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Problems of Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae) that increased and escalated in the last 40 years seem to be related to one or more aggressive biotypes that appeared to spread steadily worldwide. As well, some biological characteristics of B. tabaci have led some entomologists to change and multiply their methodology to update with the change in the pest genetic structures. This study is the 1st of its kind in Qassim region in KSA in respect of B. tabaci biotypes. Four identification methods (Squash Silverleaf Symptoms (SSL), cross mating, Cytochrome oxidase subunit I (COI) sequences, and ISSR-PCR analysis) were carried out to determine the biotypes of B. tabaci at Qassim regions. Slight SSL symptoms were observed with varying degrees on squash leaves caused by B. tabaci population at Qassim, KSA. Cross-mating among the populations that have the same or similar genetic structures produced fertilized offspring, females and males with higher sex ratios in favor of females, and produced a higher number of eggs. Whereas, B. tabaci populations that varied greatly in their genetic structures produced unfertilized eggs, which produce males only. In the same trend, ISSR-PCR analysis revealed that B. tabaci populations at Qassim regions varied genetically and gathered into four genetic groups. In conclusion, COI analysis is a perfect tool for classification between biotypes in B. tabaci. Therefore, this study declares that B. tabaci that colonized and infest Qassim horticulture has not the same genetic structures but belonging to B biotypes. It could be named as Bemisia species complex. |
