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The Utilization of Oberea erythrocephala as an Additional Bio-Control Agent on Leafy Spurge in the Little Missouri River Basin

 Denise Olson

Question 1. What major problem or issue is being resolved and how are you resolving it?

Leafy spurge root placement in the soil appears to limit the success of Aphthona spp. to only a particular range of environmental conditions, and leafy spurge inhabits a wide range of different environmental habitats. The successful establishment of Oberea erythrocphala will support the efforts of managing leafy spurge with another biological control agent in areas where Aphthona spp. have not been successful. One-thousand Oberea erythrocphala have been released at selected sites in the TEAM Leafy Spurge demonstration areas in the Little Missouri River basin to determine the suitability of this beetle as an additional biological control agent where the success of Aphthona flea beetles has been less than satisfactory.

Question 2. How serious is the problem? Why does it matter?

The economic impact of leafy spurge to agricultural and nonagricultural (recreational and watershed) lands is approximately $130 million annually in the four-state region of Montana, North Dakota, South Dakota, and Wyoming where spurge infests about 1.2 million acres. Leafy spurge can be managed using chemical, cultural and/or biological control. However in many leafy spurge infested areas the terrain is not suitable for herbicide treatment or cultural control, or the success of the biological control agent, Aphthona flea beetles, has been less than satisfactory. Thus, land managers and owners have limited tools for managing leafy spurge in these areas and, consequently they would incur an economic loss from reduced agricultural production or recreational/wetlands use on these lands.

Question 3. How does it relate to the National Program(s) and National Program Component(s)?

The TEAM Leafy Spurge project is a part of the USDA/ARS Area-Wide Management Program. It is a component of Crop and Commodity Pest Biology, Control and Quarantine(304). TEAM Leafy Spurge complements efforts to develop new and improved pest control technologies and assess component technologies for integrated pest management (IPM) systems.

Question 4. What was your most significant accomplishment this past year?

Leafy spurge root placement in the soil appears to limit the success of Aphthona spp. to only a particular range of environmental conditions, and leafy spurge inhabits a wide range of different environmental habitats. We are examining the effectiveness and population development of the long-horned beetle as the flea beetle reduces the spurge infestation over a 1-3 year period. Two-Hundred Oberea erythrocphala were released to augment the eight-hundred that were released during 1999 into four selected sites in the TEAM leafy spurge demonstration areas. Data collected on the biology and behavior of Oberea erythrocphala will provide information as to the type of environment(s) suitable for the success of this biological control agent.

Question 5. Describe your major accomplishments over the life of the project, including their predicted or actual impact.

The duration of this project has covered the period from spring 1999 to late summer 2000. We successfully released 800 Oberea erythrocphala during 1999 at each of four selected release sites in the TEAM Leafy Spurge demonstration areas in the Little Missouri River basin. Two of the sites, were augmented with an additional 200 beetles. Beetles were not augmented at the other two sites because they were eliminated from the study (see question # 4). When data was collected during late summer of 1999 (year of first release) we recorded that Oberea erythrocphala had accepted the leafy spurge in each of the four release sites, successfully using leafy spurge for reproduction.

At the remaining sites, an average of 2.2 beetles in 19 quadrants and 1.33 beetles in 9 quadrants, were visually observed the first year after the original release year (1999). An average of 1.25 beetles were observed in 5 quadrants before the cattle were allowed to graze at the third site. This data indicates that the long-horned beetle has established and has moved out from the points of release at the two remaining sites, and was established at the third (eliminated) site. The plant density and height changed by -5.96/m2, -2.49/m2, +4.55/m2, and -27.14 cm, -8.85 cm, and -7.64 cm respectively at three sites between the first release in 1999 and the following spring.

Based on data that has been collected at an established Oberea erythrocphala site near Kindred ND, it appears that this beetle may establish at a slow rate, and gradually reduces the presence of leafy spurge over period of 3-4 years at the sites in the TEAM Leafy Spurge demonstration areas.

Question 6. What do you expect to accomplish year by year, over the next three years?

Data will be collected on the population development of Oberea erythrocphala and its impact on leafy spurge stands at the two remaining sites during the next three years. Additional sites (southeast and north central ND) have been set up to replace the two sites that were eliminated from the study in the TEAM leafy spurge demonstration areas. Up to 1000 beetles will be augmented at these sites during the next year. The same data will be collected from these sites, as in the sites in the TEAM Leafy Spurge demonstration areas, over the next three years. At release sites, where Oberea erythrocphala may appear to have a low establishment rate, additional beetles will be added to the sites to help increase the level of establishment over the next three years.

Question 7. What science and/or technologies have been transferred and to whom? When is the science and/or technology likely to become available to the end user (industry, farmer, other scientists)? What are the constraints, if known, to the adoption and durability of the technology?

This project was initiated during the 1999 production year and sufficient data has not been obtained to date to transfer new technologies to industry, farmers, and other scientist. We will be reporting research data, collected over the next few years, to scientist and other technical groups at the Annual Leafy Spurge Symposium, Annual North Dakota Weed Association meetings and other pertinent scientific associations. We anticipate that this new technology would be available after three to four years of testing and data collection in the field. Like the Aphthona flea beetles, Oberea erythrocephala will not be successful under all environmental conditions inhabited by leafy spurge. Therefore, this new technology will not be adoptable in all habitats where leafy spurge grows. Data collected on the biology and behavior of Oberea erythrocphala, at the two release sites in the TEAM leafy spurge demonstration areas and at the sites located in southeastern and north central ND will provide information as to the type of environment(s)suitable for the success of this biological control agent.

Question 8. List your most important publications in the popular press (no abstracts) and presentations to non-scientific organizations, and articles written about your work (NOTE: this does not replace your peer-reviewed publications which are listed below).

None.

Question 9. Scientific publications

None.

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