Advances in screening methods and breeding for resistance to downy mildew and stem borers in maize

Maize is the most important cereal in sub-Saharan Africa. It is relatively inexpensive and provides many families with much-needed nutrients. For the farmers, it matures early and Is a source of ready income. Maize production Is being threatened by some diseases and pests, among which are downy mildew and stem borers. Serious yield losses often occur. This paper summarizes two studies that report the efforts of liT A scientists to screen and breed maize varieties for resistance to downy mildew and stem borers

Bionomics of Mussidia nigrivenella (Lepidoptera: Pyralidae) on three host plants

Life table studies of Mussidia nigrivenella Ragonot, a pest of maize in Benin, showed that host plant species had a significant effect on larval survival and developmental time. The maximum percentage of larvae surviving was recorded on jackbean, Canavalia ensiformis (36%) and lowest on maize (18%). Mean developmental time for larvae was longest on maize (19.8 days) and shortest on jackbean (17.2 days). The number of eggs laid was highest for females from larvae fed on jackbean (x̄ = 176), followed by velvetbean, Mucuna pruriens (x̄ = 143), and lowest for females where larvae had fed on maize (x̄ = 127). Longevity of ovipositing females was higher on jackbean (5.4 days) than of those from any other host plants. According to the growth index and life table statistics, jackbean was the most suitable host plant, followed by velvetbean, and maize, the least suitable. Thus, jackbeans should be recommended for use in mass rearing programmes of M. nigrivenella, e.g. as a host for parasitoids in future biological control programmes. Because of the high suitability of jack- and velvetbeans for M. nigrivenella, planting of these increasingly important cover crops should be timed in such a manner that the emergence of female moths from mature pods does not coincide with maize plants in a suitable developmental stage for oviposition and development of young M. nigrivenella larvae

Principaux insectes nuisibles du mais en Afrique; biologie et methodes de lutte: guide de recherche de lIita, No. 30

La production du mals, I'une des eerolalea lei plus cultivees dans Ie monde, est serieusement mena-cole par les insectes nuisibles. Lea pertea annuelles ae chiffrent en millions de dollars. Le. molthodes de lutte culturale, chimique et biologique viennent compltlter la rolsistance varietale. La protection ine, alloeiant cea ditTerentes methodes, respecte Ie milieu environ-nant. Seule une approche basee sur la connaissance des degats, de la biologie, de la repartition et du cycle olvolutif des insectes permet d'obtenir del rtllultate pro-bants

Major insects pests of maize in Africa: biology and control

Insect pests severely limit the production of maize, one of the most important cereal crops world-wide. Losses reach millions of dollars annually. Control includes cultural, chemical, and biological methods in addition to plant resistance. Integrated pest management combines control methods in an environ-mentally sound manner. Effective control requires knowledge on damage, biology, distribution, and life cycles of insects

Distribution and species composition of lepidopterous maize borers in southern Nigeria

The distribution and species composition of lepidopterous maize borers was studied in six locations in southern Nigeria during the second planting season (August-November) of 1985 and 1986. Sesamia calamistis Hampson (Noctuidae) and Eldana saccharina Walker (Pyralidae) were the stem borers most abundantly found in the locations sampled. S. calamistis was the dominant species up to eight weeks after planting in all locations. E. saccharina was the most abundant species from nine weeks after planting onwards, except at Umuahia where S. calamistis always comprised over 50% of the borer population. Mussidia nigrivenella Ragonot (Pyralidae) was found attacking maize ears in all locations, while Busseola fusca Fuller (Noctuidae) was found only at Idah and Alabata, and even there constituted only a small proportion of the population. Other borer species found were Coniesta (= Acigona) ignefusalis (Hampson) (Pyralidae) and Cryptophlebia species (Olethreutidae)

Insectes nuisibles du mais entrepose; biologie et methodes du lutte: Guide de recherche de lIita, No. 32

En Afrique, Ie mals entrepose subit souvent des dgRts et des pertes considerables. II importe des lors d'identifier les insectes des produits entreposes d'une region don nee alin de determiner leur impor-tance et de choisir, Ie cas echeant, les methodes de lutte appropriees. La comprehension des facteurs determi-nant !'infestation avant et apres la recolte, ainsi que la connaissance de la biologie des ravageurs sont indis-pensables pour maitriser les insectes du maiS entre-pose

Les cicadelles et le virus de la striure du mais (MSV): Guide de recherche de lIita, No. 38

Apres Ie groupe des pu ce rons , c'est Ie groupe des cicadelles qui cornporte Ie plus grand n ornbr e de vecteurs de virus. Les especes de Cicadulina se rencon• trent da ns les regions tropicales et chaudes du rnonde; elles sont, pour la plupart, d'origine africaine. Le virus de la Stl iure du rnals (MSY), t ra n s rnis par Cica• dulina, est une irnportante con t rainte il la production de rna ls en Afrique. II est facile de cornbattre la striure en pl antant des varietes resistantes il cette virose. L'ecolo • gie et I'epicierniologie du MSY sont etroiternent liees il la biologie et il la dyna rnique des populations de cica dulina