Comparison of Biological and Chemical Control of Greenhouse Whitefly on Poinsettia Stock Plants

Abstract

<jats:p>A demonstration study was conducted to compare the effectiveness of biological and chemical control treatments on the greenhouse whitefly (GHWF) <jats:italic>(Trialeurodes vaporariorum,</jats:italic> Westwood) using poinsettia <jats:italic>(Euphorbia pulcherrima</jats:italic> Wild.) stock plants. Two identical greenhouse compartments, each containing 84 stock plants, were used. In the biological control compartment, three biweekly releases of <jats:italic>Encarsia formosa</jats:italic> (EF) were made, while in the chemical control compartment eight weekly applications of resmethrin or acephate aerosol treatments were made. Results showed that overall greenhouse whitefly populations in the chemical con<jats:italic>trol</jats:italic> compartment <jats:italic>were</jats:italic> slightly lower than in the biological control compartment. Cuttings taken from stock plants in the biological control compartment at the end of the experiment were commercially acceptable with regard to the presence of GHWF adults. Chemical names used: O,S-dimethyl acetylphosphoramidothioate (acephate), [5-(phenylmethyl)-3-furanyl] methyl 2,2-dimethyl-3-(2-methyl-1-propenyl)cyclopropane-carboxylate (resmethrin).</jats:p>

BIOLOGY AND USE OF THE WHITEFLY PARASITOIDENCARSIA FORMOSA

“…Inundative releases of E. formosa have been successful in some instances for control of T. vaporariorum on poinsettia (76). Control of B. argentifolii with weekly releases of more than three adult parasitoids per plant per week, has not been accomplished (56, 90).…”

Comparison of Commercially and Locally Produced Encarsia formosa Gahan on the Control of Sweetpotato Whitefly on Poinsettias

“…The total release rate of 9.2 EF per plant is considerably lower than that implemented by other researchers for both GHWF and SPWF control studies (Parrella et al, 1991: Benuzzi et al, 1990McMahon et al, 1992). At a cost of $10.00 per 1000 EF and Fig.…”

“…Poinsettias are an excellent crop for biological control, as the crop typically is grown as a monoculture and there are only two insect pests of significance: the GHWF and the sweetpotato whitefly (SPWF) (Ecke et al, 1990). McMahon et al (1992) showed that poinsettia stock plants could produce terminal stem cuttings free of GHWF adults through three biweekly releases of 9.5 EF per plant. Releases were made when the GHWF infestation was small (i.e., two GHWF per plant), which is essential when implementing biological control agents (Albert, 1990).…”