Browsing by Author "Lamp, William O."
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- Contrasting Role of Temperature in Structuring Regional Patterns of Invasive and Native Pestilential Stink BugsVenugopal, P. Dilip; Dively, Galen P.; Herbert, D. Ames Jr.; Malone, Sean M.; Whalen, Joanne; Lamp, William O. (PLOS, 2016-02-29)Objectives Assessment and identification of spatial structures in the distribution and abundance of invasive species is important for unraveling the underlying ecological processes. The invasive agricultural insect pest Halyomorpha halys that causes severe economic losses in the United States is currently expanding both within United States and across Europe. We examined the drivers of H. halys invasion by characterizing the distribution and abundance patterns of H. halys and native stink bugs (Chinavia hilaris and Euschistus servus) across eight different spatial scales. We then quantified the interactive and individual influences of temperature, and measures of resource availability and distance from source populations, and their relevant spatial scales. We used Moran’s Eigenvector Maps based on Gabriel graph framework to quantify spatial relationships among the soybean fields in mid-Atlantic Unites States surveyed for stink bugs. Findings Results from the multi-spatial scale, multivariate analyses showed that temperature and its interaction with resource availability and distance from source populations structures the patterns in H. halys at very broad spatial scale. H. halys abundance decreased with increasing average June temperature and distance from source population. H. halys were not recorded at fields with average June temperature higher than 23.5°C. In parts with suitable climate, high H. halys abundance was positively associated with percentage developed open area and percentage deciduous forests at 250m scale. Broad scale patterns in native stink bugs were positively associated with increasing forest cover and, in contrast to the invasive H. halys, increasing mean July temperature. Our results identify the contrasting role of temperature in structuring regional patterns in H. halys and native stink bugs, while demonstrating its interaction with resource availability and distance from source populations for structuring H. halys patterns. Conclusion These results help predicting the pest potential of H. halys and vulnerability of agricultural systems at various regions, given the climatic conditions, and its interaction with resource availability and distance from source populations. Monitoring and control efforts within parts of the United States and Europe with more suitable climate could focus in areas of peri-urban developments with deciduous forests and other host plants, along with efforts to reduce propagule pressure.
- Evaluation of Alfalfa-Tall Fescue Mixtures across Multiple EnvironmentsTracy, Benjamin F.; Albrecht, Ken; Flores, Joao; Hall, Marvin; Islam, Anowarul; Jones, Gordon M.; Lamp, William O.; MacAdam, Jennifer W.; Skinner, Howard; Teutsch, Christopher D. (2016-07)Binary grass-legume mixtures can benefit forage production systems in different ways helping growers cope both with increasing input costs (e.g., N fertilizer, herbicides) and potentially more variable weather. The main objective of this study was to evaluate alfalfa (Medicago sativa L.) and tall fescue [Schedonorus phoenix (Scop.) Holub] mixtures across a wide range of environments to assess herbage accumulation, weed suppression and fertilizer nitrogen replacement values (FNRV). A common field experiment was established in 2009 and 2010 at six study sites in the United States: Maryland, Pennsylvania, Utah, Virginia, Wisconsin, and Wyoming. Experimental treatments included an alfalfa monoculture, three alfalfa-fescue mixtures with seed ratios of 75: 25, 50: 50, and 25: 75 of alfalfa/tall fescue, and tall fescue monocultures that received nitrogen applications of 0, 50, 100, 150, 200, and 300 kg N ha(-1), respectively. Data were collected over a 2-yr period. The responses of tall fescue monocultures to N fertilization differed among sites, and this contrasted with mixture yields, which did not exhibit site x treatment interactions (P > 0.05). Herbage accumulation and weed suppression were consistently higher in mixtures compared with alfalfa monocultures and tall fescue monocultures receiving less than 100 kg N ha(-1). The FNRVs for alfalfa were within the range reported for other studies and averaged 143 kg N ha(-1). The consistent herbage accumulations across these multiple environments suggest binary mixtures of alfalfa-tall fescue may be a good option for many forage-livestock producers although yields could be improved with location specific cultivar selection.