title: Effects of biotic and abiotic factors on grape root borer (Lepidoptera: Sesiidae) infestations in commercial vineyards in Virginia.
abstract: Larval grape root borer, Vitacea polistiformis (Harris) (Lepidoptera: Sesiidae), feed on roots of wild Vitis and commercially important Vitis species and rootstocks in portions of the eastern United States. Grape root borer pupal exuviae sampling in Virginia vineyards from 2008 to 2012 revealed that infestation levels varied substantially among 48 vineyard blocks. Data on horticultural (cultivar, rootstock, vine age, and planting area), cultural (insecticide use, ground cover, weed control, and irrigation), and environmental variables (proximity to forest, soil composition, soil moisture holding capacity, pH, organic matter, bulk density, and cation exchange capacity) from each block were subjected to optimal quantification using categorical principal component analysis (CATPCA). Variables with component loading values ≥0.70 from the CATPCA were used as predictors and pupal exuviae density as the dependent variable in binary logistic regression. A prediction model was developed by including statistically significant variables in the logistic regression. CATPCA showed that seven vineyard factors (ground cover, soil texture, soil mass moisture, soil pH, clay/sand ratio, clay/silt ratio, and sand/silt ratio) based on three selected principal components were significant for subsequent regression analysis. Binary logistic regression showed that soil mass moisture and clay/sand ratio were statistically significant factors contributing to differences in infestation among vineyard blocks. Based on these two factors, a risk prediction model for calculating the probability of grape root borer infestation in vineyards was developed and validated using receiver operating characteristic curve. Results are discussed in relation to the practical implications of a predictive, risk assessment model for grape root borer management.
authors.affiliation: Department of Entomology, Virginia Tech, Alson H. Smith, Jr. Agricultural Research and Extension Center, 595 Laurel Grove Rd., Winchester, VA 22602, USA.
authors.forename: Jhalendra P
authors.initials: JP
authors.lastname: Rijal
authors.forename: C C
authors.initials: CC
authors.lastname: Brewster
authors.forename: J C
authors.initials: JC
authors.lastname: Bergh
mesh_terms: D000383:Agriculture; D000818:Animals; D004777:Environment; D060434:Herbivory; D007300:Insect Control; D007814:Larva / Q000254:growth & development / Q000502:physiology; D016015:Logistic Models; D008954:Models, Biological; D009036:Moths / Q000254:growth & development / Q000502:physiology*; D018517:Plant Roots / Q000254:growth & development; D011679:Pupa / Q000254:growth & development / Q000502:physiology; D012621:Seasons; D014768:Virginia; D027843:Vitis / Q000254:growth & development*