Cassava mosaic disease (CMD) is caused by whiteflyborne viruses of the genus Begomovirus (family Geminiviridae ). The disease has long been regarded as the most important of those affecting cassava in sub-Saharan Africa, and has been the subject of much research, especially since the onset of the current very damaging pandemic in eastern and central Africa. This review considers the main features of CMD and the various possible means of control. The main emphasis to date has been on the development and deployment of virus-resistant varieties. These are widely adopted in countries where CMD has caused serious problems, and provided a powerful incentive for farmers to abandon some of the most susceptible of their traditional varieties. Only limited use has been made of phytosanitation involving CMD-free planting material and the removal (roguing) of diseased plants. Cultural methods of control using varietal mixtures, intercrops or other cropping practices have also been neglected, and there is a need for much additional research before they can be deployed effectively. Nevertheless, the severe losses now being caused by CMD in many parts of sub-Saharan Africa could be greatly decreased through the application of existing knowledge.

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Flight mills are commonly used to assess the relative flight performance of migratory insects, but uncertainties about the rate of energy expenditure on the mill mean that absolute estimates of flight endurance are not usually attempted. In this paper we describe how we measured the power delivered to a lightweight flight mill by tethered Cicadulina storeyi China leafhoppers (Homoptera: Cicadellidae), and compared this to estimates of the power they use to maintain free flight. Our results showed that the leafhoppers were generating more than 0.90 μW of mechanical power when on the mill, and that they probably have 3–4 μW available for free flight. We conclude that whilst flying on the mill, the insects were generating at least 20–30% of the mechanical power needed for free flight, and that this percentage may have been significantly higher.