[01] Ekeruo Godspower Chibuike, Department of Plant Breeding and Seed Science, College of Agronomy, Federal University of Agriculture Makurdi, Makurdi, Nigeria; Molecular Biology Laboratory, Federal University of Agriculture Makurdi, Makurdi, Nigeria; Molecular Biology Laboratory, Federal University of Agriculture Makurdi, Makurdi, Nigeria. [02] Lucky Omoigui, Department of Plant Breeding and Seed Science, College of Agronomy, Federal University of Agriculture Makurdi, Makurdi, Nigeria; International Institute for Tropical Agriculture (IITA), Kano Station, Kano, Nigeria; Molecular Biology Laboratory, Federal University of Agriculture Makurdi, Makurdi, Nigeria. [03] Lateef Lekan Bello, Department of Plant Breeding and Seed Science, College of Agronomy, Federal University of Agriculture Makurdi, Makurdi, Nigeria; Molecular Biology Laboratory, Federal University of Agriculture Makurdi, Makurdi, Nigeria. [04] Macsamuel Ugbaa, Department of Plant Breeding and Seed Science, College of Agronomy, Federal University of Agriculture Makurdi, Makurdi, Nigeria, Molecular Biology Laboratory, Federal University of Agriculture Makurdi, Makurdi, Nigeria. [05] Iyorkaa Nater, Department of Plant Breeding and Seed Science, College of Agronomy, Federal University of Agriculture Makurdi, Makurdi, Nigeria; Molecular Biology Laboratory, Federal University of Agriculture Makurdi, Makurdi, Nigeria.

Cowpea cultivation is constrained by a variety of biotic and abiotic stresses among which insect pests constitute a serious setback. A major pest constraining cowpea production in the drier region of the tropics is the cowpea aphids (Aphis craccivora). Apart from aphids transmitting viruses while feeding, heavy colonization causes rapid wilting and eventual plant death. Among the several strategies employed for its control (chemical, cultural and biological control measures) on cowpea the use of resistant varieties helps to control the insects’ population and thus regarded to be more viable and economical for resource poor farmers. This study was designed to identify cowpea genotypes with good source of genetic resistance and elucidate the inheritance pattern of aphid resistance in cowpea. Sixty cowpea genotypes were screened at the Federal University of Agriculture Makurdi, Benue State, Nigeria for resistance to cowpea Aphids using insect cages that only allows air passage but not the insect. Two cowpea genotypes (TVu-2876 and Aloka Local) contrasting clearly with reactions to the cowpea aphid identified in this study as resistant and susceptible respectively were selected for hybridization. Hybridization was carried out in the screen house of the Molecular Biology Laboratory by hand emasculation. The F₂ population obtained from the cross between TVu-2876 and Aloka Local was used for inheritance studies for aphid resistance under artificial infestation with aphids in insect proof cages. Out of the 227 F₂ plants evaluated, 168 showed resistant to cowpea aphid, while 59 plants were identified as susceptible. The Chi-square (χ²) analysis for goodness-of-fit revealed a segregation pattern that fits the 3:1 genetic ratio, thus indicating that a single dominant gene confers resistance to cowpea aphids in TVu-2876. In the same order, the backcross segregating population involving the F_I plants and susceptible parent segregated into 1:1 ratio confirming the single gene inheritance model. This information will be helpful in breeding elite cowpea lines with genetic resistance to aphids in cowpea.

