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

Abstract

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 F 1 , backcrosses and F 2 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 F 1 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) F 2 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.

Preferences and demographic parameters of cowpea aphid on advanced lines of semiprostrate cowpea

“…Thus, when cross-breeding used genotypes CE-315 and TE97-304G-12 as parents, susceptible offsprings were generated, as with 'BR 17-Gurguéia', which had CE-315 as a parent. According to Babura & Mustapha (2012), when crossing V. unguiculata using resistant and susceptible genotypes to A. craccivora in the F 1 , offsprings that are highly resistant to aphids will be obtained in the F 2 and subsequent backcrosses. This is because, in A. craccivora, resistance to cowpea aphid is linked to a dominant gene.…”

Demographic parameters of cowpea aphids on advanced semi-erect cowpea lines

“…'BRS Guariba', in which the cultivar would transfer the resistance gene to its progeny. According to Babura & Mustapha (2012), when crossbreeding of cowpea varieties susceptible to the cowpea aphid is carried out with resistant materials, it is possible to produce highly resistant progenies, implying that the transmission of the gene conferring cowpea resistance to A. craccivora is heritable. Silva et al (2012) evaluated the genetic diversity between cowpea genotypes with resistance to the cowpea aphid, and the best combinations among resistant genotypes, and confirmed that 'BRS Guariba' is favorable to genetic combinations and suitable for breeding programs as a source of resistance to the aphid.…”