Browsing by Author "Dively, Galen P."

Now showing 1 - 2 of 2
  • Thumbnail Image
    Contrasting Role of Temperature in Structuring Regional Patterns of Invasive and Native Pestilential Stink Bugs
    Venugopal, 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.
  • Thumbnail Image
    Extended Sentinel Monitoring of Helicoverpa zea Resistance to Cry and Vip3Aa Toxins in Bt Sweet Corn: Assessing Changes in Phenotypic and Allele Frequencies of Resistance
    Dively, Galen P.; Kuhar, Tom P.; Taylor, Sally V.; Doughty, Helene; Holmstrom, Kristian; Gilrein, Daniel O.; Nault, Brian A.; Ingerson-Mahar, Joseph; Huseth, Anders; Reisig, Dominic; Fleischer, Shelby; Owens, David; Tilmon, Kelley; Reay-Jones, Francis; Porter, Pat; Smith, Jocelyn; Saguez, Julien; Wells, Jason; Congdon, Caitlin; Byker, Holly; Jensen, Bryan; DiFonzo, Chris; Hutchison, William D.; Burkness, Eric; Wright, Robert; Crossley, Michael; Darby, Heather; Bilbo, Tom; Seiter, Nicholas; Krupke, Christian; Abel, Craig; Coates, Brad S.; McManus, Bradley; Fuller, Billy; Bradshaw, Jeffrey; Peterson, Julie A.; Buntin, David; Paula-Moraes, Silvana; Kesheimer, Katelyn; Crow, Whitney; Gore, Jeffrey; Huang, Fangneng; Ludwick, Dalton C.; Raudenbush, Amy; Jimenez, Sebastian; Carrière, Yves; Elkner, Timothy; Hamby, Kelly (MDPI, 2023-06-25)
    Transgenic corn and cotton that produce Cry and Vip3Aa toxins derived from Bacillus thuringiensis (Bt) are widely planted in the United States to control lepidopteran pests. The sustainability of these Bt crops is threatened because the corn earworm/bollworm, Helicoverpa zea (Boddie), is evolving a resistance to these toxins. Using Bt sweet corn as a sentinel plant to monitor the evolution of resistance, collaborators established 146 trials in twenty-five states and five Canadian provinces during 2020–2022. The study evaluated overall changes in the phenotypic frequency of resistance (the ratio of larval densities in Bt ears relative to densities in non-Bt ears) in H. zea populations and the range of resistance allele frequencies for Cry1Ab and Vip3Aa. The results revealed a widespread resistance to Cry1Ab, Cry2Ab2, and Cry1A.105 Cry toxins, with higher numbers of larvae surviving in Bt ears than in non-Bt ears at many trial locations. Depending on assumptions about the inheritance of resistance, allele frequencies for Cry1Ab ranged from 0.465 (dominant resistance) to 0.995 (recessive resistance). Although Vip3Aa provided high control efficacy against H. zea, the results show a notable increase in ear damage and a number of surviving older larvae, particularly at southern locations. Assuming recessive resistance, the estimated resistance allele frequencies for Vip3Aa ranged from 0.115 in the Gulf states to 0.032 at more northern locations. These findings indicate that better resistance management practices are urgently needed to sustain efficacy the of corn and cotton that produce Vip3Aa.