Bemisia tabaci (Gennadius) population density and pupal size are dependent on rootstock and nitrogen in hydroponic tomato crop

Abstract

Abstract Bemisia tabaci is one of the most damaging pests in tomato greenhouse production. The resistance of B. tabaci to insecticides requires a new approach with respect to the integrated management of this pest. The effect of grafting (nongrafted and tomato grafted on the rootstock Arnold) and nitrogen (N) rates (75, 140 and 205 mg/L) on the density of B. tabaci large nymphs (fourth instar to pupae) was studied in 2012. In 2013, large nymphs density was examined in relation to grafting treatments (nongrafted, self‐grafted and tomatoes grafted onto the rootstocks Arnold and He‐Man) and NO3− : NH4+ ratios (92 : 8, 85 : 15 and 70 : 30). A reduction of B. tabaci population density was found for rootstock Arnold grown at 140 and 205 mg/L N in the nutrient solution. Pupal size decreased with decreasing N fertilization. In the second experiment, rootstocks contributed to a reduction of B. tabaci density at different NO3− : NH4+ ratios. The lowest B. tabaci population density was found on plants grafted onto He‐Man rootstock supplied with an 85 : 15 and 70 : 30 NO3− : NH4+ ratio in nutrient solutions. The increased proportion of NH4+ in the 85 : 15 NO3− : NH4+ ratio generally reduced the B. tabaci pupal size for all rootstocks. Grafting and N adjustment could represent useful tools for integrated greenhouse pest management.