Screening for Development of Host Plant Resistance to Infestation by Aphid (Aphis Craccivora Koch) in Cowpea (Vigna Unguiculata [L] Walp)

A study was carried out at International Institute of Tropical Agriculture (IITA) Kano station during 2009 and 2010 growing season, to screen fifty two (52) cowpea varieties for resistance to aphids (Aphis craccivora) attack. It was found that only seven (7) varieties were highly resistant, nine (9) were highly susceptible and the remaining thirty six (36) varieties were neither resistant nor susceptible (intermediate) to aphids attack. Five (5) varieties were selected from the two extremes for multiple crosses to raise F1 , backcrosses and F2 populations in which three (3) varieties including Danila, IT98K-131-2 and IT98K-1092-1 were among highly resistant and two (2) varieties including Aloka L and IT98K-1263 were among the highly susceptible varieties, Nine (9) progenies were obtained for F1 generation from which only five (5) were found to be resistant to aphids attacks while four (4) were susceptible, Out of the nine (9) backcross populations, six (6) progenies were found to be resistant while the remaining three (3) were susceptible. From the nine (9) F2 progeny obtained, six (6) were also found to be resistant while three (3) were susceptible. The investigation revealed that crossing susceptible with resistant varieties of cowpea yields progenies that are highly resistant. This is an indication that the gene for resistance is highly heritable.