title: Differential Probing Behavior of Blissus insularis (Hemiptera: Blissidae) on Resistant and Susceptible St. Augustinegrasses.
abstract: Southern chinch bug, Blissus insularis Barber, is a severe pest of St. Augustinegrass throughout the southern United States. Host plant resistance is an environmentally friendly method to manage chinch bug infestations and is increasingly important, as the southern chinch bug develops resistance to insecticides. In this study, in an effort to understand resistance mechanisms in two varieties of St. Augustinegrass ('FX-10' and 'NUF-76'), we used the electrical penetration graph method to quantify stylet probing behaviors in two resistant and two susceptible St. Augustinegrass varieties. Overall, chinch bugs spent less time probing on resistant FX-10 and NUF-76 than on susceptible 'Floratam' and 'Palmetto', and individual probes were shorter in average duration but more numerous in resistant varieties than in susceptible varieties. During probing, chinch bugs spent more time in pathway-associated stylet activities (i.e., penetration through epidermal and mesophyll tissue) in the resistant varieties than in the susceptible varieties, likely indicating difficulty in finding and accessing an ingestion site. As a consequence, chinch bugs spent proportionately much less time engaged in xylem ingestion in both resistant varieties than in susceptible varieties but only in FX-10 were phloem-associated activities significantly reduced compared with those in susceptible varieties. We conclude that there is evidence for non-phloem-associated chinch-bug resistance factors in both NUF-76 and FX-10, and phloem-associated factors in FX-10.
authors.affiliation: Department of Entomology and Nematology, University of Florida, Gainesville, FL 32611.
authors.forename: Murugesan
authors.initials: M
authors.lastname: Rangasamy
authors.affiliation: Department of Entomology and Nematology, University of Florida, Gainesville, FL 32611. Corresponding author, e-mail: hjmca@ufl.edu.
authors.forename: Heather J
authors.initials: HJ
authors.lastname: McAuslane
authors.affiliation: USDA Agricultural Research Service, Crop Diseases, Pests and Genetics, 9611 S. Riverbend Ave., Parlier, CA 93648.
authors.forename: Elaine A
authors.initials: EA
authors.lastname: Backus
authors.affiliation: UF/IFAS Everglades Research and Education Center, 3200 E Palm Beach Rd., Belle Glade, FL 33430.
authors.forename: Ronald H
authors.initials: RH
authors.lastname: Cherry
mesh_terms: D000818:Animals; D001522:Behavior, Animal / Q000502:physiology*; D006430:Hemiptera / Q000502:physiology*; D006109:Poaceae / Q000276:immunology*
keywords: electrical penetration graph; feeding monitor; host plant resistance; southern chinch bug; turfgrass