Arthropod Management Tests, 2017, 1–2
SALVIA (NEW DIMENSION BLUE): Salvia nemorosa L.
doi: 10.1093/amt/tsx054 Section G: Ornamentals & Turf
Effect of Foliar Application of Pymetrozine on Bemisia tabaci (MED Whitefly) and Amblyseius swirskii, 2016* Vivek Kumar,1,2 Garima Kakkar,3 Cindy L. McKenzie,4 and Lance S. Osborne1,5 1
Mid-Florida Research and Education Center, University of Florida-IFAS, 2725, S. Binion Rd., Apopka, FL 32703, Phone: 772-462-5978, Fax: 772-462-5986 (
[email protected]), 2Corresponding author, e-mail:
[email protected], 3 University of Florida-IFAS Extension, 8400 Picos Rd., Suite 101, Ft. Pierce, FL 34945, Phone: 772-462-1660, Fax: 772-462-1510 (
[email protected]), , 4USDA, ARS, USHRL, 2001 South Rock Rd., Fort Pierce, FL 34945, Phone: 772-462-5912, Fax: 772-462-5986 (
[email protected]), and 5Mid-Florida Research and Education Center, University of Florida-IFAS, 2725, S. Binion Rd., Apopka, FL-32703, Phone: 407-884-2035, Fax: 407-814-6186 (
[email protected]) Section Editor: Carlos Bogran MED (Q) whitefly: Bemisia tabaci (Gennadius) Swirskii mite: Amblyseius swirskii (Athias-Henriot) Salvia sp. j Salvia nemorosa sweetpotato whitefly j Bemisia tabaci, swirskii mite j Amblyseius swirskii 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 pymetrozine, a pyridine azomethine derivative for whitefly control, and assess its compatibility with swirskii mite. The trial was conducted on an ornamental host, Salvia nemorosa L. (New dimension blue) 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 inside plexiglass screened cages (61 cm 91 cm 61 cm) for 8 wk to prevent contamination prior to experimentation. Plants in seedling trays were then transplanted into one-gal 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 ProfessionalV 20-10-20 (325 ppm) (Scotts Co., Marysville, OH). Four treatments — (1) control, (2) pymetrozine, (3) swirskii, and (4) swirskii þ pymetrozine were arranged in a randomized complete block design with six replicates, where each replicate (cage) consisted of four plants per cage. Salvia plants were inoculated with MED whitefly by releasing 100 adults per cage (25 per plant) three times at weekly intervals. Treatment cages with swirskii mite were inoculated with 20 mites/plant (3) starting one week after first whitefly inoculation and prior to insecticide application. Plants in cages were sampled to obtain pre-treatment counts and to confirm whitefly biotype. Foliar applications of pymetrozine were made on R
week 0 and week 4 at the rate of 5 oz/100 gal and 10 oz/100 gal, respectively. Treatment evaluation was made at weekly intervals for a period of 7 wk by destructive sampling five leaves per replicate (cage) and recording the number of A. swirskii eggs and motiles (nymph þ adult) per leaf, and MED whitefly eggs and nymphs on two discs (1 cm2) per leaf, using a binocular microscope. Whitefly adult count was taken per leaf sample by leaf-turn method (visual counting of adults before removing leaves from the plant). Counts of whitefly and swirskii mite observed in different treatments were analyzed independently using a generalized linear mixed model with the SAS (SAS Institute, Cary, NC) procedure GLIMMIX. The model was used to determine the effect of insecticide treatments, sampling period and their interaction on the arthropod counts. Since the response variable was count data with no upper bound, in model statement distribution was specified as Poisson. The autoregressive correlation structure was applied to take care of the correlation between observations collected on the same experimental units over time. Differences among treatment means were separated using Fisher’s LSD test (a ¼ 0.05) in the repeated measures model. As the number of whitefly life stages in the efficacy trial was not uniform, Henderson– Tilton’s formula was used to calculate corrected mortality. Weekly samplings showed overlapping generations of A. swirskii on host plants in combination treatment (A. swirskii þ pymetrozine) throughout the study period indicating foliar application of pymetrozine at the applied rates was compatible with A. swirskii.
