Effect of Soil Application of Cyantraniliprole on Bemisia tabaci (MED Whitefly) and Amblyseius swirskii, 2016*

With the overall goal to integrate predatory mite Amblyseius swirskii in the management program of MED whitefly, the specific objective of this study was to evaluate cyantraniliprole, a diamide insecticide for whitefly control, and assess its compatibility with swirskii mite. The trial was conducted on an ornamental host, salvia under greenhouse condition at U.S. Horticultural Research Laboratory (USHRL). Salvia plants were grown from seed in Premier Pro-mix General Purpose Growing Medium in seedling trays, and placed into a plexiglass screened cage (61 cm × 91 cm × 61 cm) for ∼8 wk to prevent contamination prior to experimentation. Plants in seedling trays were then transplanted into one-gallon plastic pots and placed in mesh screened cage (61 cm × 61 cm × 61 cm). Potted plants were irrigated as needed and fertilized with 50 ml/pot of Peters Professional® 20–10–20 (325 ppm) (Scotts Co., Marysville, OHo). Four treatments were arranged in a randomized complete block design with six replicates, where each replicate consisted of four plants per cage. Salvia plants in each cage (replicate) were infested with 100 MED whitefly (3×) at weekly intervals (25 whitefly/plant), and treatment cages with swirskii mite were inoculated with 20 mites/plant (3×) starting one week after whitefly infestations and prior to the first insecticide application. Pre-treat sampling to determine an initial count of arthropods and whitefly biotype confirmation was made prior to the drench application of cyantraniliprole. Treatment evaluation was made at weekly intervals for a period of 7 wk by randomly sampling five leaves per replicate and recording the number of A. swirskii eggs and motiles (nymph + adult) per leaf. For MED whitefly, eggs, early immature and late immature stages were recorded by taking two discs (∼1 cm²) per leaf. Count data were subjected to square root transformation prior to conducting the ANOVA and mean separation procedure. The data presented are the untransformed means. Means separation was performed using the least significant difference (LSD) mean separation test P <0.05.

Weekly samplings showed overlapping generations of A. swirskii on host plants throughout the study period indicating drench application of cyantraniliprole at the applied rate was compatible with A. swirskii. In mite only treated plots, a significantly higher mean number of A. swirskii eggs on weeks 1, 5, and 7 (Table 1) and motiles on weeks 2, 4, 5, and 6 (Table 1) were found compared with the rest of the three treatments. No significant difference in A. swirskii eggs and motiles between mite treated and combination plots (A. swirskii + cyantraniliprole) were reported on weeks 2, 3, 4, and 6 and 1, 3, and 7, respectively. Cyantraniliprole was effective in suppressing MED whitefly life-stages throughout the study period. A significantly lower whitefly eggs, early immatures, and late immatures were recorded on all the sampling dates (except for wk3 for late immatures) in two insecticide-treated plots (cyantraniliprole alone and in combination with swirskii) compared to the untreated control (Table 2). A. swirskii was as effective in reducing whitefly life stages as cyantraniliprole treated plots, and numerically, combination treatment provided the best suppression in MED whitefly population among three treated plots. Overall whitefly mortality in different treatments ranged between 62 and 96% for A. swirskii, 91–99% for cyantraniliprole, and 95–100% for combination treatments. No phytotoxicity was observed for any treatment.

Author notes