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Biological Control in Pest Management Systems of Plants
Department of Entomology
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.
2010 Project Description
Research is continuing throughout North America across a range of different cropping systems (winter wheat, corn, alfalfa, potato) to further understand the role of generalist predators in biological control. This research includes the training of four graduate students and two postdoctoral research associates in the agricultural sciences. This research seeks to better understand the mechanisms of foraging and, crucially, how diversity impacts ecosystem services provided by these natural enemies. In addition to the utilization of molecular biology techniques to better address these questions, behavioral and ecological field experiments are being integrated into research projects that provide complimentarity to the molecular approach.
A major thrust of the project is the development of alternative management practices that promote predator diversity that can translate into reduced pest impacts across crops. The research has a wide utility across systems such that data collected in, e.g., Kentucky can be subsequently utilized in other regions or countries. For example, research published in Naturwissenschaften examined the biological control capacity of coffee berry borer in Africa. This pest is now impacting coffee production in Hawaii and efforts are underway to integrate these approaches into Hawaiian coffee.
(1). Coffee berry borer biological control. The coffee berry borer is the most important pest of coffee throughout the world, causing an estimated $500 million in losses per year. Research developed molecular markers to this pest that enabled the identification of predation events by a predatory thrips, confirming a previously unreported predator-prey relationship. Prey availability was significantly correlated with prey consumption thereby suggesting a potential role in biological control.
(2). Pollenivory in spiders. Dietary diversification, including consumption of plant tissues, can enhance the fecundity of generalist predators resulting in improved control of pest prey. However, documentation of such a phenomenon in spiders is rare despite their foraging behavior placing them in contact with such a food source. Published research revealed the high capacity for pollenivory to occur in spiders and, crucially, the likelihood for high interception frequency of pollen under field conditions.
(3). Aphid falling rate and spider interception. The restriction of aphid reestablishment onto plants by epigeal predators represents a critical component of integrated pest management. It is therefore necessary to quantify the falling rates of aphids in order to better understand the role of ground-based predators. This study examined falling rates of aphids and revealed high (up to 70% of the population) falling rates per day. This has important implications for pest management and biological control in winter wheat and other agricultural systems.
(4). Food limitation in spiders. Understanding the food availability to generalist predators forms a critical part of pest management approaches. This study examined diel and seasonal variation in prey availability and revealed significant levels of food limitation to linyphiid spiders. Additionally, significant variation in availability of prey over a diel cycle was evident, revealing clear trends for prey availability in the field. (5). Molecular characterization of sampling techniques. Molecular tools that characterize the structure of complex food webs and identify trophic connectedness have become widely used in recent years. However, these approaches are also subject to error due to inappropriate sampling methodology. In a technical advance, the likelihood for misinterpretation of food web connections was examined under field conditions and revealed to be insignificant thereby validating vacuum suction sampling for molecular gut content analysis.
(5). Field Guide to the Slugs of Kentucky. A booklet was published that documents the status and basic biology of slugs in Kentucky. Although the primary focus is on Kentucky, this publication has relevance across most states east of the Rockies.
Peterson, J.A., Romero, S., Harwood, J.D. (2010). Pollen interception by linyphiid spiders in a corn agroecosystem: implications for dietary diversification and risk assessment. Arthropod-Plant Interactions, 4, 207-217.
Chapman, E.G., Romero, S., Harwood, J.D. (2010). Maximizing collection and minimizing risk: does vacuum sampling increase the likelihood for misinterpretation of food web connections? Molecular Ecology Resources, 10, 1023-1033.
Jaramillo, J., Chapman, E.G., Vega, F.E., Harwood, J.D. (2010). Molecular diagnosis of a previously unreported predator-prey association in coffee: Karnyothrips flavipes Jones (Thysanoptera: Phlaeothripidae) predation on the coffee berry borer. Naturwissenschaften, 97, 291-298.
Kerzicnik, L.M., Peairs, F.B., Harwood, J.D. (2010). Implications of Russian wheat aphid, Diuraphis noxia (Kurdjumov), falling rates for biological control in resistant and susceptible winter wheat lines. Arthropod-Plant Interactions, 4, 129-138.
Romero, S., Harwood, J.D. (2010). Prey utilization by a community of linyphiid spiders: variation across diel and seasonal gradients. Biological Control, 52, 84-90.
Thomas, A.J., Mc Donnell, R.J., Paine, T.D., Harwood, J.D. (2010). A Field Guide to the Slugs of Kentucky. University of Kentucky Agricultural Experiment Station Publication SR-103. 34 pp.