Feeding and oviposition preference of Frankliniella occidentalis for crops and weeds in Kenyan French bean fields

Western flower thrips (WFT), Frankliniella occidentalis (Pergande) (Thysanoptera: Thripidae), is an important pest of French beans in Kenya. However, information on the feeding activity and oviposition preference of WFT on crop and weed hosts associated with French beans in Kenya and other parts of the world is lacking. To determine the feeding and oviposition preference of WFT for crop and weed plants commonly encountered in French bean fields in Kenya, no-choice and choice experiments were conducted using four important crop and weed plants. Among the crop plants tested, highest feeding and oviposition activity of WFT was recorded on courgette/zucchini (Cucurbita pepo L.) and French beans (Phaseolus vulgaris L.). Spinach beet (Beta vulgaris L.) and sweet pepper (Capsicum annuum L.) were of relatively minor importance for feeding and oviposition. Among the weeds tested, gallant soldier (Galinsoga parviflora Cav.) was the most preferred host plant for feeding and oviposition compared with Chinese lantern (Nicandra physaloides L.), wild crucifer (Erucastrum arabicum Fisch. & C.A. Mey.) and pigweed (Amaranthus hybridus L.). Phaseolus vulgaris was the most preferred host for feeding and oviposition in the presence of G.parviflora, E.arabicum and A.hybridus. A positive correlation between the number of feeding punctures and the number of eggs oviposited by WFT on crop and weed plants was observed. The results of this study show that P.vulgaris, C.pepo and G.parviflora are both relatively good feeding and oviposition hosts of WFT. Cucurbita pepo and G.parviflora may serve as potential sources of WFT outbreaks within French bean fields.