FIG. 3.
Bioassays of vip3Aa1-transformed strain BbV28 and wild-type strain BbW on second-instar larvae of S. litura. (a to f) Cumulative mortalities caused by BbW (top) and BbV28 (bottom) in assay 1 (left; sprayed larvae feeding on unsprayed leaf discs), assay 2 (middle; unsprayed larvae feeding on sprayed leaf discs), and assay 3 (right; sprayed larvae feeding on sprayed leaf discs). Symbols denote low, middle, and high conidial concentrations (no. of conidia/mm2) or a blank control (BC). Each value in parentheses is the total number of larvae in a given treatment. Error bars are standard deviations. (g) Healthy larvae in blank control (1) or larvae killed by BbW (left) and BbV28 (right) through cuticle infection (2) and by BbV28 through conidial ingestion (3) on day 4 after treatment. Fungal outgrowths were typical on the larvae killed by both strains through cuticle infection (4) but sparse on those killed by BbV28 through ingestion (5) after 3 days of incubation at 25°C at saturated humidity. Bars, 2 mm.