Sources of black aphid resistance in the cowpea

Abstract

For a variety of agronomic reasons, landraces have strategic importance for cowpea Vigna
 unguiculata (L.) Walp. genetic breeding programs. The aim of the current research was to identify black
 aphid, Aphis craccivora Koch resistance in cowpea landraces. Twenty-three landraces from different regions
 of the state of Ceará, Brazil, were compared to four literature-cited standards: BRS Guariba and TVu 408
 P2 (resistant); BR 17-Gurguéia and VITA 7 (susceptible). Experiments were conducted in a greenhouse
 located at Campus do Pici, Universidade Federal do Ceará, in Fortaleza, Ceará state, Brazil. A completely
 randomized block design was used, with six replicates, each composed of one plant in a 300 mL pot. Plants
 were individually infested with five six-day-old adult insects. Adults were subsequently evaluated two days
 after infestation and nymphs at four days. Six landraces were highly resistant (Um-named 1-DIP, Feijão de
 arrancada, Feijão moitinha, Feijão de moita, Cara preta and Roxim miúdo) to levels compatible to the BRS
 Guariba standard. Three other landraces (Feijão da Bahia, Cojó and Feijão da Consuelo Rocha) showed
 moderate resistance, similar to the TVu 408 P2 standard. In addition to the high genetic variability found in the
 landraces, antibiosis was the main resistance mechanism observed.

Resistance in advanced cowpea lines to Aphis craccivora Koch, 1854 (Hemiptera: Aphididae)

“…Those that exist generally use the VITA 7 cultivar, which is little-used agriculturally and which is highly susceptible to infestation BLEICHER, 2007;SILVA et al, 2018). On the other hand, many of the cowpea cultivars already on the market are susceptible to cowpea aphid BLEICHER, 2007;SILVA et al, 2012;BANDEIRA et al, 2015;MELVILLE et al, 2016;LOURENÇO et al, 2018;SILVA et al, 2018), This both decreases productivity and increases production costs for farmers using pest control products.…”