Abstract Whiteflies are a group of worldwide devastating agricultural pests of economic importance from Aleyrodidae family. These pests cause quantitative and qualitative damage to plants by direct feeding from sap and transmission plant virus. Bemisia tabaci and Trialeurodes vaporariorum are two of the most important species of this family that cause great damage in greenhouse vegetables. Two of the best-known biotypes are B and Q and are the most globally widespread species. In this study, population fluctuations of B. tabaci and T. vaporariorum were investigated in two consecutive years, 2022 and 2023, on cucumber, tomato, eggplant, and pepper in greenhouses located in Mobarakeh, Isfahan. eva‎luation of population fluctuations in 2022 was done throughout the year and for this purpose, by cumulation each greenhouse, the nearest greenhouse of the same crop was replaced. Sampling was done in the first year from two cucumber, three tomato, two eggplant, and one pepper greenhouses. The study of population fluctuations was continued by selecting one greenhouse from each host in the second year. In each round of greenhouse sampling, five plants were randomly selected and sampling was done weekly in the first year and once every 10 days in the second year. Whitefly populations collected in this study from different greenhouses were identified initially based on Bem 23 F/R primers. The results showed that both species of whiteflies were present in both years and on all hosts. Biotype B was the only B. tabaci species detected in the studied greenhouses. In the first year, adults appeared in the greenhouses from mid-May, but in the second year, adults of both species were observed from mid-June. In 2022 and 2023, in pepper greenhouses, B. tabaci was the dominant species and T. vaporariorum had a much lower population. In tomato and cucumber greenhouses, in the first year, no significant difference was observed between the populations of the two species, but in the second year, T. vaporariorum was dominant. B. tabaci was dominant in eggplant greenhouses in 2022, while in 2023 T. vaporariorum was dominant on this host in the sampled time period. The study of whitefly population fluctuations throughout 2022 in eggplant and tomato greenhouses showed that T. vaporariorum had a higher population in spring and autumn, while B. tabaci was dominant in summer. The competition points of two species, which was actually the change point of dominant species, were observed at a certain density of their population and were strongly influenced by temperature. Continuous sampling on pepper, cucumber, tomato and eggplant plants showed that although both species were present in greenhouses almost all of the year, the temperature-dependent activity pattern is not a constant. It seems that species population density and species main effect are strongly influenced by various biotic and abiotic factors, including winter cold weather or early season low temperature; to the extent that in the eggplant greenhouses, the fluctuations of two species were opposite in two consecutive years. Key words: Aleyrodidae, biotype B, co-occurrence, seasonal changes

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نفيسه پورجواد

جهانگير خواجه علي , حسن كريم مجني