Some Cultural Strategies For Management Of Bean Stem Maggots (Diptera: Agromyzidae) On Beans In Tanzania

We compared cultural practices commonly used in bean (Phaseolus vulgaris L.) and other vegetable cropping systems to assess the effect of individual as well as combinations of practices on bean stem maggot (BSM) (Ophiomyia spp. Diptera: Agromyzidae) infestation and subsequent damage to bean plants. The cultural practices used included mulching, application of fertilizer and chemical seed dressing. Chemical seed dressing reduced pest incidence during early growth stages and enhanced plant survival. Mulches and application of fertilizer did not reduce pest infestation but enhanced plant tolerance to the pest; it also reduced subsequent plant mortality compared to the control. Combinations of these practices were even more effective in reducing BSM induced plant mortality and increasing crop yield. Their efficiencies varied with location.Des pratiques culturarles commun\ue9ment utilis\ue9es dans les syst\ue8mes de culture du haricot (Phaseolus vulgaris L.) et d'autres v\ue9g\ue9taux ont \ue9t\ue9 compar\ue9es pour \ue9valuer l'effet des pratiques individuelles ou combin\ue9es sur l'infestation de la mouche du haricot (Ophiomyia spp. Diptera: Agromyzidae) et les d\ue9g\ue2ts caus\ue9s aux plants du haricot. Les pratiques culturales utilis\ue9es comprenaient le paillage, l'application des engrais et le traitement des semences. Comme attendu, le traitement des semences avec les produits chimiques a r\ue9duit l'incidence de la mouche au d\ue9but des stades de croissance et a augment\ue9 la survie des plants. Les paillages et l'application des engrais n'ont pas r\ue9duit l'infestatuion de la peste mais ils ont, au contraire, augment\ue9 la tol\ue9rance \ue0 la mouche et r\ue9duit la mortalit\ue9 des plants par rapport au contr\uf4le. Les combinaisons de ces pratiques \ue9taient encore plus efficaces en r\ue9duisant la mortalit\ue9 des plants induite par la mouche du haricot et en augmentant le rendement en graines. Cependant, leur efficacit\ue9 variait avec le milieu

Factors Influencing the Incidence of the Black Bean Aphid, Aphis fabae Scop., on Common beans intercropped with maize

The incidence of the black bean aphid, Aphis fabae scop. (Homoptera: Aphididae), and its colonization of common beans (phaseolus vulgaris L.) grown as sole crop and as intercrops with maize ( Zea mays L.) of varying growth stages was evaluated in the field and glasshouse. Modification of bean micro-climate and its effects on A. fabae, and the species range and abundance of coccinellid predators (Coleoptera: Coccinellidae) of the aphid were also assessed. Results showed that A. fabae infestation of beans was greatly reduced when intercropped with older and taller maize plants. Larger maize plants interfered with aphid colonization of beans and only small proportions of beans were infested by the aphid. Shading by older maize plants significantly (P 64 0.01) reduced the level of solar radiation reaching intercropped beans; this reduced the build-up of A. fabae populations. Intercropping also reduced the number and diversity of coccinellid predators on beans, contrary to the prediction based on the "enemies hypothesis". Reduced aphid incidence on intercrop beans was attributed to maize interference with aphid host finding behavior and bean colonization and, to a lesser extent, to reduced build-up of A. fabae populations due to shading

Factors Influencing the Incidence of the Black Bean Aphid, Aphis fabae Scop., on Common beans intercropped with maize

The incidence of the black bean aphid, Aphis fabae scop. (Homoptera: Aphididae), and its colonization of common beans (phaseolus vulgaris L.) grown as sole crop and as intercrops with maize ( Zea mays L.) of varying growth stages was evaluated in the field and glasshouse. Modification of bean micro-climate and its effects on A. fabae, and the species range and abundance of coccinellid predators (Coleoptera: Coccinellidae) of the aphid were also assessed. Results showed that A. fabae infestation of beans was greatly reduced when intercropped with older and taller maize plants. Larger maize plants interfered with aphid colonization of beans and only small proportions of beans were infested by the aphid. Shading by older maize plants significantly (P≤ 0.01) reduced the level of solar radiation reaching intercropped beans; this reduced the build-up of A. fabae populations. Intercropping also reduced the number and diversity of coccinellid predators on beans, contrary to the prediction based on the "enemies hypothesis". Reduced aphid incidence on intercrop beans was attributed to maize interference with aphid host finding behavior and bean colonization and, to a lesser extent, to reduced build-up of A. fabae populations due to shading