BASELINE TOXICITY OF SPIROMESIFEN TO BIOTYPE B OF BEMISIA TABACI IN FLORIDA

Biotype B of the sweetpotato whitefly, Bemisia tabaci (Gennadius), is a worldwide pest of many agronomic and horticultural crops, including tomato. Extensive pesticide use targeting this pest has led to the development of resistance to every major class of insecticides. The baseline toxicity of spiromesifen was established for laboratory susceptible and field collected B tabaci biotype B. populations in Florida in 2005 and 2006, respectively, using a leaf dip bioassay method for 2nd instar. LC50 values for field populations of B. tabaci ranged from 0.63 mg[AI]l(-1) to 0.86 mg[AI]l(-1) in 2005 and from 0.46 mg[AI]l(-1) to 2.08 mg[AI]l(-1) in 2006. No population had a RR50 value over 3.5 in either year and the fiducial limits of the LC50 values for the laboratory and field populations overlapped, indicating no differences among them. The laboratory and field baseline toxicity data generated in this study confirmed the susceptibility of field populations of B. tabaci to spiromesifen and will be useful in documenting any future changes in the susceptibility of the whitefly to the insecticide.