer. The coffee berry borer, Hypothenemus hampei (Coleoptera: Curculionidae), is the most important pest of coffee worldwide, causing an estimated $500 million in damage annually. H. hampei-specific primers were designed to demonstrate that H. hampei DNA can be detected in DNA extractions of a predatory thrips species, Karnyothrips flavipes, which preys on H. hampei. The potential of this molecular technique was demonstrated as being viable for unraveling the trophic interactions that occur inside the coffee berry. This research is particularly relevant given the status of coffee production in the United States; should the coffee berry borer become established, a fundamental knowledge of the interaction pathways and biological control potential are essential to provide a rapid response for management of this destructive pest.

2009 Publications

Obrycki, J.J., Harwood, J.D., Kring, T.J., ONeil, R.J. (2009). Aphidophagy by Coccinellidae: application of biological control in agroecosystems. Biological Control, 51, 244-254.

Thomas, R.S., Harwood, J.D., Glen, D.M., Symondson, W.O.C. (2009). Tracking subterranean density-dependent predation by carabid larvae on slugs using monoclonal antibodies. Ecological Entomology, 34, 569-579.

Harwood, J.D., Phillips, S.W., Lello, J., Sunderland, K.D., Glen, D.M., Bruford, M.W., Harper, G.L., Symondson, W.O.C. (2009). Reduced invertebrate biodiversity affects predator fitness and hence ability to control crop pests. Biological Control, 51, 499-506.

Chapman, E.G., Jaramillo, J., Vega, F.E., Harwood, J.D. (2009). Biological control of coffee berry borer: the role of DNA-based gut-content analysis in assessment of predation. In: 3rd International Symposium on Biological Control of Arthropods (Eds. Mason, P.G., Gillespie, D.R. & Vincent, C.). USDA-FHTET, Morgantown, WV, pp. 475-484.