Influence of the development and host-plant on the differential haemocyte counts in the cotton whitefly, Bemisia tabaci Genn. (Hom.:Aleyrodidae).

Haemocytes of different developmental stages of Bemisia labaci Genn. were examined. In all stages, six types of haemocytes were recognized and found : prohaemocytes (Pr.), granulocytes (Gr.), non-granulocytes (nGr.), oenocytes (Oen.) and spherule cells (Sph.). Changes occurring in the differential haemocyte count (DHC) and in surface area were investigated during the different metamorphic stages of the subject insect. The regression analysis of the obtarned results showed a positive regression between the age and DHC in each of Pr., Gr., Oen. and Sph.. In the contrary, negative regression was recorded between the age and counts of Pl. and nGr. In addition, the data showed a positive relationship between the age and E-uriäce area of all haemocyte types. The changes in haemocytes picture were examined in both male and female of B tabaci adults reared on different host-plants (tobacco, tomato and malabar nut). The results proved the existence of host-correlated variations phenomena in DHC of adults. The DHC were highly significantly affected by host-plant, and significantly afTected by adult-sex. In addition, the dual interacting effect of the studied factors (DHC and host-plant; sex and host-plant) proved to be highly significant. While, the dual interacting effect between DHC and sex proved to be significantly different. Also, the interacting effect of the three studied factors (DHC, sex and host-plant), ail together, proved to have highly significant influence. Tobacco plants had a positive superior effect on the DHC of Pl., Gr. and nGr. However, malabar nut plants showed a supreme effect on Oen. count. On the other hand, no significant differences were recorded in Sph. counts among tested host-plants. Concerning the sex effect on DHC, the study proved that Pr. counts always exceed in females than that in males within the same host-plant. However, irrespective of Pl. counts in malabar nut culture, Oen. and Sph. in tobacco culture, the DHC in males always exceed than those in females.