Resource Information

Efficacy of Insecticides Against Thrips on Dendrobium, Hawaii, 1994  

By: T. Y. Hata, A. H. Hara and Ben K.S. Hu

Beaumont Agri. Res. Center, University of Hawaii-Manoa, 461 W. Lanikaula St., Hilo, Hawaii 96720, Phone (808) 935-2885

HOST: Dendrobium Orchid: Dendrobium 'Uniwai Blush'
TARGETED PEST: Western flower thrips: Frankliniella
occidentalis (Pergande)

Tests were conducted from 14 Jul through 8 Sep 1994 on 8 year old orchid plants at a commercial dendrobium farm in Kailua-Kona, Hawaii. Plants were growing in 1.3 cm crushed basaltic rock under 30% polypropylene shade using standard cultural practices. Experimental plots measured 40 square feet with 58 plants per plot arranged in a randomized complete block (RCB) with four blocks. Four weekly applications of insecticides were applied beginning 14 Jul and ending 4 Aug. A spreader-sticker (Ad-here, J.R. Simplot, Lanthrop, CA) was added to all foliar treatments, including the control, at a rate of 0.5 ml per liter solution. Insecticides were applied at 1,345 liters/ha using a backpack sprayer (Solo Inc., Newport News, VA) equipped with an 8004 Teejet nozzle (Spraying systems Co. Wheaton, IL) at 276 KPa. The control was sprayed with water. Treatment efficacy was evaluated by randomly harvesting 5 inflorescences weekly from each block. Blossoms were removed from the inflorescences, counted, and placed in Berlese funnels heated with a 60 watt incandescent light bulb. Thrips were collected in an 8:2:1:1 solution of ethanol, distilled H2O, acetic acid and glycerin, and the number of nymphs and adults counted. Because the number of blossoms per inflorescences varied, thrips counts were adjusted to the number of thrips per blossom by dividing the total number of thrips recovered by the total number of blossoms. Data were transformed to log10 (x+1) and analyzed by analysis of variance (ANOVA) (P > 0.05).

The sex ratio of F. occidentalis was 6:4 (female/male). Avid 0.15EC significantly reduced the mean number of thrips per blossom after 4 weekly spray applications; however, control did not persist 2 weeks after the last insecticide application. Phytotoxicity was not observed with any of the treatments.

  Azatin Avid Marathon Control
lb AI 0.03 / 100 gal 0.01 / 100 gal 0.04 / acre  
14 Jul (Pretreatment) 0.8a 0.5a 0.6a 0.6a
21 Jul 1.3a 0.6a 1.6a 0.9a
28 Jul 0.9a 0.6a 1.4a 1.9a
04 Aug 1.4a 0.4a 1.3a 0.8a
11 Aug 1.2a 0.3b* 1.2a 0.8a
26 Aug 0.2a 0.3a 0.6a 0.4a

Means followed by the same letter in a row are not significantly different (Waller-Duncan k-ratio t test, k=100).


Use pesticides safely. Follow the pesticide label. Consult with the Cooperative Extension Service or the Hawai'i State Department of Agriculture for authorized special local need registrations or additional information. The user is responsible for the proper use, application, storage, and disposal of pesticides.

Reference to a company or product name does not imply approval or recommendation of the product by the College of Tropical Agriculture and Human Resources, Cooperative Extension Service University of Hawaii, or the United State Department of Agriculture and does not imply its approval to the exclusion of other products that may be suitable. All materials should be used in accordance with label instructions or manufacturer's directions.

Product Name: Avid 0.15EC
Manufacturer’s Name: MSD-Ag Vet.
Address: P.O. Box 2000, Rahway, NJ 07065-0912
Composition: avermectin-B 0.15 lb active per gallon

Product Name: Azatin EC
Manufacturer’s Name: AgriDyne Technologies Inc.
Address: 2401 So. Foothill Dr., Salt Lake City, UT 84109
Composition: azadirachtin 0.265 lb active per gallon

Product Name: Marathon 1% Granular
Manufacturer’s Name: Miles Inc.
Address: P.O. Box 4913, 8400 Hawthorn Road, Kansas City, MO 64120
Composition: imidacloprid 1%G