The 2008 Joint Meeting of the Society for Range Management and the America Forage and Grassland Council. |
Monday, January 28, 2008
35
Utilization of Two Aphthona Flea Beetle Species and Oberea Erythrocephala within A Twice Over, Multi-Species Rotational Grazing System for the Control of Leafy Spurge (Euphorbia esula)
Anthony T. Perlinski, William T. Barker, and Dennis L. Whitted. Natural Resources Sciences, North Dakota State University, 204 Hastings Hall, Centennial Blvd at Bolley Drive, Fargo, ND 58105
This study was conducted to evaluate the effectiveness of introducing multiple biological control agents into a multi-species grazing system to increase control of leafy spurge in southeastern, North Dakota. This study was conducted on the Albert Ekre Grassland Preserve (AEGP) near Kindred, ND. Past attempts to establish biological control agents on the AEGP have had little success. The treatments were applied in a complete random design in which eight treatments were randomly assigned to sixteen. Treatments were: 1) Aphthona spp. alone; 2) Aphthona spp. with grazing; 3) Oberea erythrocephala alone; 4) O. erythrocephala with grazing; 5) Aphthona spp. with O. erythrocephala; 6) Aphthona spp. with O. erythrocephala and grazing; 7) Grazing alone; and 8) No treatment. During the first season sites receiving Aphthona species included a mixture of A. lacertosa and A. flava at approximately 500 adult beetles. Those sites treated with Obrea erythrocephala received 75 adult beetles. Prior to the second season releases, four sweep transects through each release site were conducted and number of adult beetles per transect were counted. The results of these transects showed positive establishment of all released species at all release sites. During the second season Aphthona releases consisted of 1000 adult beetles and O. erythrocephala releases containing 100 adult beetles. The grazing system in place consists of 259 hectare pasture divided into four equally sized pastures grazed with 90 cow calf pairs and 160 ewes using a twice-over rotation grazing system. Results from a one-way ANOVA found no difference (P > 0.05) in above ground production of leafy spurge between any of the treatment. The most significant result of this study was the establishment of two biological control agents on the AEGP regardless of whether the release sites were grazed or ungrazed.