Cowpea, Aphids, Resistance, Inheritance, Gene Action, Segregation

[01] FAO, (2017). Food and Agricultural Organization of the United Nations statistical database. www.fao.org Accessed 5^th June, 2019. [02] Singh, B. B. (2007). Potential and constraints of improved cowpea varieties in increasing the productivity of cowpea-cereal systems in the dry Savannas of West Africa. Pages 14-26 in Majiwa, P., Odera, M., Muchiri, N., Omanya, G. and Werehire, P. (eds). A plan to apply technology in the improvement of cowpea productivity and utilisation for the benefit of farmers and consumers in Africa: Proceedings of cowpea stakeholder’s workshop. Nairobi Kenya: African Agricultural Technology Foundation. [03] Awe, O. A. (2008). Preliminary evaluation of three Asian yards long bean cowpea lines in Ibadan, Southern western Nigeria. In: Proceedings of the 42^nd Annual Conference of ASN held at Ebonyi State University, Abakaliki, Nigeria between 19^th and 23^rd of October, 2008. Pp. 246 – 249. [04] Kay, D. E. (1979). Food legumes. Tropical Development and Research Institute, London. [05] Steele, W. M. and Mehra K. L. (1980). Structure, evolution and adaptation to farming systems and environments in Vigna. In: Summerfield, R. J., Bunting, A. H. (eds.). Advances in Legume Science. Royal Botanic Gardens, Kew, UK, Pp. 393–404. [06] Ricardo, B. (1985). Nutritive value of cowpea. Pages 353-359 ln Cowpea research production and utilization, edited by Singh, S. R. and Rachie K. O John Wiley and Sons Chichester, UK. [07] Brader, L. (2002). Foreword. Page vi, In: Challenges and opportunities for enhancing sustainable cowpea production, edited by Fatokun, C. A., Tarawali, S. A., Singh, B. B., Kormawa, P. M. and Tamo’, M. IITA, Ibadan, Nigeria. [08] Fashakin, J. B. and Ojo, F. A. (1988). Chemical composition and nutritive changes of some improved varieties of cowpea (Vigna unguiculata (L.) Walp) 2: new breeds of varieties from the IITA Ibadan, Nigeria. Tropical Science. 28: 191-199. [09] Fashakin, J. B. and Fasanya, J. I. (1988). Chemical composition and nutritive changes of some improved varieties of cowpea (Vigna unguiculata (L.) Walp): some selected varieties from IITA, Ibadan, Nigeria. Tropical Science. 28: 111–118. [10] Asumugha, V. U. (2002). Sensory and functional properties of dry vegetable cowpea product (Akara). In: Ubbanu, C. N., Eke, O. S. and Uzomah, A. (eds.). Proceedings of the 26^th Annual Conference of the Nigerian Institute of Food Science and Technology (NIFST) held at the Federal University of Technology, Owerri, Imo State between 4^th and 8^th of November, 2002. Pp. 66–67. [11] Islam, S., Cowmen, R. C., and Ganer, J. O. (2006). Screening for tolerance of stress temperature during germination of twenty-five cowpea (Vigna unguiculata (L.) Walp) cultivars. Journal of Food, Agriculture and Environment. 4(2): 189-191. [12] Duke, J. A. (1981). Vigna uniguiculata (L.) Walp spp. unguiculata. In:Okeson, O. N. (ed.). Legumes of world importance. Plenum Press, New York. Pp. 303–305. [13] Bittenbender, H. C., Barret, R. P. and Indire-Lauvsa, B. M. (1984). Beans and cowpeas as leaf vegetables and grains legumes. Monograph No. 1 Bean/Cowpea Collaborative Research Support Programme. Michigan State University, East Lansing. [14] Tarawali, S. A. Singh, B. B., Peters, M. and Blade, S. F. (1997). Cowpea haulms as fodder Pages 313-325 in Advances in cowpea research, edited by Singh, B. B. Mohan Raj. D. R., Dashiel, K. E. and Jackai L. E. N. Co-publication of international institute of Tropical Agriculture (IITA) and Japan International Research Centre for Agricultural Sciences (JIRCAS). IITA, Ibadan, Nigeria. [15] Langyintuo, A. S., Lowenberg-Deboer, J., Faye, M., G., Mloussa, B., Kergna, A., Kushwaha, S. and Ntoukam, G. (2003). Cowpea supply and demand in West and Central Africa. Field Crops Research. 82 (2): 215-231. [16] Fatokun, C. A. (2002). Breeding Cowpea for Resistance to Insect Pests: Attempted Crosses between Cowpea and Vigna vexillata. Challenges and Opportunities for Enhancing Sustainable Cowpea Production. International Institute of Tropical Agriculture (IITA), Ibadan, Nigeria. 