Time-dose-mortality data and modeling for the entomopathogenic fungus Aschersonia placenta against the whitefly Bemisia tabaci.

The fungus Aschersonia placenta FJSM was evaluated for control of the sweet potato whitefly, Bemisia tabaci. Bemisia tabaci nymphs (1st-4th instars) on tomato plants in the greenhouse (25-27 °C, 70%-85% relative humidity) were sprayed with suspensions containing 0, 10(4), 10(5), 10(6), 10(7), or 10(8) A. placenta FJSM conidia/mL. Mortality of fungus-treated 1st to 3rd instar nymphs ranged from 93% to 100% but was <25% for 4th instar nymphs; the fungus sporulated from 70% to 80% of the fungus-treated B. tabaci cadavers. LD50 and LD90 values decreased with time after treatment and increased with instar. LT50 values decreased with conidial concentration. The data were then described with time-dose-mortality models. The results indicate that A. placenta FJSM has potential as a mycoinsecticide for control of B. tabaci.