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Gregory J. McKee, Frank G. Zalom, and Rachael E. Goodhue

The greenhouse whitefly, Trialeurodes vaporariorum (Westwood), is a cosmopolitan pest of greenhouse crops and ornamentals. It damages plants by feeding on nutrients in a plant's phloem, which may result in yield loss ( Byrne et al., 1990 ), and

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Diana Carolina Núñez-López, Augusto Ramírez-Godoy, and Hermann Restrepo-Díaz

ones treated with insecticides along the experiment. Fig. 1. Summary of population growth of Trialeurodes vaporariorum for adults, nymphs, and eggs per leaflet in ‘ICA-Cerinza’ plants for Expt. 1 ( A , D , and G ), Expt. 2 ( B , E , and H ), and

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Marie E. Maiuro

Fifty greenhouse whitefly (Trialeurodes) were placed in each of 10, one-meter square nylon chiffon cages containing nine regal geraniums in 6-inch pots. After allowing the whitefly to reproduce for 2 weeks, the treatments tested were Delphastus pusillus alone, Azatin sprays alone, D. pusillus and Azatin together, and no control method. Two repetitions for each treatment were conducted. The Azatin, 14 oz/100 gallons, and a spreader/sticker were applied weekly with a mist sprayer. Delphastus pusillus, nine per cage, were released every 2 weeks. Sampling was conducted weekly by placing yellow sticky traps into each box for a 24-hour period, then counting the number of adults caught. All treatments gave statistically significant fewer whitefly than the cages with no control method. The cages with Azatin and/or D. pusillus were not statistically different from each other. Results indicate that D. pusillus can control whitefly as well as a growth regulator/botanical insecticide.

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Hiram G. Larew and James C. Locke

The repellency and toxicity of a petroleum-based proprietary horticultural oil, Sunspray 6E Plus, was tested against the greenhouse whitefly, Trialeurodes vapor-ariorum (Westwood), on greenhouse-grown chrysanthemums [Dendranthema ×grandiflorum (Ramat.) Kitamura cv. Iceberg]. A 2% (v/v) aqueous spray repelled adult whiteflies for at least 11 days after spraying and it was toxic to newly hatched and third stage larval whiteflies. No phytotoxicity was observed when four weekly sprays of 1%, 2%, and 4% oil were applied.

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J.L. Bi, N.C. Toscano, and G.R. Ballmer

The efficacy of two novel chloronicotinyls and two novel insect growth regulators against the greenhouse whitefly [Trialeurodes vaporariorum (Westwood)] on summer-planted strawberries was evaluated in field experiments. Imidacloprid applied in soil 3 weeks after planting decreased whitefly adult numbers by 58% to 90%, first and second instars by 78% to 93% up to 56 days postapplication, and third and fourth instars by 42% to 86% up to 77 days postapplication, whereas thiamethoxam applied similarly reduced adults by 58% to 80%, first and second instars by 78% to 93% up to 6 weeks posttreatment, and third and fourth instars by 48% to 80% up to 10 weeks after initial application, compared to nontreated controls. Imidacloprid applied in soil immediately prior to planting further suppressed numbers of whiteflies by 71% to 83% (adults), 58% to 74% (first and second instars), and 52% to 74% (third and fourth instars), in comparison with the same compound applied through drip irrigation lines 4 weeks after planting. Buprofezin and pyriproxifen applied 6 weeks after planting reduced numbers of adult whiteflies by 25% to 81% and 40% to 73%, respectively; first and second instars by 61% to 92% and 51% to 100%, respectively; and third and fourth instars by 45% to 100% and 37% to 87%, respectively, on most sampling dates up to 7 weeks postapplication. The potential roles of these insecticides in integrated greenhouse whitefly management programs are discussed.

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J.L. Bi and N.C. Toscano

California is a world leader in strawberry production. Since the late 1990s, strawberry production has been threatened by a major insect pest, the greenhouse whitefly, Trialeurodes vaporariorum Westwood (Homoptera: Aleyrodidae) ( Bi et al., 2002

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Heather S. Costa, Julie Newman, and Karen L. Robb

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Kim E. Tripp, William K. Kroen, Mary M. Peet, and Daniel H. Willits

Eight tomato (Lycopersicon esculentum) cultivars were grown for 16 weeks in greenhouses enriched for an average of 8.1 hours daily to 1000 μl CO /liter of air or in greenhouses maintained at ambient CO. Carbon dioxide enrichment significantly decreased the mean number of greenhouse whiteflies [Trialeurodes vaporariorum (Westward), Homoptera: Aleyrodidae] as measured by counts from commercial yellow sticky traps. The number of whiteflies present was negatively correlated with both seasonal foliar C: N ratio and percent C but positively correlated with percent N in the foliage. Thus, CO enrichment apparently alters plant composition in such a way as to reduce significantly the population growth of greenhouse whiteflies.

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Masood Hadi and Mark P. Bridgen

Callus cultures of Torenia fournieri `Compacta Blue' were initiated on a modified Murashige and Skoog salt medium (MS) with 2.26 uM 2,4-dichloro-phenoxy acetic acid. Shoots were regenerated from these cultures using the MS medium amended with 2.46 uM 3-indolebutyric acid and 8.88 uM 6-benzylaminopurine. These shoots were subjected to Tetranychus urticae Koch (twospotted spidermite) and Trialeurodes vaporariorum (Westwood) (greenhouse whitefly) in vitro. Pests were allowed to feed until such time that the pest population started to decrease due to lack of food. Remaining shoot tissue was placed on MS medium amended with 2.28 uM zeatin to -induce shoot formation. Shoots were acclimated to greenhouse conditions and evaluated for resistance to the pest to which they were subjected in vitro. Highly significant differences in pest numbers were found in somaclones when compared to control plants. A wide range of variability was observed within the somaclonal population.

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R.W. McMahon, R.K. Lindquist, M.L. Casey, A.C. Witt, and S.H. Kinnamon

A demonstration study was conducted to compare the effectiveness of biological and chemical control treatments on the greenhouse whitefly (GHWF) (Trialeurodes vaporariorum, Westwood) using poinsettia (Euphorbia pulcherrima Wild.) stock plants. Two identical greenhouse compartments, each containing 84 stock plants, were used. In the biological control compartment, three biweekly releases of Encarsia formosa (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 control compartment were 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).