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Current research projects include:
Soybean Aphid Population Regulation
The soybean aphid is a major new invasive pest of soybean in North America. In 2003, over 42 million acres of soybean in the North Central US were infested and over 7 million acres were treated with insecticides to control soybean aphid. Because of its dispersal behavior, virus transmission capabilities, and interactions with other pests, soybean aphid is responsible for driving pest management decisions in multiple crops at the landscape level.
We are investigating the role of top down and bottom up forces in regulating soybean aphid populations. A complex assemblage of generalist predators including the multi-colored Asian lady beetle, Harmonia axyridis and minute pirate bug, Orius insidiosus are important in suppression of A. glycines, however, predators alone have not brought this pest under adequate control. Since 2001, parasitism of A. glycines has steadily increased, dominated by the native parasitoid Lysiphlebus testaceipes. A previously introduced parasitoid, Aphelinus albipodus also occurs on A. glycines and host-adapted strains are being screened for possible future introduction. However, there is increasing evidence that generalist predators may limit the impact of parasitoids on A. glycines via intraguild predation.
The overall goal of the proposed research is to elucidate the impacts of IGP in the soybean aphid system. Specific objectives are to: 1) Determine the spatial pattern and impact of predator and parasitoid attack on A. glycines. 2) Assess IGP on native parasitoids by H. axyridis and O. insidious alone and in combination. 3) Determine if IGP impacts parasitism in the field. Our findings will add to a fundamental understanding of IGP by examining the joint impact of two simultaneously interacting IG predators and by exploring the spatial pattern of enemy attack and enemy dispersal in response to prey density as mechanisms that may provide refuges from IGP.
Funding:
USDA NRI
MSU Sustainable Agriculture Special Grant
NSF Long Term Ecological Research
Potential for Biological Control of Garlic Mustard
Garlic mustard, Alliaria petiolata (M. Bieb.) Cavara and Grande is a major invasive plant in North America. A native of Eurasia, A. petiolata invades forested communities where it can displace native herbaceous flora, compete with timber species regeneration, alter litter layer depth and composition, impact mycorrhizal associations and result in cascading ecosystem impacts. Conventional methods have failed to yield techniques for practical control of this plant on landscape scales. A biological control program is under development, and currently five agents are in host-specificity testing in anticipation of possible North American release.
The objective of this project is to develop baseline information on A. petiolata biology, impacts and response to herbivore damage to determine the potential for biological control in Michigan. Specifically we hope to predict the most effective natural enemy(s) of garlic mustard in North America as a guide to importation decisions. We use plant demographic analysis and prospective modeling to predict the impact of Alliaria petiolata biological control across varying habitats and landscapes. This project provides a critical test of how basic data coupled with simulation modeling can be used to improve the performance and safety of invasive species biocontrol.
Funding:
Michigan Department of Natural Resources, Wildlife Division.
Michigan Department of Military and Veterans Affairs
USDA NRI
Biological Control of Purple Loosestrife in Michigan
Purple loosestrife, Lythrum salicaria L. (Lythraceae) is an invasive wetland perennial plant of Eurasian origin that is widely established in North America and is considered a threat to native wetland flora and fauna. Two European beetles, Galerucella calmariensis L. and G. pusilla Duft. (Coleoptera: Chrysomelidae) have been introduced and widely distributed in North America for biological control of L. salicaria. Experimental releases of Galerucella spp. beetles were made in three locations in Michigan in 1994. In 1997 we initiated a project to rear, redistribute, and evaluate the impacts of Galerucella calmariensis in 19 additional sites throughout Michigan.
Galerucella calmariensis became established at 100% of the 24 release locations monitored in these studies and have persisted for up to ten years while G. pusilla apparently failed to establish. Large populations of G. calmariensis developed from each of the 1994 releases and caused 100% defoliation of L. salicaria. From 1995 to 2000, L. salicaria stem height was reduced 73-85%, percent plant cover was reduced 61-95% and richness of nontarget plant species increased significantly at four out of five sites. By 2001, L. salicaria stem height and percent cover were reduced 38-81% and 32-74% respectively and nontarget plant species richness increased significantly at all five sites in contrast to the situation in 1995. Beetles have spread 3-10 kilometers from these original release sites. The successful establishment, spread, and impacts of G. calmariensis indicate the critical need for additional research on its role in the restoration of desirable plant communities in areas formerly dominated by L. salicaria.
Funding: Michigan Department of Natural Resources, Wildlife Division
Utilizing Native Plants to Enhance Natural Enemy Performance
This study investigates conservation biological control through habitat manipulation using native plants. Many natural enemies require access to floral nectar and/or pollen for maximum longevity and effectiveness at controlling pest insects and recommendations of beneficial plants can be readily found. However, most recommendations of nectar/pollen plants utilize non-native species and the research basis for these recommendations is often lacking.
This project contrasts native plants with non-native plant species that are frequently recommended as nectar and pollen resources for natural enemies. We are also interested in quantifying if specific plant characteristics attract natural enemies. The experimental design consists of five randomized blocks of fifty plant species, including grasses, flowering forbs, and shrubs, native to Michigan established in 2003 in 1m2 blocks with a neutral background (mown orchard grass). We measure the abundance and diversity of insects visiting each plant species in bloom, as well as plant height, minimum and maximum flowering height, number of open flowers, flower apparency, flower color, nectar quantity and quality, and pollen availability.
The information gained in early stages of experimentation will be applied to larger scale trials in experimental fields and on farms. Findings gained through this project will be disseminated through on-site field days in collaboration with native plant producers, Extension and USDA NRCS personnel. Ultimately, these recommendations will be useful in crop, orchard, vineyard, and garden systems, and have the potential to decrease the need for agricultural pesticides through biological pest control, provide beneficial insect habitat, and increase area of native plant species.
Funding: USDA NC-SARE
MSU Sustainable Agriculture Special Grant
204
Center for Integrated Plant Systems
Michigan State University
East
Lansing, MI 48824
Michigan State University