52-61. [17] Singh, S. R., Jakai, L. E. N., Dos Santos, J. H. R. and Adalla, C. B. (1990). Insect pests of cowpea. Insect pest of tropical food legumes, John wiley and sons, Chichester, UK. Pages 43-89. In: Singh, S. R. (ed). [18] Gunilla, E. (1985). Studies on Aphis craccivora (Koch); Preference Test Using Different Cowpea Extracts and Rearing Experiments on Artificial Diets. http://www.vaxteko.nu/html/sll/slu/ex_arb_vaxt_skogsskydd/EVS86-08/EVS86-08.HTM [19] Schreiner, I. (2000): Cowpea Aphids (Aphids craccivora Koch). Agricultural pests of the pacific, ADAP (Agricultural Development in the African Pacific). [20] Singh, B. B., Chambalis, O. L. and Sharma, B. (1996). Recent advance in cowpea breeding. In: Advance in cowpea research, IITA Ibadan. Pp 182-189. [21] Annan, I. B., Schafers, G. A., and Tingey, W. M. (1996). Impact of Density of Aphids craccivora (Aphididae) on Growth and Yield of Susceptible and Resistant cowpea Cultivars. Annals of Applied Biology, 128: 183-193. [22] Kitch, L. W., Battenberg, H., and Wolfson, J. L. (1999). Indigenous Knowledge and Cowpea Pest Management in Sub-Saharan Africa: Entomology Department, Purdus University, West Lafayette, IN 47007, USA. [23] Cardinali, A., Linsalata, V., Perriono, P., Lattanzio, V., Brouillard, R., Jay, M. and Scalbert, A. (1995). Chemotaxonomy of wild Vigna Species as Potential Sources of Resistance to Insects. Polyphenols 94: 17th International Conference, Palma de Mallorca, Spain. Pp 375–376. [24] Dogimont, C., Bendahmane, A., Chovelon, V., Boissot, N. (2010). Host Plant Resistance to Aphids in Cultivated Crops: Genetic and Molecular Bases, and Interactions with Aphid Populations. Comptes Rendus Biologies Journal, Elsevier, 333:566-573. [25] Dedryver, C. A., Le Ralec, A., Frederic, F. (2010). The Conflicting Relationships between Aphids and Men: A Review of Aphid Damages and of their Control Strategies. Comptes Rendus Biologies Journal, Elsevier, 333:539–553. [26] Charassri, N., Somsak, P., Jitra, J., Dušan, M., Wuttiwong, K., Benchasri, S. and Maneelert, V. (2012): Evaluation and Utilization of Cowpea (Vigna unguiculata (L.) Walp.) Germplasm for Varietal Improvement of Resistance to Cowpea Aphid (Aphis craccivora Koch.) in Thailand. [27] Souleymane, A. 1., Aken’Ova1, M. E., Fatokun C. A. and Alabi O. Y. (2013). Screening for Resistance to Cowpea Aphid (Aphis craccivora Koch) in Wild and Cultivated Cowpea (Vigna unguiculata L. Walp.) Accessions. International Institute for Tropical Agriculture, Ibadan. [28] Benchasri, S., Chunya, B. and Charassri, N. (2011). Investigation of Cowpea and Yardlong Bean for Resistance to Bean Aphids (Aphis craccivora Koch). 2nd International Conference on Agricultural and Animal Science. [29] Gerald, O, M. (1996). Hand Crossing of Cowpeas. IITA Research Guide 42. [30] Somsak, P. (2012). Inheritance of Resistance to Cowpea Aphid (Aphis craccivora Koch.) in Yardlong Bean and Cowpea by Microsatellite Maekers. Masters Thesis. Prince of Songkla Universisty. Pp. 44. [31] Babura, S. R. and Mustapha, Y. (2012). Screening for Development of Host Plant Resistance to Infestation by Aphid (Aphis Craccivora Koch) in Cowpea (Vigna unguiculata [L] WALP). Bayero Journal of Pure and Applied Sciences, 5 (1): 44–47. [32] Aliyu, H., Ishiyaku, M. F. (2013). Identification of Novel Resistance Gene Sources to Cowpea Aphids (Aphid craccivara Koch) in Cowpea (Vigna unguiculata L.) at Zaria. Pakistan Journal of Biological Sciences. 16 (15): 743-746. [33] Chang-chao, S., Hu-Qu, Z., Chun-Ming, W., Li-Hong, S. and Jian-Min, W. (2006). SSR Mapping of Brown Plant Hopper Resistance Gene Bph9 in Kaharamana, an India Rice (Oryza sativa L,). Acata Genetica Sinica. 33:262-268. [34] Bata, H. D., Singh, B. B., Singh, S. R. and Ladeinde, T. A. O. (1987). Inheritance of resistance to Aphid in Cowpea. Crop Science Journal, 27:89 –894. [35] Pathak, R. S. (1988). Genetics of Resistance to Aphid in Cowpea. Crop Science Journal, 28:474–476. [36] Ombakho, G. A., Tyagi, A. P. and Pathak, R. S. (1987). Inheritance of Resistance to the Cowpea Aphid in Cowpea. Theory of Applied Genetics. 74: 817-819.