Intercrops, Cicadulina spp., and maize streak virus disease
ABSTRACT Intercrops of bean and finger millet were tested as a possible means of controlling maize streak virus disease (MSVD) in maize by disrupting the mating behaviour of the insect vectors of the maize streak virus, Cicadulina mbila and C. storeyi. A series of three trials were done. In the first, MSVD incidence 2 months after sowing was reduced to 14.9% and 17.4% in millet and bean intercrops compared to 29.5% in the pure maize stand. The number of male Cicadulina spp. caught on sticky pole traps was also significantly reduced relative to the control, but there was little effect on the catch of females. There was no significant yield penalty for the millet intercrop but maize yield was 49% lower in the bean intercrop treatment than in the pure stand. In the second trial, there were two millet and two bean intercrop treatments and a maize only control. Fewer male Cicadulina spp. were caught in the intercrop treatments relative to the control but MSVD incidence was reduced in one millet intercrop treatment only for which the associated maize yield penalty was 89%. In the final trial the bean intercrop was again tested but it had no effect on MSVD incidence. These experiments demonstrated that intercropping maize with bean or millet decreased vector activity and/or vector numbers. Vector catches were predominantly male, and catches of males but not females were reduced in the intercrop treatments compared with pure stands. However the lower vector catch was not consistently associated with a significant reduction in MSVD incidence, and when it was there was often an associated yield penalty in the maize due to the intercrop.
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ABSTRACT: Maize streak virus (MSV), the causal agent of maize streak disease (MSD), is one of the most significant biological threats to food security in sub-Saharan Africa. By reducing yields of Africa’s most important food crop, it seriously undermines the already precarious social and economic wellbeing of subsistence farmers throughout the continent. Despite the availability of MSD control strategies—ranging from good farm management to the use of chemical insecticides, and the planting of MSD tolerant maize –MSD remains a problem. The main reason for this is the inherent unpredictability of MSD epidemics which makes it difficult for farmers to decide where and when to apply appropriate control strategies. Also, without better estimates of the economic impacts of the disease, there is unlikely to be any motivation for large scale efforts by scientists and national governments to refine and apply effective control measures. Besides reviewing the epidemiological factors that would need to be modeled to achieve predictive forecasting of epidemics, we approximate how much MSD costs national economies in sub-Saharan Africa and evaluate various possible approaches to minimizing the over-all economic impact of the disease. Keywords Cicadulina -Mastrevirus-Geminivirus-Genetic modification-Breeding-InsecticidesFood Security 1(3):305-315. · 2.07 Impact Factor
- Advances in Virus Research 02/2006; 67:245-95. · 2.84 Impact Factor
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ABSTRACT: Barrier plants are a management tool based on secondary plants used within or bordering a primary crop for the purpose of disease control. Aphid-transmitted viruses account for approximately 50% of the 600 known viruses with an invertebrate vector. Barrier plants may act as real natural sinks for non-persistent aphid-transmitted viruses and have proved in the past to be an effective crop management strategy to protect against virus infection. Increasing the knowledge on aphid host seeking and flying behaviour, and on how barrier plants may affect the behaviour of aphids and their natural enemies will allow further development of this environmentally-friendly habitat manipulation strategy. An ideal plant barrier should be a non-host for the virus and the vector, but appealing to aphid landing and attractive to their natural enemies and should allow sufficient residence time to allow aphid probing before taking-off occurs. In this review, we have addressed why aphids are manageable by barrier cropping, the mechanisms by which barrier plants affect the occurrence of non-persistently aphid-transmitted viruses and the limitations of using barrier plants as a virus control strategy. Finally, we have pointed out future directions of research that should be conducted to integrate barrier cropping with other disease management strategies, and optimise and extend the use of barrier plants as a strategy for managing aphid-transmitted virus diseases.Virus Research 10/2006; 120(1-2):1-16. · 2.75 Impact Factor