| Recently the whitefly Bemisia tabaci (Genn.) (Homoptera: Aleyrodiae) had becomeone of the most serious pests in economic plants in China. This kind of the pest had thefollowing characters: wide host range, quick population increasement, high resistance andso on. It was difficult to control it with chemicals. Because of the shortcoming of the usageof the chemicals such as pesticide contamination, pesticide residue, environmentalpollution, ecological unbalance and the needs of the development of the nuisance free foodand green vegetables, it was urgent to enhance the study of the integrated managementsystem with biological control as the base. Since Encarsiaformosa (Gahan) was proven tobe efficient under conditions in greenhouse in temperate regions, attention has primarilyfocused on this parasitoid as a candidate for biological control of B. tabaci. Still moredetailed information on the biology and efficiency of the parasitoid with respect to B.tabaci was needed to extend the knowledge to pest-beneficial interactions, to improvebiological control and evaluate the potential of E. formosa.The research on the influence of the photoperiod, temperature, food on thedevelopment time, fecundity, emergence rate, longevity of E. formosa and the relatedinvestigation of the influencing factors of the parasitism rate of were carried out betweenAug 2005 and Feb 2007 by feed an E. formosa in leaf cage. In addition, a comparison onthe control efficiency and the costs between the traditional chemicals and the E. formosawere given.1 the adult developmental time was 15.2d, 14.7d, 15.2d respectively, the fecunditywas 78.9, 61.3, 52.6 respectively, the emergence rate was 96.3%, 97.0%, 92.8%; When thetemperature were 20℃, 23℃, 26℃, 29℃and 32℃, the adult developmental time was23.2d, 14.4d, 14.7d, 12.0d, 14.0d respectively, the fecundity was 88.8, 64.6, 84.7,77.1 and 68.9 respectively, the emergence rate was 94.7%, 99.5%, 98.4%,99.5%and85.7%;In the photoperiod of 16h, 13h, 10h, when the food B. tabaci was provided, the adultlongevity was 13.1d, 12.7d, 11.8d and when not provided, the adult longevity was shorter,from 2.2h to 1.9h.In the temperature of 20℃, 23℃, 26℃, 29℃and 32℃, when the food B. tabaci wasprovided, the adult longevity was 22.4d, 16.4d, 13d, 10.3d and 9.0d and when not provided,the adult longevity was 2.8d, 2.8d, 2.3d, 2.3d and 2.0d.2 This spatial distribution of Trialeurodes vaporariorum (Westwood) nymphs, adultsand their black "pseudo pupae" parasitized by Encarsia formosa (Gahan) on the cherrytomato was investigated in the sunlight greenhouse. In the level of the vertical distribution, the number of nymphs and adults of T. vaporariorum on the upper, tender and fully openleaves was the most, an single average plant is the most respectively reaching at 1.6, 17; inthe level of the horizontal distribution, the adults didn't show an obvious regularity, thelarvae underneath the leaning shady-side and the vent plant are the most, an single averageplant reaching 40, but those on the southern plants was the least, an single average plantreaching at only 7.0The black "pupa" which was parasitized by E. formosa was the most on the upper ofthe plants, an single average plant reaching at 20, in the vertical distribution; those on theplants in the north were the most, an single average reaching at 88, but those were the least,an single average plant only reaching at 3.03 The effectiveness between E. Formosa and insecticides was used to control T.vaporariorum in solar greenhouse in Deng zhuang County, Hebei Province from late Aprilto early June when cherry tomato was vigorous fruiting. In the greenhouse which E.formosa was released (GE): the average and maximum of the parasitism rate of E. formosawere 61.9% and 81.8%; the average and maximum of the percentage of black "pupa" plantwere 87.16% and 100%; the number of the whitefly adult was 0.47-2.4 per plant. In thegreenhouse which the chemicals was used (GC): the number of the whitefly were unstable,the adult was 0,3-37.6 per plant and the larvae was 8.2-85.2 per plant.The cost was about￥45-100 during one growing season in GE, but the cost wasabout￥120-180 in GC.In summary, considering various factors, 13h illumination and 26℃were quitesuitable for the development and propagation at different lighting and temperature; nomatter what the illumination time length, the existence of the host B. tabaci or not hadquite obvious effects in the adult longevity, the greenhouse whitefly larvae and adults wereaddicted to feed, activity or oviposit on the leaves of the upper of the young tender andventilated plants and the spatial distribution of the black "pupa" parasitized by E. formosawas approximately consistent in the larvae of T. vaporariorum.The parasitic capacity of E.formosa on the whitefly was quite strong and the control efficiency of the whitefly wassignificantly higher than the traditional chemicals and had the advantages of low cost andsafe.
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