Anatomical and Biochemical Parameters of Resistance of the wild Cowpea, Vigna Vexillata benth (ACC. TVNU 72) to Maruca Testulalis Geyer (Lepidoptera: Pyralidae)

Assessment of chemical resistance of wild and cultivated Vigna species to the brown pod‐bug Clavigralla tomentosicollis Stal (Hem., Coreidae)

“…The presence of these secondary compounds on the pod wall of Vigna species has not been clearly established, in spite of numerous reports on the interference of different pod factors with Vigna resistance to insects (C hiang and J ackai , 1988; O ghiakhe et al., 1993; J ackai et al., 2001; K oona et al., 2001, 2002a,b). Based on the high insect mortality observed on the neutral fraction of whole pod extracts, it could be speculated that the same or similar compounds found in Vigna seeds are also present in the pod wall.…”

“…In support of this hypothesis is the pronounced deleterious effects of extracts from the two wild accessions TVnu 151 and TVnu 72 as compared with the activity of extracts from the two cultivated genotypes IT84S‐2246 and TVu 1890. Wild Vigna accessions are known for their high density of toxic glandular trichomes and high concentrations of allelochemics in their seeds, in comparison with the cultivated genotypes (C arnovale et al., 1991; O ghiakhe et al., 1993; C hang et al., 1994).…”

“…Feeding by neonates and adults of this pod‐bug on different Vigna species has proved to have considerable effects on insect growth, reproduction and dispersal (E gwuatu and T aylor , 1977; H ammond , 1983), the most deleterious effects being observed on wild species (IITA, 1987; J ackai and O ghiakhe , 1989). These wild Vigna species, in comparison with the cultivated ones, are known for high concentrations of both primary and secondary metabolites (G atehouse et al., 1979; C arnovale et al., 1991; O ghiakhe et al., 1993; M arconi et al., 1997). So far only the role of primary metabolites in the resistance of Vigna species to C. tomentosicollis and other pests has garnered most of the research attention (G atehouse and B oulter , 1983; U moren , 1995), contrasting with the paucity of data on the contribution of secondary compounds in this resistance.…”

Progress and future prospects in utilisation of host plant resistance in the control of insect pests of cowpea, Vigna unguiculata in Africa

“…A number of reports have indicated a higher level of allelochemicals in resistant than in susceptible cowpea cultivars, resulting in failures of survival, development or egg production (fecundity) in the target insect pests (Gatehouse et al, 1979;Otieno et al, 1985;Birch et al, 1986;Salifu, 1986;Lattanzio et al, 1990 andOghiakhe, 1990). However, Oghiakhe et al (1993b) suggested that the evolution of trichomes in the wild cowpea, V. vexillata (Ace. A recent report by Marconi et al (1990) showed a significantly higher tannin content in wild species of cowpea than in cultivated varieties.…”