Comparison of AC electronic monitoring and field data for estimating tolerance to Empoasca kraemeri (Homoptera : Cicadellidae) in common bean genotypes

Two methods for estimating the tolerance of common beau genotypes to Empoas ca kraemeri Ross & Moore were compared, using a yield trial carried out at Centro Internacional de Agricultura Tropical (CIAT), Call, Colombia versus stylet penetration tactics measured by AC electronic feeding monitors. A st ylet penetration index was devised based on principal component scores of t hree penetration tactics identified (pulsing laceration, cell rupturing and lancing sap ingestion), combined with knowledge of the hopperburn symptoms caused by each tactic. Tolerant genotypes, as classified by the CIAT yield index, showed significantly more unprotected yield and lower hopperburn sc ores than the susceptible control. They also induced performance of less pu lsing laceration (the tactic considered most damaging to the plant), lund m ore of the other two, mitigating tactics, especially cell rupturing. When i ndex: values were calculated for each genotype, stylet penetration index va lues matched those of the yield index for three out of five genotypes: two EMP-coded tolerant lines ('EMP 385' and 'EMP 392') and die susceptible cont rol 'BAT 41'. Thus, for these three genotypes, all subsequent hopperburn sy mptoms are predictable by the type of feeding behavior performed on them. ' Porrillo Sintetico' and 'EMP 84', considered borderline genotypes by the yi eld index, were overestimated and underestimated, respectively, by the styl et penetration index. We postulate that, for these two genotypes, plant phy siological responses to feeding (either compensatory or heightened sensitiv ity respectively) synergize with type of feeding performed to generate the overall hopperburn condition. This multivariate analysis of electronic moni toring data was Successfully used to devise an index of resistance. The imp lications of using the stylet penetration index and the advantages of using electronic monitoring in a bean-breeding program are discussed.