Evaluation of Bean (Lablab purpureas Linn.) Varieties/Entries against Aphid, Aphis craccivora Koch with their Relative Population of Coccinellid Beetles

摘要

The field experiment was conducted during kharif season to evaluate eight varieties/entries of bean (Lablab purpureus Linn.) for their relative susceptibility against bean aphid, Aphis craccivora Koch. None of the varieties/entries escaped the infestation of A. craccivora. The build-up of aphid infestation started from second week of August (30 DAS) and reached at its peak in the first to third week of September on different varieties/entries, then gradually declined. On the basis of grade index of mean population, the varieties, Pusa Sem-3 (67 aphids/5 plants) and Pusa Early Prolific (68.8 aphids/5 plants) were least susceptible (resistant) and Pusa Sem-2 (72.2 aphids/5 plants), EC-27598 (77.6 aphids/5 plants), 1C-10189 (81 aphids/5 plants) and Jobner local (88.8 aphids/5 plants) were categorized as moderately susceptible, whereas entries IC-6121 (97.50 aphids/5 plants) and EC-18544 (98.80 aphids/5 plants) were highly susceptible. The relative population of coccinellid beetle, Menochilus sexmaculatus Fabricius was also maximum in the month of September corresponding to aphid incidence on bean.