* This research was supported by the Floriculture and Nursery Research Initiative & USDA Farm Bill. C The Authors 2017. Published by Oxford University Press on behalf of Entomological Society of America. V
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Arthropod Management Tests, 2017, Vol. 42, No. 1
Table 1 Treatments
Rate/100 gal
Mean number of A. swirskii life-stages per salvia leaf Wk 0
Eggs Control Pymetrozine A. swirskii Pymetrozine þ A. swirskii Motiles Control Pymetrozine A. swirskii Pymetrozine þ A. swirskii
Wk 1
Wk 2
Wk 3
Wk 4
Wk 5
Wk 6
Wk 7
– 5 ozþ10 oz – 5 ozþ10 oz
0.00a 0.00a 1.20b 1.27b
0.00a 0.00a 0.67b 0.17ab
0.00a 0.00a 0.60b 0.40b
0.00a 0.00a 1.13b 0.73b
0.00a 0.00a 0.30ab 0.70b
0.00a 0.00a 0.33a 0.23ab
0.00a 0.00a 0.20a 0.10a
0.00a 0.00a 0.03a 0.13a
– 5 ozþ10 oz – 5 ozþ10 oz
0.00a 0.00a 1.13b 0.90b
0.00a 0.00a 1.07b 0.67b
0.00a 0.00a 0.43a 0.27ab
0.00a 0.00a 0.70a 0.70a
0.00a 0.00a 0.27ab 0.43b
0.00a 0.00a 0.43a 0.17ab
0.00a 0.00a 0.20a 0.10a
0.00a 0.00a 0.07a 0.13a
Means within a column followed by the same letter are not significantly different (P > 0.05, LSD test).
Table 2 Treatments
Rate/100 gal
Mean number of whitefly life-stages Wk 0
Wk 1
Wk 2
Wk 3
Wk 4
Wk 5
Wk 6
Wk 7
0.47ab 0.77a 0.00b 0.00b
0.47a 0.50a 0.00b 0.00b
1.93a 2.17a 0.10b 0.00b
9.83a 4.37b 0.00c 0.00c
12.03a 6.23a 0.00b 0.00b
27.77a 14.13a 0.07b 0.00b
44.33a 22.87a 0.07b 0.00b
47.13a 18.83b 0.00c 0.00c
2.13a 2.10a 0.33b 0.43b
4.87a 4.07a 0.03b 0.20b
10.13a 4.00b 0.03c 0.07c
45.37a 21.13b 0.33c 0.00c
35.10a 25.80a 0.07b 0.00b
43.10a 22.73a 0.50b 0.17b
53.33a 26.60b 0.63c 0.20c
52.77a 30.30a 0.50b 0.13b
0.00a 0.00a 0.00a 0.00a
1.07a 0.67ab 0.10c 0.17bc
3.63a 2.07a 0.13b 0.10b
13.60a 1.60b 0.07c 0.00c
7.87a 1.20b 0.17c 0.00c
8.47a 3.67a 0.20b 0.03b
10.33a 1.57b 0.10c 0.07c
5.97a 4.80a 0.07b 0.00b
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Eggs/two leaf discs (1 cm ) of salvia Control – Pymetrozine 5 ozþ10 oz A. swirskii – Pymetrozine þ A. swirskii 5 ozþ10 oz Nymphs/two leaf discs (1 cm2) of salvia Control – Pymetrozine 5 ozþ10 oz A. swirskii – Pymetrozine þ A. swirskii 5 ozþ10 oz Adults/salvia leaf Control – Pymetrozine 5 ozþ10 oz A. swirskii – Pymetrozine þ A. swirskii 5 ozþ10 oz
Means within a column followed by the same letter are not significantly different (P > 0.05, LSD test).
No significant difference in A. swirskii eggs and motiles between mite treated and combination treatment were reported on any of the sampling dates (Table 1). Pymetrozine alone was not consistent in suppressing MED whitefly life-stages. A significantly lower number of whitefly eggs, nymphs and adults compared to untreated control were recorded on week 3 and 7, week 2, 3 and 6, and on week 3, 4 and 6, respectively (Table 2). A. swirskii
provided higher suppression in whitefly life-stages than the pymetrozine treatment, and were as effective as combination treatment throughout the study period. Overall whitefly mortality in different treatments ranged between 84 and 97% for A. swirskii, 26–64% for pymetrozine, and 66–100% for combination treatments. No phytotoxicity was observed for any treatment.
