Yield and insect injury in leafhopper (Empoasca fabae Harris and Empoasca kraemeri Ross & Moore) infested dry beans in Ontario and Colombia

Recombinant inbred lines derived from a cross between a leafhopper-susceptible bean (Phaseolus vulgaris L.), Berna Dutch brown and leafhopper-resistant selection EMP 419 were examined for resistance to the leafhopper species Empoasca fabae (Harris) and Empoasca kraemeri Ross and Moore in Ontario, Canada and Colombia, South America, respectively. In both Ontario and Colombia there were significant positive correlations of visual injury scores with percent reductions in seed count, seed yield and seed weights. Leafhopper injury symptoms were significantly correlated with degree of stunting in Ontario, while only leaf burn scores were correlated with stunting in Colombia. Nymph counts were significantly and positively correlated with leaf curl scores in Ontario but not in Colombia, despite significant rank correlations of leaf burn scores and leaf curl scores between these locations. In a second experiment comparing the effects of E. fabae nymph infestations on set of 23 resistant and 5 susceptible recombinant inbred lines (RILs), the latter lines were infested by significantly fewer nymphs. Possible resistance mechanisms to E. fabae and E. kraemeri are discussed.