Baseline susceptibility of Bemisia tabaci (Genn.) biotype B in southern Florida to cyantraniliprole

Cyantraniliprole 200 mg ai l(-1) (Cyazypyr (TM) 200 SC) is a new xylem systemic insecticide in the anthranilic diamide chemistry class. A systemic laboratory bioassay using cut stems of cotton seedlings was developed to quantify the baseline susceptibility of nymphs and adults of the sweet potato whitefly, Bemisia tabaci (Genn.) biotype B, to cyantraniliprole. Bioassays were conducted on a susceptible laboratory colony and nine field populations collected in 2008, 2009 and 2010 in southern Florida. Bioassays with cyantraniliprole on the susceptible colony (targeting nymphs with exposure initiated at the egg stage) revealed pooled LC50 and slope values of 0.017 mg ai l(-1) and 1.766 (SE = 0.125) in 2008, respectively, and 0.013 mg ai l(-1) and 1355 (SE = 0.156) in 2009, correspondingly. Adult bioassays generated pooled LC50 and slope values of 0.049 mg ai l(-1) and 3.201 (SE = 0367) in 2010, respectively. LC50 and slope values targeting nymphs (as above) of field populations ranged from 0.013 to 0.023 mg ai l(-1) and 1.425 (SE = 0.167) to 1.923 (SE = 0.187), respectively, in 2008, and 0.023 to 0.034 mg ai l(-1) and 1.682 (SE = 0.140) to 2.318 (SE = 0.226), respectively, in 2009. Resistance ratio values at 50% mortality (RR50) on nymphs of field colonies ranged from 0.784 to 1.346 in 2008 and from 1.760 to 2.589 in 2009. Bioassays with adult field populations yielded LC50 and slope values ranging from 0.037 to 0.059 mg ai l(-1) and 2.639 (SE = 0.561) to 6.948 (SE = 1.294), respectively, in 2010. The RR50 values for adults from field colonies ranged from 0.752 to 1.207. The overlapping fiducial limits of the LC50 values, the low RR50 values, and the lack of significant differences in the slopes of probit lines between laboratory and field colonies, indicate that the B. tabaci populations present in southern Florida fields were highly sensitive to cyantraniliprole. These data will be helpful in monitoring for any changes in susceptibility as a result of use of the insecticide. The baseline information developed in the present study confirmed the susceptibility of field populations in Florida to cyantraniliprole and will be an essential component of a resistance management program to help ensure the continued viability of cyantraniliprole for B. tabaci management. (C) 2012 Elsevier Ltd. All rights reserved.