Abstract:
Western flower thrips; Frankliniella occidentalis (Pergande) and Megalurothrips
sjostedti (Trybom) (Thysanoptera: Thripidae) are among the most important pests of
French beans, (Phaseolus vulgaris) in Kenya. Attack by thrips leads to flower
malformation, distortion, and discoloration while in severe infestations, flower buds
do not open and may abort prematurely, hence, the need for urgent and effective
alternative intervention strategies. The study was aimed at evaluating various French
bean cultivars for their susceptibility to thrips and the effect of nitrogen fertilizer and
natural enemies on population dynamics of thrips and hence come up with
innovative integrated pest management (IPM) strategies for management of thrips in
French beans. This was done through a study of changes in the population of flower
thrips based on different French bean cultivars: Paulista, Army Star, Julia, Samantha
and Alexandra, grown under varied top dressing nitrogenous fertilizer regimes. This
was done between August 2007 and January 2008 in, JKUAT farm and KARI
Mwea. The experiment was laid in a Randomized Block Design with two treatments
and four replications. Ten flowers and leaves were sampled at random from each of
the experimental plots and taken to the laboratory for counting of thrips and Natural
enemies. There was significant difference in the mean number of both F.
occidentalis and M. sjostedti population among the six French bean cultivars.
Results from this study demonstrated that some French bean cultivars were more
resistant to flower thrips. Julia had the highest overall mean while Paulista had the
least number of thrips. This suggests that the most susceptible variety among the six
