Rami Horowitz, A., The George S. Wise Faculty of Life Sciences, Tel-Aviv University, Department Zoology, Ramat-Aviv, 69978, Israel

Population studies of the tobacco whitefly, Bemisia tabaci (Gennadius), have been conducted recently in several regions of the world. The whiteflies were sampled by diverse sampling methods. Distribution of adults, eggs and nymphs of B. tabaci among and within the cotton plants, showed a strong tendency for aggregation. In cotton fields, four phases of population growth were observed, i.e., moderate, exponential (most common) stabilized (observed sometimes) and decline. Life-table analyses were recently applied, in order to define the main mortality factors affecting the population on cotton. Mortality of the first instar was identified as the key factor during the season studied, the main mortality factors being climatic. Parasitism, though present, was not a decisive mortality factor in the system studied. © 1986.