Category of Resistance, Antixenosis, Antibiosis, and Tolerance to Acyrthosiphon pisum (H.) (Hemiptera: Aphididae) in Selected Lentil Genotypes ( Lens Culinaris M.)

The pea aphid (Acyrthosiphon pisum Harris) is an economically important insect pest of lentil in Ethiopia. The development of pea aphid resistant lentil genotypes with known resistance mechanism is an economical and effective way to manage this pest. Hence, the current study was conducted to determine the mechanisms (antibiosis, antixenosis, and tolerance) of resistance in six lentil (Lens culinaris Medikus.) genotypes to pea aphid. Three released varieties (Alemaya, Chalew, and R-186), three accessions (ILL-2595 and ILL-4422, and ILL-7664) and one susceptible accession were included in this study. A no-choice study was conducted to determine the categories of antibiosis and tolerance while free choice studies were conducted to determine antixenosis resistance mechanism. In the antibiosis test, there were significant differences in life table characteristics and demographic statistics among the resistant and susceptible lentil genotypes. ILL-7664 had high levels of an antibiotic effect than the others. Alemaya had high levels of tolerance to pea aphid. Choice studies indicated the presence of antixenosis resistance in the lentil genotype, Chalew, ILL-2595 and ILL-4422. The evaluated lentil genotypes exhibited different types of resistance mechanism and level of expression. Chalew showed a three mode of resistance, i.e., antibiosis, antixenosis, and tolerance. Further research should concentrate on levels of antibiosis, i.e., toxins and growth inhibitors to A. pisum.