Group Title: Research Report - University of Florida Central Florida Research and Education Center ; 90-09
Title: Bioassay of two new insecticides, CGA-106630 and CGA-184699, against sweetpotato whitefly, Bemisia tabaci (Gennadius
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 Material Information
Title: Bioassay of two new insecticides, CGA-106630 and CGA-184699, against sweetpotato whitefly, Bemisia tabaci (Gennadius
Series Title: Research Report - University of Florida Central Florida Research and Education Center ; 90-09
Physical Description: Book
Language: English
Creator: Leibee, Gary L.
Savage, Kenneth E.
Publisher: University of Florida, Central Florida Research and Education Center
Publication Date: 1989
 Record Information
Bibliographic ID: UF00076082
Volume ID: VID00001
Source Institution: University of Florida
Rights Management: All rights reserved by the source institution and holding location.
Resource Identifier: oclc - 122930205

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University of Florida
CENTRAL FLORIDA RESEARCH AND EDUCATION CENTER
Sanford, Florida

.- SaEppRtpr SAN 90-09 December 1989
Cenil ScenceBIOASSAY OF TWO NEW INSECTICIDES, CGA-106630 AND CGA-184699,
Library AGAINST SWEETPOTATO WHITEFLY, BEMISIA TABACI (GENNADIUS)

JAN 11 1990 Gary L. Leibee and Kenneth E. Savage

University of Florida
CGA-106630 SC500 and CGA-184699 50EC (Ciba-Geigy Corp.) were evaluated for
activity against sweetpotato whitefly, Bemisia tabaci (Gennadius), with a
leaf-dip technique in the laboratory. Abamectin (MK-936, Merck & Co.) was
included in the test as a standard material. Cowpea leaves infested with all
stages of sweetpotato whitefly were harvested from plants maintained in a
greenhouse heavily infested with sweetpotato whitefly. Thirty trifoliate leaves
were cut and placed individually into foam grow cubes saturated with water to
,maintain the leaves until the dosing procedure was completed. Five trifoliates
(15 leaflets) were used for each treatment. The following treatment
concentrations were prepared: CGA-106630 SC500 at 0.6 and 0.85 g ai/liter,
CGA-184699 50EC at 0.13 and 0.19 g ai/liter, and MK-936 at 0.024 g of ai/liter
(based on a field use rate of 0.01 lb ai/acre in 50 gpa). X-77 (Chevron Chemical
Co.) was added to the leaf-dip at the rate of 0.62 ml/liter (8 oz/100 gallons)
to promote wetting of the leaves. The untreated checks were dipped into water
containing only X-77. Each trifoliate was removed from its growth cube, emersed
for five seconds in one-liter of the appropriate mixture, the excess material
shaken off, and returned to the growth cube. One hour later, after the
trifoliates had dried, the 15 leaflets were clipped and each leaflet was placed
in a 100 x 15 mm plastic Petri dish (FISHERbrand Cat. #8-757-12). Each leaflet
was considered a replication. The plastic Petri dishes were used in the upside
down position. The top and the bottom of the Petri dish, which normally fit
loosely, were made to fit snugly by laying three 11-cm diam P8 filter papers
(FISHERbrand Cat. #09-795D) on the upside down lid and pressing the Petri dish
bottom into the lid after placing the leaflet on the filter paper. Before
assembling, the Petri dish bottom, which is now the top of the container, was
wiped with a thin layer of soybean oil to trap the emerging adults. The treated
leaves were maintained at 25 10 C and a 12-hr photoperiod. Three days after
dipping the tops of the containers were removed and replaced. Before changing
the tops, the containers were placed in the freezer compartment of a refrigerator
for 1-3 minutes to immobilize the adults that were not stuck in the soybean oil.
The whiteflies on the lids were counted with a dissecting microscope. Six days
after dipping, the second set of tops was removed to make another count. The
tops were replaced, but this time without soybean oil. Seventeen days after
dipping the Petri dishes were opened and inspected for the final count.

Results indicated that both CGA-106630 and CGA-184699 were as active as
MK-936 (abamectin) on the sweetpotato whitefly. Even though the insecticides
appeared to reduce the whitefly counts for all but one treatment three days after
dipping, the differences in whitefly counts were not significant (P > 0.05)
until the sixth day after dipping. Ninety-seven percent of the whitefly
emergence had occurred by the 6-day reading in the untreated check. Ninety-two
to 100% of the whitefly emergence had occurred by the 6-day reading in the










treated plants. The lack of significance (P > 0.05) for the three-day counts
may have been due to an adult emergence from older pupae before the insecticides
had taken effect.




Table 1. Results of bioassay conducted to evaluate the
effectiveness of CGA-106630 and CGA-184699 on the sweetpotato
whitefly, Bemisia tabaci (Gennadius), relative to abamectin.

Number of adults collecteda
from each cowpea leaflet
0-3 days 3-6 days 0-17 days
Grams after after after
Insecticide ai/liter dipping dipping dipping


Untreated check
(water + X-77) --- 10.2NS 28.3 a 39.8 a

CGA-106630 SC500 0.600 9.3 5.1 b 14.6 b

CGA-106630 SC500 0.850 5.6 2.6 b 8.2 b

CGA-184699 50EC 0.130 5.3 1.3 b 6.7 b

CGA-184699 50EC 0.190 3.0 2.4 b 5.9 b

MK 936 0.15EC 0.024 4.8 2.5 b 7.3 b

'Means in the same column followed by the same letter are
not significantly different at the 0.01 by DMRT. ANOVA
performed on transformed [sq. rt. (x + 0.5)] data.




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