Cowpea plant architecture in relation to infestation and damage by the legume pod borer, Maruca testulalis Geyer (Lepidoptera: Pyralidae) — 2. Effect of pod angle

Abstract

The effect of pod angle on the resistance of cowpea, Vigna unguiculata (L.) Walp. to the legume pod borer, Maruca testulalis Geyer, was investigated under field conditions at the International Institute of Tropical Agriculture (IITA), Ibadan, Nigeria, using two cowpea cultivars: IT82D-716 (susceptible to borer damage) and T Vu 946 (resistant to borer damage). Three different pod angles were used in the study -a normal angle, a decreased angle and an increased angle. Negative and highly significant (P < 0.01) relationships were found between pod angle and per cent pod damage, as well as the seed damage Index In the two cowpea cultivars. Pods with wide angles (5 89°) were damaged on only one and rarely on both pods. Apart from biochemical and other bio-physical factors, selection and breeding for wide pod angle is suggested as a strategy for reducing M. testulalis damage to cowpea pods. Resuml-L'effet de Tangle des gousses sur la resistance du niebe, Vigna unguiculata a la foreuse des gousses, Maruca testulalis a ete Itudie en champ a 1'institut international d'agriculture tropicale (IITA), Ibadan (Nigeria) sur deux cultivars de niebl: IT82D-716 (sensible) et TVu 946 (resistant). Trois angles differents des gousses ont ete Studies: angle ferml, angle normal et angle ouvert.Des relations negatives hautetnent significatives (P < 0.01) furent observers entre Tangle des gousses, le pourcentage de degats sur les gousses et l'indice de degats sur les graines chez les deux cultivars. Dans Tensemble, pour les gousses a angle ouvert (>89°), M. testulalis a occasionne des d£gats sur une seule gousse par plant.La selection et 1'amelioratibn du niebe pour l'obtention de gousses a angle ouvert ont itt sugge>ees comme moyen de reduire les degats de M. testulalis sur les gousses de niebe.

Bionomics, host plant resistance, and management of the legume pod borer, Maruca vitrata — a review

“…Cowpea genotypes with bunched pods suffer greater damage (Usua and Singh, 1979). Oghiakhe et al (1992b) observed negative relationships between pod angle and pod damage, and seed damage index in two cowpea cultivars. Pods with wide angles ( > 89") were damaged on one side, and rarely on both sides.…”

To duck or not to duck: resistance advantages and disadvantages of the candy‐cane stem phenotype in tall goldenrod, Solidago altissima

“…The past few decades have also seen the identification of a staggering number of secondary plant chemicals that function in resistance to herbivory (Fraenkel, 1959; Norris & Kogan, 1980; Hartmann, 1996; Harborne, 1997; Pichersky & Gang, 2000). More recently, researchers have begun to appreciate that aspects of a plant's growth form may also influence the likelihood of herbivore attack (Oghiakhe et al ., 1992; Alonso & Herrera, 1996; Araújo et al ., 2006; Chang et al ., 2006; Rudgers & Whitney, 2006). Although architectural traits have obvious importance for plant growth, some may turn out to function mainly as adaptations to resist herbivory (Marquis et al ., 2002; Grubb & Jackson, 2007).…”

DUCKING AS A MEANS OF RESISTANCE TO HERBIVORY IN TALL GOLDENROD, SOLIDAGO ALTISSIMA

“…While chemical toxins and mechanical deterrents dominate the arsenal of known or suspected herbivore defenses in plants, architectural features of plants may also serve important roles in plant resistance (Lawton 1983, Kareiva and Sahakian 1990, Alonso and Herrera 1996, Espı´rito-Santo et al 2007. Investigators have identified a variety of architectural characteristics that can affect resistance to herbivory, including number of buds, branches, or flowers (Oghiakhe et al 1993, Arau´jo et al 2006), size of internodes (Larson and Whitham 1997), spacing of leaves (Marquis et al 2002), rolling of young leaves (Grubb and Jackson 2007), pod angle (Oghiakhe et al 1992), growth habit (e.g., erect, prostrate, or spreading [Oghiakhe et al 1993, Rudgers andWhitney 2006]), and architectural complexity in general (Kaitaniemi et al 2004). Perhaps the most basic feature of plant architecture, however, is size.…”