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

Abstract

Cowpea, Vigna unguiculata (L.) Walp., is susceptible to a wide spectrum of insect pests from seedling to harvest as well as in storage. Insecticide use has been the most commonly adopted method for the control of cowpea pests. However, due to the deleterious effects of insecticides on man, livestock and the environment, research over the years has been focused mainly on developing resistant/tolerant cultivars as a vital component in the integrated management of cowpea pests. This approach has, however, recorded varying degrees of success, due in part to the multiple and often overlapping pest complex attacking at different phenological growth stages of the crop.In spite of the progress in the utilisation of insect-resistant cowpea varieties, the use of resistance as a control tactic has by no means been fully realised. There are many important cowpea insect pests for which resistant varieties are not yet available for commercial cultivation. Where resistant varieties are available for a given insect, these varieties may not be widely planted because of their unsuitability to local conditions. In this paper, the status of host plant resistance research in cowpea is reviewed and some novel approaches aimed at solving its seemingly intractable pest problem are proposed, based on the state-of-the-art scientific and crop biotechnological development. The proposed framework for orientation of cowpea resistance research should ensure yield stability and sustainability for the resource-poor, smallscale farmers in Africa.Resume-Le niebe Vigna unguiculata L. (Walp.), est susceptible a une large gamine d'insectes ravageurs qui l'attaquent depuis le semis jusqu'a la recolte aussi bien qu'en emmagasinage. L'utilisation d'insecticides a ete la methode de lutte la plus utilisee contre les ravageurs du niebe. Toutefois, suite a des effets nefastes des insecticides sur l'homme, le betail et l'environnement, la recherche a ete, depuis des annees, principalement centree sur la selection de varietes tolerantes/resistantes comme composante essentielle dans la lutte integree contre les ravageurs du niebe. Cette approche a toutefois connus des degres de succes varies, suite en partie au caractere multiple et souvent imbrique du complexe des ravageurs qui attaquent la plante aux differents stades phenologiques de sa croissance.Malgre le proges de l'utilisation des varietes de niebe resistantes aux insectes, l'usage de la resistance comme tactique de lutte n'a pas du tout ete pleinement realise. II y a beaucoup d'insectes qui sont d'important ravageurs du niebe pour lesquels les varietes resistantes ne sont pas encore disponibles pour la culture commerciale. La ou des varietes resistantes sont disponibles pour un insecte donne, elles peuvent ne pas etre plantees a grande echelle a cause de leur inaptitude a s'accommoder aux conditions locales. Dans cet article, l'etat de la S. OGHIAKHE recherche sur la resistance de la plante hdte est revue et quelques nouvelles approches visant a resoudre le probleme apparemment insoluble du ravageur so...