The resistance of genotypes of two species of Phaseolus beans to the leafhopper Empoasca kraemeri

SUMMARY To determine whether two species of Phaseolus beans differ in their suitability for reproduction of the leafhopper Empoasca kraemeri, resistant and susceptible genotypes of the two species were exposed to egg laying leafhoppers and the resultant numbers of nymphs on each were compared. Resistant genotypes of P. acutifolius bore fewer nymphs than any genotype of P. vulgaris. Even susceptible P. acutifolius genotypes bore no more nymphs/leaf than resistant P. vulgaris genotypes though they did bear more nymphs/cm2 of leaf area. These results indicate that P. acutifolius may be a useful donor of oviposition non-preference, increased egg mortality, or possibly nymphal non-preference, and confirm that counts of nymphs provide a useful screening technique in the selection of parental genotypes for an improvement programme.