Abstract:
Bemisia tabaci is an important agricultural pest worldwide, which used to be a minor, pest in Ghana but has become a major pest mainly due to the misuse of insecticides. The objectives of this thesis were to examine the occurrence of biotypes, within and between-plant distribution, dispersion and sampling methods for B. tabaci adults on cassava, tomato, okra, garden egg and coral plant. Using cross- infestation, population trends and random amplified polymorphic DNA - polymerase chain reaction (RAPD-PCR) two biotypes were identified. A cassava biotype found on cassava that could survive on cassava, garden egg and eggplant. A non-cassava biotype found on tomato, garden egg and coral plant that survived on all the host plants tested except cassava. The insecticide test did not reveal any differences in population characteristics. Majority of B. tabaci adults were found on upper leaves (1st and 2nd) and bottom leaves (leaves 7th - 9th) on cassava. They were also found on the upper half of the tomato plant and on young and middle aged leaves on garden egg and okra. The insects were aggregated within-plants on tomato, garden egg and okra and between-plants on tomato and okra. The correlation coefficients for insect counts of different sampling units and whole plant counts and sample sizes at particular error levels are presented.
